Merge branch 'master' into recursive-elseif

Conflicts:

	src/Makefile
	src/comp/front/ast.rs
	src/comp/front/parser.rs
	src/comp/middle/fold.rs
	src/comp/middle/trans.rs

19 files changed, 7105 insertions, 1864 deletions

diff --git a/src/comp/back/abi.rs b/src/comp/back/abi.rs
index db17b942874..dd058590ae2 100644
--- a/src/comp/back/abi.rs
+++ b/src/comp/back/abi.rs
@@ -44,7 +44,8 @@ const int obj_field_vtbl = 0;
 const int obj_field_box = 1;
 
 const int obj_body_elt_tydesc = 0;
-const int obj_body_elt_fields = 1;
+const int obj_body_elt_typarams = 1;
+const int obj_body_elt_fields = 2;
 
 const int fn_field_code = 0;
 const int fn_field_box = 1;
@@ -59,6 +60,9 @@ const int worst_case_glue_call_args = 7;
 
 const int n_upcall_glues = 7;
 
+const int abi_x86_rustboot_cdecl = 1;
+const int abi_x86_rustc_fastcall = 2;
+
 fn memcpy_glue_name() -> str {
     ret "rust_memcpy_glue";
 }
@@ -67,6 +71,10 @@ fn bzero_glue_name() -> str {
     ret "rust_bzero_glue";
 }
 
+fn vec_append_glue_name() -> str {
+    ret "rust_vec_append_glue";
+}
+
 fn upcall_glue_name(int n) -> str {
     ret "rust_upcall_" + util.common.istr(n);
 }
diff --git a/src/comp/back/x86.rs b/src/comp/back/x86.rs
index ac52fca5baf..10227df7ca5 100644
--- a/src/comp/back/x86.rs
+++ b/src/comp/back/x86.rs
@@ -41,20 +41,117 @@ fn store_esp_to_runtime_sp() -> vec[str] {
     ret vec("movl  %esp, " + wstr(abi.task_field_runtime_sp) + "(%ecx)");
 }
 
+/*
+ * This is a bit of glue-code. It should be emitted once per
+ * compilation unit.
+ *
+ *   - save regs on C stack
+ *   - align sp on a 16-byte boundary
+ *   - save sp to task.runtime_sp (runtime_sp is thus always aligned)
+ *   - load saved task sp (switch stack)
+ *   - restore saved task regs
+ *   - return to saved task pc
+ *
+ * Our incoming stack looks like this:
+ *
+ *   *esp+4        = [arg1   ] = task ptr
+ *   *esp          = [retpc  ]
+ */
+
 fn rust_activate_glue() -> vec[str] {
     ret vec("movl  4(%esp), %ecx    # ecx = rust_task")
         + save_callee_saves()
         + store_esp_to_runtime_sp()
         + load_esp_from_rust_sp()
 
-        // This 'add' instruction is a bit surprising.
-        // See lengthy comment in boot/be/x86.ml activate_glue.
+        /*
+         * There are two paths we can arrive at this code from:
+         *
+         *
+         *   1. We are activating a task for the first time. When we switch
+         *      into the task stack and 'ret' to its first instruction, we'll
+         *      start doing whatever the first instruction says. Probably
+         *      saving registers and starting to establish a frame. Harmless
+         *      stuff, doesn't look at task->rust_sp again except when it
+         *      clobbers it during a later upcall.
+         *
+         *
+         *   2. We are resuming a task that was descheduled by the yield glue
+         *      below.  When we switch into the task stack and 'ret', we'll be
+         *      ret'ing to a very particular instruction:
+         *
+         *              "esp <- task->rust_sp"
+         *
+         *      this is the first instruction we 'ret' to after this glue,
+         *      because it is the first instruction following *any* upcall,
+         *      and the task we are activating was descheduled mid-upcall.
+         *
+         *      Unfortunately for us, we have already restored esp from
+         *      task->rust_sp and are about to eat the 5 words off the top of
+         *      it.
+         *
+         *
+         *      | ...    | <-- where esp will be once we restore + ret, below,
+         *      | retpc  |     and where we'd *like* task->rust_sp to wind up.
+         *      | ebp    |
+         *      | edi    |
+         *      | esi    |
+         *      | ebx    | <-- current task->rust_sp == current esp
+         *
+         *
+         *      This is a problem. If we return to "esp <- task->rust_sp" it
+         *      will push esp back down by 5 words. This manifests as a rust
+         *      stack that grows by 5 words on each yield/reactivate. Not
+         *      good.
+         *
+         *      So what we do here is just adjust task->rust_sp up 5 words as
+         *      well, to mirror the movement in esp we're about to
+         *      perform. That way the "esp <- task->rust_sp" we 'ret' to below
+         *      will be a no-op. Esp won't move, and the task's stack won't
+         *      grow.
+         */
         + vec("addl  $20, " + wstr(abi.task_field_rust_sp) + "(%ecx)")
 
+
+        /*
+         * In most cases, the function we're returning to (activating)
+         * will have saved any caller-saves before it yielded via upcalling,
+         * so no work to do here. With one exception: when we're initially
+         * activating, the task needs to be in the fastcall 2nd parameter
+         * expected by the rust main function. That's edx.
+         */
+        + vec("mov  %ecx, %edx")
+
         + restore_callee_saves()
         + vec("ret");
 }
 
+/* More glue code, this time the 'bottom half' of yielding.
+ *
+ * We arrived here because an upcall decided to deschedule the
+ * running task. So the upcall's return address got patched to the
+ * first instruction of this glue code.
+ *
+ * When the upcall does 'ret' it will come here, and its esp will be
+ * pointing to the last argument pushed on the C stack before making
+ * the upcall: the 0th argument to the upcall, which is always the
+ * task ptr performing the upcall. That's where we take over.
+ *
+ * Our goal is to complete the descheduling
+ *
+ *   - Switch over to the task stack temporarily.
+ *
+ *   - Save the task's callee-saves onto the task stack.
+ *     (the task is now 'descheduled', safe to set aside)
+ *
+ *   - Switch *back* to the C stack.
+ *
+ *   - Restore the C-stack callee-saves.
+ *
+ *   - Return to the caller on the C stack that activated the task.
+ *
+ */
+
 fn rust_yield_glue() -> vec[str] {
     ret vec("movl  0(%esp), %ecx    # ecx = rust_task")
         + load_esp_from_rust_sp()
diff --git a/src/comp/driver/rustc.rs b/src/comp/driver/rustc.rs
index 004c9d4c17d..7ad0cdc74fd 100644
--- a/src/comp/driver/rustc.rs
+++ b/src/comp/driver/rustc.rs
@@ -2,6 +2,7 @@
 
 import front.parser;
 import front.token;
+import front.eval;
 import middle.trans;
 import middle.resolve;
 import middle.typeck;
@@ -13,6 +14,30 @@ import std.option.none;
 import std._str;
 import std._vec;
 
+fn default_environment(session.session sess,
+                       str argv0,
+                       str input) -> eval.env {
+
+    auto libc = "libc.so";
+    alt (sess.get_targ_cfg().os) {
+        case (session.os_win32) { libc = "msvcrt.dll"; }
+        case (session.os_macos) { libc = "libc.dylib"; }
+        case (session.os_linux) { libc = "libc.so.6"; }
+    }
+
+    ret
+        vec(
+            // Target bindings.
+            tup("target_os", eval.val_str(std.os.target_os())),
+            tup("target_arch", eval.val_str("x86")),
+            tup("target_libc", eval.val_str(libc)),
+
+            // Build bindings.
+            tup("build_compiler", eval.val_str(argv0)),
+            tup("build_input", eval.val_str(input))
+            );
+}
+
 impure fn parse_input(session.session sess,
                       parser.parser p,
                       str input) -> @front.ast.crate {
@@ -25,20 +50,30 @@ impure fn parse_input(session.session sess,
     fail;
 }
 
-impure fn compile_input(session.session sess, str input, str output,
+impure fn compile_input(session.session sess,
+                        eval.env env,
+                        str input, str output,
                         bool shared) {
-    auto p = parser.new_parser(sess, 0, input);
+    auto p = parser.new_parser(sess, env, 0, input);
     auto crate = parse_input(sess, p, input);
     crate = resolve.resolve_crate(sess, crate);
     crate = typeck.check_crate(sess, crate);
     trans.trans_crate(sess, crate, output, shared);
 }
 
+impure fn pretty_print_input(session.session sess,
+                             eval.env env,
+                             str input) {
+    auto p = front.parser.new_parser(sess, env, 0, input);
+    auto crate = front.parser.parse_crate_from_source_file(p);
+    pretty.pprust.print_ast(crate.node.module);
+}
+
 fn warn_wrong_compiler() {
     log "This is the rust 'self-hosted' compiler.";
     log "The one written in rust.";
     log "It is currently incomplete.";
-    log "You may want rustboot insteaad, the compiler next door.";
+    log "You may want rustboot instead, the compiler next door.";
 }
 
 fn usage(session.session sess, str argv0) {
@@ -48,6 +83,7 @@ fn usage(session.session sess, str argv0) {
     log "    -o <filename>      write output to <filename>";
     log "    -nowarn            suppress wrong-compiler warning";
     log "    -shared            compile a shared-library crate";
+    log "    -pp                pretty-print the input instead of compiling";
     log "    -h                 display this message";
     log "";
     log "";
@@ -74,6 +110,7 @@ impure fn main(vec[str] args) {
     let option.t[str] output_file = none[str];
     let bool do_warn = true;
     let bool shared = false;
+    let bool pretty = false;
 
     auto i = 1u;
     auto len = _vec.len[str](args);
@@ -86,24 +123,21 @@ impure fn main(vec[str] args) {
                 do_warn = false;
             } else if (_str.eq(arg, "-shared")) {
                 shared = true;
-            } else {
-                // FIXME: rust could use an elif construct.
-                if (_str.eq(arg, "-o")) {
-                    if (i+1u < len) {
-                        output_file = some(args.(i+1u));
-                        i += 1u;
-                    } else {
-                        usage(sess, args.(0));
-                        sess.err("-o requires an argument");
-                    }
+            } else if (_str.eq(arg, "-pp")) {
+                pretty = true;
+            } else if (_str.eq(arg, "-o")) {
+                if (i+1u < len) {
+                    output_file = some(args.(i+1u));
+                    i += 1u;
                 } else {
-                    if (_str.eq(arg, "-h")) {
-                        usage(sess, args.(0));
-                    } else {
-                        usage(sess, args.(0));
-                        sess.err("unrecognized option: " + arg);
-                    }
+                    usage(sess, args.(0));
+                    sess.err("-o requires an argument");
                 }
+            } else if (_str.eq(arg, "-h")) {
+                usage(sess, args.(0));
+            } else {
+                usage(sess, args.(0));
+                sess.err("unrecognized option: " + arg);
             }
         } else {
             alt (input_file) {
@@ -115,8 +149,6 @@ impure fn main(vec[str] args) {
                     input_file = some[str](arg);
                 }
             }
-            // FIXME: dummy node to work around typestate mis-wiring bug.
-            i = i;
         }
         i += 1u;
     }
@@ -131,23 +163,29 @@ impure fn main(vec[str] args) {
             sess.err("no input filename");
         }
         case (some[str](?ifile)) {
-            alt (output_file) {
-                case (none[str]) {
-                    let vec[str] parts = _str.split(ifile, '.' as u8);
-                    parts = _vec.pop[str](parts);
-                    parts += ".bc";
-                    auto ofile = _str.concat(parts);
-                    compile_input(sess, ifile, ofile, shared);
-                }
-                case (some[str](?ofile)) {
-                    compile_input(sess, ifile, ofile, shared);
+
+            auto env = default_environment(sess, args.(0), ifile);
+            if (pretty) {
+                pretty_print_input(sess, env, ifile);
+            }
+            else {
+                alt (output_file) {
+                    case (none[str]) {
+                        let vec[str] parts = _str.split(ifile, '.' as u8);
+                        parts = _vec.pop[str](parts);
+                        parts += ".bc";
+                        auto ofile = _str.concat(parts);
+                        compile_input(sess, env, ifile, ofile, shared);
+                    }
+                    case (some[str](?ofile)) {
+                        compile_input(sess, env, ifile, ofile, shared);
+                    }
                 }
             }
         }
     }
 }
 
-
 // Local Variables:
 // mode: rust
 // fill-column: 78;
diff --git a/src/comp/front/ast.rs b/src/comp/front/ast.rs
index fb068dba4aa..f9d609d1842 100644
--- a/src/comp/front/ast.rs
+++ b/src/comp/front/ast.rs
@@ -5,6 +5,7 @@ import std._vec;
 import util.common.span;
 import util.common.spanned;
 import util.common.ty_mach;
+import util.common.filename;
 
 type ident = str;
 
@@ -36,11 +37,29 @@ tag def {
     def_ty_arg(def_id);
     def_binding(def_id);
     def_use(def_id);
+    def_native_ty(def_id);
+    def_native_fn(def_id);
 }
 
 type crate = spanned[crate_];
 type crate_ = rec(_mod module);
 
+tag crate_directive_ {
+    cdir_expr(@expr);
+    // FIXME: cdir_let should be eliminated
+    // and redirected to the use of const stmt_decls inside
+    // crate directive blocks.
+    cdir_let(ident, @expr, vec[@crate_directive]);
+    cdir_src_mod(ident, option.t[filename]);
+    cdir_dir_mod(ident, option.t[filename], vec[@crate_directive]);
+    cdir_view_item(@view_item);
+    cdir_meta(vec[@meta_item]);
+    cdir_syntax(path);
+    cdir_auth(path, effect);
+}
+type crate_directive = spanned[crate_directive_];
+
+
 type meta_item = spanned[meta_item_];
 type meta_item_ = rec(ident name, str value);
 
@@ -55,6 +74,7 @@ type pat = spanned[pat_];
 tag pat_ {
     pat_wild(ann);
     pat_bind(ident, def_id, ann);
+    pat_lit(@lit, ann);
     pat_tag(path, vec[@pat], option.t[variant_def], ann);
 }
 
@@ -63,6 +83,11 @@ tag mutability {
     imm;
 }
 
+tag opacity {
+    op_abstract;
+    op_transparent;
+}
+
 tag layer {
     layer_value;
     layer_state;
@@ -75,6 +100,11 @@ tag effect {
     eff_unsafe;
 }
 
+tag proto {
+    proto_iter;
+    proto_fn;
+}
+
 tag binop {
     add;
     sub;
@@ -97,12 +127,49 @@ tag binop {
     gt;
 }
 
+fn binop_to_str(binop op) -> str {
+    alt (op) {
+        case (add) {ret "+";}
+        case (sub) {ret "-";}
+        case (mul) {ret "*";}
+        case (div) {ret "/";}
+        case (rem) {ret "%";}
+        case (and) {ret "&&";}
+        case (or) {ret "||";}
+        case (bitxor) {ret "^";}
+        case (bitand) {ret "&";}
+        case (bitor) {ret "|";}
+        case (lsl) {ret "<<";}
+        case (lsr) {ret ">>";}
+        case (asr) {ret ">>>";}
+        case (eq) {ret "==";}
+        case (lt) {ret "<";}
+        case (le) {ret "<=";}
+        case (ne) {ret "!=";}
+        case (ge) {ret ">=";}
+        case (gt) {ret ">";}
+    }
+}
+
+
 tag unop {
     box;
     deref;
     bitnot;
     not;
     neg;
+    _mutable;
+}
+
+fn unop_to_str(unop op) -> str {
+    alt (op) {
+        case (box) {ret "@";}
+        case (deref) {ret "*";}
+        case (bitnot) {ret "~";}
+        case (not) {ret "!";}
+        case (neg) {ret "-";}
+        case (_mutable) {ret "mutable";}
+    }
 }
 
 tag mode {
@@ -113,11 +180,9 @@ tag mode {
 type stmt = spanned[stmt_];
 tag stmt_ {
     stmt_decl(@decl);
-    stmt_ret(option.t[@expr]);
-    stmt_log(@expr);
-    stmt_check_expr(@expr);
-    stmt_fail;
     stmt_expr(@expr);
+    // These only exist in crate-level blocks.
+    stmt_crate_directive(@crate_directive);
 }
 
 type local = rec(option.t[@ty] ty,
@@ -142,7 +207,7 @@ type expr = spanned[expr_];
 tag expr_ {
     expr_vec(vec[@expr], ann);
     expr_tup(vec[elt], ann);
-    expr_rec(vec[field], ann);
+    expr_rec(vec[field], option.t[@expr], ann);
     expr_call(@expr, vec[@expr], ann);
     expr_bind(@expr, vec[option.t[@expr]], ann);
     expr_binary(binop, @expr, @expr, ann);
@@ -152,6 +217,7 @@ tag expr_ {
     expr_if(@expr, block, option.t[@expr], ann);
     expr_while(@expr, block, ann);
     expr_for(@decl, @expr, block, ann);
+    expr_for_each(@decl, @expr, block, ann);
     expr_do_while(block, @expr, ann);
     expr_alt(@expr, vec[arm], ann);
     expr_block(block, ann);
@@ -160,6 +226,13 @@ tag expr_ {
     expr_field(@expr, ident, ann);
     expr_index(@expr, @expr, ann);
     expr_path(path, option.t[def], ann);
+    expr_ext(path, vec[@expr], option.t[@expr], @expr, ann);
+    expr_fail;
+    expr_ret(option.t[@expr]);
+    expr_put(option.t[@expr]);
+    expr_be(@expr);
+    expr_log(@expr);
+    expr_check_expr(@expr);
 }
 
 type lit = spanned[lit_];
@@ -179,7 +252,8 @@ tag lit_ {
 type ty_field = rec(ident ident, @ty ty);
 type ty_arg = rec(mode mode, @ty ty);
 // TODO: effect
-type ty_method = rec(ident ident, vec[ty_arg] inputs, @ty output);
+type ty_method = rec(proto proto, ident ident,
+                     vec[ty_arg] inputs, @ty output);
 type ty = spanned[ty_];
 tag ty_ {
     ty_nil;
@@ -193,17 +267,28 @@ tag ty_ {
     ty_vec(@ty);
     ty_tup(vec[@ty]);
     ty_rec(vec[ty_field]);
-    ty_fn(vec[ty_arg], @ty);        // TODO: effect
+    ty_fn(proto, vec[ty_arg], @ty);        // TODO: effect
     ty_obj(vec[ty_method]);
     ty_path(path, option.t[def]);
     ty_mutable(@ty);
+    ty_type;
+    ty_constr(@ty, vec[@constr]);
+}
+
+tag constr_arg_ {
+    carg_base;
+    carg_ident(ident);
 }
+type constr_arg = spanned[constr_arg_];
+type constr_ = rec(path path, vec[@constr_arg] args);
+type constr = spanned[constr_];
 
 type arg = rec(mode mode, @ty ty, ident ident, def_id id);
-type _fn = rec(effect effect,
-               bool is_iter,
-               vec[arg] inputs,
-               @ty output,
+type fn_decl = rec(effect effect,
+                   vec[arg] inputs,
+                   @ty output);
+type _fn = rec(fn_decl decl,
+               proto proto,
                block body);
 
 
@@ -212,8 +297,8 @@ type method = spanned[method_];
 
 type obj_field = rec(@ty ty, ident ident, def_id id, ann ann);
 type _obj = rec(vec[obj_field] fields,
-                vec[@method] methods);
-
+                vec[@method] methods,
+                option.t[block] dtor);
 
 tag mod_index_entry {
     mie_view_item(@view_item);
@@ -221,11 +306,28 @@ tag mod_index_entry {
     mie_tag_variant(@item /* tag item */, uint /* variant index */);
 }
 
+tag native_mod_index_entry {
+    nmie_view_item(@view_item);
+    nmie_item(@native_item);
+}
+
 type mod_index = hashmap[ident,mod_index_entry];
 type _mod = rec(vec[@view_item] view_items,
                 vec[@item] items,
                 mod_index index);
 
+tag native_abi {
+    native_abi_rust;
+    native_abi_cdecl;
+}
+
+type native_mod = rec(str native_name,
+                      native_abi abi,
+                      vec[@view_item] view_items,
+                      vec[@native_item] items,
+                      native_mod_index index);
+type native_mod_index = hashmap[ident,native_mod_index_entry];
+
 type variant_arg = rec(@ty ty, def_id id);
 type variant = rec(str name, vec[variant_arg] args, def_id id, ann ann);
 
@@ -233,6 +335,7 @@ type view_item = spanned[view_item_];
 tag view_item_ {
     view_item_use(ident, vec[@meta_item], def_id);
     view_item_import(ident, vec[ident], def_id, option.t[def]);
+    view_item_export(ident);
 }
 
 type item = spanned[item_];
@@ -240,11 +343,18 @@ tag item_ {
     item_const(ident, @ty, @expr, def_id, ann);
     item_fn(ident, _fn, vec[ty_param], def_id, ann);
     item_mod(ident, _mod, def_id);
+    item_native_mod(ident, native_mod, def_id);
     item_ty(ident, @ty, vec[ty_param], def_id, ann);
     item_tag(ident, vec[variant], vec[ty_param], def_id);
     item_obj(ident, _obj, vec[ty_param], def_id, ann);
 }
 
+type native_item = spanned[native_item_];
+tag native_item_ {
+    native_item_ty(ident, def_id);
+    native_item_fn(ident, fn_decl, vec[ty_param], def_id, ann);
+}
+
 fn index_view_item(mod_index index, @view_item it) {
     alt (it.node) {
         case(ast.view_item_use(?id, _, _)) {
@@ -253,6 +363,11 @@ fn index_view_item(mod_index index, @view_item it) {
         case(ast.view_item_import(?def_ident,_,_,_)) {
             index.insert(def_ident, ast.mie_view_item(it));
         }
+        case(ast.view_item_export(_)) {
+            // NB: don't index these, they might collide with
+            // the import or use that they're exporting. Have
+            // to do linear search for exports.
+        }
     }
 }
 
@@ -267,6 +382,9 @@ fn index_item(mod_index index, @item it) {
         case (ast.item_mod(?id, _, _)) {
             index.insert(id, ast.mie_item(it));
         }
+        case (ast.item_native_mod(?id, _, _)) {
+            index.insert(id, ast.mie_item(it));
+        }
         case (ast.item_ty(?id, _, _, _, _)) {
             index.insert(id, ast.mie_item(it));
         }
@@ -285,6 +403,41 @@ fn index_item(mod_index index, @item it) {
     }
 }
 
+fn index_native_item(native_mod_index index, @native_item it) {
+    alt (it.node) {
+        case (ast.native_item_ty(?id, _)) {
+            index.insert(id, ast.nmie_item(it));
+        }
+        case (ast.native_item_fn(?id, _, _, _, _)) {
+            index.insert(id, ast.nmie_item(it));
+        }
+    }
+}
+
+fn index_native_view_item(native_mod_index index, @view_item it) {
+    alt (it.node) {
+        case(ast.view_item_import(?def_ident,_,_,_)) {
+            index.insert(def_ident, ast.nmie_view_item(it));
+        }
+        case(ast.view_item_export(_)) {
+            // NB: don't index these, they might collide with
+            // the import or use that they're exporting. Have
+            // to do linear search for exports.
+        }
+    }
+}
+
+fn is_call_expr(@expr e) -> bool {
+    alt (e.node) {
+        case (expr_call(_, _, _)) {
+            ret true;
+        }
+        case (_) {
+            ret false;
+        }
+    }
+}
+
 //
 // Local Variables:
 // mode: rust
diff --git a/src/comp/front/eval.rs b/src/comp/front/eval.rs
new file mode 100644
index 00000000000..881797c9064
--- /dev/null
+++ b/src/comp/front/eval.rs
@@ -0,0 +1,436 @@
+import std._vec;
+import std._str;
+import std.option;
+import std.option.some;
+import std.option.none;
+import std.map.hashmap;
+
+import driver.session;
+import ast.ident;
+import front.parser.parser;
+import front.parser.spanned;
+import front.parser.new_parser;
+import front.parser.parse_mod_items;
+import util.common;
+import util.common.filename;
+import util.common.append;
+import util.common.span;
+import util.common.new_str_hash;
+
+
+// Simple dynamic-typed value type for eval_expr.
+tag val {
+    val_bool(bool);
+    val_int(int);
+    val_str(str);
+}
+
+type env = vec[tup(ident, val)];
+
+fn mk_env() -> env {
+    let env e = vec();
+    ret e;
+}
+
+fn val_is_bool(val v) -> bool {
+    alt (v) {
+        case (val_bool(_)) { ret true; }
+        case (_) { }
+    }
+    ret false;
+}
+
+fn val_is_int(val v) -> bool {
+    alt (v) {
+        case (val_bool(_)) { ret true; }
+        case (_) { }
+    }
+    ret false;
+}
+
+fn val_is_str(val v) -> bool {
+    alt (v) {
+        case (val_str(_)) { ret true; }
+        case (_) { }
+    }
+    ret false;
+}
+
+fn val_as_bool(val v) -> bool {
+    alt (v) {
+        case (val_bool(?b)) { ret b; }
+        case (_) { }
+    }
+    fail;
+}
+
+fn val_as_int(val v) -> int {
+    alt (v) {
+        case (val_int(?i)) { ret i; }
+        case (_) { }
+    }
+    fail;
+}
+
+fn val_as_str(val v) -> str {
+    alt (v) {
+        case (val_str(?s)) { ret s; }
+        case (_) { }
+    }
+    fail;
+}
+
+fn lookup(session.session sess, env e, span sp, ident i) -> val {
+    for (tup(ident, val) pair in e) {
+        if (_str.eq(i, pair._0)) {
+            ret pair._1;
+        }
+    }
+    sess.span_err(sp, "unknown variable: " + i);
+    fail;
+}
+
+fn eval_lit(session.session sess, env e, span sp, @ast.lit lit) -> val {
+    alt (lit.node) {
+        case (ast.lit_bool(?b)) { ret val_bool(b); }
+        case (ast.lit_int(?i)) { ret val_int(i); }
+        case (ast.lit_str(?s)) { ret val_str(s); }
+        case (_) {
+            sess.span_err(sp, "evaluating unsupported literal");
+        }
+    }
+    fail;
+}
+
+fn eval_expr(session.session sess, env e, @ast.expr x) -> val {
+    alt (x.node) {
+        case (ast.expr_path(?pth, _, _)) {
+            if (_vec.len[ident](pth.node.idents) == 1u &&
+                _vec.len[@ast.ty](pth.node.types) == 0u) {
+                ret lookup(sess, e, x.span, pth.node.idents.(0));
+            }
+            sess.span_err(x.span, "evaluating structured path-name");
+        }
+
+        case (ast.expr_lit(?lit, _)) {
+            ret eval_lit(sess, e, x.span, lit);
+        }
+
+        case (ast.expr_unary(?op, ?a, _)) {
+            auto av = eval_expr(sess, e, a);
+            alt (op) {
+                case (ast.not) {
+                    if (val_is_bool(av)) {
+                        ret val_bool(!val_as_bool(av));
+                    }
+                    sess.span_err(x.span, "bad types in '!' expression");
+                }
+                case (_) {
+                    sess.span_err(x.span, "evaluating unsupported unop");
+                }
+            }
+        }
+
+        case (ast.expr_binary(?op, ?a, ?b, _)) {
+            auto av = eval_expr(sess, e, a);
+            auto bv = eval_expr(sess, e, b);
+            alt (op) {
+                case (ast.add) {
+                    if (val_is_int(av) && val_is_int(bv)) {
+                        ret val_int(val_as_int(av) + val_as_int(bv));
+                    }
+                    if (val_is_str(av) && val_is_str(bv)) {
+                        ret val_str(val_as_str(av) + val_as_str(bv));
+                    }
+                    sess.span_err(x.span, "bad types in '+' expression");
+                }
+
+                case (ast.sub) {
+                    if (val_is_int(av) && val_is_int(bv)) {
+                        ret val_int(val_as_int(av) - val_as_int(bv));
+                    }
+                    sess.span_err(x.span, "bad types in '-' expression");
+                }
+
+                case (ast.mul) {
+                    if (val_is_int(av) && val_is_int(bv)) {
+                        ret val_int(val_as_int(av) * val_as_int(bv));
+                    }
+                    sess.span_err(x.span, "bad types in '*' expression");
+                }
+
+                case (ast.div) {
+                    if (val_is_int(av) && val_is_int(bv)) {
+                        ret val_int(val_as_int(av) / val_as_int(bv));
+                    }
+                    sess.span_err(x.span, "bad types in '/' expression");
+                }
+
+                case (ast.rem) {
+                    if (val_is_int(av) && val_is_int(bv)) {
+                        ret val_int(val_as_int(av) % val_as_int(bv));
+                    }
+                    sess.span_err(x.span, "bad types in '%' expression");
+                }
+
+                case (ast.and) {
+                    if (val_is_bool(av) && val_is_bool(bv)) {
+                        ret val_bool(val_as_bool(av) && val_as_bool(bv));
+                    }
+                    sess.span_err(x.span, "bad types in '&&' expression");
+                }
+
+                case (ast.or) {
+                    if (val_is_bool(av) && val_is_bool(bv)) {
+                        ret val_bool(val_as_bool(av) || val_as_bool(bv));
+                    }
+                    sess.span_err(x.span, "bad types in '||' expression");
+                }
+
+                case (ast.eq) {
+                    ret val_bool(val_eq(sess, x.span, av, bv));
+                }
+
+                case (ast.ne) {
+                    ret val_bool(! val_eq(sess, x.span, av, bv));
+                }
+
+                case (_) {
+                    sess.span_err(x.span, "evaluating unsupported binop");
+                }
+            }
+        }
+        case (_) {
+            sess.span_err(x.span, "evaluating unsupported expression");
+        }
+    }
+    fail;
+}
+
+fn val_eq(session.session sess, span sp, val av, val bv) -> bool {
+    if (val_is_bool(av) && val_is_bool(bv)) {
+        ret val_as_bool(av) == val_as_bool(bv);
+    }
+    if (val_is_int(av) && val_is_int(bv)) {
+        ret val_as_int(av) == val_as_int(bv);
+    }
+    if (val_is_str(av) && val_is_str(bv)) {
+        ret _str.eq(val_as_str(av),
+                    val_as_str(bv));
+    }
+    sess.span_err(sp, "bad types in comparison");
+    fail;
+}
+
+impure fn eval_crate_directives(parser p,
+                                env e,
+                                vec[@ast.crate_directive] cdirs,
+                                str prefix,
+                                &mutable vec[@ast.view_item] view_items,
+                                &mutable vec[@ast.item] items,
+                                hashmap[ast.ident,
+                                        ast.mod_index_entry] index) {
+
+    for (@ast.crate_directive sub_cdir in cdirs) {
+        eval_crate_directive(p, e, sub_cdir, prefix,
+                             view_items, items, index);
+    }
+}
+
+
+impure fn eval_crate_directives_to_mod(parser p,
+                                       env e,
+                                       vec[@ast.crate_directive] cdirs,
+                                       str prefix) -> ast._mod {
+    let vec[@ast.view_item] view_items = vec();
+    let vec[@ast.item] items = vec();
+    auto index = new_str_hash[ast.mod_index_entry]();
+
+    eval_crate_directives(p, e, cdirs, prefix,
+                          view_items, items, index);
+
+    ret rec(view_items=view_items, items=items, index=index);
+}
+
+
+impure fn eval_crate_directive_block(parser p,
+                                     env e,
+                                     &ast.block blk,
+                                     str prefix,
+                                     &mutable vec[@ast.view_item] view_items,
+                                     &mutable vec[@ast.item] items,
+                                     hashmap[ast.ident,
+                                             ast.mod_index_entry] index) {
+
+    for (@ast.stmt s in blk.node.stmts) {
+        alt (s.node) {
+            case (ast.stmt_crate_directive(?cdir)) {
+                eval_crate_directive(p, e, cdir, prefix,
+                                     view_items, items, index);
+            }
+            case (_) {
+                auto sess = p.get_session();
+                sess.span_err(s.span,
+                              "unsupported stmt in crate-directive block");
+            }
+        }
+    }
+}
+
+impure fn eval_crate_directive_expr(parser p,
+                                    env e,
+                                    @ast.expr x,
+                                    str prefix,
+                                    &mutable vec[@ast.view_item] view_items,
+                                    &mutable vec[@ast.item] items,
+                                    hashmap[ast.ident,
+                                            ast.mod_index_entry] index) {
+    auto sess = p.get_session();
+
+    alt (x.node) {
+
+        case (ast.expr_if(?cond, ?thn, ?elopt, _)) {
+            auto cv = eval_expr(sess, e, cond);
+            if (!val_is_bool(cv)) {
+                sess.span_err(x.span, "bad cond type in 'if'");
+            }
+
+            if (val_as_bool(cv)) {
+                ret eval_crate_directive_block(p, e, thn, prefix,
+                                               view_items, items,
+                                               index);
+            }
+
+            alt (elopt) {
+                case (some[@ast.expr](?els)) {
+                    ret eval_crate_directive_expr(p, e, els, prefix,
+                                                  view_items, items,
+                                                  index);
+                }
+                case (_) {
+                    // Absent-else is ok.
+                }
+            }
+        }
+
+        case (ast.expr_alt(?v, ?arms, _)) {
+            auto vv = eval_expr(sess, e, v);
+            for (ast.arm arm in arms) {
+                alt (arm.pat.node) {
+                    case (ast.pat_lit(?lit, _)) {
+                        auto pv = eval_lit(sess, e,
+                                           arm.pat.span, lit);
+                        if (val_eq(sess, arm.pat.span, vv, pv)) {
+                            ret eval_crate_directive_block
+                                (p, e, arm.block, prefix,
+                                 view_items, items, index);
+                        }
+                    }
+                    case (ast.pat_wild(_)) {
+                        ret eval_crate_directive_block
+                            (p, e, arm.block, prefix,
+                             view_items, items, index);
+                    }
+                    case (_) {
+                        sess.span_err(arm.pat.span,
+                                      "bad pattern type in 'alt'");
+                    }
+                }
+            }
+            sess.span_err(x.span, "no cases matched in 'alt'");
+        }
+
+        case (ast.expr_block(?block, _)) {
+            ret eval_crate_directive_block(p, e, block, prefix,
+                                           view_items, items,
+                                           index);
+        }
+
+        case (_) {
+            sess.span_err(x.span, "unsupported expr type");
+        }
+    }
+}
+
+impure fn eval_crate_directive(parser p,
+                               env e,
+                               @ast.crate_directive cdir,
+                               str prefix,
+                               &mutable vec[@ast.view_item] view_items,
+                               &mutable vec[@ast.item] items,
+                               hashmap[ast.ident,
+                                       ast.mod_index_entry] index) {
+    alt (cdir.node) {
+
+        case (ast.cdir_let(?id, ?x, ?cdirs)) {
+            auto v = eval_expr(p.get_session(), e, x);
+            auto e0 = vec(tup(id, v)) + e;
+            eval_crate_directives(p, e0, cdirs, prefix,
+                                  view_items, items, index);
+        }
+
+        case (ast.cdir_expr(?x)) {
+            eval_crate_directive_expr(p, e, x, prefix,
+                                      view_items, items, index);
+        }
+
+        case (ast.cdir_src_mod(?id, ?file_opt)) {
+
+            auto file_path = id + ".rs";
+            alt (file_opt) {
+                case (some[filename](?f)) {
+                    file_path = f;
+                }
+                case (none[filename]) {}
+            }
+
+            auto full_path = prefix + std.os.path_sep() + file_path;
+
+            auto p0 = new_parser(p.get_session(), e, 0, full_path);
+            auto m0 = parse_mod_items(p0, token.EOF);
+            auto im = ast.item_mod(id, m0, p.next_def_id());
+            auto i = @spanned(cdir.span, cdir.span, im);
+            ast.index_item(index, i);
+            append[@ast.item](items, i);
+        }
+
+        case (ast.cdir_dir_mod(?id, ?dir_opt, ?cdirs)) {
+
+            auto path = id;
+            alt (dir_opt) {
+                case (some[filename](?d)) {
+                    path = d;
+                }
+                case (none[filename]) {}
+            }
+
+            auto full_path = prefix + std.os.path_sep() + path;
+            auto m0 = eval_crate_directives_to_mod(p, e, cdirs, full_path);
+            auto im = ast.item_mod(id, m0, p.next_def_id());
+            auto i = @spanned(cdir.span, cdir.span, im);
+            ast.index_item(index, i);
+            append[@ast.item](items, i);
+        }
+
+        case (ast.cdir_view_item(?vi)) {
+            append[@ast.view_item](view_items, vi);
+            ast.index_view_item(index, vi);
+        }
+
+        case (ast.cdir_meta(?mi)) {}
+        case (ast.cdir_syntax(?pth)) {}
+        case (ast.cdir_auth(?pth, ?eff)) {}
+    }
+}
+
+
+//
+// Local Variables:
+// mode: rust
+// fill-column: 78;
+// indent-tabs-mode: nil
+// c-basic-offset: 4
+// buffer-file-coding-system: utf-8-unix
+// compile-command: "make -k -C ../.. 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
+// End:
+//
diff --git a/src/comp/front/extfmt.rs b/src/comp/front/extfmt.rs
new file mode 100644
index 00000000000..255614d0f07
--- /dev/null
+++ b/src/comp/front/extfmt.rs
@@ -0,0 +1,553 @@
+/* The 'fmt' extension is modeled on the posix printf system.
+ *
+ * A posix conversion ostensibly looks like this:
+ *
+ * %[parameter][flags][width][.precision][length]type
+ *
+ * Given the different numeric type bestiary we have, we omit the 'length'
+ * parameter and support slightly different conversions for 'type':
+ *
+ * %[parameter][flags][width][.precision]type
+ *
+ * we also only support translating-to-rust a tiny subset of the possible
+ * combinations at the moment.
+ */
+
+import util.common;
+
+import std._str;
+import std._vec;
+import std.option;
+import std.option.none;
+import std.option.some;
+
+export expand_syntax_ext;
+
+tag signedness {
+    signed;
+    unsigned;
+}
+
+tag caseness {
+    case_upper;
+    case_lower;
+}
+
+tag ty {
+    ty_bool;
+    ty_str;
+    ty_char;
+    ty_int(signedness);
+    ty_bits;
+    ty_hex(caseness);
+    // FIXME: More types
+}
+
+tag flag {
+    flag_left_justify;
+    flag_left_zero_pad;
+    flag_left_space_pad;
+    flag_plus_if_positive;
+    flag_alternate;
+}
+
+tag count {
+    count_is(int);
+    count_is_param(int);
+    count_is_next_param;
+    count_implied;
+}
+
+// A formatted conversion from an expression to a string
+type conv = rec(option.t[int] param,
+                vec[flag] flags,
+                count width,
+                count precision,
+                ty ty);
+
+// A fragment of the output sequence
+tag piece {
+    piece_string(str);
+    piece_conv(conv);
+}
+
+// TODO: Need to thread parser through here to handle errors correctly
+fn expand_syntax_ext(vec[@ast.expr] args,
+                     option.t[@ast.expr] body) -> @ast.expr {
+
+    if (_vec.len[@ast.expr](args) == 0u) {
+        log "malformed #fmt call";
+        fail;
+    }
+
+    auto fmt = expr_to_str(args.(0));
+
+    // log "Format string:";
+    // log fmt;
+
+    auto pieces = parse_fmt_string(fmt);
+    auto args_len = _vec.len[@ast.expr](args);
+    auto fmt_args = _vec.slice[@ast.expr](args, 1u, args_len - 1u);
+    ret pieces_to_expr(pieces, args);
+}
+
+fn expr_to_str(@ast.expr expr) -> str {
+    alt (expr.node) {
+        case (ast.expr_lit(?l, _)) {
+            alt (l.node) {
+                case (ast.lit_str(?s)) {
+                    ret s;
+                }
+            }
+        }
+    }
+    log "malformed #fmt call";
+    fail;
+}
+
+fn parse_fmt_string(str s) -> vec[piece] {
+    let vec[piece] pieces = vec();
+    auto lim = _str.byte_len(s);
+    auto buf = "";
+
+    fn flush_buf(str buf, &vec[piece] pieces) -> str {
+        if (_str.byte_len(buf) > 0u) {
+            auto piece = piece_string(buf);
+            pieces += piece;
+        }
+        ret "";
+    }
+
+    auto i = 0u;
+    while (i < lim) {
+        auto curr = _str.substr(s, i, 1u);
+        if (_str.eq(curr, "%")) {
+            i += 1u;
+            if (i >= lim) {
+                log "unterminated conversion at end of string";
+                fail;
+            }
+            auto curr2 = _str.substr(s, i, 1u);
+            if (_str.eq(curr2, "%")) {
+                i += 1u;
+            } else {
+                buf = flush_buf(buf, pieces);
+                auto res = parse_conversion(s, i, lim);
+                pieces += res._0;
+                i = res._1;
+            }
+        } else {
+            buf += curr;
+            i += 1u;
+        }
+    }
+    buf = flush_buf(buf, pieces);
+    ret pieces;
+}
+
+fn peek_num(str s, uint i, uint lim) -> option.t[tup(uint, uint)] {
+    if (i >= lim) {
+        ret none[tup(uint, uint)];
+    }
+
+    auto c = s.(i);
+    if (!('0' as u8 <= c && c <= '9' as u8)) {
+        ret option.none[tup(uint, uint)];
+    }
+
+    auto n = (c - ('0' as u8)) as uint;
+    alt (peek_num(s, i + 1u, lim)) {
+        case (none[tup(uint, uint)]) {
+            ret some[tup(uint, uint)](tup(n, i + 1u));
+        }
+        case (some[tup(uint, uint)](?next)) {
+            auto m = next._0;
+            auto j = next._1;
+            ret some[tup(uint, uint)](tup(n * 10u + m, j));
+        }
+    }
+
+}
+
+fn parse_conversion(str s, uint i, uint lim) -> tup(piece, uint) {
+    auto parm = parse_parameter(s, i, lim);
+    auto flags = parse_flags(s, parm._1, lim);
+    auto width = parse_count(s, flags._1, lim);
+    auto prec = parse_precision(s, width._1, lim);
+    auto ty = parse_type(s, prec._1, lim);
+    ret tup(piece_conv(rec(param = parm._0,
+                           flags = flags._0,
+                           width = width._0,
+                           precision = prec._0,
+                           ty = ty._0)),
+            ty._1);
+}
+
+fn parse_parameter(str s, uint i, uint lim) -> tup(option.t[int], uint) {
+    if (i >= lim) {
+        ret tup(none[int], i);
+    }
+
+    auto num = peek_num(s, i, lim);
+    alt (num) {
+        case (none[tup(uint, uint)]) {
+            ret tup(none[int], i);
+        }
+        case (some[tup(uint, uint)](?t)) {
+            auto n = t._0;
+            auto j = t._1;
+            if (j < lim && s.(j) == '$' as u8) {
+                ret tup(some[int](n as int), j + 1u);
+            }
+            else {
+                ret tup(none[int], i);
+            }
+        }
+    }
+}
+
+fn parse_flags(str s, uint i, uint lim) -> tup(vec[flag], uint) {
+    let vec[flag] noflags = vec();
+
+    if (i >= lim) {
+        ret tup(noflags, i);
+    }
+
+    fn more_(flag f, str s, uint i, uint lim) -> tup(vec[flag], uint) {
+        auto next = parse_flags(s, i + 1u, lim);
+        auto rest = next._0;
+        auto j = next._1;
+        let vec[flag] curr = vec(f);
+        ret tup(curr + rest, j);
+    }
+
+    auto more = bind more_(_, s, i, lim);
+
+    auto f = s.(i);
+    if (f == ('-' as u8)) {
+        ret more(flag_left_justify);
+    } else if (f == ('0' as u8)) {
+        ret more(flag_left_zero_pad);
+    } else if (f == (' ' as u8)) {
+        ret more(flag_left_space_pad);
+    } else if (f == ('+' as u8)) {
+        ret more(flag_plus_if_positive);
+    } else if (f == ('#' as u8)) {
+        ret more(flag_alternate);
+    } else {
+        ret tup(noflags, i);
+    }
+}
+
+fn parse_count(str s, uint i, uint lim) -> tup(count, uint) {
+    if (i >= lim) {
+        ret tup(count_implied, i);
+    }
+
+    if (s.(i) == ('*' as u8)) {
+        auto param = parse_parameter(s, i + 1u, lim);
+        auto j = param._1;
+        alt (param._0) {
+            case (none[int]) {
+                ret tup(count_is_next_param, j);
+            }
+            case (some[int](?n)) {
+                ret tup(count_is_param(n), j);
+            }
+        }
+    } else {
+        auto num = peek_num(s, i, lim);
+        alt (num) {
+            case (none[tup(uint, uint)]) {
+                ret tup(count_implied, i);
+            }
+            case (some[tup(uint, uint)](?num)) {
+                ret tup(count_is(num._0 as int), num._1);
+            }
+        }
+    }
+}
+
+fn parse_precision(str s, uint i, uint lim) -> tup(count, uint) {
+    if (i >= lim) {
+        ret tup(count_implied, i);
+    }
+
+    if (s.(i) == '.' as u8) {
+        ret parse_count(s, i + 1u, lim);
+    } else {
+        ret tup(count_implied, i);
+    }
+}
+
+fn parse_type(str s, uint i, uint lim) -> tup(ty, uint) {
+    if (i >= lim) {
+        log "missing type in conversion";
+        fail;
+    }
+
+    auto t;
+    auto tstr = _str.substr(s, i, 1u);
+    if (_str.eq(tstr, "b")) {
+        t = ty_bool;
+    } else if (_str.eq(tstr, "s")) {
+        t = ty_str;
+    } else if (_str.eq(tstr, "c")) {
+        t = ty_char;
+    } else if (_str.eq(tstr, "d")
+               || _str.eq(tstr, "i")) {
+        // TODO: Do we really want two signed types here?
+        // How important is it to be printf compatible?
+        t = ty_int(signed);
+    } else if (_str.eq(tstr, "u")) {
+        t = ty_int(unsigned);
+    } else if (_str.eq(tstr, "x")) {
+        t = ty_hex(case_lower);
+    } else if (_str.eq(tstr, "X")) {
+        t = ty_hex(case_upper);
+    } else if (_str.eq(tstr, "t")) {
+        t = ty_bits;
+    } else {
+        log "unknown type in conversion";
+        fail;
+    }
+
+    ret tup(t, i + 1u);
+}
+
+fn pieces_to_expr(vec[piece] pieces, vec[@ast.expr] args) -> @ast.expr {
+
+    fn make_new_lit(common.span sp, ast.lit_ lit) -> @ast.expr {
+        auto sp_lit = @parser.spanned[ast.lit_](sp, sp, lit);
+        auto expr = ast.expr_lit(sp_lit, ast.ann_none);
+        ret @parser.spanned[ast.expr_](sp, sp, expr);
+    }
+
+    fn make_new_str(common.span sp, str s) -> @ast.expr {
+        auto lit = ast.lit_str(s);
+        ret make_new_lit(sp, lit);
+    }
+
+    fn make_new_uint(common.span sp, uint u) -> @ast.expr {
+        auto lit = ast.lit_uint(u);
+        ret make_new_lit(sp, lit);
+    }
+
+    fn make_add_expr(common.span sp,
+                     @ast.expr lhs, @ast.expr rhs) -> @ast.expr {
+        auto binexpr = ast.expr_binary(ast.add, lhs, rhs, ast.ann_none);
+        ret @parser.spanned[ast.expr_](sp, sp, binexpr);
+    }
+
+    fn make_call(common.span sp, vec[ast.ident] fn_path,
+                 vec[@ast.expr] args) -> @ast.expr {
+        let vec[ast.ident] path_idents = fn_path;
+        let vec[@ast.ty] path_types = vec();
+        auto path = rec(idents = path_idents, types = path_types);
+        auto sp_path = parser.spanned[ast.path_](sp, sp, path);
+        auto pathexpr = ast.expr_path(sp_path, none[ast.def], ast.ann_none);
+        auto sp_pathexpr = @parser.spanned[ast.expr_](sp, sp, pathexpr);
+        auto callexpr = ast.expr_call(sp_pathexpr, args, ast.ann_none);
+        auto sp_callexpr = @parser.spanned[ast.expr_](sp, sp, callexpr);
+        ret sp_callexpr;
+    }
+
+    fn make_new_conv(conv cnv, @ast.expr arg) -> @ast.expr {
+
+        auto unsupported = "conversion not supported in #fmt string";
+
+        alt (cnv.param) {
+            case (option.none[int]) {
+            }
+            case (_) {
+                log unsupported;
+                fail;
+            }
+        }
+
+        if (_vec.len[flag](cnv.flags) != 0u) {
+            log unsupported;
+            fail;
+        }
+
+        alt (cnv.width) {
+            case (count_implied) {
+            }
+            case (_) {
+                log unsupported;
+                fail;
+            }
+        }
+
+        alt (cnv.precision) {
+            case (count_implied) {
+            }
+            case (_) {
+                log unsupported;
+                fail;
+            }
+        }
+
+        alt (cnv.ty) {
+            case (ty_str) {
+                ret arg;
+            }
+            case (ty_int(?sign)) {
+                alt (sign) {
+                    case (signed) {
+                        let vec[str] path = vec("std", "_int", "to_str");
+                        auto radix_expr = make_new_uint(arg.span, 10u);
+                        let vec[@ast.expr] args = vec(arg, radix_expr);
+                        ret make_call(arg.span, path, args);
+                    }
+                    case (unsigned) {
+                        let vec[str] path = vec("std", "_uint", "to_str");
+                        auto radix_expr = make_new_uint(arg.span, 10u);
+                        let vec[@ast.expr] args = vec(arg, radix_expr);
+                        ret make_call(arg.span, path, args);
+                    }
+                }
+            }
+            case (_) {
+                log unsupported;
+                fail;
+            }
+        }
+    }
+
+    fn log_conv(conv c) {
+        alt (c.param) {
+            case (some[int](?p)) {
+                log "param: " + std._int.to_str(p, 10u);
+            }
+            case (_) {
+                log "param: none";
+            }
+        }
+        for (flag f in c.flags) {
+            alt (f) {
+                case (flag_left_justify) {
+                    log "flag: left justify";
+                }
+                case (flag_left_zero_pad) {
+                    log "flag: left zero pad";
+                }
+                case (flag_left_space_pad) {
+                    log "flag: left space pad";
+                }
+                case (flag_plus_if_positive) {
+                    log "flag: plus if positive";
+                }
+                case (flag_alternate) {
+                    log "flag: alternate";
+                }
+            }
+        }
+        alt (c.width) {
+            case (count_is(?i)) {
+                log "width: count is " + std._int.to_str(i, 10u);
+            }
+            case (count_is_param(?i)) {
+                log "width: count is param " + std._int.to_str(i, 10u);
+            }
+            case (count_is_next_param) {
+                log "width: count is next param";
+            }
+            case (count_implied) {
+                log "width: count is implied";
+            }
+        }
+        alt (c.precision) {
+            case (count_is(?i)) {
+                log "prec: count is " + std._int.to_str(i, 10u);
+            }
+            case (count_is_param(?i)) {
+                log "prec: count is param " + std._int.to_str(i, 10u);
+            }
+            case (count_is_next_param) {
+                log "prec: count is next param";
+            }
+            case (count_implied) {
+                log "prec: count is implied";
+            }
+        }
+        alt (c.ty) {
+            case (ty_bool) {
+                log "type: bool";
+            }
+            case (ty_str) {
+                log "type: str";
+            }
+            case (ty_char) {
+                log "type: char";
+            }
+            case (ty_int(?s)) {
+                alt (s) {
+                    case (signed) {
+                        log "type: signed";
+                    }
+                    case (unsigned) {
+                        log "type: unsigned";
+                    }
+                }
+            }
+            case (ty_bits) {
+                log "type: bits";
+            }
+            case (ty_hex(?cs)) {
+                alt (cs) {
+                    case (case_upper) {
+                        log "type: uhex";
+                    }
+                    case (case_lower) {
+                        log "type: lhex";
+                    }
+                }
+            }
+        }
+    }
+
+    auto sp = args.(0).span;
+    auto n = 0u;
+    auto tmp_expr = make_new_str(sp, "");
+
+    for (piece p in pieces) {
+        alt (p) {
+            case (piece_string(?s)) {
+                auto s_expr = make_new_str(sp, s);
+                tmp_expr = make_add_expr(sp, tmp_expr, s_expr);
+            }
+            case (piece_conv(?conv)) {
+                if (n >= _vec.len[@ast.expr](args)) {
+                    log "too many conversions in #fmt string";
+                    fail;
+                }
+
+                // TODO: Remove debug logging
+                // log "Building conversion:";
+                // log_conv(conv);
+
+                n += 1u;
+                auto arg_expr = args.(n);
+                auto c_expr = make_new_conv(conv, arg_expr);
+                tmp_expr = make_add_expr(sp, tmp_expr, c_expr);
+            }
+        }
+    }
+
+    // TODO: Remove this debug logging
+    // log "dumping expanded ast:";
+    // log pretty.print_expr(tmp_expr);
+    ret tmp_expr;
+}
+
+//
+// Local Variables:
+// mode: rust
+// fill-column: 78;
+// indent-tabs-mode: nil
+// c-basic-offset: 4
+// buffer-file-coding-system: utf-8-unix
+// compile-command: "make -k -C ../.. 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
+// End:
+//
diff --git a/src/comp/front/lexer.rs b/src/comp/front/lexer.rs
index a45b1113890..0e15e3d8c35 100644
--- a/src/comp/front/lexer.rs
+++ b/src/comp/front/lexer.rs
@@ -1,4 +1,4 @@
-import std._io.stdio_reader;
+import std.io.stdio_reader;
 import std._str;
 import std.map;
 import std.map.hashmap;
@@ -90,7 +90,6 @@ fn new_reader(stdio_reader rdr, str filename) -> reader
         }
 
     auto keywords = new_str_hash[token.token]();
-    auto reserved = new_str_hash[()]();
 
     keywords.insert("mod", token.MOD);
     keywords.insert("use", token.USE);
@@ -191,6 +190,16 @@ fn new_reader(stdio_reader rdr, str filename) -> reader
     keywords.insert("f32", token.MACH(common.ty_f32));
     keywords.insert("f64", token.MACH(common.ty_f64));
 
+    auto reserved = new_str_hash[()]();
+
+    reserved.insert("f16", ());  // IEEE 754-2008 'binary16' interchange fmt
+    reserved.insert("f80", ());  // IEEE 754-1985 'extended'
+    reserved.insert("f128", ()); // IEEE 754-2008 'binary128'
+    reserved.insert("m32", ());  // IEEE 754-2008 'decimal32'
+    reserved.insert("m64", ());  // IEEE 754-2008 'decimal64'
+    reserved.insert("m128", ()); // IEEE 754-2008 'decimal128'
+    reserved.insert("dec", ());  // One of m32, m64, m128
+
     ret reader(rdr, filename, rdr.getc() as char, rdr.getc() as char,
                1u, 0u, 1u, 0u, keywords, reserved);
 }
@@ -425,6 +434,12 @@ impure fn next_token(reader rdr) -> token.token {
             ret kwds.get(accum_str);
         }
 
+        auto rsvd = rdr.get_reserved();
+        if (rsvd.contains_key(accum_str)) {
+            log "reserved keyword";
+            fail;
+        }
+
         ret token.IDENT(accum_str);
     }
 
@@ -650,12 +665,9 @@ impure fn next_token(reader rdr) -> token.token {
         case ('%') {
             ret binop(rdr, token.PERCENT);
         }
-
     }
 
-    log "lexer stopping at ";
-    log c;
-    ret token.EOF;
+    fail;
 }
 
 
diff --git a/src/comp/front/parser.rs b/src/comp/front/parser.rs
index e629683c2f8..bb7b8558237 100644
--- a/src/comp/front/parser.rs
+++ b/src/comp/front/parser.rs
@@ -1,4 +1,4 @@
-import std._io;
+import std.io;
 import std._vec;
 import std._str;
 import std.option;
@@ -8,6 +8,7 @@ import std.map.hashmap;
 
 import driver.session;
 import util.common;
+import util.common.filename;
 import util.common.append;
 import util.common.span;
 import util.common.new_str_hash;
@@ -17,6 +18,11 @@ tag restriction {
     RESTRICT_NO_CALL_EXPRS;
 }
 
+tag file_type {
+    CRATE_FILE;
+    SOURCE_FILE;
+}
+
 state type parser =
     state obj {
           fn peek() -> token.token;
@@ -24,28 +30,37 @@ state type parser =
           impure fn err(str s);
           impure fn restrict(restriction r);
           fn get_restriction() -> restriction;
+          fn get_file_type() -> file_type;
+          fn get_env() -> eval.env;
           fn get_session() -> session.session;
           fn get_span() -> common.span;
           fn next_def_id() -> ast.def_id;
+          fn get_prec_table() -> vec[op_spec];
     };
 
 impure fn new_parser(session.session sess,
-                 ast.crate_num crate, str path) -> parser {
+                     eval.env env,
+                     ast.crate_num crate,
+                     str path) -> parser {
     state obj stdio_parser(session.session sess,
+                           eval.env env,
+                           file_type ftype,
                            mutable token.token tok,
                            mutable common.pos lo,
                            mutable common.pos hi,
                            mutable ast.def_num def,
                            mutable restriction res,
                            ast.crate_num crate,
-                           lexer.reader rdr)
+                           lexer.reader rdr,
+                           vec[op_spec] precs)
         {
             fn peek() -> token.token {
-                // log token.to_str(tok);
                 ret tok;
             }
 
             impure fn bump() {
+                // log rdr.get_filename()
+                //   + ":" + common.istr(lo.line as int);
                 tok = lexer.next_token(rdr);
                 lo = rdr.get_mark_pos();
                 hi = rdr.get_curr_pos();
@@ -78,12 +93,29 @@ impure fn new_parser(session.session sess,
                 def += 1;
                 ret tup(crate, def);
             }
+
+            fn get_file_type() -> file_type {
+                ret ftype;
+            }
+
+            fn get_env() -> eval.env {
+                ret env;
+            }
+
+            fn get_prec_table() -> vec[op_spec] {
+                ret precs;
+            }
         }
-    auto srdr = _io.new_stdio_reader(path);
+    auto ftype = SOURCE_FILE;
+    if (_str.ends_with(path, ".rc")) {
+        ftype = CRATE_FILE;
+    }
+    auto srdr = io.new_stdio_reader(path);
     auto rdr = lexer.new_reader(srdr, path);
     auto npos = rdr.get_curr_pos();
-    ret stdio_parser(sess, lexer.next_token(rdr),
-                     npos, npos, 0, UNRESTRICTED, crate, rdr);
+    ret stdio_parser(sess, env, ftype, lexer.next_token(rdr),
+                     npos, npos, 0, UNRESTRICTED, crate, rdr,
+                     prec_table());
 }
 
 impure fn unexpected(parser p, token.token t) {
@@ -121,9 +153,23 @@ impure fn parse_ident(parser p) -> ast.ident {
 }
 
 
-impure fn parse_str_lit(parser p) -> ast.ident {
+/* FIXME: gross hack copied from rustboot to make certain configuration-based
+ * decisions work at build-time.  We should probably change it to use a
+ * lexical sytnax-extension or something similar. For now we just imitate
+ * rustboot.
+ */
+impure fn parse_str_lit_or_env_ident(parser p) -> ast.ident {
     alt (p.peek()) {
         case (token.LIT_STR(?s)) { p.bump(); ret s; }
+        case (token.IDENT(?i)) {
+            auto v = eval.lookup(p.get_session(), p.get_env(),
+                                 p.get_span(), i);
+            if (!eval.val_is_str(v)) {
+                p.err("expecting string-valued variable");
+            }
+            p.bump();
+            ret eval.val_as_str(v);
+        }
         case (_) {
             p.err("expecting string literal");
             fail;
@@ -132,7 +178,8 @@ impure fn parse_str_lit(parser p) -> ast.ident {
 }
 
 
-impure fn parse_ty_fn(parser p, ast.span lo) -> ast.ty_ {
+impure fn parse_ty_fn(ast.proto proto, parser p,
+                      ast.span lo) -> ast.ty_ {
     impure fn parse_fn_input_ty(parser p) -> rec(ast.mode mode, @ast.ty ty) {
         auto mode;
         if (p.peek() == token.BINOP(token.AND)) {
@@ -158,6 +205,10 @@ impure fn parse_ty_fn(parser p, ast.span lo) -> ast.ty_ {
     auto inputs = parse_seq[rec(ast.mode mode, @ast.ty ty)](token.LPAREN,
         token.RPAREN, some(token.COMMA), f, p);
 
+    // FIXME: dropping constrs on the floor at the moment.
+    // pick them up when they're used by typestate pass.
+    parse_constrs(p);
+
     let @ast.ty output;
     if (p.peek() == token.RARROW) {
         p.bump();
@@ -166,20 +217,33 @@ impure fn parse_ty_fn(parser p, ast.span lo) -> ast.ty_ {
         output = @spanned(lo, inputs.span, ast.ty_nil);
     }
 
-    ret ast.ty_fn(inputs.node, output);
+    ret ast.ty_fn(proto, inputs.node, output);
+}
+
+impure fn parse_proto(parser p) -> ast.proto {
+    alt (p.peek()) {
+        case (token.ITER) { p.bump(); ret ast.proto_iter; }
+        case (token.FN) { p.bump(); ret ast.proto_fn; }
+        case (?t) { unexpected(p, t); }
+    }
+    fail;
 }
 
 impure fn parse_ty_obj(parser p, &mutable ast.span hi) -> ast.ty_ {
     expect(p, token.OBJ);
     impure fn parse_method_sig(parser p) -> ast.ty_method {
         auto flo = p.get_span();
-        expect(p, token.FN);
+
+        // FIXME: do something with this, currently it's dropped on the floor.
+        let ast.effect eff = parse_effect(p);
+        let ast.proto proto = parse_proto(p);
         auto ident = parse_ident(p);
-        auto f = parse_ty_fn(p, flo);
+        auto f = parse_ty_fn(proto, p, flo);
         expect(p, token.SEMI);
         alt (f) {
-            case (ast.ty_fn(?inputs, ?output)) {
-                ret rec(ident=ident, inputs=inputs, output=output);
+            case (ast.ty_fn(?proto, ?inputs, ?output)) {
+                ret rec(proto=proto, ident=ident,
+                        inputs=inputs, output=output);
             }
         }
         fail;
@@ -200,10 +264,72 @@ impure fn parse_ty_field(parser p) -> ast.ty_field {
     ret rec(ident=id, ty=ty);
 }
 
+impure fn parse_constr_arg(parser p) -> @ast.constr_arg {
+    auto lo = p.get_span();
+    auto carg = ast.carg_base;
+    if (p.peek() == token.BINOP(token.STAR)) {
+        p.bump();
+    } else {
+        carg = ast.carg_ident(parse_ident(p));
+    }
+    ret @spanned(lo, lo, carg);
+}
+
+impure fn parse_ty_constr(parser p) -> @ast.constr {
+    auto lo = p.get_span();
+    auto path = parse_path(p, GREEDY);
+    auto pf = parse_constr_arg;
+    auto args = parse_seq[@ast.constr_arg](token.LPAREN,
+                                         token.RPAREN,
+                                         some(token.COMMA), pf, p);
+    auto hi = args.span;
+    ret @spanned(lo, hi, rec(path=path, args=args.node));
+}
+
+impure fn parse_constrs(parser p) -> common.spanned[vec[@ast.constr]] {
+    auto lo = p.get_span();
+    auto hi = lo;
+    let vec[@ast.constr] constrs = vec();
+    if (p.peek() == token.COLON) {
+        p.bump();
+        let bool more = true;
+        while (more) {
+            alt (p.peek()) {
+                case (token.IDENT(_)) {
+                    auto constr = parse_ty_constr(p);
+                    hi = constr.span;
+                    append[@ast.constr](constrs, constr);
+                    if (p.peek() == token.COMMA) {
+                        p.bump();
+                        more = false;
+                    }
+                }
+                case (_) { more = false; }
+            }
+        }
+    }
+   ret spanned(lo, hi, constrs);
+}
+
+impure fn parse_ty_constrs(@ast.ty t, parser p) -> @ast.ty {
+   if (p.peek() == token.COLON) {
+       auto constrs = parse_constrs(p);
+       ret @spanned(t.span, constrs.span,
+                    ast.ty_constr(t, constrs.node));
+   }
+   ret t;
+}
+
 impure fn parse_ty(parser p) -> @ast.ty {
     auto lo = p.get_span();
     auto hi = lo;
     let ast.ty_ t;
+
+    // FIXME: do something with these; currently they're
+    // dropped on the floor.
+    let ast.effect eff = parse_effect(p);
+    let ast.layer lyr = parse_layer(p);
+
     alt (p.peek()) {
         case (token.BOOL) { p.bump(); t = ast.ty_bool; }
         case (token.INT) { p.bump(); t = ast.ty_int; }
@@ -275,9 +401,20 @@ impure fn parse_ty(parser p) -> @ast.ty {
         case (token.FN) {
             auto flo = p.get_span();
             p.bump();
-            t = parse_ty_fn(p, flo);
+            t = parse_ty_fn(ast.proto_fn, p, flo);
+            alt (t) {
+                case (ast.ty_fn(_, _, ?out)) {
+                    hi = out.span;
+                }
+            }
+        }
+
+        case (token.ITER) {
+            auto flo = p.get_span();
+            p.bump();
+            t = parse_ty_fn(ast.proto_iter, p, flo);
             alt (t) {
-                case (ast.ty_fn(_, ?out)) {
+                case (ast.ty_fn(_, _, ?out)) {
                     hi = out.span;
                 }
             }
@@ -297,7 +434,8 @@ impure fn parse_ty(parser p) -> @ast.ty {
             fail;
         }
     }
-    ret @spanned(lo, hi, t);
+
+    ret parse_ty_constrs(@spanned(lo, hi, t), p);
 }
 
 impure fn parse_arg(parser p) -> ast.arg {
@@ -341,9 +479,9 @@ impure fn parse_seq[T](token.token bra,
     ret spanned(lo, hi, v);
 }
 
-impure fn parse_lit(parser p) -> option.t[ast.lit] {
+impure fn parse_lit(parser p) -> ast.lit {
     auto lo = p.get_span();
-    let ast.lit_ lit;
+    let ast.lit_ lit = ast.lit_nil;
     alt (p.peek()) {
         case (token.LIT_INT(?i)) {
             p.bump();
@@ -369,12 +507,11 @@ impure fn parse_lit(parser p) -> option.t[ast.lit] {
             p.bump();
             lit = ast.lit_str(s);
         }
-        case (_) {
-            lit = ast.lit_nil;  // FIXME: typestate bug requires this
-            ret none[ast.lit];
+        case (?t) {
+            unexpected(p, t);
         }
     }
-    ret some(spanned(lo, lo, lit));
+    ret spanned(lo, lo, lit);
 }
 
 fn is_ident(token.token t) -> bool {
@@ -520,14 +657,37 @@ impure fn parse_bottom_expr(parser p) -> @ast.expr {
 
         case (token.REC) {
             p.bump();
-            auto pf = parse_field;
-            auto fs =
-                parse_seq[ast.field](token.LPAREN,
-                                     token.RPAREN,
-                                     some(token.COMMA),
-                                     pf, p);
-            hi = fs.span;
-            ex = ast.expr_rec(fs.node, ast.ann_none);
+            expect(p, token.LPAREN);
+            auto fields = vec(parse_field(p));
+
+            auto more = true;
+            auto base = none[@ast.expr];
+            while (more) {
+                alt (p.peek()) {
+                    case (token.RPAREN) {
+                        hi = p.get_span();
+                        p.bump();
+                        more = false;
+                    }
+                    case (token.WITH) {
+                        p.bump();
+                        base = some[@ast.expr](parse_expr(p));
+                        hi = p.get_span();
+                        expect(p, token.RPAREN);
+                        more = false;
+                    }
+                    case (token.COMMA) {
+                        p.bump();
+                        fields += parse_field(p);
+                    }
+                    case (?t) {
+                        unexpected(p, t);
+                    }
+                }
+
+            }
+
+            ex = ast.expr_rec(fields, base, ast.ann_none);
         }
 
         case (token.BIND) {
@@ -554,22 +714,124 @@ impure fn parse_bottom_expr(parser p) -> @ast.expr {
             ex = ast.expr_bind(e, es.node, ast.ann_none);
         }
 
-        case (_) {
-            alt (parse_lit(p)) {
-                case (some[ast.lit](?lit)) {
-                    hi = lit.span;
-                    ex = ast.expr_lit(@lit, ast.ann_none);
+        case (token.POUND) {
+            p.bump();
+            auto pth = parse_path(p, GREEDY);
+            auto pf = parse_expr;
+            auto es = parse_seq[@ast.expr](token.LPAREN,
+                                           token.RPAREN,
+                                           some(token.COMMA),
+                                           pf, p);
+            hi = es.span;
+            ex = expand_syntax_ext(p, es.span, pth, es.node,
+                                   none[@ast.expr]);
+        }
+
+        case (token.FAIL) {
+            p.bump();
+            ex = ast.expr_fail;
+        }
+
+        case (token.LOG) {
+            p.bump();
+            auto e = parse_expr(p);
+            auto hi = e.span;
+            ex = ast.expr_log(e);
+        }
+
+        case (token.CHECK) {
+            p.bump();
+            alt (p.peek()) {
+                case (token.LPAREN) {
+                    auto e = parse_expr(p);
+                    auto hi = e.span;
+                    ex = ast.expr_check_expr(e);
                 }
-                case (none[ast.lit]) {
-                    p.err("expecting expression");
+                case (_) {
+                    p.get_session().unimpl("constraint-check stmt");
                 }
             }
         }
+
+        case (token.RET) {
+            p.bump();
+            alt (p.peek()) {
+                case (token.SEMI) {
+                    ex = ast.expr_ret(none[@ast.expr]);
+                }
+                case (_) {
+                    auto e = parse_expr(p);
+                    hi = e.span;
+                    ex = ast.expr_ret(some[@ast.expr](e));
+                }
+            }
+        }
+
+        case (token.PUT) {
+            p.bump();
+            alt (p.peek()) {
+                case (token.SEMI) {
+                    ex = ast.expr_put(none[@ast.expr]);
+                }
+                case (_) {
+                    auto e = parse_expr(p);
+                    hi = e.span;
+                    ex = ast.expr_put(some[@ast.expr](e));
+                }
+            }
+        }
+
+        case (token.BE) {
+            p.bump();
+            auto e = parse_expr(p);
+            // FIXME: Is this the right place for this check?
+            if /*check*/ (ast.is_call_expr(e)) {
+                    hi = e.span;
+                    ex = ast.expr_be(e);
+            }
+            else {
+                p.err("Non-call expression in tail call");
+            }
+        }
+
+        case (_) {
+            auto lit = parse_lit(p);
+            hi = lit.span;
+            ex = ast.expr_lit(@lit, ast.ann_none);
+        }
     }
 
     ret @spanned(lo, hi, ex);
 }
 
+/*
+ * FIXME: This is a crude approximation of the syntax-extension system,
+ * for purposes of prototyping and/or hard-wiring any extensions we
+ * wish to use while bootstrapping. The eventual aim is to permit
+ * loading rust crates to process extensions, but this will likely
+ * require a rust-based frontend, or an ocaml-FFI-based connection to
+ * rust crates. At the moment we have neither.
+ */
+
+impure fn expand_syntax_ext(parser p, ast.span sp,
+                     &ast.path path, vec[@ast.expr] args,
+                     option.t[@ast.expr] body) -> ast.expr_ {
+
+    check (_vec.len[ast.ident](path.node.idents) > 0u);
+    auto extname = path.node.idents.(0);
+    if (_str.eq(extname, "fmt")) {
+        auto expanded = extfmt.expand_syntax_ext(args, body);
+        auto newexpr = ast.expr_ext(path, args, body,
+                                    expanded,
+                                    ast.ann_none);
+
+        ret newexpr;
+    } else {
+        p.err("unknown syntax extension");
+        fail;
+    }
+}
+
 impure fn extend_expr_by_ident(parser p, span lo, span hi,
                                @ast.expr e, ast.ident i) -> @ast.expr {
     auto e_ = e.node;
@@ -705,6 +967,13 @@ impure fn parse_prefix_expr(parser p) -> @ast.expr {
             ex = ast.expr_unary(ast.box, e, ast.ann_none);
         }
 
+        case (token.MUTABLE) {
+            p.bump();
+            auto e = parse_prefix_expr(p);
+            hi = e.span;
+            ex = ast.expr_unary(ast._mutable, e, ast.ann_none);
+        }
+
         case (_) {
             ret parse_dot_or_call_expr(p);
         }
@@ -712,144 +981,73 @@ impure fn parse_prefix_expr(parser p) -> @ast.expr {
     ret @spanned(lo, hi, ex);
 }
 
-impure fn parse_binops(parser p,
-                   (impure fn(parser) -> @ast.expr) sub,
-                   vec[tup(token.binop, ast.binop)] ops)
+type op_spec = rec(token.token tok, ast.binop op, int prec);
+
+// FIXME make this a const, don't store it in parser state
+fn prec_table() -> vec[op_spec] {
+    ret vec(rec(tok=token.BINOP(token.STAR), op=ast.mul, prec=11),
+            rec(tok=token.BINOP(token.SLASH), op=ast.div, prec=11),
+            rec(tok=token.BINOP(token.PERCENT), op=ast.rem, prec=11),
+            rec(tok=token.BINOP(token.PLUS), op=ast.add, prec=10),
+            rec(tok=token.BINOP(token.MINUS), op=ast.sub, prec=10),
+            rec(tok=token.BINOP(token.LSL), op=ast.lsl, prec=9),
+            rec(tok=token.BINOP(token.LSR), op=ast.lsr, prec=9),
+            rec(tok=token.BINOP(token.ASR), op=ast.asr, prec=9),
+            rec(tok=token.BINOP(token.AND), op=ast.bitand, prec=8),
+            rec(tok=token.BINOP(token.CARET), op=ast.bitxor, prec=6),
+            rec(tok=token.BINOP(token.OR), op=ast.bitor, prec=6),
+            // ast.mul is a bogus placeholder here, AS is special
+            // cased in parse_more_binops
+            rec(tok=token.AS, op=ast.mul, prec=5),
+            rec(tok=token.LT, op=ast.lt, prec=4),
+            rec(tok=token.LE, op=ast.le, prec=4),
+            rec(tok=token.GE, op=ast.ge, prec=4),
+            rec(tok=token.GT, op=ast.gt, prec=4),
+            rec(tok=token.EQEQ, op=ast.eq, prec=3),
+            rec(tok=token.NE, op=ast.ne, prec=3),
+            rec(tok=token.ANDAND, op=ast.and, prec=2),
+            rec(tok=token.OROR, op=ast.or, prec=1));
+}
+
+impure fn parse_binops(parser p) -> @ast.expr {
+    ret parse_more_binops(p, parse_prefix_expr(p), 0);
+}
+
+impure fn parse_more_binops(parser p, @ast.expr lhs, int min_prec)
     -> @ast.expr {
-    auto lo = p.get_span();
-    auto hi = lo;
-    auto e = sub(p);
-    auto more = true;
-    while (more) {
-        more = false;
-        for (tup(token.binop, ast.binop) pair in ops) {
-            alt (p.peek()) {
-                case (token.BINOP(?op)) {
-                    if (pair._0 == op) {
-                        p.bump();
-                        auto rhs = sub(p);
-                        hi = rhs.span;
-                        auto exp = ast.expr_binary(pair._1, e, rhs,
-                                                   ast.ann_none);
-                        e = @spanned(lo, hi, exp);
-                        more = true;
-                    }
-                }
-                case (_) { /* fall through */ }
-            }
-        }
+    // Magic nonsense to work around rustboot bug
+    fn op_eq(token.token a, token.token b) -> bool {
+        if (a == b) {ret true;}
+        else {ret false;}
     }
-    ret e;
-}
-
-impure fn parse_binary_exprs(parser p,
-                            (impure fn(parser) -> @ast.expr) sub,
-                            vec[tup(token.token, ast.binop)] ops)
-    -> @ast.expr {
-    auto lo = p.get_span();
-    auto hi = lo;
-    auto e = sub(p);
-    auto more = true;
-    while (more) {
-        more = false;
-        for (tup(token.token, ast.binop) pair in ops) {
-            if (pair._0 == p.peek()) {
-                p.bump();
-                auto rhs = sub(p);
-                hi = rhs.span;
-                auto exp = ast.expr_binary(pair._1, e, rhs, ast.ann_none);
-                e = @spanned(lo, hi, exp);
-                more = true;
-            }
-        }
-    }
-    ret e;
-}
-
-impure fn parse_factor_expr(parser p) -> @ast.expr {
-    auto sub = parse_prefix_expr;
-    ret parse_binops(p, sub, vec(tup(token.STAR, ast.mul),
-                                 tup(token.SLASH, ast.div),
-                                 tup(token.PERCENT, ast.rem)));
-}
-
-impure fn parse_term_expr(parser p) -> @ast.expr {
-    auto sub = parse_factor_expr;
-    ret parse_binops(p, sub, vec(tup(token.PLUS, ast.add),
-                                 tup(token.MINUS, ast.sub)));
-}
-
-impure fn parse_shift_expr(parser p) -> @ast.expr {
-    auto sub = parse_term_expr;
-    ret parse_binops(p, sub, vec(tup(token.LSL, ast.lsl),
-                                 tup(token.LSR, ast.lsr),
-                                 tup(token.ASR, ast.asr)));
-}
-
-impure fn parse_bitand_expr(parser p) -> @ast.expr {
-    auto sub = parse_shift_expr;
-    ret parse_binops(p, sub, vec(tup(token.AND, ast.bitand)));
-}
-
-impure fn parse_bitxor_expr(parser p) -> @ast.expr {
-    auto sub = parse_bitand_expr;
-    ret parse_binops(p, sub, vec(tup(token.CARET, ast.bitxor)));
-}
-
-impure fn parse_bitor_expr(parser p) -> @ast.expr {
-    auto sub = parse_bitxor_expr;
-    ret parse_binops(p, sub, vec(tup(token.OR, ast.bitor)));
-}
-
-impure fn parse_cast_expr(parser p) -> @ast.expr {
-    auto lo = p.get_span();
-    auto e = parse_bitor_expr(p);
-    auto hi = e.span;
-    while (true) {
-        alt (p.peek()) {
-            case (token.AS) {
-                p.bump();
-                auto t = parse_ty(p);
-                hi = t.span;
-                e = @spanned(lo, hi, ast.expr_cast(e, t, ast.ann_none));
-            }
-
-            case (_) {
-                ret e;
+    auto peeked = p.peek();
+    for (op_spec cur in p.get_prec_table()) {
+        if (cur.prec > min_prec && op_eq(cur.tok, peeked)) {
+            p.bump();
+            alt (cur.tok) {
+                case (token.AS) {
+                    auto rhs = parse_ty(p);
+                    auto _as = ast.expr_cast(lhs, rhs, ast.ann_none);
+                    auto span = @spanned(lhs.span, rhs.span, _as);
+                    ret parse_more_binops(p, span, min_prec);
+                }
+                case (_) {
+                    auto rhs = parse_more_binops(p, parse_prefix_expr(p),
+                                                 cur.prec);
+                    auto bin = ast.expr_binary(cur.op, lhs, rhs,
+                                               ast.ann_none);
+                    auto span = @spanned(lhs.span, rhs.span, bin);
+                    ret parse_more_binops(p, span, min_prec);
+                }
             }
         }
     }
-    ret e;
-}
-
-impure fn parse_relational_expr(parser p) -> @ast.expr {
-    auto sub = parse_cast_expr;
-    ret parse_binary_exprs(p, sub, vec(tup(token.LT, ast.lt),
-                                       tup(token.LE, ast.le),
-                                       tup(token.GE, ast.ge),
-                                       tup(token.GT, ast.gt)));
-}
-
-
-impure fn parse_equality_expr(parser p) -> @ast.expr {
-    auto sub = parse_relational_expr;
-    ret parse_binary_exprs(p, sub, vec(tup(token.EQEQ, ast.eq),
-                                       tup(token.NE, ast.ne)));
-}
-
-impure fn parse_and_expr(parser p) -> @ast.expr {
-    auto sub = parse_equality_expr;
-    ret parse_binary_exprs(p, sub, vec(tup(token.ANDAND, ast.and)));
-}
-
-impure fn parse_or_expr(parser p) -> @ast.expr {
-    auto sub = parse_and_expr;
-    ret parse_binary_exprs(p, sub, vec(tup(token.OROR, ast.or)));
+    ret lhs;
 }
 
 impure fn parse_assign_expr(parser p) -> @ast.expr {
     auto lo = p.get_span();
-    auto lhs = parse_or_expr(p);
+    auto lhs = parse_binops(p);
     alt (p.peek()) {
         case (token.EQ) {
             p.bump();
@@ -901,6 +1099,7 @@ impure fn parse_if_expr(parser p) -> @ast.expr {
         }
         case (_) { /* fall through */ }
     }
+
     ret @spanned(lo, hi, ast.expr_if(cond, thn, els, ast.ann_none));
 }
 
@@ -935,8 +1134,14 @@ impure fn parse_head_local(parser p) -> @ast.decl {
 impure fn parse_for_expr(parser p) -> @ast.expr {
     auto lo = p.get_span();
     auto hi = lo;
+    auto is_each = false;
 
     expect(p, token.FOR);
+    if (p.peek() == token.EACH) {
+        is_each = true;
+        p.bump();
+    }
+
     expect (p, token.LPAREN);
 
     auto decl = parse_head_local(p);
@@ -946,9 +1151,16 @@ impure fn parse_for_expr(parser p) -> @ast.expr {
     expect(p, token.RPAREN);
     auto body = parse_block(p);
     hi = body.span;
-    ret @spanned(lo, hi, ast.expr_for(decl, seq, body, ast.ann_none));
+    if (is_each) {
+        ret @spanned(lo, hi, ast.expr_for_each(decl, seq, body,
+                                               ast.ann_none));
+    } else {
+        ret @spanned(lo, hi, ast.expr_for(decl, seq, body,
+                                          ast.ann_none));
+    }
 }
 
+
 impure fn parse_while_expr(parser p) -> @ast.expr {
     auto lo = p.get_span();
     auto hi = lo;
@@ -996,6 +1208,23 @@ impure fn parse_alt_expr(parser p) -> @ast.expr {
                 auto block = parse_block(p);
                 arms += vec(rec(pat=pat, block=block, index=index));
             }
+
+            // FIXME: this is a vestigial form left over from
+            // rustboot, we're keeping it here for source-compat
+            // for the time being but it should be flushed out
+            // once we've bootstrapped. When we see 'else {' here,
+            // we pretend we saw 'case (_) {'. It has the same
+            // meaning, and only exists due to the cexp/pexp split
+            // in rustboot, which we're not maintaining.
+
+            case (token.ELSE) {
+                p.bump();
+                auto hi = p.get_span();
+                auto pat = @spanned(lo, hi, ast.pat_wild(ast.ann_none));
+                auto index = index_arm(pat);
+                auto block = parse_block(p);
+                arms += vec(rec(pat=pat, block=block, index=index));
+            }
             case (token.RBRACE) { /* empty */ }
             case (?tok) {
                 p.err("expected 'case' or '}' when parsing 'alt' statement " +
@@ -1062,10 +1291,12 @@ impure fn parse_initializer(parser p) -> option.t[@ast.expr] {
 
 impure fn parse_pat(parser p) -> @ast.pat {
     auto lo = p.get_span();
+    auto hi = lo;
+    auto pat;
 
-    auto pat = ast.pat_wild(ast.ann_none);  // FIXME: typestate bug
     alt (p.peek()) {
         case (token.UNDERSCORE) {
+            hi = p.get_span();
             p.bump();
             pat = ast.pat_wild(ast.ann_none);
         }
@@ -1073,6 +1304,7 @@ impure fn parse_pat(parser p) -> @ast.pat {
             p.bump();
             alt (p.peek()) {
                 case (token.IDENT(?id)) {
+                    hi = p.get_span();
                     p.bump();
                     pat = ast.pat_bind(id, p.next_def_id(), ast.ann_none);
                 }
@@ -1085,13 +1317,16 @@ impure fn parse_pat(parser p) -> @ast.pat {
         }
         case (token.IDENT(?id)) {
             auto tag_path = parse_path(p, GREEDY);
+            hi = tag_path.span;
 
             let vec[@ast.pat] args;
             alt (p.peek()) {
                 case (token.LPAREN) {
                     auto f = parse_pat;
-                    args = parse_seq[@ast.pat](token.LPAREN, token.RPAREN,
-                                               some(token.COMMA), f, p).node;
+                    auto a = parse_seq[@ast.pat](token.LPAREN, token.RPAREN,
+                                                 some(token.COMMA), f, p);
+                    args = a.node;
+                    hi = a.span;
                 }
                 case (_) { args = vec(); }
             }
@@ -1099,13 +1334,13 @@ impure fn parse_pat(parser p) -> @ast.pat {
             pat = ast.pat_tag(tag_path, args, none[ast.variant_def],
                               ast.ann_none);
         }
-        case (?tok) {
-            p.err("expected pattern but found " + token.to_str(tok));
-            fail;
+        case (_) {
+            auto lit = parse_lit(p);
+            hi = lit.span;
+            pat = ast.pat_lit(@lit, ast.ann_none);
         }
     }
 
-    auto hi = p.get_span();
     ret @spanned(lo, hi, pat);
 }
 
@@ -1147,49 +1382,22 @@ impure fn parse_auto(parser p) -> @ast.decl {
 }
 
 impure fn parse_stmt(parser p) -> @ast.stmt {
-    auto lo = p.get_span();
-    alt (p.peek()) {
-
-        case (token.LOG) {
-            p.bump();
-            auto e = parse_expr(p);
-            auto hi = p.get_span();
-            ret @spanned(lo, hi, ast.stmt_log(e));
-        }
-
-        case (token.CHECK) {
-            p.bump();
-            alt (p.peek()) {
-                case (token.LPAREN) {
-                    auto e = parse_expr(p);
-                    auto hi = p.get_span();
-                    ret @spanned(lo, hi, ast.stmt_check_expr(e));
-                }
-                case (_) {
-                    p.get_session().unimpl("constraint-check stmt");
-                }
-            }
-        }
+    if (p.get_file_type() == SOURCE_FILE) {
+        ret parse_source_stmt(p);
+    } else {
+        ret parse_crate_stmt(p);
+    }
+}
 
-        case (token.FAIL) {
-            p.bump();
-            ret @spanned(lo, p.get_span(), ast.stmt_fail);
-        }
+impure fn parse_crate_stmt(parser p) -> @ast.stmt {
+    auto cdir = parse_crate_directive(p);
+    ret @spanned(cdir.span, cdir.span,
+                 ast.stmt_crate_directive(@cdir));
+}
 
-        case (token.RET) {
-            p.bump();
-            alt (p.peek()) {
-                case (token.SEMI) {
-                    ret @spanned(lo, p.get_span(),
-                                 ast.stmt_ret(none[@ast.expr]));
-                }
-                case (_) {
-                    auto e = parse_expr(p);
-                    ret @spanned(lo, e.span,
-                                 ast.stmt_ret(some[@ast.expr](e)));
-                }
-            }
-        }
+impure fn parse_source_stmt(parser p) -> @ast.stmt {
+    auto lo = p.get_span();
+    alt (p.peek()) {
 
         case (token.LET) {
             auto decl = parse_let(p);
@@ -1260,31 +1468,28 @@ fn index_block(vec[@ast.stmt] stmts, option.t[@ast.expr] expr) -> ast.block_ {
     auto index = new_str_hash[uint]();
     auto u = 0u;
     for (@ast.stmt s in stmts) {
-        // FIXME: typestate bug requires we do this up top, not
-        // down below loop. Sigh.
-        u += 1u;
         alt (s.node) {
             case (ast.stmt_decl(?d)) {
                 alt (d.node) {
                     case (ast.decl_local(?loc)) {
-                        index.insert(loc.ident, u-1u);
+                        index.insert(loc.ident, u);
                     }
                     case (ast.decl_item(?it)) {
                         alt (it.node) {
                             case (ast.item_fn(?i, _, _, _, _)) {
-                                index.insert(i, u-1u);
+                                index.insert(i, u);
                             }
                             case (ast.item_mod(?i, _, _)) {
-                                index.insert(i, u-1u);
+                                index.insert(i, u);
                             }
                             case (ast.item_ty(?i, _, _, _, _)) {
-                                index.insert(i, u-1u);
+                                index.insert(i, u);
                             }
                             case (ast.item_tag(?i, _, _, _)) {
-                                index.insert(i, u-1u);
+                                index.insert(i, u);
                             }
                             case (ast.item_obj(?i, _, _, _, _)) {
-                                index.insert(i, u-1u);
+                                index.insert(i, u);
                             }
                         }
                     }
@@ -1292,6 +1497,7 @@ fn index_block(vec[@ast.stmt] stmts, option.t[@ast.expr] expr) -> ast.block_ {
             }
             case (_) { /* fall through */ }
         }
+        u += 1u;
     }
     ret rec(stmts=stmts, expr=expr, index=index);
 }
@@ -1301,6 +1507,7 @@ fn index_arm(@ast.pat pat) -> hashmap[ast.ident,ast.def_id] {
         alt (pat.node) {
             case (ast.pat_bind(?i, ?def_id, _)) { index.insert(i, def_id); }
             case (ast.pat_wild(_)) { /* empty */ }
+            case (ast.pat_lit(_, _)) { /* empty */ }
             case (ast.pat_tag(_, ?pats, _, _)) {
                 for (@ast.pat p in pats) {
                     do_index_arm(index, p);
@@ -1330,15 +1537,11 @@ fn stmt_ends_with_semi(@ast.stmt stmt) -> bool {
                 case (ast.decl_item(_)) { ret false; }
             }
         }
-        case (ast.stmt_ret(_))                  { ret true; }
-        case (ast.stmt_log(_))                  { ret true; }
-        case (ast.stmt_check_expr(_))           { ret true; }
-        case (ast.stmt_fail)                    { ret true; }
         case (ast.stmt_expr(?e)) {
             alt (e.node) {
                 case (ast.expr_vec(_,_))        { ret true; }
                 case (ast.expr_tup(_,_))        { ret true; }
-                case (ast.expr_rec(_,_))        { ret true; }
+                case (ast.expr_rec(_,_,_))      { ret true; }
                 case (ast.expr_call(_,_,_))     { ret true; }
                 case (ast.expr_binary(_,_,_,_)) { ret true; }
                 case (ast.expr_unary(_,_,_))    { ret true; }
@@ -1346,18 +1549,28 @@ fn stmt_ends_with_semi(@ast.stmt stmt) -> bool {
                 case (ast.expr_cast(_,_,_))     { ret true; }
                 case (ast.expr_if(_,_,_,_))     { ret false; }
                 case (ast.expr_for(_,_,_,_))    { ret false; }
+                case (ast.expr_for_each(_,_,_,_))
+                    { ret false; }
                 case (ast.expr_while(_,_,_))    { ret false; }
                 case (ast.expr_do_while(_,_,_)) { ret false; }
                 case (ast.expr_alt(_,_,_))      { ret false; }
                 case (ast.expr_block(_,_))      { ret false; }
                 case (ast.expr_assign(_,_,_))   { ret true; }
                 case (ast.expr_assign_op(_,_,_,_))
-                                                { ret true; }
+                    { ret true; }
                 case (ast.expr_field(_,_,_))    { ret true; }
                 case (ast.expr_index(_,_,_))    { ret true; }
                 case (ast.expr_path(_,_,_))     { ret true; }
+                case (ast.expr_fail)            { ret true; }
+                case (ast.expr_ret(_))          { ret true; }
+                case (ast.expr_put(_))          { ret true; }
+                case (ast.expr_be(_))           { ret true; }
+                case (ast.expr_log(_))          { ret true; }
+                case (ast.expr_check_expr(_))   { ret true; }
             }
         }
+        // We should not be calling this on a cdir.
+        case (ast.stmt_crate_directive(?cdir))  { fail; }
     }
 }
 
@@ -1401,8 +1614,13 @@ impure fn parse_block(parser p) -> ast.block {
                     case (none[@ast.expr]) {
                         // Not an expression statement.
                         stmts += vec(stmt);
-                        if (stmt_ends_with_semi(stmt)) {
-                            expect(p, token.SEMI);
+                        // FIXME: crazy differentiation between conditions
+                        // used in branches and binary expressions in rustboot
+                        // means we cannot use && here. I know, right?
+                        if (p.get_file_type() == SOURCE_FILE) {
+                            if (stmt_ends_with_semi(stmt)) {
+                                expect(p, token.SEMI);
+                            }
                         }
                     }
                 }
@@ -1432,7 +1650,7 @@ impure fn parse_ty_params(parser p) -> vec[ast.ty_param] {
     ret ty_params;
 }
 
-impure fn parse_fn(parser p, ast.effect eff, bool is_iter) -> ast._fn {
+impure fn parse_fn_decl(parser p, ast.effect eff) -> ast.fn_decl {
     auto pf = parse_arg;
     let util.common.spanned[vec[ast.arg]] inputs =
         // FIXME: passing parse_arg as an lval doesn't work at the
@@ -1444,34 +1662,41 @@ impure fn parse_fn(parser p, ast.effect eff, bool is_iter) -> ast._fn {
          pf, p);
 
     let @ast.ty output;
+
+    // FIXME: dropping constrs on the floor at the moment.
+    // pick them up when they're used by typestate pass.
+    parse_constrs(p);
+
     if (p.peek() == token.RARROW) {
         p.bump();
         output = parse_ty(p);
     } else {
         output = @spanned(inputs.span, inputs.span, ast.ty_nil);
     }
+    ret rec(effect=eff, inputs=inputs.node, output=output);
+}
 
+impure fn parse_fn(parser p, ast.effect eff, ast.proto proto) -> ast._fn {
+    auto decl = parse_fn_decl(p, eff);
     auto body = parse_block(p);
-
-    ret rec(effect = eff,
-            is_iter = is_iter,
-            inputs = inputs.node,
-            output = output,
+    ret rec(decl = decl,
+            proto = proto,
             body = body);
 }
 
-impure fn parse_item_fn_or_iter(parser p, ast.effect eff,
-                                bool is_iter) -> @ast.item {
-    auto lo = p.get_span();
-    if (is_iter) {
-        expect(p, token.ITER);
-    } else {
-        expect(p, token.FN);
-    }
+impure fn parse_fn_header(parser p)
+    -> tup(ast.ident, vec[ast.ty_param]) {
     auto id = parse_ident(p);
     auto ty_params = parse_ty_params(p);
-    auto f = parse_fn(p, eff, is_iter);
-    auto item = ast.item_fn(id, f, ty_params,
+    ret tup(id, ty_params);
+}
+
+impure fn parse_item_fn_or_iter(parser p, ast.effect eff) -> @ast.item {
+    auto lo = p.get_span();
+    auto proto = parse_proto(p);
+    auto t = parse_fn_header(p);
+    auto f = parse_fn(p, eff, proto);
+    auto item = ast.item_fn(t._0, f, t._1,
                             p.next_def_id(), ast.ann_none);
     ret @spanned(lo, f.body.span, item);
 }
@@ -1486,14 +1711,9 @@ impure fn parse_obj_field(parser p) -> ast.obj_field {
 impure fn parse_method(parser p) -> @ast.method {
     auto lo = p.get_span();
     auto eff = parse_effect(p);
-    auto is_iter = false;
-    alt (p.peek()) {
-        case (token.FN) { p.bump(); }
-        case (token.ITER) { p.bump(); is_iter = true; }
-        case (?t) { unexpected(p, t); }
-    }
+    auto proto = parse_proto(p);
     auto ident = parse_ident(p);
-    auto f = parse_fn(p, eff, is_iter);
+    auto f = parse_fn(p, eff, proto);
     auto meth = rec(ident=ident, meth=f,
                     id=p.next_def_id(), ann=ast.ann_none);
     ret @spanned(lo, f.body.span, meth);
@@ -1512,21 +1732,33 @@ impure fn parse_item_obj(parser p, ast.layer lyr) -> @ast.item {
          some(token.COMMA),
          pf, p);
 
-    auto pm = parse_method;
-    let util.common.spanned[vec[@ast.method]] meths =
-        parse_seq[@ast.method]
-        (token.LBRACE,
-         token.RBRACE,
-         none[token.token],
-         pm, p);
+    let vec[@ast.method] meths = vec();
+    let option.t[ast.block] dtor = none[ast.block];
+
+    expect(p, token.LBRACE);
+    while (p.peek() != token.RBRACE) {
+        alt (p.peek()) {
+            case (token.DROP) {
+                p.bump();
+                dtor = some[ast.block](parse_block(p));
+            }
+            case (_) {
+                append[@ast.method](meths,
+                                    parse_method(p));
+            }
+        }
+    }
+    auto hi = p.get_span();
+    expect(p, token.RBRACE);
 
     let ast._obj ob = rec(fields=fields.node,
-                          methods=meths.node);
+                          methods=meths,
+                          dtor=dtor);
 
     auto item = ast.item_obj(ident, ob, ty_params,
                              p.next_def_id(), ast.ann_none);
 
-    ret @spanned(lo, meths.span, item);
+    ret @spanned(lo, hi, item);
 }
 
 impure fn parse_mod_items(parser p, token.token term) -> ast._mod {
@@ -1568,18 +1800,127 @@ impure fn parse_item_mod(parser p) -> @ast.item {
     ret @spanned(lo, hi, item);
 }
 
-impure fn parse_item_type(parser p) -> @ast.item {
+impure fn parse_item_native_type(parser p) -> @ast.native_item {
+    auto t = parse_type_decl(p);
+    auto hi = p.get_span();
+    expect(p, token.SEMI);
+    auto item = ast.native_item_ty(t._1, p.next_def_id());
+    ret @spanned(t._0, hi, item);
+}
+
+impure fn parse_item_native_fn(parser p, ast.effect eff) -> @ast.native_item {
+    auto lo = p.get_span();
+    expect(p, token.FN);
+    auto t = parse_fn_header(p);
+    auto decl = parse_fn_decl(p, eff);
+    auto hi = p.get_span();
+    expect(p, token.SEMI);
+    auto item = ast.native_item_fn(t._0, decl, t._1, p.next_def_id(),
+                                   ast.ann_none);
+    ret @spanned(lo, hi, item);
+}
+
+impure fn parse_native_item(parser p) -> @ast.native_item {
+    let ast.effect eff = parse_effect(p);
+    let ast.opacity opa = parse_opacity(p);
+    let ast.layer lyr = parse_layer(p);
+    alt (p.peek()) {
+        case (token.TYPE) {
+            ret parse_item_native_type(p);
+        }
+        case (token.FN) {
+            ret parse_item_native_fn(p, eff);
+        }
+        case (?t) {
+            unexpected(p, t);
+            fail;
+        }
+    }
+}
+
+impure fn parse_native_mod_items(parser p,
+                                 str native_name,
+                                 ast.native_abi abi) -> ast.native_mod {
+    auto index = new_str_hash[ast.native_mod_index_entry]();
+    let vec[@ast.native_item] items = vec();
+
+    auto view_items = parse_native_view(p, index);
+
+    while (p.peek() != token.RBRACE) {
+        auto item = parse_native_item(p);
+        items += vec(item);
+
+        // Index the item.
+        ast.index_native_item(index, item);
+    }
+    ret rec(native_name=native_name, abi=abi,
+            view_items=view_items,
+            items=items,
+            index=index);
+}
+
+fn default_native_name(session.session sess, str id) -> str {
+    alt (sess.get_targ_cfg().os) {
+        case (session.os_win32) {
+            ret id + ".dll";
+        }
+        case (session.os_macos) {
+            ret "lib" + id + ".dylib";
+        }
+        case (session.os_linux) {
+            ret "lib" + id + ".so";
+        }
+    }
+}
+
+impure fn parse_item_native_mod(parser p) -> @ast.item {
+    auto lo = p.get_span();
+    expect(p, token.NATIVE);
+    auto abi = ast.native_abi_cdecl;
+    if (p.peek() != token.MOD) {
+        auto t = parse_str_lit_or_env_ident(p);
+        if (_str.eq(t, "cdecl")) {
+        } else if (_str.eq(t, "rust")) {
+            abi = ast.native_abi_rust;
+        } else {
+            p.err("unsupported abi: " + t);
+            fail;
+        }
+    }
+    expect(p, token.MOD);
+    auto id = parse_ident(p);
+    auto native_name;
+    if (p.peek() == token.EQ) {
+        expect(p, token.EQ);
+        native_name = parse_str_lit_or_env_ident(p);
+    } else {
+        native_name = default_native_name(p.get_session(), id);
+    }
+    expect(p, token.LBRACE);
+    auto m = parse_native_mod_items(p, native_name, abi);
+    auto hi = p.get_span();
+    expect(p, token.RBRACE);
+    auto item = ast.item_native_mod(id, m, p.next_def_id());
+    ret @spanned(lo, hi, item);
+}
+
+impure fn parse_type_decl(parser p) -> tup(span, ast.ident) {
     auto lo = p.get_span();
     expect(p, token.TYPE);
     auto id = parse_ident(p);
+    ret tup(lo, id);
+}
+
+impure fn parse_item_type(parser p) -> @ast.item {
+    auto t = parse_type_decl(p);
     auto tps = parse_ty_params(p);
 
     expect(p, token.EQ);
     auto ty = parse_ty(p);
     auto hi = p.get_span();
     expect(p, token.SEMI);
-    auto item = ast.item_ty(id, ty, tps, p.next_def_id(), ast.ann_none);
-    ret @spanned(lo, hi, item);
+    auto item = ast.item_ty(t._1, ty, tps, p.next_def_id(), ast.ann_none);
+    ret @spanned(t._0, hi, item);
 }
 
 impure fn parse_item_tag(parser p) -> @ast.item {
@@ -1631,6 +1972,19 @@ impure fn parse_item_tag(parser p) -> @ast.item {
     ret @spanned(lo, hi, item);
 }
 
+impure fn parse_opacity(parser p) -> ast.opacity {
+    alt (p.peek()) {
+        case (token.ABS) {
+            p.bump();
+            ret ast.op_abstract;
+        }
+        case (_) {
+            ret ast.op_transparent;
+        }
+    }
+    fail;
+}
+
 impure fn parse_layer(parser p) -> ast.layer {
     alt (p.peek()) {
         case (token.STATE) {
@@ -1686,6 +2040,7 @@ fn peeking_at_item(parser p) -> bool {
 
 impure fn parse_item(parser p) -> @ast.item {
     let ast.effect eff = parse_effect(p);
+    let ast.opacity opa = parse_opacity(p);
     let ast.layer lyr = parse_layer(p);
 
     alt (p.peek()) {
@@ -1697,17 +2052,22 @@ impure fn parse_item(parser p) -> @ast.item {
 
         case (token.FN) {
             check (lyr == ast.layer_value);
-            ret parse_item_fn_or_iter(p, eff, false);
+            ret parse_item_fn_or_iter(p, eff);
         }
         case (token.ITER) {
             check (lyr == ast.layer_value);
-            ret parse_item_fn_or_iter(p, eff, true);
+            ret parse_item_fn_or_iter(p, eff);
         }
         case (token.MOD) {
             check (eff == ast.eff_pure);
             check (lyr == ast.layer_value);
             ret parse_item_mod(p);
         }
+        case (token.NATIVE) {
+            check (eff == ast.eff_pure);
+            check (lyr == ast.layer_value);
+            ret parse_item_native_mod(p);
+        }
         case (token.TYPE) {
             check (eff == ast.eff_pure);
             ret parse_item_type(p);
@@ -1840,7 +2200,16 @@ impure fn parse_import(parser p) -> @ast.view_item {
     fail;
 }
 
-impure fn parse_use_or_import(parser p) -> @ast.view_item {
+impure fn parse_export(parser p) -> @ast.view_item {
+    auto lo = p.get_span();
+    expect(p, token.EXPORT);
+    auto id = parse_ident(p);
+    auto hi = p.get_span();
+    expect(p, token.SEMI);
+    ret @spanned(lo, hi, ast.view_item_export(id));
+}
+
+impure fn parse_view_item(parser p) -> @ast.view_item {
     alt (p.peek()) {
         case (token.USE) {
             ret parse_use(p);
@@ -1848,23 +2217,26 @@ impure fn parse_use_or_import(parser p) -> @ast.view_item {
         case (token.IMPORT) {
             ret parse_import(p);
         }
+        case (token.EXPORT) {
+            ret parse_export(p);
+        }
     }
 }
 
-fn is_use_or_import(token.token t) -> bool {
-    if (t == token.USE) {
-        ret true;
-    }
-    if (t == token.IMPORT) {
-        ret true;
+fn is_view_item(token.token t) -> bool {
+    alt (t) {
+        case (token.USE) { ret true; }
+        case (token.IMPORT) { ret true; }
+        case (token.EXPORT) { ret true; }
+        case (_) {}
     }
     ret false;
 }
 
 impure fn parse_view(parser p, ast.mod_index index) -> vec[@ast.view_item] {
     let vec[@ast.view_item] items = vec();
-    while (is_use_or_import(p.peek())) {
-        auto item = parse_use_or_import(p);
+    while (is_view_item(p.peek())) {
+        auto item = parse_view_item(p);
         items += vec(item);
 
         ast.index_view_item(index, item);
@@ -1872,6 +2244,19 @@ impure fn parse_view(parser p, ast.mod_index index) -> vec[@ast.view_item] {
     ret items;
 }
 
+impure fn parse_native_view(parser p, ast.native_mod_index index)
+    -> vec[@ast.view_item] {
+    let vec[@ast.view_item] items = vec();
+    while (is_view_item(p.peek())) {
+        auto item = parse_view_item(p);
+        items += vec(item);
+
+        ast.index_native_view_item(index, item);
+    }
+    ret items;
+}
+
+
 impure fn parse_crate_from_source_file(parser p) -> @ast.crate {
     auto lo = p.get_span();
     auto hi = lo;
@@ -1885,33 +2270,46 @@ impure fn parse_crate_from_source_file(parser p) -> @ast.crate {
 //
 // Each directive imperatively extends its environment with 0 or more items.
 
-impure fn parse_crate_directive(str prefix, parser p,
-                                &mutable vec[@ast.item] items,
-                                hashmap[ast.ident,ast.mod_index_entry] index)
+impure fn parse_crate_directive(parser p) -> ast.crate_directive
 {
     auto lo = p.get_span();
     auto hi = lo;
     alt (p.peek()) {
-        case (token.CONST) {
-            auto c = parse_item_const(p);
-            ast.index_item(index, c);
-            append[@ast.item](items, c);
-         }
+        case (token.AUTH) {
+            // FIXME: currently dropping auth clauses on the floor,
+            // as there is no effect-checking pass.
+            p.bump();
+            auto n = parse_path(p, GREEDY);
+            expect(p, token.EQ);
+            auto e = parse_effect(p);
+            hi = p.get_span();
+            expect(p, token.SEMI);
+            ret spanned(lo, hi, ast.cdir_auth(n, e));
+        }
+
+        case (token.META) {
+            // FIXME: currently dropping meta clauses on the floor,
+            // as there is no crate metadata system
+            p.bump();
+            auto mis = parse_meta(p);
+            hi = p.get_span();
+            expect(p, token.SEMI);
+            ret spanned(lo, hi, ast.cdir_meta(mis));
+        }
+
         case (token.MOD) {
             p.bump();
             auto id = parse_ident(p);
-            auto file_path = id;
+            auto file_opt = none[filename];
             alt (p.peek()) {
                 case (token.EQ) {
                     p.bump();
                     // FIXME: turn this into parse+eval expr
-                    file_path = parse_str_lit(p);
+                    file_opt = some[filename](parse_str_lit_or_env_ident(p));
                 }
                 case (_) {}
             }
 
-            // dir-qualify file path.
-            auto full_path = prefix + std.os.path_sep() + file_path;
 
             alt (p.peek()) {
 
@@ -1920,29 +2318,18 @@ impure fn parse_crate_directive(str prefix, parser p,
                 case (token.SEMI) {
                     hi = p.get_span();
                     p.bump();
-                    if (!_str.ends_with(full_path, ".rs")) {
-                        full_path += ".rs";
-                    }
-                    auto p0 = new_parser(p.get_session(), 0, full_path);
-                    auto m0 = parse_mod_items(p0, token.EOF);
-                    auto im = ast.item_mod(id, m0, p.next_def_id());
-                    auto i = @spanned(lo, hi, im);
-                    ast.index_item(index, i);
-                    append[@ast.item](items, i);
+                    ret spanned(lo, hi, ast.cdir_src_mod(id, file_opt));
                 }
 
                 // mod x = "foo_dir" { ...directives... }
 
                 case (token.LBRACE) {
                     p.bump();
-                    auto m0 = parse_crate_directives(full_path, p,
-                                                     token.RBRACE);
+                    auto cdirs = parse_crate_directives(p, token.RBRACE);
                     hi = p.get_span();
                     expect(p, token.RBRACE);
-                    auto im = ast.item_mod(id, m0, p.next_def_id());
-                    auto i = @spanned(lo, hi, im);
-                    ast.index_item(index, i);
-                    append[@ast.item](items, i);
+                    ret spanned(lo, hi,
+                                ast.cdir_dir_mod(id, file_opt, cdirs));
                 }
 
                 case (?t) {
@@ -1950,28 +2337,65 @@ impure fn parse_crate_directive(str prefix, parser p,
                 }
             }
         }
+
+        case (token.LET) {
+            p.bump();
+            expect(p, token.LPAREN);
+            auto id = parse_ident(p);
+            expect(p, token.EQ);
+            auto x = parse_expr(p);
+            expect(p, token.RPAREN);
+            expect(p, token.LBRACE);
+            auto v = parse_crate_directives(p, token.RBRACE);
+            hi = p.get_span();
+            expect(p, token.RBRACE);
+            ret spanned(lo, hi, ast.cdir_let(id, x, v));
+        }
+
+        case (token.USE) {
+            auto vi = parse_view_item(p);
+            ret spanned(lo, vi.span, ast.cdir_view_item(vi));
+        }
+
+        case (token.IMPORT) {
+            auto vi = parse_view_item(p);
+            ret spanned(lo, vi.span, ast.cdir_view_item(vi));
+        }
+
+        case (token.EXPORT) {
+            auto vi = parse_view_item(p);
+            ret spanned(lo, vi.span, ast.cdir_view_item(vi));
+        }
+
+        case (_) {
+            auto x = parse_expr(p);
+            ret spanned(lo, x.span, ast.cdir_expr(x));
+        }
     }
+    fail;
 }
 
-impure fn parse_crate_directives(str prefix, parser p,
-                                 token.token term) -> ast._mod {
-    auto index = new_str_hash[ast.mod_index_entry]();
-    auto view_items = parse_view(p, index);
 
-    let vec[@ast.item] items = vec();
+impure fn parse_crate_directives(parser p, token.token term)
+    -> vec[@ast.crate_directive] {
+
+    let vec[@ast.crate_directive] cdirs = vec();
 
     while (p.peek() != term) {
-        parse_crate_directive(prefix, p, items, index);
+        auto cdir = @parse_crate_directive(p);
+        append[@ast.crate_directive](cdirs, cdir);
     }
 
-    ret rec(view_items=view_items, items=items, index=index);
+    ret cdirs;
 }
 
 impure fn parse_crate_from_crate_file(parser p) -> @ast.crate {
     auto lo = p.get_span();
     auto hi = lo;
     auto prefix = std.path.dirname(lo.filename);
-    auto m = parse_crate_directives(prefix, p, token.EOF);
+    auto cdirs = parse_crate_directives(p, token.EOF);
+    auto m = eval.eval_crate_directives_to_mod(p, p.get_env(),
+                                               cdirs, prefix);
     hi = p.get_span();
     expect(p, token.EOF);
     ret @spanned(lo, hi, rec(module=m));
diff --git a/src/comp/front/pretty.rs b/src/comp/front/pretty.rs
new file mode 100644
index 00000000000..2fd58126cee
--- /dev/null
+++ b/src/comp/front/pretty.rs
@@ -0,0 +1,87 @@
+import std._int;
+import std._str;
+import std._uint;
+import std._vec;
+
+export print_expr;
+
+// FIXME this is superseded by ../pretty/pprust.rs. can it be dropped?
+
+fn unknown() -> str {
+    ret "<unknown ast node>";
+}
+
+fn print_expr(@ast.expr expr) -> str {
+    alt (expr.node) {
+        case (ast.expr_lit(?lit, _)) {
+            ret print_lit(lit);
+        }
+        case (ast.expr_binary(?op, ?lhs, ?rhs, _)) {
+            ret print_expr_binary(op, lhs, rhs);
+        }
+        case (ast.expr_call(?path, ?args, _)) {
+            ret print_expr_call(path, args);
+        }
+        case (ast.expr_path(?path, _, _)) {
+            ret print_path(path);
+        }
+        case (_) {
+            ret unknown();
+        }
+    }
+}
+
+fn print_lit(@ast.lit lit) -> str {
+    alt (lit.node) {
+        case (ast.lit_str(?s)) {
+            ret "\"" + s + "\"";
+        }
+        case (ast.lit_int(?i)) {
+            ret _int.to_str(i, 10u);
+        }
+        case (ast.lit_uint(?u)) {
+            ret _uint.to_str(u, 10u);
+        }
+        case (_) {
+            ret unknown();
+        }
+    }
+}
+
+fn print_expr_binary(ast.binop op, @ast.expr lhs, @ast.expr rhs) -> str {
+    alt (op) {
+        case (ast.add) {
+            auto l = print_expr(lhs);
+            auto r = print_expr(rhs);
+            ret l + " + " + r;
+        }
+    }
+}
+
+fn print_expr_call(@ast.expr path_expr, vec[@ast.expr] args) -> str {
+    auto s = print_expr(path_expr);
+
+    s += "(";
+    fn print_expr_ref(&@ast.expr e) -> str { ret print_expr(e); }
+    auto mapfn = print_expr_ref;
+    auto argstrs = _vec.map[@ast.expr, str](mapfn, args);
+    s += _str.connect(argstrs, ", ");
+    s += ")";
+
+    ret s;
+}
+
+fn print_path(ast.path path) -> str {
+    ret _str.connect(path.node.idents, ".");
+}
+
+//
+// Local Variables:
+// mode: rust
+// fill-column: 78;
+// indent-tabs-mode: nil
+// c-basic-offset: 4
+// buffer-file-coding-system: utf-8-unix
+// compile-command: "make -k -C ../.. 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
+// End:
+//
diff --git a/src/comp/lib/llvm.rs b/src/comp/lib/llvm.rs
index 624c56f93c4..f75bdbe1ce8 100644
--- a/src/comp/lib/llvm.rs
+++ b/src/comp/lib/llvm.rs
@@ -76,6 +76,25 @@ const uint LLVMIntSLT = 40u;
 const uint LLVMIntSLE = 41u;
 
 
+// Consts for the LLVM RealPredicate type, pre-case to uint.
+// FIXME: as above.
+
+const uint LLVMRealOEQ = 1u;
+const uint LLVMRealOGT = 2u;
+const uint LLVMRealOGE = 3u;
+const uint LLVMRealOLT = 4u;
+const uint LLVMRealOLE = 5u;
+const uint LLVMRealONE = 6u;
+
+const uint LLVMRealORD = 7u;
+const uint LLVMRealUNO = 8u;
+const uint LLVMRealUEQ = 9u;
+const uint LLVMRealUGT = 10u;
+const uint LLVMRealUGE = 11u;
+const uint LLVMRealULT = 12u;
+const uint LLVMRealULE = 13u;
+const uint LLVMRealUNE = 14u;
+
 native mod llvm = llvm_lib {
 
     type ModuleRef;
@@ -657,7 +676,7 @@ native mod llvm = llvm_lib {
     fn LLVMBuildICmp(BuilderRef B, uint Op,
                      ValueRef LHS, ValueRef RHS,
                      sbuf Name) -> ValueRef;
-    fn LLVMBuildFCmp(BuilderRef B, RealPredicate Op,
+    fn LLVMBuildFCmp(BuilderRef B, uint Op,
                      ValueRef LHS, ValueRef RHS,
                      sbuf Name) -> ValueRef;
 
@@ -1034,7 +1053,7 @@ obj builder(BuilderRef B) {
         ret llvm.LLVMBuildICmp(B, Op, LHS, RHS, _str.buf(""));
     }
 
-    fn FCmp(RealPredicate Op, ValueRef LHS, ValueRef RHS) -> ValueRef {
+    fn FCmp(uint Op, ValueRef LHS, ValueRef RHS) -> ValueRef {
         ret llvm.LLVMBuildFCmp(B, Op, LHS, RHS, _str.buf(""));
     }
 
@@ -1151,18 +1170,70 @@ fn mk_type_handle() -> type_handle {
     ret rec(llth=th, dtor=type_handle_dtor(th));
 }
 
-fn type_to_str(TypeRef ty) -> str {
+
+state obj type_names(std.map.hashmap[TypeRef, str] type_names,
+                    std.map.hashmap[str, TypeRef] named_types) {
+
+    fn associate(str s, TypeRef t) {
+        check (!named_types.contains_key(s));
+        check (!type_names.contains_key(t));
+        type_names.insert(t, s);
+        named_types.insert(s, t);
+    }
+
+    fn type_has_name(TypeRef t) -> bool {
+        ret type_names.contains_key(t);
+    }
+
+    fn get_name(TypeRef t) -> str {
+        ret type_names.get(t);
+    }
+
+    fn name_has_type(str s) -> bool {
+        ret named_types.contains_key(s);
+    }
+
+    fn get_type(str s) -> TypeRef {
+        ret named_types.get(s);
+    }
+}
+
+fn mk_type_names() -> type_names {
+    auto nt = util.common.new_str_hash[TypeRef]();
+
+    fn hash(&TypeRef t) -> uint {
+        ret t as uint;
+    }
+
+    fn eq(&TypeRef a, &TypeRef b) -> bool {
+        ret (a as uint) == (b as uint);
+    }
+
+    let std.map.hashfn[TypeRef] hasher = hash;
+    let std.map.eqfn[TypeRef] eqer = eq;
+    auto tn = std.map.mk_hashmap[TypeRef,str](hasher, eqer);
+
+    ret type_names(tn, nt);
+}
+
+fn type_to_str(type_names names, TypeRef ty) -> str {
     let vec[TypeRef] v = vec();
-    ret type_to_str_inner(v, ty);
+    ret type_to_str_inner(names, v, ty);
 }
 
-fn type_to_str_inner(vec[TypeRef] outer0, TypeRef ty) -> str {
+fn type_to_str_inner(type_names names,
+                     vec[TypeRef] outer0, TypeRef ty) -> str {
+
+    if (names.type_has_name(ty)) {
+        ret names.get_name(ty);
+    }
 
     auto outer = outer0 + vec(ty);
 
     let int kind = llvm.LLVMGetTypeKind(ty);
 
-    fn tys_str(vec[TypeRef] outer, vec[TypeRef] tys) -> str {
+    fn tys_str(type_names names,
+               vec[TypeRef] outer, vec[TypeRef] tys) -> str {
         let str s = "";
         let bool first = true;
         for (TypeRef t in tys) {
@@ -1171,7 +1242,7 @@ fn type_to_str_inner(vec[TypeRef] outer0, TypeRef ty) -> str {
             } else {
                 s += ", ";
             }
-            s += type_to_str_inner(outer, t);
+            s += type_to_str_inner(names, outer, t);
         }
         ret s;
     }
@@ -1200,9 +1271,9 @@ fn type_to_str_inner(vec[TypeRef] outer0, TypeRef ty) -> str {
             let vec[TypeRef] args =
                 _vec.init_elt[TypeRef](0 as TypeRef, n_args);
             llvm.LLVMGetParamTypes(ty, _vec.buf[TypeRef](args));
-            s += tys_str(outer, args);
+            s += tys_str(names, outer, args);
             s += ") -> ";
-            s += type_to_str_inner(outer, out_ty);
+            s += type_to_str_inner(names, outer, out_ty);
             ret s;
         }
 
@@ -1212,7 +1283,7 @@ fn type_to_str_inner(vec[TypeRef] outer0, TypeRef ty) -> str {
             let vec[TypeRef] elts =
                 _vec.init_elt[TypeRef](0 as TypeRef, n_elts);
             llvm.LLVMGetStructElementTypes(ty, _vec.buf[TypeRef](elts));
-            s += tys_str(outer, elts);
+            s += tys_str(names, outer, elts);
             s += "}";
             ret s;
         }
@@ -1228,7 +1299,8 @@ fn type_to_str_inner(vec[TypeRef] outer0, TypeRef ty) -> str {
                     ret "*\\" + util.common.istr(n as int);
                 }
             }
-            ret "*" + type_to_str_inner(outer, llvm.LLVMGetElementType(ty));
+            ret "*" + type_to_str_inner(names, outer,
+                                        llvm.LLVMGetElementType(ty));
         }
 
         case (12) { ret "Opaque"; }
diff --git a/src/comp/middle/fold.rs b/src/comp/middle/fold.rs
index ca10e79fe2d..d7660460e04 100644
--- a/src/comp/middle/fold.rs
+++ b/src/comp/middle/fold.rs
@@ -10,6 +10,7 @@ import util.common.ty_mach;
 import util.common.append;
 
 import front.ast;
+import front.ast.fn_decl;
 import front.ast.ident;
 import front.ast.path;
 import front.ast.mutability;
@@ -20,6 +21,7 @@ import front.ast.block;
 import front.ast.item;
 import front.ast.view_item;
 import front.ast.meta_item;
+import front.ast.native_item;
 import front.ast.arg;
 import front.ast.pat;
 import front.ast.decl;
@@ -28,6 +30,7 @@ import front.ast.def;
 import front.ast.def_id;
 import front.ast.ann;
 
+import std._uint;
 import std._vec;
 
 type ast_fold[ENV] =
@@ -56,6 +59,7 @@ type ast_fold[ENV] =
          vec[ast.ty_method] meths) -> @ty)        fold_ty_obj,
 
      (fn(&ENV e, &span sp,
+         ast.proto proto,
          vec[rec(ast.mode mode, @ty ty)] inputs,
          @ty output) -> @ty)                      fold_ty_fn,
 
@@ -72,7 +76,8 @@ type ast_fold[ENV] =
          vec[ast.elt] es, ann a) -> @expr)        fold_expr_tup,
 
      (fn(&ENV e, &span sp,
-         vec[ast.field] fields, ann a) -> @expr)  fold_expr_rec,
+         vec[ast.field] fields,
+         option.t[@expr] base, ann a) -> @expr)   fold_expr_rec,
 
      (fn(&ENV e, &span sp,
          @expr f, vec[@expr] args,
@@ -108,6 +113,10 @@ type ast_fold[ENV] =
          ann a) -> @expr)                         fold_expr_for,
 
      (fn(&ENV e, &span sp,
+         @decl decl, @expr seq, &block body,
+         ann a) -> @expr)                         fold_expr_for_each,
+
+     (fn(&ENV e, &span sp,
          @expr cond, &block body,
          ann a) -> @expr)                         fold_expr_while,
 
@@ -144,6 +153,29 @@ type ast_fold[ENV] =
          &option.t[def] d,
          ann a) -> @expr)                         fold_expr_path,
 
+     (fn(&ENV e, &span sp,
+         &path p, vec[@expr] args,
+         option.t[@expr] body,
+         @expr expanded,
+         ann a) -> @expr)                         fold_expr_ext,
+
+     (fn(&ENV e, &span sp) -> @expr)              fold_expr_fail,
+
+     (fn(&ENV e, &span sp,
+         &option.t[@expr] rv) -> @expr)           fold_expr_ret,
+
+     (fn(&ENV e, &span sp,
+         &option.t[@expr] rv) -> @expr)           fold_expr_put,
+
+     (fn(&ENV e, &span sp,
+         @expr e) -> @expr)                       fold_expr_be,
+
+     (fn(&ENV e, &span sp,
+         @expr e) -> @expr)                       fold_expr_log,
+
+     (fn(&ENV e, &span sp,
+         @expr e) -> @expr)                       fold_expr_check_expr,
+
      // Decl folds.
      (fn(&ENV e, &span sp,
          @ast.local local) -> @decl)              fold_decl_local,
@@ -157,6 +189,9 @@ type ast_fold[ENV] =
          ann a) -> @pat)                          fold_pat_wild,
 
      (fn(&ENV e, &span sp,
+         @ast.lit lit, ann a) -> @pat)            fold_pat_lit,
+
+     (fn(&ENV e, &span sp,
          ident i, def_id did, ann a) -> @pat)     fold_pat_bind,
 
      (fn(&ENV e, &span sp,
@@ -170,15 +205,6 @@ type ast_fold[ENV] =
          @decl decl) -> @stmt)                    fold_stmt_decl,
 
      (fn(&ENV e, &span sp,
-         &option.t[@expr] rv) -> @stmt)           fold_stmt_ret,
-
-     (fn(&ENV e, &span sp,
-         @expr e) -> @stmt)                       fold_stmt_log,
-
-     (fn(&ENV e, &span sp,
-         @expr e) -> @stmt)                       fold_stmt_check_expr,
-
-     (fn(&ENV e, &span sp,
          @expr e) -> @stmt)                       fold_stmt_expr,
 
      // Item folds.
@@ -192,13 +218,24 @@ type ast_fold[ENV] =
          def_id id, ann a) -> @item)              fold_item_fn,
 
      (fn(&ENV e, &span sp, ident ident,
+         &ast.fn_decl decl,
+         vec[ast.ty_param] ty_params,
+         def_id id, ann a) -> @native_item)       fold_native_item_fn,
+
+     (fn(&ENV e, &span sp, ident ident,
          &ast._mod m, def_id id) -> @item)        fold_item_mod,
 
      (fn(&ENV e, &span sp, ident ident,
+         &ast.native_mod m, def_id id) -> @item)  fold_item_native_mod,
+
+     (fn(&ENV e, &span sp, ident ident,
          @ty t, vec[ast.ty_param] ty_params,
          def_id id, ann a) -> @item)              fold_item_ty,
 
      (fn(&ENV e, &span sp, ident ident,
+         def_id id) -> @native_item)              fold_native_item_ty,
+
+     (fn(&ENV e, &span sp, ident ident,
          vec[ast.variant] variants,
          vec[ast.ty_param] ty_params,
          def_id id) -> @item)                     fold_item_tag,
@@ -220,23 +257,30 @@ type ast_fold[ENV] =
      (fn(&ENV e, &span sp,
          &ast.block_) -> block)                   fold_block,
 
+     (fn(&ENV e, &fn_decl decl,
+         ast.proto proto,
+         &block body) -> ast._fn)                 fold_fn,
+
      (fn(&ENV e, ast.effect effect,
-         bool is_iter,
          vec[arg] inputs,
-         @ty output, &block body) -> ast._fn)     fold_fn,
+         @ty output) -> ast.fn_decl)              fold_fn_decl,
 
      (fn(&ENV e, &ast._mod m) -> ast._mod)        fold_mod,
 
+     (fn(&ENV e, &ast.native_mod m) -> ast.native_mod) fold_native_mod,
+
      (fn(&ENV e, &span sp,
          &ast._mod m) -> @ast.crate)              fold_crate,
 
      (fn(&ENV e,
          vec[ast.obj_field] fields,
-         vec[@ast.method] methods) -> ast._obj)   fold_obj,
+         vec[@ast.method] methods,
+         option.t[block] dtor) -> ast._obj)       fold_obj,
 
      // Env updates.
      (fn(&ENV e, @ast.crate c) -> ENV) update_env_for_crate,
      (fn(&ENV e, @item i) -> ENV) update_env_for_item,
+     (fn(&ENV e, @native_item i) -> ENV) update_env_for_native_item,
      (fn(&ENV e, @view_item i) -> ENV) update_env_for_view_item,
      (fn(&ENV e, &block b) -> ENV) update_env_for_block,
      (fn(&ENV e, @stmt s) -> ENV) update_env_for_stmt,
@@ -312,11 +356,13 @@ fn fold_ty[ENV](&ENV env, ast_fold[ENV] fld, @ty t) -> @ty {
         case (ast.ty_obj(?meths)) {
             let vec[ast.ty_method] meths_ = vec();
             for (ast.ty_method m in meths) {
-                auto tfn = fold_ty_fn(env_, fld, t.span, m.inputs, m.output);
+                auto tfn = fold_ty_fn(env_, fld, t.span, m.proto,
+                                      m.inputs, m.output);
                 alt (tfn.node) {
-                    case (ast.ty_fn(?ins, ?out)) {
+                    case (ast.ty_fn(?p, ?ins, ?out)) {
                         append[ast.ty_method]
-                            (meths_, rec(inputs=ins, output=out with m));
+                            (meths_, rec(proto=p, inputs=ins, output=out
+                                         with m));
                     }
                 }
             }
@@ -333,13 +379,14 @@ fn fold_ty[ENV](&ENV env, ast_fold[ENV] fld, @ty t) -> @ty {
             ret fld.fold_ty_mutable(env_, t.span, ty_);
         }
 
-        case (ast.ty_fn(?inputs, ?output)) {
-            ret fold_ty_fn(env_, fld, t.span, inputs, output);
+        case (ast.ty_fn(?proto, ?inputs, ?output)) {
+            ret fold_ty_fn(env_, fld, t.span, proto, inputs, output);
         }
     }
 }
 
 fn fold_ty_fn[ENV](&ENV env, ast_fold[ENV] fld, &span sp,
+                   ast.proto proto,
                    vec[rec(ast.mode mode, @ty ty)] inputs,
                    @ty output) -> @ty {
     auto output_ = fold_ty(env, fld, output);
@@ -349,7 +396,7 @@ fn fold_ty_fn[ENV](&ENV env, ast_fold[ENV] fld, &span sp,
         auto input_ = rec(ty=ty_ with input);
         inputs_ += vec(input_);
     }
-    ret fld.fold_ty_fn(env, sp, inputs_, output_);
+    ret fld.fold_ty_fn(env, sp, proto, inputs_, output_);
 }
 
 fn fold_decl[ENV](&ENV env, ast_fold[ENV] fld, @decl d) -> @decl {
@@ -397,6 +444,9 @@ fn fold_pat[ENV](&ENV env, ast_fold[ENV] fld, @ast.pat p) -> @ast.pat {
 
     alt (p.node) {
         case (ast.pat_wild(?t)) { ret fld.fold_pat_wild(env_, p.span, t); }
+        case (ast.pat_lit(?lt, ?t)) {
+            ret fld.fold_pat_lit(env_, p.span, lt, t);
+        }
         case (ast.pat_bind(?id, ?did, ?t)) {
             ret fld.fold_pat_bind(env_, p.span, id, did, t);
         }
@@ -449,12 +499,19 @@ fn fold_expr[ENV](&ENV env, ast_fold[ENV] fld, &@expr e) -> @expr {
             ret fld.fold_expr_tup(env_, e.span, elts, t);
         }
 
-        case (ast.expr_rec(?fs, ?t)) {
+        case (ast.expr_rec(?fs, ?base, ?t)) {
             let vec[ast.field] fields = vec();
+            let option.t[@expr] b = none[@expr];
             for (ast.field f in fs) {
                 fields += fold_rec_field(env, fld, f);
             }
-            ret fld.fold_expr_rec(env_, e.span, fields, t);
+            alt (base) {
+                case (none[@ast.expr]) { }
+                case (some[@ast.expr](?eb)) {
+                    b = some[@expr](fold_expr(env_, fld, eb));
+                }
+            }
+            ret fld.fold_expr_rec(env_, e.span, fields, b, t);
         }
 
         case (ast.expr_call(?f, ?args, ?t)) {
@@ -521,6 +578,13 @@ fn fold_expr[ENV](&ENV env, ast_fold[ENV] fld, &@expr e) -> @expr {
             ret fld.fold_expr_for(env_, e.span, ddecl, sseq, bbody, t);
         }
 
+        case (ast.expr_for_each(?decl, ?seq, ?body, ?t)) {
+            auto ddecl = fold_decl(env_, fld, decl);
+            auto sseq = fold_expr(env_, fld, seq);
+            auto bbody = fold_block(env_, fld, body);
+            ret fld.fold_expr_for_each(env_, e.span, ddecl, sseq, bbody, t);
+        }
+
         case (ast.expr_while(?cnd, ?body, ?t)) {
             auto ccnd = fold_expr(env_, fld, cnd);
             auto bbody = fold_block(env_, fld, body);
@@ -574,9 +638,59 @@ fn fold_expr[ENV](&ENV env, ast_fold[ENV] fld, &@expr e) -> @expr {
             auto p_ = fold_path(env_, fld, p);
             ret fld.fold_expr_path(env_, e.span, p_, r, t);
         }
+
+        case (ast.expr_ext(?p, ?args, ?body, ?expanded, ?t)) {
+            // Only fold the expanded expression, not the
+            // expressions involved in syntax extension
+            auto exp = fold_expr(env_, fld, expanded);
+            ret fld.fold_expr_ext(env_, e.span, p, args, body,
+                                  exp, t);
+        }
+
+        case (ast.expr_fail) {
+            ret fld.fold_expr_fail(env_, e.span);
+        }
+
+        case (ast.expr_ret(?oe)) {
+            auto oee = none[@expr];
+            alt (oe) {
+                case (some[@expr](?x)) {
+                    oee = some(fold_expr(env_, fld, x));
+                }
+                case (_) { /* fall through */  }
+            }
+            ret fld.fold_expr_ret(env_, e.span, oee);
+        }
+
+        case (ast.expr_put(?oe)) {
+            auto oee = none[@expr];
+            alt (oe) {
+                case (some[@expr](?x)) {
+                    oee = some(fold_expr(env_, fld, x));
+                }
+                case (_) { /* fall through */  }
+            }
+            ret fld.fold_expr_put(env_, e.span, oee);
+        }
+
+        case (ast.expr_be(?x)) {
+            auto ee = fold_expr(env_, fld, x);
+            ret fld.fold_expr_be(env_, e.span, ee);
+        }
+
+        case (ast.expr_log(?x)) {
+            auto ee = fold_expr(env_, fld, x);
+            ret fld.fold_expr_log(env_, e.span, ee);
+        }
+
+        case (ast.expr_check_expr(?x)) {
+            auto ee = fold_expr(env_, fld, x);
+            ret fld.fold_expr_check_expr(env_, e.span, ee);
+        }
+
     }
 
-    ret e;
+    fail;
 }
 
 
@@ -594,37 +708,12 @@ fn fold_stmt[ENV](&ENV env, ast_fold[ENV] fld, &@stmt s) -> @stmt {
             ret fld.fold_stmt_decl(env_, s.span, dd);
         }
 
-        case (ast.stmt_ret(?oe)) {
-            auto oee = none[@expr];
-            alt (oe) {
-                case (some[@expr](?e)) {
-                    oee = some(fold_expr(env_, fld, e));
-                }
-                case (_) { /* fall through */  }
-            }
-            ret fld.fold_stmt_ret(env_, s.span, oee);
-        }
-
-        case (ast.stmt_log(?e)) {
-            auto ee = fold_expr(env_, fld, e);
-            ret fld.fold_stmt_log(env_, s.span, ee);
-        }
-
-        case (ast.stmt_check_expr(?e)) {
-            auto ee = fold_expr(env_, fld, e);
-            ret fld.fold_stmt_check_expr(env_, s.span, ee);
-        }
-
-        case (ast.stmt_fail) {
-            ret s;
-        }
-
         case (ast.stmt_expr(?e)) {
             auto ee = fold_expr(env_, fld, e);
             ret fld.fold_stmt_expr(env_, s.span, ee);
         }
     }
-    ret s;
+    fail;
 }
 
 fn fold_block[ENV](&ENV env, ast_fold[ENV] fld, &block blk) -> block {
@@ -666,17 +755,22 @@ fn fold_arg[ENV](&ENV env, ast_fold[ENV] fld, &arg a) -> arg {
     ret rec(ty=ty with a);
 }
 
-
-fn fold_fn[ENV](&ENV env, ast_fold[ENV] fld, &ast._fn f) -> ast._fn {
-
+fn fold_fn_decl[ENV](&ENV env, ast_fold[ENV] fld,
+                     &ast.fn_decl decl) -> ast.fn_decl {
     let vec[ast.arg] inputs = vec();
-    for (ast.arg a in f.inputs) {
+    for (ast.arg a in decl.inputs) {
         inputs += fold_arg(env, fld, a);
     }
-    auto output = fold_ty[ENV](env, fld, f.output);
+    auto output = fold_ty[ENV](env, fld, decl.output);
+    ret fld.fold_fn_decl(env, decl.effect, inputs, output);
+}
+
+fn fold_fn[ENV](&ENV env, ast_fold[ENV] fld, &ast._fn f) -> ast._fn {
+    auto decl = fold_fn_decl(env, fld, f.decl);
+
     auto body = fold_block[ENV](env, fld, f.body);
 
-    ret fld.fold_fn(env, f.effect, f.is_iter, inputs, output, body);
+    ret fld.fold_fn(env, decl, f.proto, body);
 }
 
 
@@ -701,6 +795,13 @@ fn fold_obj[ENV](&ENV env, ast_fold[ENV] fld, &ast._obj ob) -> ast._obj {
     for (ast.obj_field f in ob.fields) {
         fields += fold_obj_field(env, fld, f);
     }
+    let option.t[block] dtor = none[block];
+    alt (ob.dtor) {
+        case (none[block]) { }
+        case (some[block](?b)) {
+            dtor = some[block](fold_block[ENV](env, fld, b));
+        }
+    }
     let vec[ast.ty_param] tp = vec();
     for (@ast.method m in ob.methods) {
         // Fake-up an ast.item for this method.
@@ -715,7 +816,7 @@ fn fold_obj[ENV](&ENV env, ast_fold[ENV] fld, &ast._obj ob) -> ast._obj {
         let ENV _env = fld.update_env_for_item(env, i);
         append[@ast.method](meths, fold_method(_env, fld, m));
     }
-    ret fld.fold_obj(env, fields, meths);
+    ret fld.fold_obj(env, fields, meths, dtor);
 }
 
 fn fold_view_item[ENV](&ENV env, ast_fold[ENV] fld, @view_item vi)
@@ -768,6 +869,11 @@ fn fold_item[ENV](&ENV env, ast_fold[ENV] fld, @item i) -> @item {
             ret fld.fold_item_mod(env_, i.span, ident, mm_, id);
         }
 
+        case (ast.item_native_mod(?ident, ?mm, ?id)) {
+            let ast.native_mod mm_ = fold_native_mod[ENV](env_, fld, mm);
+            ret fld.fold_item_native_mod(env_, i.span, ident, mm_, id);
+        }
+
         case (ast.item_ty(?ident, ?ty, ?params, ?id, ?ann)) {
             let @ast.ty ty_ = fold_ty[ENV](env_, fld, ty);
             ret fld.fold_item_ty(env_, i.span, ident, ty_, params, id, ann);
@@ -798,7 +904,6 @@ fn fold_item[ENV](&ENV env, ast_fold[ENV] fld, @item i) -> @item {
     fail;
 }
 
-
 fn fold_mod[ENV](&ENV e, ast_fold[ENV] fld, &ast._mod m) -> ast._mod {
 
     let vec[@view_item] view_items = vec();
@@ -818,7 +923,50 @@ fn fold_mod[ENV](&ENV e, ast_fold[ENV] fld, &ast._mod m) -> ast._mod {
     }
 
     ret fld.fold_mod(e, rec(view_items=view_items, items=items, index=index));
- }
+}
+
+fn fold_native_item[ENV](&ENV env, ast_fold[ENV] fld,
+                         @native_item i) -> @native_item {
+    let ENV env_ = fld.update_env_for_native_item(env, i);
+
+    if (!fld.keep_going(env_)) {
+        ret i;
+    }
+    alt (i.node) {
+        case (ast.native_item_ty(?ident, ?id)) {
+            ret fld.fold_native_item_ty(env_, i.span, ident, id);
+        }
+        case (ast.native_item_fn(?ident, ?fn_decl, ?ty_params, ?id, ?ann)) {
+            auto d = fold_fn_decl[ENV](env_, fld, fn_decl);
+            ret fld.fold_native_item_fn(env_, i.span, ident, d,
+                                        ty_params, id, ann);
+        }
+    }
+}
+
+fn fold_native_mod[ENV](&ENV e, ast_fold[ENV] fld,
+                        &ast.native_mod m) -> ast.native_mod {
+    let vec[@view_item] view_items = vec();
+    let vec[@native_item] items = vec();
+    auto index = new_str_hash[ast.native_mod_index_entry]();
+
+    for (@view_item vi in m.view_items) {
+        auto new_vi = fold_view_item[ENV](e, fld, vi);
+        append[@view_item](view_items, new_vi);
+    }
+
+    for (@native_item i in m.items) {
+        auto new_item = fold_native_item[ENV](e, fld, i);
+        append[@native_item](items, new_item);
+        ast.index_native_item(index, new_item);
+    }
+
+    ret fld.fold_native_mod(e, rec(native_name=m.native_name,
+                                   abi=m.abi,
+                                   view_items=view_items,
+                                   items=items,
+                                   index=index));
+}
 
 fn fold_crate[ENV](&ENV env, ast_fold[ENV] fld, @ast.crate c) -> @ast.crate {
     let ENV env_ = fld.update_env_for_crate(env, c);
@@ -894,9 +1042,10 @@ fn identity_fold_ty_obj[ENV](&ENV env, &span sp,
 }
 
 fn identity_fold_ty_fn[ENV](&ENV env, &span sp,
+                            ast.proto proto,
                             vec[rec(ast.mode mode, @ty ty)] inputs,
                             @ty output) -> @ty {
-    ret @respan(sp, ast.ty_fn(inputs, output));
+    ret @respan(sp, ast.ty_fn(proto, inputs, output));
 }
 
 fn identity_fold_ty_path[ENV](&ENV env, &span sp, ast.path p,
@@ -922,8 +1071,9 @@ fn identity_fold_expr_tup[ENV](&ENV env, &span sp,
 }
 
 fn identity_fold_expr_rec[ENV](&ENV env, &span sp,
-                               vec[ast.field] fields, ann a) -> @expr {
-    ret @respan(sp, ast.expr_rec(fields, a));
+                               vec[ast.field] fields,
+                               option.t[@expr] base, ann a) -> @expr {
+    ret @respan(sp, ast.expr_rec(fields, base, a));
 }
 
 fn identity_fold_expr_call[ENV](&ENV env, &span sp, @expr f,
@@ -971,6 +1121,12 @@ fn identity_fold_expr_for[ENV](&ENV env, &span sp,
     ret @respan(sp, ast.expr_for(d, seq, body, a));
 }
 
+fn identity_fold_expr_for_each[ENV](&ENV env, &span sp,
+                                    @decl d, @expr seq,
+                                    &block body, ann a) -> @expr {
+    ret @respan(sp, ast.expr_for_each(d, seq, body, a));
+}
+
 fn identity_fold_expr_while[ENV](&ENV env, &span sp,
                                  @expr cond, &block body, ann a) -> @expr {
     ret @respan(sp, ast.expr_while(cond, body, a));
@@ -1019,6 +1175,40 @@ fn identity_fold_expr_path[ENV](&ENV env, &span sp,
     ret @respan(sp, ast.expr_path(p, d, a));
 }
 
+fn identity_fold_expr_ext[ENV](&ENV env, &span sp,
+                               &path p, vec[@expr] args,
+                               option.t[@expr] body,
+                               @expr expanded,
+                               ann a) -> @expr {
+    ret @respan(sp, ast.expr_ext(p, args, body, expanded, a));
+}
+
+fn identity_fold_expr_fail[ENV](&ENV env, &span sp) -> @expr {
+    ret @respan(sp, ast.expr_fail);
+}
+
+fn identity_fold_expr_ret[ENV](&ENV env, &span sp,
+                               &option.t[@expr] rv) -> @expr {
+    ret @respan(sp, ast.expr_ret(rv));
+}
+
+fn identity_fold_expr_put[ENV](&ENV env, &span sp,
+                               &option.t[@expr] rv) -> @expr {
+    ret @respan(sp, ast.expr_put(rv));
+}
+
+fn identity_fold_expr_be[ENV](&ENV env, &span sp, @expr x) -> @expr {
+    ret @respan(sp, ast.expr_be(x));
+}
+
+fn identity_fold_expr_log[ENV](&ENV e, &span sp, @expr x) -> @expr {
+    ret @respan(sp, ast.expr_log(x));
+}
+
+fn identity_fold_expr_check_expr[ENV](&ENV e, &span sp, @expr x) -> @expr {
+    ret @respan(sp, ast.expr_check_expr(x));
+}
+
 
 // Decl identities.
 
@@ -1038,6 +1228,10 @@ fn identity_fold_pat_wild[ENV](&ENV e, &span sp, ann a) -> @pat {
     ret @respan(sp, ast.pat_wild(a));
 }
 
+fn identity_fold_pat_lit[ENV](&ENV e, &span sp, @ast.lit lit, ann a) -> @pat {
+    ret @respan(sp, ast.pat_lit(lit, a));
+}
+
 fn identity_fold_pat_bind[ENV](&ENV e, &span sp, ident i, def_id did, ann a)
         -> @pat {
     ret @respan(sp, ast.pat_bind(i, did, a));
@@ -1055,19 +1249,6 @@ fn identity_fold_stmt_decl[ENV](&ENV env, &span sp, @decl d) -> @stmt {
     ret @respan(sp, ast.stmt_decl(d));
 }
 
-fn identity_fold_stmt_ret[ENV](&ENV env, &span sp,
-                               &option.t[@expr] rv) -> @stmt {
-    ret @respan(sp, ast.stmt_ret(rv));
-}
-
-fn identity_fold_stmt_log[ENV](&ENV e, &span sp, @expr x) -> @stmt {
-    ret @respan(sp, ast.stmt_log(x));
-}
-
-fn identity_fold_stmt_check_expr[ENV](&ENV e, &span sp, @expr x) -> @stmt {
-    ret @respan(sp, ast.stmt_check_expr(x));
-}
-
 fn identity_fold_stmt_expr[ENV](&ENV e, &span sp, @expr x) -> @stmt {
     ret @respan(sp, ast.stmt_expr(x));
 }
@@ -1087,17 +1268,34 @@ fn identity_fold_item_fn[ENV](&ENV e, &span sp, ident i,
     ret @respan(sp, ast.item_fn(i, f, ty_params, id, a));
 }
 
+fn identity_fold_native_item_fn[ENV](&ENV e, &span sp, ident i,
+                                     &ast.fn_decl decl,
+                                     vec[ast.ty_param] ty_params,
+                                     def_id id, ann a) -> @native_item {
+    ret @respan(sp, ast.native_item_fn(i, decl, ty_params, id, a));
+}
+
 fn identity_fold_item_mod[ENV](&ENV e, &span sp, ident i,
                                &ast._mod m, def_id id) -> @item {
     ret @respan(sp, ast.item_mod(i, m, id));
 }
 
+fn identity_fold_item_native_mod[ENV](&ENV e, &span sp, ident i,
+                                      &ast.native_mod m, def_id id) -> @item {
+    ret @respan(sp, ast.item_native_mod(i, m, id));
+}
+
 fn identity_fold_item_ty[ENV](&ENV e, &span sp, ident i,
                               @ty t, vec[ast.ty_param] ty_params,
                               def_id id, ann a) -> @item {
     ret @respan(sp, ast.item_ty(i, t, ty_params, id, a));
 }
 
+fn identity_fold_native_item_ty[ENV](&ENV e, &span sp, ident i,
+                                     def_id id) -> @native_item {
+    ret @respan(sp, ast.native_item_ty(i, id));
+}
+
 fn identity_fold_item_tag[ENV](&ENV e, &span sp, ident i,
                                vec[ast.variant] variants,
                                vec[ast.ty_param] ty_params,
@@ -1132,28 +1330,38 @@ fn identity_fold_block[ENV](&ENV e, &span sp, &ast.block_ blk) -> block {
     ret respan(sp, blk);
 }
 
+fn identity_fold_fn_decl[ENV](&ENV e,
+                              ast.effect effect,
+                              vec[arg] inputs,
+                              @ty output) -> ast.fn_decl {
+    ret rec(effect=effect, inputs=inputs, output=output);
+}
+
 fn identity_fold_fn[ENV](&ENV e,
-                         ast.effect effect,
-                         bool is_iter,
-                         vec[arg] inputs,
-                         @ast.ty output,
+                         &fn_decl decl,
+                         ast.proto proto,
                          &block body) -> ast._fn {
-    ret rec(effect=effect, is_iter=is_iter, inputs=inputs,
-            output=output, body=body);
+    ret rec(decl=decl, proto=proto, body=body);
 }
 
 fn identity_fold_mod[ENV](&ENV e, &ast._mod m) -> ast._mod {
     ret m;
 }
 
+fn identity_fold_native_mod[ENV](&ENV e,
+                                 &ast.native_mod m) -> ast.native_mod {
+    ret m;
+}
+
 fn identity_fold_crate[ENV](&ENV e, &span sp, &ast._mod m) -> @ast.crate {
     ret @respan(sp, rec(module=m));
 }
 
 fn identity_fold_obj[ENV](&ENV e,
                           vec[ast.obj_field] fields,
-                          vec[@ast.method] methods) -> ast._obj {
-    ret rec(fields=fields, methods=methods);
+                          vec[@ast.method] methods,
+                          option.t[block] dtor) -> ast._obj {
+    ret rec(fields=fields, methods=methods, dtor=dtor);
 }
 
 
@@ -1167,6 +1375,10 @@ fn identity_update_env_for_item[ENV](&ENV e, @item i) -> ENV {
     ret e;
 }
 
+fn identity_update_env_for_native_item[ENV](&ENV e, @native_item i) -> ENV {
+    ret e;
+}
+
 fn identity_update_env_for_view_item[ENV](&ENV e, @view_item i) -> ENV {
     ret e;
 }
@@ -1224,13 +1436,13 @@ fn new_identity_fold[ENV]() -> ast_fold[ENV] {
          fold_ty_tup     = bind identity_fold_ty_tup[ENV](_,_,_),
          fold_ty_rec     = bind identity_fold_ty_rec[ENV](_,_,_),
          fold_ty_obj     = bind identity_fold_ty_obj[ENV](_,_,_),
-         fold_ty_fn      = bind identity_fold_ty_fn[ENV](_,_,_,_),
+         fold_ty_fn      = bind identity_fold_ty_fn[ENV](_,_,_,_,_),
          fold_ty_path    = bind identity_fold_ty_path[ENV](_,_,_,_),
          fold_ty_mutable = bind identity_fold_ty_mutable[ENV](_,_,_),
 
          fold_expr_vec    = bind identity_fold_expr_vec[ENV](_,_,_,_),
          fold_expr_tup    = bind identity_fold_expr_tup[ENV](_,_,_,_),
-         fold_expr_rec    = bind identity_fold_expr_rec[ENV](_,_,_,_),
+         fold_expr_rec    = bind identity_fold_expr_rec[ENV](_,_,_,_,_),
          fold_expr_call   = bind identity_fold_expr_call[ENV](_,_,_,_,_),
          fold_expr_bind   = bind identity_fold_expr_bind[ENV](_,_,_,_,_),
          fold_expr_binary = bind identity_fold_expr_binary[ENV](_,_,_,_,_,_),
@@ -1239,6 +1451,8 @@ fn new_identity_fold[ENV]() -> ast_fold[ENV] {
          fold_expr_cast   = bind identity_fold_expr_cast[ENV](_,_,_,_,_),
          fold_expr_if     = bind identity_fold_expr_if[ENV](_,_,_,_,_,_),
          fold_expr_for    = bind identity_fold_expr_for[ENV](_,_,_,_,_,_),
+         fold_expr_for_each
+             = bind identity_fold_expr_for_each[ENV](_,_,_,_,_,_),
          fold_expr_while  = bind identity_fold_expr_while[ENV](_,_,_,_,_),
          fold_expr_do_while
                           = bind identity_fold_expr_do_while[ENV](_,_,_,_,_),
@@ -1250,25 +1464,36 @@ fn new_identity_fold[ENV]() -> ast_fold[ENV] {
          fold_expr_field  = bind identity_fold_expr_field[ENV](_,_,_,_,_),
          fold_expr_index  = bind identity_fold_expr_index[ENV](_,_,_,_,_),
          fold_expr_path   = bind identity_fold_expr_path[ENV](_,_,_,_,_),
+         fold_expr_ext    = bind identity_fold_expr_ext[ENV](_,_,_,_,_,_,_),
+         fold_expr_fail   = bind identity_fold_expr_fail[ENV](_,_),
+         fold_expr_ret    = bind identity_fold_expr_ret[ENV](_,_,_),
+         fold_expr_put    = bind identity_fold_expr_put[ENV](_,_,_),
+         fold_expr_be     = bind identity_fold_expr_be[ENV](_,_,_),
+         fold_expr_log    = bind identity_fold_expr_log[ENV](_,_,_),
+         fold_expr_check_expr
+                          = bind identity_fold_expr_check_expr[ENV](_,_,_),
 
          fold_decl_local  = bind identity_fold_decl_local[ENV](_,_,_),
          fold_decl_item   = bind identity_fold_decl_item[ENV](_,_,_),
 
          fold_pat_wild    = bind identity_fold_pat_wild[ENV](_,_,_),
+         fold_pat_lit     = bind identity_fold_pat_lit[ENV](_,_,_,_),
          fold_pat_bind    = bind identity_fold_pat_bind[ENV](_,_,_,_,_),
          fold_pat_tag     = bind identity_fold_pat_tag[ENV](_,_,_,_,_,_),
 
          fold_stmt_decl   = bind identity_fold_stmt_decl[ENV](_,_,_),
-         fold_stmt_ret    = bind identity_fold_stmt_ret[ENV](_,_,_),
-         fold_stmt_log    = bind identity_fold_stmt_log[ENV](_,_,_),
-         fold_stmt_check_expr
-                          = bind identity_fold_stmt_check_expr[ENV](_,_,_),
          fold_stmt_expr   = bind identity_fold_stmt_expr[ENV](_,_,_),
 
          fold_item_const= bind identity_fold_item_const[ENV](_,_,_,_,_,_,_),
          fold_item_fn   = bind identity_fold_item_fn[ENV](_,_,_,_,_,_,_),
+         fold_native_item_fn =
+             bind identity_fold_native_item_fn[ENV](_,_,_,_,_,_,_),
          fold_item_mod  = bind identity_fold_item_mod[ENV](_,_,_,_,_),
+         fold_item_native_mod =
+             bind identity_fold_item_native_mod[ENV](_,_,_,_,_),
          fold_item_ty   = bind identity_fold_item_ty[ENV](_,_,_,_,_,_,_),
+         fold_native_item_ty =
+             bind identity_fold_native_item_ty[ENV](_,_,_,_),
          fold_item_tag  = bind identity_fold_item_tag[ENV](_,_,_,_,_,_),
          fold_item_obj  = bind identity_fold_item_obj[ENV](_,_,_,_,_,_,_),
 
@@ -1278,13 +1503,17 @@ fn new_identity_fold[ENV]() -> ast_fold[ENV] {
              bind identity_fold_view_item_import[ENV](_,_,_,_,_,_),
 
          fold_block = bind identity_fold_block[ENV](_,_,_),
-         fold_fn = bind identity_fold_fn[ENV](_,_,_,_,_,_),
+         fold_fn = bind identity_fold_fn[ENV](_,_,_,_),
+         fold_fn_decl = bind identity_fold_fn_decl[ENV](_,_,_,_),
          fold_mod = bind identity_fold_mod[ENV](_,_),
+         fold_native_mod = bind identity_fold_native_mod[ENV](_,_),
          fold_crate = bind identity_fold_crate[ENV](_,_,_),
-         fold_obj = bind identity_fold_obj[ENV](_,_,_),
+         fold_obj = bind identity_fold_obj[ENV](_,_,_,_),
 
          update_env_for_crate = bind identity_update_env_for_crate[ENV](_,_),
          update_env_for_item = bind identity_update_env_for_item[ENV](_,_),
+         update_env_for_native_item =
+             bind identity_update_env_for_native_item[ENV](_,_),
          update_env_for_view_item =
              bind identity_update_env_for_view_item[ENV](_,_),
          update_env_for_block = bind identity_update_env_for_block[ENV](_,_),
diff --git a/src/comp/middle/resolve.rs b/src/comp/middle/resolve.rs
index 1af3b20596c..5b6db631665 100644
--- a/src/comp/middle/resolve.rs
+++ b/src/comp/middle/resolve.rs
@@ -18,6 +18,7 @@ import std._vec;
 tag scope {
     scope_crate(@ast.crate);
     scope_item(@ast.item);
+    scope_native_item(@ast.native_item);
     scope_loop(@ast.decl); // there's only 1 decl per loop.
     scope_block(ast.block);
     scope_arm(ast.arm);
@@ -34,6 +35,7 @@ tag def_wrap {
     def_wrap_use(@ast.view_item);
     def_wrap_import(@ast.view_item);
     def_wrap_mod(@ast.item);
+    def_wrap_native_mod(@ast.item);
     def_wrap_other(def);
     def_wrap_expr_field(uint, def);
     def_wrap_resolving;
@@ -103,6 +105,29 @@ fn find_final_def(&env e, import_map index,
     // should return what a.b.c.d points to in the end.
     fn found_something(&env e, import_map index,
                        &span sp, vec[ident] idents, def_wrap d) -> def_wrap {
+
+        fn found_mod(&env e, &import_map index, &span sp,
+                     vec[ident] idents, @ast.item i) -> def_wrap {
+            auto len = _vec.len[ident](idents);
+            auto rest_idents = _vec.slice[ident](idents, 1u, len);
+            auto empty_e = rec(scopes = nil[scope],
+                               sess = e.sess);
+            auto tmp_e = update_env_for_item(empty_e, i);
+            auto next_i = rest_idents.(0);
+            auto next_ = lookup_name_wrapped(tmp_e, next_i);
+            alt (next_) {
+                case (none[tup(@env, def_wrap)]) {
+                    e.sess.span_err(sp, "unresolved name: " + next_i);
+                    fail;
+                }
+                case (some[tup(@env, def_wrap)](?next)) {
+                    auto combined_e = update_env_for_item(e, i);
+                    ret found_something(combined_e, index, sp,
+                                        rest_idents, next._1);
+                }
+            }
+        }
+
         alt (d) {
             case (def_wrap_import(?imp)) {
                 alt (imp.node) {
@@ -122,23 +147,10 @@ fn find_final_def(&env e, import_map index,
         }
         alt (d) {
             case (def_wrap_mod(?i)) {
-                auto rest_idents = _vec.slice[ident](idents, 1u, len);
-                auto empty_e = rec(scopes = nil[scope],
-                                   sess = e.sess);
-                auto tmp_e = update_env_for_item(empty_e, i);
-                auto next_i = rest_idents.(0);
-                auto next_ = lookup_name_wrapped(tmp_e, next_i);
-                alt (next_) {
-                    case (none[tup(@env, def_wrap)]) {
-                        e.sess.span_err(sp, "unresolved name: " + next_i);
-                        fail;
-                    }
-                    case (some[tup(@env, def_wrap)](?next)) {
-                        auto combined_e = update_env_for_item(e, i);
-                        ret found_something(combined_e, index, sp,
-                                            rest_idents, next._1);
-                    }
-                }
+                ret found_mod(e, index, sp, idents, i);
+            }
+            case (def_wrap_native_mod(?i)) {
+                ret found_mod(e, index, sp, idents, i);
             }
             case (def_wrap_use(?c)) {
                 e.sess.span_err(sp, "Crate access is not implemented");
@@ -201,6 +213,9 @@ fn lookup_name_wrapped(&env e, ast.ident i) -> option.t[tup(@env, def_wrap)] {
             case (ast.item_mod(_, _, ?id)) {
                 ret def_wrap_mod(i);
             }
+            case (ast.item_native_mod(_, _, ?id)) {
+                ret def_wrap_native_mod(i);
+            }
             case (ast.item_ty(_, _, _, ?id, _)) {
                 ret def_wrap_other(ast.def_ty(id));
             }
@@ -213,6 +228,17 @@ fn lookup_name_wrapped(&env e, ast.ident i) -> option.t[tup(@env, def_wrap)] {
         }
     }
 
+    fn found_def_native_item(@ast.native_item i) -> def_wrap {
+        alt (i.node) {
+            case (ast.native_item_ty(_, ?id)) {
+                ret def_wrap_other(ast.def_native_ty(id));
+            }
+            case (ast.native_item_fn(_, _, _, ?id, _)) {
+                ret def_wrap_other(ast.def_native_fn(id));
+            }
+        }
+    }
+
     fn found_decl_stmt(@ast.stmt s) -> def_wrap {
         alt (s.node) {
             case (ast.stmt_decl(?d)) {
@@ -267,11 +293,47 @@ fn lookup_name_wrapped(&env e, ast.ident i) -> option.t[tup(@env, def_wrap)] {
                     }
                 }
             }
-            case (none[ast.mod_index_entry]) { /* fall through */ }
+            case (none[ast.mod_index_entry]) {
+                ret none[def_wrap];
+            }
+        }
+    }
+
+    fn check_native_mod(ast.ident i, ast.native_mod m) -> option.t[def_wrap] {
+
+        alt (m.index.find(i)) {
+            case (some[ast.native_mod_index_entry](?ent)) {
+                alt (ent) {
+                    case (ast.nmie_view_item(?view_item)) {
+                        ret some(found_def_view(view_item));
+                    }
+                    case (ast.nmie_item(?item)) {
+                        ret some(found_def_native_item(item));
+                    }
+                }
+            }
+            case (none[ast.native_mod_index_entry]) {
+                ret none[def_wrap];
+            }
         }
-        ret none[def_wrap];
     }
 
+    fn handle_fn_decl(ast.ident i, &ast.fn_decl decl,
+                      &vec[ast.ty_param] ty_params) -> option.t[def_wrap] {
+        for (ast.arg a in decl.inputs) {
+            if (_str.eq(a.ident, i)) {
+                auto t = ast.def_arg(a.id);
+                ret some(def_wrap_other(t));
+            }
+        }
+        for (ast.ty_param tp in ty_params) {
+            if (_str.eq(tp.ident, i)) {
+                auto t = ast.def_ty_arg(tp.id);
+                ret some(def_wrap_other(t));
+            }
+        }
+        ret none[def_wrap];
+    }
 
     fn in_scope(ast.ident i, &scope s) -> option.t[def_wrap] {
         alt (s) {
@@ -283,9 +345,12 @@ fn lookup_name_wrapped(&env e, ast.ident i) -> option.t[tup(@env, def_wrap)] {
             case (scope_item(?it)) {
                 alt (it.node) {
                     case (ast.item_fn(_, ?f, ?ty_params, _, _)) {
-                        for (ast.arg a in f.inputs) {
-                            if (_str.eq(a.ident, i)) {
-                                auto t = ast.def_arg(a.id);
+                        ret handle_fn_decl(i, f.decl, ty_params);
+                    }
+                    case (ast.item_obj(_, ?ob, ?ty_params, _, _)) {
+                        for (ast.obj_field f in ob.fields) {
+                            if (_str.eq(f.ident, i)) {
+                                auto t = ast.def_obj_field(f.id);
                                 ret some(def_wrap_other(t));
                             }
                         }
@@ -296,13 +361,7 @@ fn lookup_name_wrapped(&env e, ast.ident i) -> option.t[tup(@env, def_wrap)] {
                             }
                         }
                     }
-                    case (ast.item_obj(_, ?ob, ?ty_params, _, _)) {
-                        for (ast.obj_field f in ob.fields) {
-                            if (_str.eq(f.ident, i)) {
-                                auto t = ast.def_obj_field(f.id);
-                                ret some(def_wrap_other(t));
-                            }
-                        }
+                    case (ast.item_tag(_, _, ?ty_params, _)) {
                         for (ast.ty_param tp in ty_params) {
                             if (_str.eq(tp.ident, i)) {
                                 auto t = ast.def_ty_arg(tp.id);
@@ -313,6 +372,9 @@ fn lookup_name_wrapped(&env e, ast.ident i) -> option.t[tup(@env, def_wrap)] {
                     case (ast.item_mod(_, ?m, _)) {
                         ret check_mod(i, m);
                     }
+                    case (ast.item_native_mod(_, ?m, _)) {
+                        ret check_native_mod(i, m);
+                    }
                     case (ast.item_ty(_, _, ?ty_params, _, _)) {
                         for (ast.ty_param tp in ty_params) {
                             if (_str.eq(tp.ident, i)) {
@@ -325,6 +387,14 @@ fn lookup_name_wrapped(&env e, ast.ident i) -> option.t[tup(@env, def_wrap)] {
                 }
             }
 
+            case (scope_native_item(?it)) {
+                alt (it.node) {
+                    case (ast.native_item_fn(_, ?decl, ?ty_params, _, _)) {
+                        ret handle_fn_decl(i, decl, ty_params);
+                    }
+                }
+            }
+
             case (scope_loop(?d)) {
                 alt (d.node) {
                     case (ast.decl_local(?local)) {
@@ -432,8 +502,7 @@ fn fold_expr_path(&env e, &span sp, &ast.path p, &option.t[def] d,
             path_len = n_idents - remaining + 1u;
         }
         case (def_wrap_other(_)) {
-            check (n_idents == 1u);
-            path_len = 1u;
+            path_len = n_idents;
         }
         case (def_wrap_mod(?m)) {
             e.sess.span_err(sp,
@@ -491,6 +560,10 @@ fn update_env_for_item(&env e, @ast.item i) -> env {
     ret rec(scopes = cons[scope](scope_item(i), @e.scopes) with e);
 }
 
+fn update_env_for_native_item(&env e, @ast.native_item i) -> env {
+    ret rec(scopes = cons[scope](scope_native_item(i), @e.scopes) with e);
+}
+
 fn update_env_for_block(&env e, &ast.block b) -> env {
     ret rec(scopes = cons[scope](scope_block(b), @e.scopes) with e);
 }
@@ -500,6 +573,9 @@ fn update_env_for_expr(&env e, @ast.expr x) -> env {
         case (ast.expr_for(?d, _, _, _)) {
             ret rec(scopes = cons[scope](scope_loop(d), @e.scopes) with e);
         }
+        case (ast.expr_for_each(?d, _, _, _)) {
+            ret rec(scopes = cons[scope](scope_loop(d), @e.scopes) with e);
+        }
         case (_) { }
     }
     ret e;
@@ -517,6 +593,8 @@ fn resolve_imports(session.session sess, @ast.crate crate) -> @ast.crate {
                     = bind fold_view_item_import(_,_,import_index,_,_,_,_),
                 update_env_for_crate = bind update_env_for_crate(_,_),
                 update_env_for_item = bind update_env_for_item(_,_),
+                update_env_for_native_item =
+                    bind update_env_for_native_item(_,_),
                 update_env_for_block = bind update_env_for_block(_,_),
                 update_env_for_arm = bind update_env_for_arm(_,_),
                 update_env_for_expr = bind update_env_for_expr(_,_)
@@ -539,6 +617,8 @@ fn resolve_crate(session.session sess, @ast.crate crate) -> @ast.crate {
                 fold_ty_path = bind fold_ty_path(_,_,_,_),
                 update_env_for_crate = bind update_env_for_crate(_,_),
                 update_env_for_item = bind update_env_for_item(_,_),
+                update_env_for_native_item =
+                    bind update_env_for_native_item(_,_),
                 update_env_for_block = bind update_env_for_block(_,_),
                 update_env_for_arm = bind update_env_for_arm(_,_),
                 update_env_for_expr = bind update_env_for_expr(_,_)
diff --git a/src/comp/middle/trans.rs b/src/comp/middle/trans.rs
index c2b0ae48bbc..728f20dd0eb 100644
--- a/src/comp/middle/trans.rs
+++ b/src/comp/middle/trans.rs
@@ -1,3 +1,4 @@
+import std._int;
 import std._str;
 import std._uint;
 import std._vec;
@@ -16,6 +17,7 @@ import back.x86;
 import back.abi;
 
 import middle.ty.pat_ty;
+import middle.ty.plain_ty;
 
 import util.common;
 import util.common.append;
@@ -27,9 +29,11 @@ import lib.llvm.llvm;
 import lib.llvm.builder;
 import lib.llvm.target_data;
 import lib.llvm.type_handle;
+import lib.llvm.type_names;
 import lib.llvm.mk_pass_manager;
 import lib.llvm.mk_target_data;
 import lib.llvm.mk_type_handle;
+import lib.llvm.mk_type_names;
 import lib.llvm.llvm.ModuleRef;
 import lib.llvm.llvm.ValueRef;
 import lib.llvm.llvm.TypeRef;
@@ -53,27 +57,33 @@ type glue_fns = rec(ValueRef activate_glue,
                     vec[ValueRef] upcall_glues,
                     ValueRef no_op_type_glue,
                     ValueRef memcpy_glue,
-                    ValueRef bzero_glue);
+                    ValueRef bzero_glue,
+                    ValueRef vec_append_glue);
 
-tag arity { nullary; n_ary; }
-type tag_info = rec(type_handle th,
-                    mutable vec[tup(ast.def_id,arity)] variants,
-                    mutable uint size);
+type tydesc_info = rec(ValueRef tydesc,
+                       ValueRef take_glue,
+                       ValueRef drop_glue);
 
 state type crate_ctxt = rec(session.session sess,
                             ModuleRef llmod,
                             target_data td,
+                            type_names tn,
                             ValueRef crate_ptr,
                             hashmap[str, ValueRef] upcalls,
                             hashmap[str, ValueRef] intrinsics,
                             hashmap[str, ValueRef] item_names,
                             hashmap[ast.def_id, ValueRef] item_ids,
                             hashmap[ast.def_id, @ast.item] items,
-                            hashmap[ast.def_id, @tag_info] tags,
+                            hashmap[ast.def_id,
+                                    @ast.native_item] native_items,
+                            // TODO: hashmap[tup(tag_id,subtys), @tag_info]
+                            hashmap[@ty.t, uint] tag_sizes,
+                            hashmap[ast.def_id, ValueRef] discrims,
                             hashmap[ast.def_id, ValueRef] fn_pairs,
                             hashmap[ast.def_id, ValueRef] consts,
                             hashmap[ast.def_id,()] obj_methods,
-                            hashmap[@ty.t, ValueRef] tydescs,
+                            hashmap[@ty.t, @tydesc_info] tydescs,
+                            vec[ast.ty_param] obj_typarams,
                             vec[ast.obj_field] obj_fields,
                             @glue_fns glues,
                             namegen names,
@@ -81,9 +91,10 @@ state type crate_ctxt = rec(session.session sess,
 
 state type fn_ctxt = rec(ValueRef llfn,
                          ValueRef lltaskptr,
-                         ValueRef llclosure,
+                         ValueRef llenv,
+                         ValueRef llretptr,
                          mutable option.t[ValueRef] llself,
-                         mutable option.t[ValueRef] llretptr,
+                         mutable option.t[ValueRef] lliterbody,
                          hashmap[ast.def_id, ValueRef] llargs,
                          hashmap[ast.def_id, ValueRef] llobjfields,
                          hashmap[ast.def_id, ValueRef] lllocals,
@@ -119,21 +130,25 @@ tag block_parent {
 state type result = rec(mutable @block_ctxt bcx,
                         mutable ValueRef val);
 
+fn sep() -> str {
+    ret "_";
+}
+
 fn res(@block_ctxt bcx, ValueRef val) -> result {
     ret rec(mutable bcx = bcx,
             mutable val = val);
 }
 
-fn ty_str(TypeRef t) -> str {
-    ret lib.llvm.type_to_str(t);
+fn ty_str(type_names tn, TypeRef t) -> str {
+    ret lib.llvm.type_to_str(tn, t);
 }
 
 fn val_ty(ValueRef v) -> TypeRef {
     ret llvm.LLVMTypeOf(v);
 }
 
-fn val_str(ValueRef v) -> str {
-    ret ty_str(val_ty(v));
+fn val_str(type_names tn, ValueRef v) -> str {
+    ret ty_str(tn, val_ty(v));
 }
 
 
@@ -206,9 +221,9 @@ fn T_fn(vec[TypeRef] inputs, TypeRef output) -> TypeRef {
                               False);
 }
 
-fn T_fn_pair(TypeRef tfn) -> TypeRef {
+fn T_fn_pair(type_names tn, TypeRef tfn) -> TypeRef {
     ret T_struct(vec(T_ptr(tfn),
-                     T_opaque_closure_ptr()));
+                     T_opaque_closure_ptr(tn)));
 }
 
 fn T_ptr(TypeRef t) -> TypeRef {
@@ -225,25 +240,56 @@ fn T_opaque() -> TypeRef {
     ret llvm.LLVMOpaqueType();
 }
 
-fn T_task() -> TypeRef {
-    ret T_struct(vec(T_int(),      // Refcount
-                     T_int(),      // Delegate pointer
-                     T_int(),      // Stack segment pointer
-                     T_int(),      // Runtime SP
-                     T_int(),      // Rust SP
-                     T_int(),      // GC chain
-                     T_int(),      // Domain pointer
-                     T_int()       // Crate cache pointer
-                     ));
+fn T_task(type_names tn) -> TypeRef {
+    auto s = "task";
+    if (tn.name_has_type(s)) {
+        ret tn.get_type(s);
+    }
+
+    auto t = T_struct(vec(T_int(),      // Refcount
+                          T_int(),      // Delegate pointer
+                          T_int(),      // Stack segment pointer
+                          T_int(),      // Runtime SP
+                          T_int(),      // Rust SP
+                          T_int(),      // GC chain
+                          T_int(),      // Domain pointer
+                          T_int()       // Crate cache pointer
+                          ));
+    tn.associate(s, t);
+    ret t;
 }
 
-fn T_tydesc() -> TypeRef {
+fn T_glue_fn(type_names tn) -> TypeRef {
+    auto s = "glue_fn";
+    if (tn.name_has_type(s)) {
+        ret tn.get_type(s);
+    }
+
+    // Bit of a kludge: pick the fn typeref out of the tydesc..
+    let vec[TypeRef] tydesc_elts = _vec.init_elt[TypeRef](T_nil(), 10u);
+    llvm.LLVMGetStructElementTypes(T_tydesc(tn),
+                                   _vec.buf[TypeRef](tydesc_elts));
+    auto t =
+        llvm.LLVMGetElementType
+        (tydesc_elts.(abi.tydesc_field_drop_glue_off));
+    tn.associate(s, t);
+    ret t;
+}
+
+fn T_tydesc(type_names tn) -> TypeRef {
+
+    auto s = "tydesc";
+    if (tn.name_has_type(s)) {
+        ret tn.get_type(s);
+    }
 
     auto th = mk_type_handle();
     auto abs_tydesc = llvm.LLVMResolveTypeHandle(th.llth);
     auto tydescpp = T_ptr(T_ptr(abs_tydesc));
     auto pvoid = T_ptr(T_i8());
-    auto glue_fn_ty = T_ptr(T_fn(vec(T_taskptr(),
+    auto glue_fn_ty = T_ptr(T_fn(vec(T_ptr(T_nil()),
+                                     T_taskptr(tn),
+                                     T_ptr(T_nil()),
                                      tydescpp,
                                      pvoid), T_void()));
     auto tydesc = T_struct(vec(tydescpp,          // first_param
@@ -258,7 +304,9 @@ fn T_tydesc() -> TypeRef {
                                glue_fn_ty));      // is_stateful
 
     llvm.LLVMRefineType(abs_tydesc, tydesc);
-    ret llvm.LLVMResolveTypeHandle(th.llth);
+    auto t = llvm.LLVMResolveTypeHandle(th.llth);
+    tn.associate(s, t);
+    ret t;
 }
 
 fn T_array(TypeRef t, uint n) -> TypeRef {
@@ -273,6 +321,10 @@ fn T_vec(TypeRef t) -> TypeRef {
                      ));
 }
 
+fn T_opaque_vec_ptr() -> TypeRef {
+    ret T_ptr(T_vec(T_int()));
+}
+
 fn T_str() -> TypeRef {
     ret T_vec(T_i8());
 }
@@ -281,165 +333,307 @@ fn T_box(TypeRef t) -> TypeRef {
     ret T_struct(vec(T_int(), t));
 }
 
-fn T_crate() -> TypeRef {
-    ret T_struct(vec(T_int(),      // ptrdiff_t image_base_off
-                     T_int(),      // uintptr_t self_addr
-                     T_int(),      // ptrdiff_t debug_abbrev_off
-                     T_int(),      // size_t debug_abbrev_sz
-                     T_int(),      // ptrdiff_t debug_info_off
-                     T_int(),      // size_t debug_info_sz
-                     T_int(),      // size_t activate_glue_off
-                     T_int(),      // size_t yield_glue_off
-                     T_int(),      // size_t unwind_glue_off
-                     T_int(),      // size_t gc_glue_off
-                     T_int(),      // size_t main_exit_task_glue_off
-                     T_int(),      // int n_rust_syms
-                     T_int(),      // int n_c_syms
-                     T_int()       // int n_libs
-                     ));
+fn T_crate(type_names tn) -> TypeRef {
+    auto s = "crate";
+    if (tn.name_has_type(s)) {
+        ret tn.get_type(s);
+    }
+
+    auto t = T_struct(vec(T_int(),      // ptrdiff_t image_base_off
+                          T_int(),      // uintptr_t self_addr
+                          T_int(),      // ptrdiff_t debug_abbrev_off
+                          T_int(),      // size_t debug_abbrev_sz
+                          T_int(),      // ptrdiff_t debug_info_off
+                          T_int(),      // size_t debug_info_sz
+                          T_int(),      // size_t activate_glue_off
+                          T_int(),      // size_t yield_glue_off
+                          T_int(),      // size_t unwind_glue_off
+                          T_int(),      // size_t gc_glue_off
+                          T_int(),      // size_t main_exit_task_glue_off
+                          T_int(),      // int n_rust_syms
+                          T_int(),      // int n_c_syms
+                          T_int(),      // int n_libs
+                          T_int()       // uintptr_t abi_tag
+                          ));
+    tn.associate(s, t);
+    ret t;
 }
 
 fn T_double() -> TypeRef {
     ret llvm.LLVMDoubleType();
 }
 
-fn T_taskptr() -> TypeRef {
-    ret T_ptr(T_task());
+fn T_taskptr(type_names tn) -> TypeRef {
+    ret T_ptr(T_task(tn));
 }
 
-fn T_typaram_ptr() -> TypeRef {
-    ret T_ptr(T_i8());
+// This type must never be used directly; it must always be cast away.
+fn T_typaram(type_names tn) -> TypeRef {
+    auto s = "typaram";
+    if (tn.name_has_type(s)) {
+        ret tn.get_type(s);
+    }
+
+    auto t = T_i8();
+    tn.associate(s, t);
+    ret t;
 }
 
-fn T_closure_ptr(TypeRef lltarget_ty,
-                 TypeRef llbindings_ty) -> TypeRef {
-    ret T_ptr(T_box(T_struct(vec(T_ptr(T_tydesc()),
+fn T_typaram_ptr(type_names tn) -> TypeRef {
+    ret T_ptr(T_typaram(tn));
+}
+
+fn T_closure_ptr(type_names tn,
+                 TypeRef lltarget_ty,
+                 TypeRef llbindings_ty,
+                 uint n_ty_params) -> TypeRef {
+    ret T_ptr(T_box(T_struct(vec(T_ptr(T_tydesc(tn)),
                                  lltarget_ty,
-                                 llbindings_ty)
-                             // FIXME: add captured typarams.
+                                 llbindings_ty,
+                                 T_captured_tydescs(tn, n_ty_params))
                              )));
 }
 
-fn T_opaque_closure_ptr() -> TypeRef {
-    ret T_closure_ptr(T_struct(vec(T_ptr(T_nil()),
-                                   T_ptr(T_nil()))),
-                      T_nil());
+fn T_opaque_closure_ptr(type_names tn) -> TypeRef {
+    auto s = "*closure";
+    if (tn.name_has_type(s)) {
+        ret tn.get_type(s);
+    }
+    auto t = T_closure_ptr(tn, T_struct(vec(T_ptr(T_nil()),
+                                            T_ptr(T_nil()))),
+                           T_nil(),
+                           0u);
+    tn.associate(s, t);
+    ret t;
+}
+
+fn T_tag(type_names tn, uint size) -> TypeRef {
+    auto s = "tag_" + _uint.to_str(size, 10u);
+    if (tn.name_has_type(s)) {
+        ret tn.get_type(s);
+    }
+    auto t = T_struct(vec(T_int(), T_array(T_i8(), size)));
+    tn.associate(s, t);
+    ret t;
+}
+
+fn T_opaque_tag(type_names tn) -> TypeRef {
+    auto s = "tag";
+    if (tn.name_has_type(s)) {
+        ret tn.get_type(s);
+    }
+    auto t = T_struct(vec(T_int(), T_i8()));
+    tn.associate(s, t);
+    ret t;
+}
+
+fn T_opaque_tag_ptr(type_names tn) -> TypeRef {
+    ret T_ptr(T_opaque_tag(tn));
+}
+
+fn T_captured_tydescs(type_names tn, uint n) -> TypeRef {
+    ret T_struct(_vec.init_elt[TypeRef](T_ptr(T_tydesc(tn)), n));
+}
+
+fn T_obj_ptr(type_names tn, uint n_captured_tydescs) -> TypeRef {
+    // This function is not publicly exposed because it returns an incomplete
+    // type. The dynamically-sized fields follow the captured tydescs.
+    fn T_obj(type_names tn, uint n_captured_tydescs) -> TypeRef {
+        ret T_struct(vec(T_ptr(T_tydesc(tn)),
+                         T_captured_tydescs(tn, n_captured_tydescs)));
+    }
+
+    ret T_ptr(T_box(T_obj(tn, n_captured_tydescs)));
+}
+
+fn T_opaque_obj_ptr(type_names tn) -> TypeRef {
+    ret T_obj_ptr(tn, 0u);
 }
 
 
+// This function now fails if called on a type with dynamic size (as its
+// return value was always meaningless in that case anyhow). Beware!
+//
+// TODO: Enforce via a predicate.
 fn type_of(@crate_ctxt cx, @ty.t t) -> TypeRef {
-    let TypeRef llty = type_of_inner(cx, t);
-    check (llty as int != 0);
-    llvm.LLVMAddTypeName(cx.llmod, _str.buf(ty.ty_to_str(t)), llty);
-    ret llty;
+    if (ty.type_has_dynamic_size(t)) {
+        log "type_of() called on a type with dynamic size: " +
+            ty.ty_to_str(t);
+        fail;
+    }
+
+    ret type_of_inner(cx, t, false);
+}
+
+fn type_of_explicit_args(@crate_ctxt cx,
+                     vec[ty.arg] inputs) -> vec[TypeRef] {
+    let vec[TypeRef] atys = vec();
+    for (ty.arg arg in inputs) {
+        if (ty.type_has_dynamic_size(arg.ty)) {
+            check (arg.mode == ast.alias);
+            atys += T_typaram_ptr(cx.tn);
+        } else {
+            let TypeRef t;
+            alt (arg.mode) {
+                case (ast.alias) {
+                    t = T_ptr(type_of_inner(cx, arg.ty, true));
+                }
+                case (_) {
+                    t = type_of_inner(cx, arg.ty, false);
+                }
+            }
+            atys += t;
+        }
+    }
+    ret atys;
 }
 
-// NB: this must match trans_args and create_llargs_for_fn_args.
+// NB: must keep 4 fns in sync:
+//
+//  - type_of_fn_full
+//  - create_llargs_for_fn_args.
+//  - new_fn_ctxt
+//  - trans_args
+
 fn type_of_fn_full(@crate_ctxt cx,
+                   ast.proto proto,
                    option.t[TypeRef] obj_self,
                    vec[ty.arg] inputs,
                    @ty.t output) -> TypeRef {
-    let vec[TypeRef] atys = vec(T_taskptr());
-
-    auto fn_ty = ty.plain_ty(ty.ty_fn(inputs, output));
-    auto ty_param_count = ty.count_ty_params(fn_ty);
-    auto i = 0u;
-    while (i < ty_param_count) {
-        atys += T_ptr(T_tydesc());
-        i += 1u;
-    }
+    let vec[TypeRef] atys = vec();
 
+    // Arg 0: Output pointer.
     if (ty.type_has_dynamic_size(output)) {
-        atys += T_typaram_ptr();
+        atys += T_typaram_ptr(cx.tn);
+    } else {
+        atys += T_ptr(type_of_inner(cx, output, false));
     }
 
+    // Arg 1: Task pointer.
+    atys += T_taskptr(cx.tn);
+
+    // Arg 2: Env (closure-bindings / self-obj)
     alt (obj_self) {
         case (some[TypeRef](?t)) {
             check (t as int != 0);
             atys += t;
         }
         case (_) {
-            atys += T_opaque_closure_ptr();
+            atys += T_opaque_closure_ptr(cx.tn);
         }
     }
 
-    for (ty.arg arg in inputs) {
-        if (ty.type_has_dynamic_size(arg.ty)) {
-            check (arg.mode == ast.alias);
-            atys += T_typaram_ptr();
-        } else {
-            let TypeRef t = type_of(cx, arg.ty);
-            alt (arg.mode) {
-                case (ast.alias) {
-                    t = T_ptr(t);
-                }
-                case (_) { /* fall through */  }
-            }
-            atys += t;
+    // Args >3: ty params, if not acquired via capture...
+    if (obj_self == none[TypeRef]) {
+        auto ty_param_count =
+            ty.count_ty_params(plain_ty(ty.ty_fn(proto,
+                                                 inputs,
+                                                 output)));
+        auto i = 0u;
+        while (i < ty_param_count) {
+            atys += T_ptr(T_tydesc(cx.tn));
+            i += 1u;
         }
     }
 
-    auto ret_ty;
-    if (ty.type_is_nil(output) || ty.type_has_dynamic_size(output)) {
-        ret_ty = llvm.LLVMVoidType();
-    } else {
-        ret_ty = type_of(cx, output);
+    if (proto == ast.proto_iter) {
+        // If it's an iter, the 'output' type of the iter is actually the
+        // *input* type of the function we're given as our iter-block
+        // argument.
+        atys += T_fn_pair(cx.tn,
+                          type_of_fn_full(cx, ast.proto_fn, none[TypeRef],
+                                          vec(rec(mode=ast.val, ty=output)),
+                                          plain_ty(ty.ty_nil)));
     }
 
-    ret T_fn(atys, ret_ty);
+    // ... then explicit args.
+    atys += type_of_explicit_args(cx, inputs);
+
+    ret T_fn(atys, llvm.LLVMVoidType());
 }
 
-fn type_of_fn(@crate_ctxt cx, vec[ty.arg] inputs, @ty.t output) -> TypeRef {
-    ret type_of_fn_full(cx, none[TypeRef], inputs, output);
+fn type_of_fn(@crate_ctxt cx,
+              ast.proto proto,
+              vec[ty.arg] inputs, @ty.t output) -> TypeRef {
+    ret type_of_fn_full(cx, proto, none[TypeRef], inputs, output);
+}
+
+fn type_of_native_fn(@crate_ctxt cx, ast.native_abi abi,
+                     vec[ty.arg] inputs,
+                     @ty.t output) -> TypeRef {
+    let vec[TypeRef] atys = vec();
+    if (abi == ast.native_abi_rust) {
+        atys += T_taskptr(cx.tn);
+        auto t = ty.ty_native_fn(abi, inputs, output);
+        auto ty_param_count = ty.count_ty_params(plain_ty(t));
+        auto i = 0u;
+        while (i < ty_param_count) {
+            atys += T_ptr(T_tydesc(cx.tn));
+            i += 1u;
+        }
+    }
+    atys += type_of_explicit_args(cx, inputs);
+    ret T_fn(atys, type_of_inner(cx, output, false));
 }
 
-fn type_of_inner(@crate_ctxt cx, @ty.t t) -> TypeRef {
+fn type_of_inner(@crate_ctxt cx, @ty.t t, bool boxed) -> TypeRef {
+    let TypeRef llty = 0 as TypeRef;
+
     alt (t.struct) {
-        case (ty.ty_nil) { ret T_nil(); }
-        case (ty.ty_bool) { ret T_bool(); }
-        case (ty.ty_int) { ret T_int(); }
-        case (ty.ty_uint) { ret T_int(); }
+        case (ty.ty_native) { llty = T_ptr(T_i8()); }
+        case (ty.ty_nil) { llty = T_nil(); }
+        case (ty.ty_bool) { llty = T_bool(); }
+        case (ty.ty_int) { llty = T_int(); }
+        case (ty.ty_uint) { llty = T_int(); }
         case (ty.ty_machine(?tm)) {
             alt (tm) {
-                case (common.ty_i8) { ret T_i8(); }
-                case (common.ty_u8) { ret T_i8(); }
-                case (common.ty_i16) { ret T_i16(); }
-                case (common.ty_u16) { ret T_i16(); }
-                case (common.ty_i32) { ret T_i32(); }
-                case (common.ty_u32) { ret T_i32(); }
-                case (common.ty_i64) { ret T_i64(); }
-                case (common.ty_u64) { ret T_i64(); }
-                case (common.ty_f32) { ret T_f32(); }
-                case (common.ty_f64) { ret T_f64(); }
+                case (common.ty_i8) { llty = T_i8(); }
+                case (common.ty_u8) { llty = T_i8(); }
+                case (common.ty_i16) { llty = T_i16(); }
+                case (common.ty_u16) { llty = T_i16(); }
+                case (common.ty_i32) { llty = T_i32(); }
+                case (common.ty_u32) { llty = T_i32(); }
+                case (common.ty_i64) { llty = T_i64(); }
+                case (common.ty_u64) { llty = T_i64(); }
+                case (common.ty_f32) { llty = T_f32(); }
+                case (common.ty_f64) { llty = T_f64(); }
             }
         }
-        case (ty.ty_char) { ret T_char(); }
-        case (ty.ty_str) { ret T_ptr(T_str()); }
-        case (ty.ty_tag(?tag_id)) {
-            ret llvm.LLVMResolveTypeHandle(cx.tags.get(tag_id).th.llth);
+        case (ty.ty_char) { llty = T_char(); }
+        case (ty.ty_str) { llty = T_ptr(T_str()); }
+        case (ty.ty_tag(_, _)) {
+            if (boxed) {
+                llty = T_opaque_tag(cx.tn);
+            } else {
+                auto size = static_size_of_tag(cx, t);
+                llty = T_tag(cx.tn, size);
+            }
         }
         case (ty.ty_box(?t)) {
-            ret T_ptr(T_box(type_of(cx, t)));
+            llty = T_ptr(T_box(type_of_inner(cx, t, true)));
         }
         case (ty.ty_vec(?t)) {
-            ret T_ptr(T_vec(type_of(cx, t)));
+            llty = T_ptr(T_vec(type_of_inner(cx, t, true)));
         }
         case (ty.ty_tup(?elts)) {
             let vec[TypeRef] tys = vec();
             for (@ty.t elt in elts) {
-                tys += type_of(cx, elt);
+                tys += type_of_inner(cx, elt, boxed);
             }
-            ret T_struct(tys);
+            llty = T_struct(tys);
         }
         case (ty.ty_rec(?fields)) {
             let vec[TypeRef] tys = vec();
             for (ty.field f in fields) {
-                tys += type_of(cx, f.ty);
+                tys += type_of_inner(cx, f.ty, boxed);
             }
-            ret T_struct(tys);
+            llty = T_struct(tys);
         }
-        case (ty.ty_fn(?args, ?out)) {
-            ret T_fn_pair(type_of_fn(cx, args, out));
+        case (ty.ty_fn(?proto, ?args, ?out)) {
+            llty = T_fn_pair(cx.tn, type_of_fn(cx, proto, args, out));
+        }
+        case (ty.ty_native_fn(?abi, ?args, ?out)) {
+            llty = T_fn_pair(cx.tn, type_of_native_fn(cx, abi, args, out));
         }
         case (ty.ty_obj(?meths)) {
             auto th = mk_type_handle();
@@ -448,39 +642,54 @@ fn type_of_inner(@crate_ctxt cx, @ty.t t) -> TypeRef {
             let vec[TypeRef] mtys = vec();
             for (ty.method m in meths) {
                 let TypeRef mty =
-                    type_of_fn_full(cx,
+                    type_of_fn_full(cx, m.proto,
                                     some[TypeRef](self_ty),
                                     m.inputs, m.output);
                 mtys += T_ptr(mty);
             }
             let TypeRef vtbl = T_struct(mtys);
-            let TypeRef body = T_struct(vec(T_ptr(T_tydesc()),
-                                            T_nil()));
-            let TypeRef pair =
-                T_struct(vec(T_ptr(vtbl),
-                             T_ptr(T_box(body))));
+            let TypeRef pair = T_struct(vec(T_ptr(vtbl),
+                                            T_opaque_obj_ptr(cx.tn)));
+
             auto abs_pair = llvm.LLVMResolveTypeHandle(th.llth);
             llvm.LLVMRefineType(abs_pair, pair);
             abs_pair = llvm.LLVMResolveTypeHandle(th.llth);
-            ret abs_pair;
+            llty = abs_pair;
         }
         case (ty.ty_var(_)) {
             log "ty_var in trans.type_of";
             fail;
         }
         case (ty.ty_param(_)) {
-            ret T_typaram_ptr();
+            llty = T_i8();
         }
+        case (ty.ty_type) { llty = T_ptr(T_tydesc(cx.tn)); }
     }
-    fail;
+
+    check (llty as int != 0);
+    llvm.LLVMAddTypeName(cx.llmod, _str.buf(ty.ty_to_str(t)), llty);
+    ret llty;
 }
 
 fn type_of_arg(@crate_ctxt cx, &ty.arg arg) -> TypeRef {
-    auto ty = type_of(cx, arg.ty);
+    alt (arg.ty.struct) {
+        case (ty.ty_param(_)) {
+            if (arg.mode == ast.alias) {
+                ret T_typaram_ptr(cx.tn);
+            }
+        }
+        case (_) {
+            // fall through
+        }
+    }
+
+    auto typ;
     if (arg.mode == ast.alias) {
-        ty = T_ptr(ty);
+        typ = T_ptr(type_of_inner(cx, arg.ty, true));
+    } else {
+        typ = type_of_inner(cx, arg.ty, false);
     }
-    ret ty;
+    ret typ;
 }
 
 // Name sanitation. LLVM will happily accept identifiers with weird names, but
@@ -606,11 +815,11 @@ fn decl_fastcall_fn(ModuleRef llmod, str name, TypeRef llty) -> ValueRef {
     ret decl_fn(llmod, name, lib.llvm.LLVMFastCallConv, llty);
 }
 
-fn decl_glue(ModuleRef llmod, str s) -> ValueRef {
-    ret decl_cdecl_fn(llmod, s, T_fn(vec(T_taskptr()), T_void()));
+fn decl_glue(ModuleRef llmod, type_names tn, str s) -> ValueRef {
+    ret decl_cdecl_fn(llmod, s, T_fn(vec(T_taskptr(tn)), T_void()));
 }
 
-fn decl_upcall(ModuleRef llmod, uint _n) -> ValueRef {
+fn decl_upcall_glue(ModuleRef llmod, type_names tn, uint _n) -> ValueRef {
     // It doesn't actually matter what type we come up with here, at the
     // moment, as we cast the upcall function pointers to int before passing
     // them to the indirect upcall-invocation glue.  But eventually we'd like
@@ -618,7 +827,7 @@ fn decl_upcall(ModuleRef llmod, uint _n) -> ValueRef {
     let int n = _n as int;
     let str s = abi.upcall_glue_name(n);
     let vec[TypeRef] args =
-        vec(T_taskptr(), // taskptr
+        vec(T_taskptr(tn), // taskptr
             T_int())     // callee
         + _vec.init_elt[TypeRef](T_int(), n as uint);
 
@@ -629,7 +838,7 @@ fn get_upcall(@crate_ctxt cx, str name, int n_args) -> ValueRef {
     if (cx.upcalls.contains_key(name)) {
         ret cx.upcalls.get(name);
     }
-    auto inputs = vec(T_taskptr());
+    auto inputs = vec(T_taskptr(cx.tn));
     inputs += _vec.init_elt[TypeRef](T_int(), n_args as uint);
     auto output = T_int();
     auto f = decl_cdecl_fn(cx.llmod, name, T_fn(inputs, output));
@@ -644,14 +853,16 @@ fn trans_upcall(@block_ctxt cx, str name, vec[ValueRef] args) -> result {
 
     let ValueRef llglue = cx.fcx.ccx.glues.upcall_glues.(n);
     let vec[ValueRef] call_args = vec(cx.fcx.lltaskptr, llupcall);
+
     for (ValueRef a in args) {
         call_args += cx.build.ZExtOrBitCast(a, T_int());
     }
+
     ret res(cx, cx.build.FastCall(llglue, call_args));
 }
 
 fn trans_non_gc_free(@block_ctxt cx, ValueRef v) -> result {
-    ret trans_upcall(cx, "upcall_free", vec(cx.build.PtrToInt(v, T_int()),
+    ret trans_upcall(cx, "upcall_free", vec(vp2i(cx, v),
                                             C_int(0)));
 }
 
@@ -680,6 +891,11 @@ fn align_to(@block_ctxt cx, ValueRef off, ValueRef align) -> ValueRef {
     ret cx.build.And(bumped, cx.build.Not(mask));
 }
 
+// Returns the real size of the given type for the current target.
+fn llsize_of_real(@crate_ctxt cx, TypeRef t) -> uint {
+    ret llvm.LLVMStoreSizeOfType(cx.td.lltd, t);
+}
+
 fn llsize_of(TypeRef t) -> ValueRef {
     ret llvm.LLVMConstIntCast(lib.llvm.llvm.LLVMSizeOf(t), T_int(), False);
 }
@@ -702,51 +918,111 @@ fn align_of(@block_ctxt cx, @ty.t t) -> result {
     ret dynamic_align_of(cx, t);
 }
 
+// Computes the size of the data part of a non-dynamically-sized tag.
+fn static_size_of_tag(@crate_ctxt cx, @ty.t t) -> uint {
+    if (ty.type_has_dynamic_size(t)) {
+        log "dynamically sized type passed to static_size_of_tag()";
+        fail;
+    }
+
+    if (cx.tag_sizes.contains_key(t)) {
+        ret cx.tag_sizes.get(t);
+    }
+
+    auto tid;
+    let vec[@ty.t] subtys;
+    alt (t.struct) {
+        case (ty.ty_tag(?tid_, ?subtys_)) {
+            tid = tid_;
+            subtys = subtys_;
+        }
+        case (_) {
+            log "non-tag passed to static_size_of_tag()";
+            fail;
+        }
+    }
+
+    // Compute max(variant sizes).
+    auto max_size = 0u;
+    auto variants = tag_variants(cx, tid);
+    for (ast.variant variant in variants) {
+        let vec[@ty.t] tys = variant_types(cx, variant);
+        auto tup_ty = ty.plain_ty(ty.ty_tup(tys));
+
+        // Here we possibly do a recursive call.
+        auto this_size = llsize_of_real(cx, type_of(cx, tup_ty));
+
+        if (max_size < this_size) {
+            max_size = this_size;
+        }
+    }
+
+    cx.tag_sizes.insert(t, max_size);
+    ret max_size;
+}
+
 fn dynamic_size_of(@block_ctxt cx, @ty.t t) -> result {
+    fn align_elements(@block_ctxt cx, vec[@ty.t] elts) -> result {
+        //
+        // C padding rules:
+        //
+        //
+        //   - Pad after each element so that next element is aligned.
+        //   - Pad after final structure member so that whole structure
+        //     is aligned to max alignment of interior.
+        //
+        auto off = C_int(0);
+        auto max_align = C_int(1);
+        auto bcx = cx;
+        for (@ty.t e in elts) {
+            auto elt_align = align_of(bcx, e);
+            bcx = elt_align.bcx;
+            auto elt_size = size_of(bcx, e);
+            bcx = elt_size.bcx;
+            auto aligned_off = align_to(bcx, off, elt_align.val);
+            off = cx.build.Add(aligned_off, elt_size.val);
+            max_align = umax(bcx, max_align, elt_align.val);
+        }
+        off = align_to(bcx, off, max_align);
+        ret res(bcx, off);
+    }
+
     alt (t.struct) {
         case (ty.ty_param(?p)) {
             auto szptr = field_of_tydesc(cx, t, abi.tydesc_field_size);
             ret res(szptr.bcx, szptr.bcx.build.Load(szptr.val));
         }
         case (ty.ty_tup(?elts)) {
-            //
-            // C padding rules:
-            //
-            //
-            //   - Pad after each element so that next element is aligned.
-            //   - Pad after final structure member so that whole structure
-            //     is aligned to max alignment of interior.
-            //
-            auto off = C_int(0);
-            auto max_align = C_int(1);
-            auto bcx = cx;
-            for (@ty.t e in elts) {
-                auto elt_align = align_of(bcx, e);
-                bcx = elt_align.bcx;
-                auto elt_size = size_of(bcx, e);
-                bcx = elt_size.bcx;
-                auto aligned_off = align_to(bcx, off, elt_align.val);
-                off = cx.build.Add(aligned_off, elt_size.val);
-                max_align = umax(bcx, max_align, elt_align.val);
-            }
-            off = align_to(bcx, off, max_align);
-            ret res(bcx, off);
+            ret align_elements(cx, elts);
         }
         case (ty.ty_rec(?flds)) {
-            auto off = C_int(0);
-            auto max_align = C_int(1);
-            auto bcx = cx;
+            let vec[@ty.t] tys = vec();
             for (ty.field f in flds) {
-                auto elt_align = align_of(bcx, f.ty);
-                bcx = elt_align.bcx;
-                auto elt_size = size_of(bcx, f.ty);
-                bcx = elt_size.bcx;
-                auto aligned_off = align_to(bcx, off, elt_align.val);
-                off = cx.build.Add(aligned_off, elt_size.val);
-                max_align = umax(bcx, max_align, elt_align.val);
+                tys += vec(f.ty);
             }
-            off = align_to(bcx, off, max_align);
-            ret res(bcx, off);
+            ret align_elements(cx, tys);
+        }
+        case (ty.ty_tag(?tid, ?tps)) {
+            auto bcx = cx;
+
+            // Compute max(variant sizes).
+            let ValueRef max_size = bcx.build.Alloca(T_int());
+            bcx.build.Store(C_int(0), max_size);
+
+            auto variants = tag_variants(bcx.fcx.ccx, tid);
+            for (ast.variant variant in variants) {
+                let vec[@ty.t] tys = variant_types(bcx.fcx.ccx, variant);
+                auto rslt = align_elements(bcx, tys);
+                bcx = rslt.bcx;
+
+                auto this_size = rslt.val;
+                auto old_max_size = bcx.build.Load(max_size);
+                bcx.build.Store(umax(bcx, this_size, old_max_size), max_size);
+            }
+
+            auto max_size_val = bcx.build.Load(max_size);
+            auto total_size = bcx.build.Add(max_size_val, llsize_of(T_int()));
+            ret res(bcx, total_size);
         }
     }
 }
@@ -781,10 +1057,10 @@ fn dynamic_align_of(@block_ctxt cx, @ty.t t) -> result {
 }
 
 // Replacement for the LLVM 'GEP' instruction when field-indexing into a
-// tuple-like structure (tup, rec, tag) with a static index. This one is
-// driven off ty.struct and knows what to do when it runs into a ty_param
-// stuck in the middle of the thing it's GEP'ing into. Much like size_of and
-// align_of, above.
+// tuple-like structure (tup, rec) with a static index. This one is driven off
+// ty.struct and knows what to do when it runs into a ty_param stuck in the
+// middle of the thing it's GEP'ing into. Much like size_of and align_of,
+// above.
 
 fn GEP_tup_like(@block_ctxt cx, @ty.t t,
                 ValueRef base, vec[int] ixs) -> result {
@@ -868,38 +1144,86 @@ fn GEP_tup_like(@block_ctxt cx, @ty.t t,
     // flattened the incoming structure.
 
     auto s = split_type(t, ixs, 0u);
-    auto prefix_ty = ty.plain_ty(ty.ty_tup(s.prefix));
+    auto prefix_ty = plain_ty(ty.ty_tup(s.prefix));
     auto bcx = cx;
     auto sz = size_of(bcx, prefix_ty);
     bcx = sz.bcx;
     auto raw = bcx.build.PointerCast(base, T_ptr(T_i8()));
     auto bumped = bcx.build.GEP(raw, vec(sz.val));
-    alt (s.target.struct) {
-        case (ty.ty_param(_)) { ret res(bcx, bumped); }
-        case (_) {
-            auto ty = T_ptr(type_of(bcx.fcx.ccx, s.target));
-            ret res(bcx, bcx.build.PointerCast(bumped, ty));
+
+    if (ty.type_has_dynamic_size(s.target)) {
+        ret res(bcx, bumped);
+    }
+
+    auto typ = T_ptr(type_of(bcx.fcx.ccx, s.target));
+    ret res(bcx, bcx.build.PointerCast(bumped, typ));
+}
+
+// Replacement for the LLVM 'GEP' instruction when field indexing into a tag.
+// This function uses GEP_tup_like() above and automatically performs casts as
+// appropriate. @llblobptr is the data part of a tag value; its actual type is
+// meaningless, as it will be cast away.
+fn GEP_tag(@block_ctxt cx, ValueRef llblobptr, &ast.variant variant, int ix)
+        -> result {
+    // Synthesize a tuple type so that GEP_tup_like() can work its magic.
+    // Separately, store the type of the element we're interested in.
+    auto arg_tys = arg_tys_of_fn(variant.ann);
+    auto elem_ty = ty.plain_ty(ty.ty_nil);  // typestate infelicity
+    auto i = 0;
+    let vec[@ty.t] true_arg_tys = vec();
+    for (ty.arg a in arg_tys) {
+        true_arg_tys += vec(a.ty);
+        if (i == ix) {
+            elem_ty = a.ty;
         }
+
+        i += 1;
     }
+    auto tup_ty = ty.plain_ty(ty.ty_tup(true_arg_tys));
+
+    // Cast the blob pointer to the appropriate type, if we need to (i.e. if
+    // the blob pointer isn't dynamically sized).
+    let ValueRef llunionptr;
+    if (!ty.type_has_dynamic_size(tup_ty)) {
+        auto llty = type_of(cx.fcx.ccx, tup_ty);
+        llunionptr = cx.build.TruncOrBitCast(llblobptr, T_ptr(llty));
+    } else {
+        llunionptr = llblobptr;
+    }
+
+    // Do the GEP_tup_like().
+    auto rslt = GEP_tup_like(cx, tup_ty, llunionptr, vec(0, ix));
+
+    // Cast the result to the appropriate type, if necessary.
+    auto val;
+    if (!ty.type_has_dynamic_size(elem_ty)) {
+        auto llelemty = type_of(rslt.bcx.fcx.ccx, elem_ty);
+        val = rslt.bcx.build.PointerCast(rslt.val, T_ptr(llelemty));
+    } else {
+        val = rslt.val;
+    }
+
+    ret res(rslt.bcx, val);
 }
 
 
-fn trans_malloc_inner(@block_ctxt cx, TypeRef llptr_ty) -> result {
-    auto llbody_ty = lib.llvm.llvm.LLVMGetElementType(llptr_ty);
+fn trans_raw_malloc(@block_ctxt cx, TypeRef llptr_ty, ValueRef llsize)
+        -> result {
     // FIXME: need a table to collect tydesc globals.
     auto tydesc = C_int(0);
-    auto sz = llsize_of(llbody_ty);
-    auto sub = trans_upcall(cx, "upcall_malloc", vec(sz, tydesc));
-    sub.val = sub.bcx.build.IntToPtr(sub.val, llptr_ty);
-    ret sub;
+    auto rslt = trans_upcall(cx, "upcall_malloc", vec(llsize, tydesc));
+    rslt = res(rslt.bcx, vi2p(cx, rslt.val, llptr_ty));
+    ret rslt;
 }
 
-fn trans_malloc(@block_ctxt cx, @ty.t t) -> result {
-    auto scope_cx = find_scope_cx(cx);
-    auto llptr_ty = type_of(cx.fcx.ccx, t);
-    auto sub = trans_malloc_inner(cx, llptr_ty);
-    scope_cx.cleanups += clean(bind drop_ty(_, sub.val, t));
-    ret sub;
+fn trans_malloc_boxed(@block_ctxt cx, @ty.t t) -> result {
+    // Synthesize a fake box type structurally so we have something
+    // to measure the size of.
+    auto boxed_body = plain_ty(ty.ty_tup(vec(plain_ty(ty.ty_int), t)));
+    auto box_ptr = plain_ty(ty.ty_box(t));
+    auto sz = size_of(cx, boxed_body);
+    auto llty = type_of(cx.fcx.ccx, box_ptr);
+    ret trans_raw_malloc(sz.bcx, llty, sz.val);
 }
 
 
@@ -941,6 +1265,7 @@ fn linearize_ty_params(@block_ctxt cx, @ty.t t)
                         r.defs += pid;
                     }
                 }
+                case (_) { }
             }
             ret t;
         }
@@ -960,6 +1285,7 @@ fn get_tydesc(&@block_ctxt cx, @ty.t t) -> result {
     // Is the supplied type a type param? If so, return the passed-in tydesc.
     alt (ty.type_param(t)) {
         case (some[ast.def_id](?id)) {
+            check (cx.fcx.lltydescs.contains_key(id));
             ret res(cx, cx.fcx.lltydescs.get(id));
         }
         case (none[ast.def_id])      { /* fall through */ }
@@ -975,16 +1301,23 @@ fn get_tydesc(&@block_ctxt cx, @ty.t t) -> result {
         check (n_params == _vec.len[ValueRef](tys._1));
 
         if (!cx.fcx.ccx.tydescs.contains_key(t)) {
-            make_tydesc(cx.fcx.ccx, t, tys._0);
+            declare_tydesc(cx.fcx.ccx, t);
+            define_tydesc(cx.fcx.ccx, t, tys._0);
         }
 
-        auto root = cx.fcx.ccx.tydescs.get(t);
+        auto root = cx.fcx.ccx.tydescs.get(t).tydesc;
+
+        auto tydescs = cx.build.Alloca(T_array(T_ptr(T_tydesc(cx.fcx.ccx.tn)),
+                                               n_params));
 
-        auto tydescs = cx.build.Alloca(T_array(T_ptr(T_tydesc()), n_params));
         auto i = 0;
+        auto tdp = cx.build.GEP(tydescs, vec(C_int(0), C_int(i)));
+        cx.build.Store(root, tdp);
+        i += 1;
         for (ValueRef td in tys._1) {
             auto tdp = cx.build.GEP(tydescs, vec(C_int(0), C_int(i)));
             cx.build.Store(td, tdp);
+            i += 1;
         }
 
         auto bcx = cx;
@@ -997,75 +1330,121 @@ fn get_tydesc(&@block_ctxt cx, @ty.t t) -> result {
                               vec(p2i(bcx.fcx.ccx.crate_ptr),
                                   sz.val,
                                   align.val,
-                                  C_int(n_params as int),
-                                  bcx.build.PtrToInt(tydescs, T_int())));
+                                  C_int((1u + n_params) as int),
+                                  vp2i(bcx, tydescs)));
 
-        ret res(v.bcx, v.bcx.build.IntToPtr(v.val, T_ptr(T_tydesc())));
+        ret res(v.bcx, vi2p(v.bcx, v.val,
+                            T_ptr(T_tydesc(cx.fcx.ccx.tn))));
     }
 
     // Otherwise, generate a tydesc if necessary, and return it.
     if (!cx.fcx.ccx.tydescs.contains_key(t)) {
         let vec[ast.def_id] defs = vec();
-        make_tydesc(cx.fcx.ccx, t, defs);
+        declare_tydesc(cx.fcx.ccx, t);
+        define_tydesc(cx.fcx.ccx, t, defs);
     }
-    ret res(cx, cx.fcx.ccx.tydescs.get(t));
+    ret res(cx, cx.fcx.ccx.tydescs.get(t).tydesc);
 }
 
-fn make_tydesc(@crate_ctxt cx, @ty.t t, vec[ast.def_id] typaram_defs) {
-    auto tg = make_take_glue;
-    auto take_glue = make_generic_glue(cx, t, "take", tg, typaram_defs);
-    auto dg = make_drop_glue;
-    auto drop_glue = make_generic_glue(cx, t, "drop", dg, typaram_defs);
+// Generates the declaration for (but doesn't fill in) a type descriptor. This
+// needs to be separate from make_tydesc() below, because sometimes type glue
+// functions needs to refer to their own type descriptors.
+fn declare_tydesc(@crate_ctxt cx, @ty.t t) {
+    auto take_glue = declare_generic_glue(cx, t, "take");
+    auto drop_glue = declare_generic_glue(cx, t, "drop");
 
-    auto llty = type_of(cx, t);
-    auto pvoid = T_ptr(T_i8());
-    auto glue_fn_ty = T_ptr(T_fn(vec(T_taskptr(),
-                                     T_ptr(T_ptr(T_tydesc())),
-                                     pvoid), T_void()));
-    auto tydesc = C_struct(vec(C_null(T_ptr(T_ptr(T_tydesc()))),
-                               llsize_of(llty),
-                               llalign_of(llty),
-                               take_glue,             // take_glue_off
-                               drop_glue,             // drop_glue_off
+    auto llsize;
+    auto llalign;
+    if (!ty.type_has_dynamic_size(t)) {
+        auto llty = type_of(cx, t);
+        llsize = llsize_of(llty);
+        llalign = llalign_of(llty);
+    } else {
+        // These will be overwritten as the derived tydesc is generated, so
+        // we create placeholder values.
+        llsize = C_int(0);
+        llalign = C_int(0);
+    }
+
+    auto glue_fn_ty = T_ptr(T_glue_fn(cx.tn));
+
+    // FIXME: this adjustment has to do with the ridiculous encoding of
+    // glue-pointer-constants in the tydesc records: They are tydesc-relative
+    // displacements.  This is purely for compatibility with rustboot and
+    // should go when it is discarded.
+    fn off(ValueRef tydescp,
+           ValueRef gluefn) -> ValueRef {
+        ret i2p(llvm.LLVMConstSub(p2i(gluefn), p2i(tydescp)),
+                val_ty(gluefn));
+    }
+
+    auto name = sanitize(cx.names.next("tydesc_" + ty.ty_to_str(t)));
+    auto gvar = llvm.LLVMAddGlobal(cx.llmod, T_tydesc(cx.tn),
+                                   _str.buf(name));
+    auto tydesc = C_struct(vec(C_null(T_ptr(T_ptr(T_tydesc(cx.tn)))),
+                               llsize,
+                               llalign,
+                               off(gvar, take_glue),  // take_glue_off
+                               off(gvar, drop_glue),  // drop_glue_off
                                C_null(glue_fn_ty),    // free_glue_off
                                C_null(glue_fn_ty),    // sever_glue_off
                                C_null(glue_fn_ty),    // mark_glue_off
                                C_null(glue_fn_ty),    // obj_drop_glue_off
                                C_null(glue_fn_ty)));  // is_stateful
 
-    auto name = sanitize(cx.names.next("tydesc_" + ty.ty_to_str(t)));
-    auto gvar = llvm.LLVMAddGlobal(cx.llmod, val_ty(tydesc), _str.buf(name));
     llvm.LLVMSetInitializer(gvar, tydesc);
     llvm.LLVMSetGlobalConstant(gvar, True);
     llvm.LLVMSetLinkage(gvar, lib.llvm.LLVMPrivateLinkage
                         as llvm.Linkage);
-    cx.tydescs.insert(t, gvar);
+
+    auto info = rec(
+        tydesc=gvar,
+        take_glue=take_glue,
+        drop_glue=drop_glue
+    );
+
+    cx.tydescs.insert(t, @info);
 }
 
-fn make_generic_glue(@crate_ctxt cx, @ty.t t, str name,
-                     val_and_ty_fn helper,
-                     vec[ast.def_id] typaram_defs) -> ValueRef {
-    auto llfnty = T_fn(vec(T_taskptr(),
-                           T_ptr(T_ptr(T_tydesc())),
-                           T_ptr(T_i8())), T_void());
+// declare_tydesc() above must have been called first.
+fn define_tydesc(@crate_ctxt cx, @ty.t t, vec[ast.def_id] typaram_defs) {
+    auto info = cx.tydescs.get(t);
+    auto gvar = info.tydesc;
+
+    auto tg = make_take_glue;
+    auto take_glue = make_generic_glue(cx, t, info.take_glue, tg,
+                                       typaram_defs);
+    auto dg = make_drop_glue;
+    auto drop_glue = make_generic_glue(cx, t, info.drop_glue, dg,
+                                       typaram_defs);
+}
 
-    auto fn_name = cx.names.next("_rust_" + name) + "." + ty.ty_to_str(t);
+fn declare_generic_glue(@crate_ctxt cx, @ty.t t, str name) -> ValueRef {
+    auto llfnty = T_glue_fn(cx.tn);
+
+    auto fn_name = cx.names.next("_rust_" + name) + sep() + ty.ty_to_str(t);
     fn_name = sanitize(fn_name);
-    auto llfn = decl_fastcall_fn(cx.llmod, fn_name, llfnty);
+    ret decl_fastcall_fn(cx.llmod, fn_name, llfnty);
+}
 
-    auto fcx = new_fn_ctxt(cx, fn_name, llfn);
+fn make_generic_glue(@crate_ctxt cx, @ty.t t, ValueRef llfn,
+                     val_and_ty_fn helper,
+                     vec[ast.def_id] typaram_defs) -> ValueRef {
+    auto fcx = new_fn_ctxt(cx, llfn);
     auto bcx = new_top_block_ctxt(fcx);
 
     auto re;
     if (!ty.type_is_scalar(t)) {
         auto llty;
-        if (ty.type_is_structural(t)) {
+        if (ty.type_has_dynamic_size(t)) {
+            llty = T_ptr(T_i8());
+        } else if (ty.type_is_structural(t)) {
             llty = T_ptr(type_of(cx, t));
         } else {
             llty = type_of(cx, t);
         }
 
-        auto lltyparams = llvm.LLVMGetParam(llfn, 1u);
+        auto lltyparams = llvm.LLVMGetParam(llfn, 3u);
         auto p = 0;
         for (ast.def_id d in typaram_defs) {
             auto llparam = bcx.build.GEP(lltyparams, vec(C_int(p)));
@@ -1074,7 +1453,7 @@ fn make_generic_glue(@crate_ctxt cx, @ty.t t, str name,
             p += 1;
         }
 
-        auto llrawptr = llvm.LLVMGetParam(llfn, 2u);
+        auto llrawptr = llvm.LLVMGetParam(llfn, 4u);
         auto llval = bcx.build.BitCast(llrawptr, llty);
 
         re = helper(bcx, llval, t);
@@ -1166,16 +1545,12 @@ fn make_drop_glue(@block_ctxt cx, ValueRef v, @ty.t t) -> result {
                                  vec(C_int(0),
                                      C_int(abi.box_rc_field_body)));
 
-                auto fields =
-                    cx.build.GEP(body,
-                                 vec(C_int(0),
-                                     C_int(abi.obj_body_elt_fields)));
                 auto tydescptr =
                     cx.build.GEP(body,
                                  vec(C_int(0),
                                      C_int(abi.obj_body_elt_tydesc)));
 
-                call_tydesc_glue_full(cx, fields, cx.build.Load(tydescptr),
+                call_tydesc_glue_full(cx, body, cx.build.Load(tydescptr),
                                       abi.tydesc_field_drop_glue_off);
 
                 // Then free the body.
@@ -1195,7 +1570,7 @@ fn make_drop_glue(@block_ctxt cx, ValueRef v, @ty.t t) -> result {
                                         T_int(), C_int(0));
         }
 
-        case (ty.ty_fn(_,_)) {
+        case (ty.ty_fn(_,_,_)) {
             fn hit_zero(@block_ctxt cx, ValueRef v) -> result {
 
                 // Call through the closure's own fields-drop glue first.
@@ -1203,7 +1578,6 @@ fn make_drop_glue(@block_ctxt cx, ValueRef v, @ty.t t) -> result {
                     cx.build.GEP(v,
                                  vec(C_int(0),
                                      C_int(abi.box_rc_field_body)));
-
                 auto bindings =
                     cx.build.GEP(body,
                                  vec(C_int(0),
@@ -1241,6 +1615,7 @@ fn make_drop_glue(@block_ctxt cx, ValueRef v, @ty.t t) -> result {
                                        bind drop_ty(_, _, _));
 
             } else if (ty.type_is_scalar(t) ||
+                       ty.type_is_native(t) ||
                        ty.type_is_nil(t)) {
                 ret res(cx, C_nil());
             }
@@ -1294,42 +1669,105 @@ fn decr_refcnt_and_if_zero(@block_ctxt cx,
     ret res(next_cx, phi);
 }
 
-fn type_of_variant(@crate_ctxt cx, &ast.variant v) -> TypeRef {
-    let vec[TypeRef] lltys = vec();
+// Tag information
+
+fn variant_types(@crate_ctxt cx, &ast.variant v) -> vec[@ty.t] {
+    let vec[@ty.t] tys = vec();
     alt (ty.ann_to_type(v.ann).struct) {
-        case (ty.ty_fn(?args, _)) {
+        case (ty.ty_fn(_, ?args, _)) {
             for (ty.arg arg in args) {
-                lltys += vec(type_of(cx, arg.ty));
+                tys += vec(arg.ty);
             }
         }
+        case (ty.ty_tag(_, _)) { /* nothing */ }
         case (_) { fail; }
     }
+    ret tys;
+}
+
+fn type_of_variant(@crate_ctxt cx, &ast.variant v) -> TypeRef {
+    let vec[TypeRef] lltys = vec();
+    auto tys = variant_types(cx, v);
+    for (@ty.t typ in tys) {
+        lltys += vec(type_of(cx, typ));
+    }
     ret T_struct(lltys);
 }
 
+// Returns the type parameters of a tag.
+fn tag_ty_params(@crate_ctxt cx, ast.def_id id) -> vec[ast.ty_param] {
+    check (cx.items.contains_key(id));
+    alt (cx.items.get(id).node) {
+        case (ast.item_tag(_, _, ?tps, _)) { ret tps; }
+    }
+    fail;   // not reached
+}
+
+// Returns the variants in a tag.
+fn tag_variants(@crate_ctxt cx, ast.def_id id) -> vec[ast.variant] {
+    check (cx.items.contains_key(id));
+    alt (cx.items.get(id).node) {
+        case (ast.item_tag(_, ?variants, _, _)) { ret variants; }
+    }
+    fail;   // not reached
+}
+
+// Returns a new plain tag type of the given ID with no type parameters. Don't
+// use this function in new code; it's a hack to keep things working for now.
+fn mk_plain_tag(ast.def_id tid) -> @ty.t {
+    let vec[@ty.t] tps = vec();
+    ret ty.plain_ty(ty.ty_tag(tid, tps));
+}
+
+
+type val_fn = fn(@block_ctxt cx, ValueRef v) -> result;
+
 type val_and_ty_fn = fn(@block_ctxt cx, ValueRef v, @ty.t t) -> result;
 
+type val_pair_and_ty_fn =
+    fn(@block_ctxt cx, ValueRef av, ValueRef bv, @ty.t t) -> result;
+
 // Iterates through the elements of a structural type.
 fn iter_structural_ty(@block_ctxt cx,
                       ValueRef v,
                       @ty.t t,
                       val_and_ty_fn f)
     -> result {
+    fn adaptor_fn(val_and_ty_fn f,
+                  @block_ctxt cx,
+                  ValueRef av,
+                  ValueRef bv,
+                  @ty.t t) -> result {
+        ret f(cx, av, t);
+    }
+    be iter_structural_ty_full(cx, v, v, t,
+                               bind adaptor_fn(f, _, _, _, _));
+}
+
+
+fn iter_structural_ty_full(@block_ctxt cx,
+                           ValueRef av,
+                           ValueRef bv,
+                           @ty.t t,
+                           val_pair_and_ty_fn f)
+    -> result {
     let result r = res(cx, C_nil());
 
     fn iter_boxpp(@block_ctxt cx,
-                  ValueRef box_cell,
-                  val_and_ty_fn f) -> result {
-        auto box_ptr = cx.build.Load(box_cell);
-        auto tnil = ty.plain_ty(ty.ty_nil);
-        auto tbox = ty.plain_ty(ty.ty_box(tnil));
+                  ValueRef box_a_cell,
+                  ValueRef box_b_cell,
+                  val_pair_and_ty_fn f) -> result {
+        auto box_a_ptr = cx.build.Load(box_a_cell);
+        auto box_b_ptr = cx.build.Load(box_b_cell);
+        auto tnil = plain_ty(ty.ty_nil);
+        auto tbox = plain_ty(ty.ty_box(tnil));
 
         auto inner_cx = new_sub_block_ctxt(cx, "iter box");
         auto next_cx = new_sub_block_ctxt(cx, "next");
-        auto null_test = cx.build.IsNull(box_ptr);
+        auto null_test = cx.build.IsNull(box_a_ptr);
         cx.build.CondBr(null_test, next_cx.llbb, inner_cx.llbb);
 
-        auto r = f(inner_cx, box_ptr, tbox);
+        auto r = f(inner_cx, box_a_ptr, box_b_ptr, tbox);
         r.bcx.build.Br(next_cx.llbb);
         ret res(next_cx, r.val);
     }
@@ -1338,9 +1776,13 @@ fn iter_structural_ty(@block_ctxt cx,
         case (ty.ty_tup(?args)) {
             let int i = 0;
             for (@ty.t arg in args) {
-                auto elt = r.bcx.build.GEP(v, vec(C_int(0), C_int(i)));
+                r = GEP_tup_like(r.bcx, t, av, vec(0, i));
+                auto elt_a = r.val;
+                r = GEP_tup_like(r.bcx, t, bv, vec(0, i));
+                auto elt_b = r.val;
                 r = f(r.bcx,
-                      load_scalar_or_boxed(r.bcx, elt, arg),
+                      load_scalar_or_boxed(r.bcx, elt_a, arg),
+                      load_scalar_or_boxed(r.bcx, elt_b, arg),
                       arg);
                 i += 1;
             }
@@ -1348,90 +1790,101 @@ fn iter_structural_ty(@block_ctxt cx,
         case (ty.ty_rec(?fields)) {
             let int i = 0;
             for (ty.field fld in fields) {
-                auto llfld = r.bcx.build.GEP(v, vec(C_int(0), C_int(i)));
+                r = GEP_tup_like(r.bcx, t, av, vec(0, i));
+                auto llfld_a = r.val;
+                r = GEP_tup_like(r.bcx, t, bv, vec(0, i));
+                auto llfld_b = r.val;
                 r = f(r.bcx,
-                      load_scalar_or_boxed(r.bcx, llfld, fld.ty),
+                      load_scalar_or_boxed(r.bcx, llfld_a, fld.ty),
+                      load_scalar_or_boxed(r.bcx, llfld_b, fld.ty),
                       fld.ty);
                 i += 1;
             }
         }
-        case (ty.ty_tag(?tid)) {
-            check (cx.fcx.ccx.tags.contains_key(tid));
-            auto info = cx.fcx.ccx.tags.get(tid);
-            auto n_variants = _vec.len[tup(ast.def_id,arity)](info.variants);
-
-            // Look up the tag in the typechecked AST.
-            check (cx.fcx.ccx.items.contains_key(tid));
-            auto tag_item = cx.fcx.ccx.items.get(tid);
-            let vec[ast.variant] variants = vec();  // FIXME: typestate bug
-            alt (tag_item.node) {
-                case (ast.item_tag(_, ?vs, _, _)) {
-                    variants = vs;
-                }
-                case (_) {
-                    log "trans: ty_tag doesn't actually refer to a tag";
-                    fail;
-                }
-            }
+        case (ty.ty_tag(?tid, ?tps)) {
+            auto variants = tag_variants(cx.fcx.ccx, tid);
+            auto n_variants = _vec.len[ast.variant](variants);
+
+            auto lldiscrim_a_ptr = cx.build.GEP(av, vec(C_int(0), C_int(0)));
+            auto llunion_a_ptr = cx.build.GEP(av, vec(C_int(0), C_int(1)));
+            auto lldiscrim_a = cx.build.Load(lldiscrim_a_ptr);
 
-            auto lldiscrim_ptr = cx.build.GEP(v, vec(C_int(0), C_int(0)));
-            auto llunion_ptr = cx.build.GEP(v, vec(C_int(0), C_int(1)));
-            auto lldiscrim = cx.build.Load(lldiscrim_ptr);
+            auto lldiscrim_b_ptr = cx.build.GEP(bv, vec(C_int(0), C_int(0)));
+            auto llunion_b_ptr = cx.build.GEP(bv, vec(C_int(0), C_int(1)));
+            auto lldiscrim_b = cx.build.Load(lldiscrim_b_ptr);
 
-            auto unr_cx = new_sub_block_ctxt(cx, "tag-iter-unr");
+            // NB: we must hit the discriminant first so that structural
+            // comparison know not to proceed when the discriminants differ.
+            auto bcx = cx;
+            bcx = f(bcx, lldiscrim_a, lldiscrim_b,
+                    plain_ty(ty.ty_int)).bcx;
+
+            auto unr_cx = new_sub_block_ctxt(bcx, "tag-iter-unr");
             unr_cx.build.Unreachable();
 
-            auto llswitch = cx.build.Switch(lldiscrim, unr_cx.llbb,
-                                            n_variants);
+            auto llswitch = bcx.build.Switch(lldiscrim_a, unr_cx.llbb,
+                                             n_variants);
 
-            auto next_cx = new_sub_block_ctxt(cx, "tag-iter-next");
+            auto next_cx = new_sub_block_ctxt(bcx, "tag-iter-next");
 
             auto i = 0u;
-            for (tup(ast.def_id,arity) variant in info.variants) {
-                auto variant_cx = new_sub_block_ctxt(cx, "tag-iter-variant-" +
+            for (ast.variant variant in variants) {
+                auto variant_cx = new_sub_block_ctxt(bcx,
+                                                     "tag-iter-variant-" +
                                                      _uint.to_str(i, 10u));
                 llvm.LLVMAddCase(llswitch, C_int(i as int), variant_cx.llbb);
 
-                alt (variant._1) {
-                    case (n_ary) {
-                        let vec[ValueRef] vals = vec(C_int(0), C_int(1),
-                                                     C_int(i as int));
-                        auto llvar = variant_cx.build.GEP(v, vals);
-                        auto llvarty = type_of_variant(cx.fcx.ccx,
-                                                       variants.(i));
-
-                        auto fn_ty = ty.ann_to_type(variants.(i).ann);
-                        alt (fn_ty.struct) {
-                            case (ty.ty_fn(?args, _)) {
-                                auto llvarp = variant_cx.build.
-                                    TruncOrBitCast(llunion_ptr,
-                                                   T_ptr(llvarty));
-
-                                auto j = 0u;
-                                for (ty.arg a in args) {
-                                    auto v = vec(C_int(0),
-                                                 C_int(j as int));
-                                    auto llfldp =
-                                        variant_cx.build.GEP(llvarp, v);
-
-                                    auto llfld =
-                                        load_scalar_or_boxed(variant_cx,
-                                                             llfldp, a.ty);
-
-                                    auto res = f(variant_cx, llfld, a.ty);
-                                    variant_cx = res.bcx;
-                                    j += 1u;
-                                }
+                if (_vec.len[ast.variant_arg](variant.args) > 0u) {
+                    // N-ary variant.
+                    auto llvarty = type_of_variant(bcx.fcx.ccx, variants.(i));
+
+                    auto fn_ty = ty.ann_to_type(variants.(i).ann);
+                    alt (fn_ty.struct) {
+                        case (ty.ty_fn(_, ?args, _)) {
+                            auto llvarp_a = variant_cx.build.
+                                TruncOrBitCast(llunion_a_ptr, T_ptr(llvarty));
+
+                            auto llvarp_b = variant_cx.build.
+                                TruncOrBitCast(llunion_b_ptr, T_ptr(llvarty));
+
+                            auto ty_params = tag_ty_params(bcx.fcx.ccx, tid);
+
+                            auto j = 0u;
+                            for (ty.arg a in args) {
+                                auto v = vec(C_int(0), C_int(j as int));
+
+                                auto llfldp_a =
+                                    variant_cx.build.GEP(llvarp_a, v);
+
+                                auto llfldp_b =
+                                    variant_cx.build.GEP(llvarp_b, v);
+
+                                auto ty_subst = ty.substitute_ty_params(
+                                    ty_params, tps, a.ty);
+
+                                auto llfld_a =
+                                    load_scalar_or_boxed(variant_cx,
+                                                         llfldp_a,
+                                                         ty_subst);
+
+                                auto llfld_b =
+                                    load_scalar_or_boxed(variant_cx,
+                                                         llfldp_b,
+                                                         ty_subst);
+
+                                auto res = f(variant_cx,
+                                             llfld_a, llfld_b, ty_subst);
+                                variant_cx = res.bcx;
+                                j += 1u;
                             }
-                            case (_) { fail; }
                         }
-
-                        variant_cx.build.Br(next_cx.llbb);
-                    }
-                    case (nullary) {
-                        // Nothing to do.
-                        variant_cx.build.Br(next_cx.llbb);
+                        case (_) { fail; }
                     }
+
+                    variant_cx.build.Br(next_cx.llbb);
+                } else {
+                    // Nullary variant; nothing to do.
+                    variant_cx.build.Br(next_cx.llbb);
                 }
 
                 i += 1u;
@@ -1439,27 +1892,96 @@ fn iter_structural_ty(@block_ctxt cx,
 
             ret res(next_cx, C_nil());
         }
-        case (ty.ty_fn(_,_)) {
-            auto box_cell =
-                cx.build.GEP(v,
+        case (ty.ty_fn(_,_,_)) {
+            auto box_cell_a =
+                cx.build.GEP(av,
+                             vec(C_int(0),
+                                 C_int(abi.fn_field_box)));
+            auto box_cell_b =
+                cx.build.GEP(bv,
                              vec(C_int(0),
                                  C_int(abi.fn_field_box)));
-            ret iter_boxpp(cx, box_cell, f);
+            ret iter_boxpp(cx, box_cell_a, box_cell_b, f);
         }
         case (ty.ty_obj(_)) {
-            auto box_cell =
-                cx.build.GEP(v,
+            auto box_cell_a =
+                cx.build.GEP(av,
+                             vec(C_int(0),
+                                 C_int(abi.obj_field_box)));
+            auto box_cell_b =
+                cx.build.GEP(bv,
                              vec(C_int(0),
                                  C_int(abi.obj_field_box)));
-            ret iter_boxpp(cx, box_cell, f);
+            ret iter_boxpp(cx, box_cell_a, box_cell_b, f);
         }
         case (_) {
-            cx.fcx.ccx.sess.unimpl("type in iter_structural_ty");
+            cx.fcx.ccx.sess.unimpl("type in iter_structural_ty_full");
         }
     }
     ret r;
 }
 
+// Iterates through a pointer range, until the src* hits the src_lim*.
+fn iter_sequence_raw(@block_ctxt cx,
+                     ValueRef src,     // elt*
+                     ValueRef src_lim, // elt*
+                     ValueRef elt_sz,
+                     val_fn f) -> result {
+
+    auto bcx = cx;
+
+    let ValueRef src_int = vp2i(bcx, src);
+    let ValueRef src_lim_int = vp2i(bcx, src_lim);
+
+    auto cond_cx = new_scope_block_ctxt(cx, "sequence-iter cond");
+    auto body_cx = new_scope_block_ctxt(cx, "sequence-iter body");
+    auto next_cx = new_sub_block_ctxt(cx, "next");
+
+    bcx.build.Br(cond_cx.llbb);
+
+    let ValueRef src_curr = cond_cx.build.Phi(T_int(),
+                                              vec(src_int), vec(bcx.llbb));
+
+    auto end_test = cond_cx.build.ICmp(lib.llvm.LLVMIntULT,
+                                       src_curr, src_lim_int);
+
+    cond_cx.build.CondBr(end_test, body_cx.llbb, next_cx.llbb);
+
+    auto src_curr_ptr = vi2p(body_cx, src_curr, T_ptr(T_i8()));
+
+    auto body_res = f(body_cx, src_curr_ptr);
+    body_cx = body_res.bcx;
+
+    auto src_next = body_cx.build.Add(src_curr, elt_sz);
+    body_cx.build.Br(cond_cx.llbb);
+
+    cond_cx.build.AddIncomingToPhi(src_curr, vec(src_next),
+                                   vec(body_cx.llbb));
+
+    ret res(next_cx, C_nil());
+}
+
+
+fn iter_sequence_inner(@block_ctxt cx,
+                       ValueRef src,     // elt*
+                       ValueRef src_lim, // elt*
+                       @ty.t elt_ty,
+                       val_and_ty_fn f) -> result {
+    fn adaptor_fn(val_and_ty_fn f,
+                  @ty.t elt_ty,
+                  @block_ctxt cx,
+                  ValueRef v) -> result {
+        auto llty = type_of(cx.fcx.ccx, elt_ty);
+        auto p = cx.build.PointerCast(v, T_ptr(llty));
+        ret f(cx, load_scalar_or_boxed(cx, p, elt_ty), elt_ty);
+    }
+
+    auto elt_sz = size_of(cx, elt_ty);
+    be iter_sequence_raw(elt_sz.bcx, src, src_lim, elt_sz.val,
+                         bind adaptor_fn(f, elt_ty, _, _));
+}
+
+
 // Iterates through the elements of a vec or str.
 fn iter_sequence(@block_ctxt cx,
                  ValueRef v,
@@ -1479,43 +2001,18 @@ fn iter_sequence(@block_ctxt cx,
 
         auto llunit_ty = type_of(cx.fcx.ccx, elt_ty);
         auto bcx = cx;
-        auto unit_sz = size_of(bcx, elt_ty);
-        bcx = unit_sz.bcx;
 
         auto len = bcx.build.Load(lenptr);
         if (trailing_null) {
+            auto unit_sz = size_of(bcx, elt_ty);
+            bcx = unit_sz.bcx;
             len = bcx.build.Sub(len, unit_sz.val);
         }
 
-        auto cond_cx = new_scope_block_ctxt(cx, "sequence-iter cond");
-        auto body_cx = new_scope_block_ctxt(cx, "sequence-iter body");
-        auto next_cx = new_sub_block_ctxt(cx, "next");
-
-        bcx.build.Br(cond_cx.llbb);
-
-        auto ix = cond_cx.build.Phi(T_int(), vec(C_int(0)), vec(cx.llbb));
-        auto scaled_ix = cond_cx.build.Phi(T_int(),
-                                           vec(C_int(0)), vec(cx.llbb));
+        auto p1 = vi2p(bcx, bcx.build.Add(vp2i(bcx, p0), len),
+                       T_ptr(llunit_ty));
 
-        auto end_test = cond_cx.build.ICmp(lib.llvm.LLVMIntNE,
-                                           scaled_ix, len);
-        cond_cx.build.CondBr(end_test, body_cx.llbb, next_cx.llbb);
-
-        auto elt = body_cx.build.GEP(p0, vec(C_int(0), ix));
-        auto body_res = f(body_cx,
-                          load_scalar_or_boxed(body_cx, elt, elt_ty),
-                          elt_ty);
-        auto next_ix = body_res.bcx.build.Add(ix, C_int(1));
-        auto next_scaled_ix = body_res.bcx.build.Add(scaled_ix, unit_sz.val);
-
-        cond_cx.build.AddIncomingToPhi(ix, vec(next_ix),
-                                       vec(body_res.bcx.llbb));
-
-        cond_cx.build.AddIncomingToPhi(scaled_ix, vec(next_scaled_ix),
-                                       vec(body_res.bcx.llbb));
-
-        body_res.bcx.build.Br(cond_cx.llbb);
-        ret res(next_cx, C_nil());
+        ret iter_sequence_inner(cx, p0, p1, elt_ty, f);
     }
 
     alt (t.struct) {
@@ -1523,7 +2020,7 @@ fn iter_sequence(@block_ctxt cx,
             ret iter_sequence_body(cx, v, et, f, false);
         }
         case (ty.ty_str) {
-            auto et = ty.plain_ty(ty.ty_machine(common.ty_u8));
+            auto et = plain_ty(ty.ty_machine(common.ty_u8));
             ret iter_sequence_body(cx, v, et, f, true);
         }
         case (_) { fail; }
@@ -1541,7 +2038,20 @@ fn call_tydesc_glue_full(@block_ctxt cx, ValueRef v,
     lltydescs = cx.build.Load(lltydescs);
     auto llfnptr = cx.build.GEP(tydesc, vec(C_int(0), C_int(field)));
     auto llfn = cx.build.Load(llfnptr);
-    cx.build.FastCall(llfn, vec(cx.fcx.lltaskptr, lltydescs, llrawptr));
+
+    // FIXME: this adjustment has to do with the ridiculous encoding of
+    // glue-pointer-constants in the tydesc records: They are tydesc-relative
+    // displacements.  This is purely for compatibility with rustboot and
+    // should go when it is discarded.
+    llfn = vi2p(cx, cx.build.Add(vp2i(cx, llfn),
+                                 vp2i(cx, tydesc)),
+                val_ty(llfn));
+
+    cx.build.FastCall(llfn, vec(C_null(T_ptr(T_nil())),
+                                cx.fcx.lltaskptr,
+                                C_null(T_ptr(T_nil())),
+                                lltydescs,
+                                llrawptr));
 }
 
 fn call_tydesc_glue(@block_ctxt cx, ValueRef v, @ty.t t, int field) {
@@ -1552,7 +2062,6 @@ fn call_tydesc_glue(@block_ctxt cx, ValueRef v, @ty.t t, int field) {
 fn incr_all_refcnts(@block_ctxt cx,
                     ValueRef v,
                     @ty.t t) -> result {
-
     if (!ty.type_is_scalar(t)) {
         call_tydesc_glue(cx, v, t, abi.tydesc_field_take_glue_off);
     }
@@ -1625,7 +2134,7 @@ fn copy_ty(@block_ctxt cx,
            ValueRef dst,
            ValueRef src,
            @ty.t t) -> result {
-    if (ty.type_is_scalar(t)) {
+    if (ty.type_is_scalar(t) || ty.type_is_native(t)) {
         ret res(cx, cx.build.Store(src, dst));
 
     } else if (ty.type_is_nil(t)) {
@@ -1744,7 +2253,11 @@ fn trans_unary(@block_ctxt cx, ast.unop op,
         case (ast.box) {
             auto e_ty = ty.expr_ty(e);
             auto e_val = sub.val;
-            sub = trans_malloc(sub.bcx, node_ann_type(sub.bcx.fcx.ccx, a));
+            auto box_ty = node_ann_type(sub.bcx.fcx.ccx, a);
+            sub = trans_malloc_boxed(sub.bcx, e_ty);
+            find_scope_cx(cx).cleanups +=
+                clean(bind drop_ty(_, sub.val, box_ty));
+
             auto box = sub.val;
             auto rc = sub.bcx.build.GEP(box,
                                         vec(C_int(0),
@@ -1753,6 +2266,15 @@ fn trans_unary(@block_ctxt cx, ast.unop op,
                                           vec(C_int(0),
                                               C_int(abi.box_rc_field_body)));
             sub.bcx.build.Store(C_int(1), rc);
+
+            // Cast the body type to the type of the value. This is needed to
+            // make tags work, since tags have a different LLVM type depending
+            // on whether they're boxed or not.
+            if (!ty.type_has_dynamic_size(e_ty)) {
+                auto llety = T_ptr(type_of(sub.bcx.fcx.ccx, e_ty));
+                body = sub.bcx.build.PointerCast(body, llety);
+            }
+
             sub = copy_ty(sub.bcx, INIT, body, e_val, e_ty);
             ret res(sub.bcx, box);
         }
@@ -1767,41 +2289,241 @@ fn trans_unary(@block_ctxt cx, ast.unop op,
             }
             ret res(sub.bcx, val);
         }
+        case (ast._mutable) {
+            ret trans_expr(cx, e);
+        }
     }
     fail;
 }
 
-fn trans_eager_binop(@block_ctxt cx, ast.binop op,
-                     ValueRef lhs, ValueRef rhs) -> ValueRef {
+fn trans_compare(@block_ctxt cx, ast.binop op, @ty.t t,
+                 ValueRef lhs, ValueRef rhs) -> result {
+
+    if (ty.type_is_scalar(t)) {
+        ret res(cx, trans_scalar_compare(cx, op, t, lhs, rhs));
+
+    } else if (ty.type_is_structural(t)) {
+        auto scx = new_sub_block_ctxt(cx, "structural compare start");
+        auto next = new_sub_block_ctxt(cx, "structural compare end");
+        cx.build.Br(scx.llbb);
+
+        /*
+         * We're doing lexicographic comparison here. We start with the
+         * assumption that the two input elements are equal. Depending on
+         * operator, this means that the result is either true or false;
+         * equality produces 'true' for ==, <= and >=. It produces 'false' for
+         * !=, < and >.
+         *
+         * We then move one element at a time through the structure checking
+         * for pairwise element equality. If we have equality, our assumption
+         * about overall sequence equality is not modified, so we have to move
+         * to the next element.
+         *
+         * If we do not have pairwise element equality, we have reached an
+         * element that 'decides' the lexicographic comparison. So we exit the
+         * loop with a flag that indicates the true/false sense of that
+         * decision, by testing the element again with the operator we're
+         * interested in.
+         *
+         * When we're lucky, LLVM should be able to fold some of these two
+         * tests together (as they're applied to the same operands and in some
+         * cases are sometimes redundant). But we don't bother trying to
+         * optimize combinations like that, at this level.
+         */
+
+        auto flag = scx.build.Alloca(T_i1());
+
+        alt (op) {
+            // ==, <= and >= default to true if they find == all the way.
+            case (ast.eq) { scx.build.Store(C_integral(1, T_i1()), flag); }
+            case (ast.le) { scx.build.Store(C_integral(1, T_i1()), flag); }
+            case (ast.ge) { scx.build.Store(C_integral(1, T_i1()), flag); }
+            case (_) {
+                // ==, <= and >= default to false if they find == all the way.
+                scx.build.Store(C_integral(0, T_i1()), flag);
+            }
+        }
+
+        fn inner(@block_ctxt last_cx,
+                 ValueRef flag,
+                 ast.binop op,
+                 @block_ctxt cx,
+                 ValueRef av,
+                 ValueRef bv,
+                 @ty.t t) -> result {
+
+            auto cnt_cx = new_sub_block_ctxt(cx, "continue comparison");
+            auto stop_cx = new_sub_block_ctxt(cx, "stop comparison");
+
+            // First 'eq' comparison: if so, continue to next elts.
+            auto eq_r = trans_compare(cx, ast.eq, t, av, bv);
+            eq_r.bcx.build.CondBr(eq_r.val, cnt_cx.llbb, stop_cx.llbb);
+
+            // Second 'op' comparison: find out how this elt-pair decides.
+            auto stop_r = trans_compare(stop_cx, op, t, av, bv);
+            stop_r.bcx.build.Store(stop_r.val, flag);
+            stop_r.bcx.build.Br(last_cx.llbb);
+            ret res(cnt_cx, C_nil());
+        }
+
+        auto r = iter_structural_ty_full(scx, lhs, rhs, t,
+                                         bind inner(next, flag, op,
+                                                    _, _, _, _));
+
+        r.bcx.build.Br(next.llbb);
+        auto v = next.build.Load(flag);
+        ret res(next, v);
+
+    } else {
+        // FIXME: compare vec, str, box?
+        cx.fcx.ccx.sess.unimpl("type in trans_compare");
+        ret res(cx, C_bool(false));
+    }
+}
+
+fn trans_scalar_compare(@block_ctxt cx, ast.binop op, @ty.t t,
+                        ValueRef lhs, ValueRef rhs) -> ValueRef {
+    if (ty.type_is_fp(t)) {
+        ret trans_fp_compare(cx, op, t, lhs, rhs);
+    } else {
+        ret trans_integral_compare(cx, op, t, lhs, rhs);
+    }
+}
+
+fn trans_fp_compare(@block_ctxt cx, ast.binop op, @ty.t fptype,
+                    ValueRef lhs, ValueRef rhs) -> ValueRef {
 
+    auto cmp = lib.llvm.LLVMIntEQ;
     alt (op) {
-        case (ast.add) { ret cx.build.Add(lhs, rhs); }
-        case (ast.sub) { ret cx.build.Sub(lhs, rhs); }
-
-        // FIXME (issue #57): switch by signedness.
-        case (ast.mul) { ret cx.build.Mul(lhs, rhs); }
-        case (ast.div) { ret cx.build.SDiv(lhs, rhs); }
-        case (ast.rem) { ret cx.build.SRem(lhs, rhs); }
-
-        case (ast.bitor) { ret cx.build.Or(lhs, rhs); }
-        case (ast.bitand) { ret cx.build.And(lhs, rhs); }
-        case (ast.bitxor) { ret cx.build.Xor(lhs, rhs); }
-        case (ast.lsl) { ret cx.build.Shl(lhs, rhs); }
-        case (ast.lsr) { ret cx.build.LShr(lhs, rhs); }
-        case (ast.asr) { ret cx.build.AShr(lhs, rhs); }
-        case (_) {
-            auto cmp = lib.llvm.LLVMIntEQ;
-            alt (op) {
-                case (ast.eq) { cmp = lib.llvm.LLVMIntEQ; }
-                case (ast.ne) { cmp = lib.llvm.LLVMIntNE; }
-
-                // FIXME (issue #57): switch by signedness.
-                case (ast.lt) { cmp = lib.llvm.LLVMIntSLT; }
-                case (ast.le) { cmp = lib.llvm.LLVMIntSLE; }
-                case (ast.ge) { cmp = lib.llvm.LLVMIntSGE; }
-                case (ast.gt) { cmp = lib.llvm.LLVMIntSGT; }
+        // FIXME: possibly use the unordered-or-< predicates here,
+        // for now we're only going with ordered-and-< style (no NaNs).
+        case (ast.eq) { cmp = lib.llvm.LLVMRealOEQ; }
+        case (ast.ne) { cmp = lib.llvm.LLVMRealONE; }
+        case (ast.lt) { cmp = lib.llvm.LLVMRealOLT; }
+        case (ast.gt) { cmp = lib.llvm.LLVMRealOGT; }
+        case (ast.le) { cmp = lib.llvm.LLVMRealOLE; }
+        case (ast.ge) { cmp = lib.llvm.LLVMRealOGE; }
+    }
+
+    ret cx.build.FCmp(cmp, lhs, rhs);
+}
+
+fn trans_integral_compare(@block_ctxt cx, ast.binop op, @ty.t intype,
+                          ValueRef lhs, ValueRef rhs) -> ValueRef {
+    auto cmp = lib.llvm.LLVMIntEQ;
+    alt (op) {
+        case (ast.eq) { cmp = lib.llvm.LLVMIntEQ; }
+        case (ast.ne) { cmp = lib.llvm.LLVMIntNE; }
+
+        case (ast.lt) {
+            if (ty.type_is_signed(intype)) {
+                cmp = lib.llvm.LLVMIntSLT;
+            } else {
+                cmp = lib.llvm.LLVMIntULT;
+            }
+        }
+        case (ast.le) {
+            if (ty.type_is_signed(intype)) {
+                cmp = lib.llvm.LLVMIntSLE;
+            } else {
+                cmp = lib.llvm.LLVMIntULE;
+            }
+        }
+        case (ast.gt) {
+            if (ty.type_is_signed(intype)) {
+                cmp = lib.llvm.LLVMIntSGT;
+            } else {
+                cmp = lib.llvm.LLVMIntUGT;
+            }
+        }
+        case (ast.ge) {
+            if (ty.type_is_signed(intype)) {
+                cmp = lib.llvm.LLVMIntSGE;
+            } else {
+                cmp = lib.llvm.LLVMIntUGE;
             }
-            ret cx.build.ICmp(cmp, lhs, rhs);
+        }
+    }
+    ret cx.build.ICmp(cmp, lhs, rhs);
+}
+
+fn trans_vec_append(@block_ctxt cx, @ty.t t,
+                    ValueRef lhs, ValueRef rhs) -> result {
+
+    auto elt_ty = ty.sequence_element_type(t);
+
+    auto skip_null = C_bool(false);
+    alt (t.struct) {
+        case (ty.ty_str) { skip_null = C_bool(true); }
+        case (_) { }
+    }
+
+    auto bcx = cx;
+
+    auto llvec_tydesc = get_tydesc(bcx, t);
+    bcx = llvec_tydesc.bcx;
+
+    auto llelt_tydesc = get_tydesc(bcx, elt_ty);
+    bcx = llelt_tydesc.bcx;
+
+    auto dst = bcx.build.PointerCast(lhs, T_ptr(T_opaque_vec_ptr()));
+    auto src = bcx.build.PointerCast(rhs, T_opaque_vec_ptr());
+
+    ret res(bcx, bcx.build.FastCall(cx.fcx.ccx.glues.vec_append_glue,
+                                    vec(cx.fcx.lltaskptr,
+                                        llvec_tydesc.val,
+                                        llelt_tydesc.val,
+                                        dst, src, skip_null)));
+}
+
+fn trans_vec_add(@block_ctxt cx, @ty.t t,
+                 ValueRef lhs, ValueRef rhs) -> result {
+    auto r = alloc_ty(cx, t);
+    auto tmp = r.val;
+    r = copy_ty(r.bcx, INIT, tmp, lhs, t);
+    auto bcx = trans_vec_append(r.bcx, t, tmp, rhs).bcx;
+    tmp = load_scalar_or_boxed(bcx, tmp, t);
+    find_scope_cx(cx).cleanups += clean(bind drop_ty(_, tmp, t));
+    ret res(bcx, tmp);
+}
+
+
+fn trans_eager_binop(@block_ctxt cx, ast.binop op, @ty.t intype,
+                     ValueRef lhs, ValueRef rhs) -> result {
+
+    alt (op) {
+        case (ast.add) {
+            if (ty.type_is_sequence(intype)) {
+                ret trans_vec_add(cx, intype, lhs, rhs);
+            }
+            ret res(cx, cx.build.Add(lhs, rhs));
+        }
+        case (ast.sub) { ret res(cx, cx.build.Sub(lhs, rhs)); }
+
+        case (ast.mul) { ret res(cx, cx.build.Mul(lhs, rhs)); }
+        case (ast.div) {
+            if (ty.type_is_signed(intype)) {
+                ret res(cx, cx.build.SDiv(lhs, rhs));
+            } else {
+                ret res(cx, cx.build.UDiv(lhs, rhs));
+            }
+        }
+        case (ast.rem) {
+            if (ty.type_is_signed(intype)) {
+                ret res(cx, cx.build.SRem(lhs, rhs));
+            } else {
+                ret res(cx, cx.build.URem(lhs, rhs));
+            }
+        }
+
+        case (ast.bitor) { ret res(cx, cx.build.Or(lhs, rhs)); }
+        case (ast.bitand) { ret res(cx, cx.build.And(lhs, rhs)); }
+        case (ast.bitxor) { ret res(cx, cx.build.Xor(lhs, rhs)); }
+        case (ast.lsl) { ret res(cx, cx.build.Shl(lhs, rhs)); }
+        case (ast.lsr) { ret res(cx, cx.build.LShr(lhs, rhs)); }
+        case (ast.asr) { ret res(cx, cx.build.AShr(lhs, rhs)); }
+        case (_) {
+            ret trans_compare(cx, op, intype, lhs, rhs);
         }
     }
     fail;
@@ -1827,6 +2549,21 @@ fn autoderef(@block_ctxt cx, ValueRef v, @ty.t t) -> result {
     }
 }
 
+fn autoderefed_ty(@ty.t t) -> @ty.t {
+    let @ty.t t1 = t;
+
+    while (true) {
+        alt (t1.struct) {
+            case (ty.ty_box(?inner)) {
+                t1 = inner;
+            }
+            case (_) {
+                ret t1;
+            }
+        }
+    }
+}
+
 fn trans_binary(@block_ctxt cx, ast.binop op,
                 @ast.expr a, @ast.expr b) -> result {
 
@@ -1876,11 +2613,14 @@ fn trans_binary(@block_ctxt cx, ast.binop op,
         case (_) {
             // Remaining cases are eager:
             auto lhs = trans_expr(cx, a);
-            lhs = autoderef(lhs.bcx, lhs.val, ty.expr_ty(a));
+            auto lhty = ty.expr_ty(a);
+            lhs = autoderef(lhs.bcx, lhs.val, lhty);
             auto rhs = trans_expr(lhs.bcx, b);
-            rhs = autoderef(rhs.bcx, rhs.val, ty.expr_ty(b));
-            ret res(rhs.bcx, trans_eager_binop(rhs.bcx, op,
-                                               lhs.val, rhs.val));
+            auto rhty = ty.expr_ty(b);
+            rhs = autoderef(rhs.bcx, rhs.val, rhty);
+            ret trans_eager_binop(rhs.bcx, op,
+                                  autoderefed_ty(lhty),
+                                  lhs.val, rhs.val);
         }
     }
     fail;
@@ -1983,6 +2723,7 @@ fn trans_for(@block_ctxt cx,
         cx.build.Br(scope_cx.llbb);
         auto local_res = alloc_local(scope_cx, local);
         auto bcx = copy_ty(local_res.bcx, INIT, local_res.val, curr, t).bcx;
+        scope_cx.cleanups += clean(bind drop_slot(_, local_res.val, t));
         bcx = trans_block(bcx, body).bcx;
         bcx.build.Br(next_cx.llbb);
         ret res(next_cx, C_nil());
@@ -2002,6 +2743,103 @@ fn trans_for(@block_ctxt cx,
                       bind inner(_, local, _, _, body));
 }
 
+fn trans_for_each(@block_ctxt cx,
+                  @ast.decl decl,
+                  @ast.expr seq,
+                  &ast.block body) -> result {
+
+    /*
+     * The translation is a little .. complex here. Code like:
+     *
+     *    let ty1 p = ...;
+     *
+     *    let ty1 q = ...;
+     *
+     *    foreach (ty v in foo(a,b)) { body(p,q,v) }
+     *
+     *
+     * Turns into a something like so (C/Rust mishmash):
+     *
+     *    type env = { *ty1 p, *ty2 q, ... };
+     *
+     *    let env e = { &p, &q, ... };
+     *
+     *    fn foreach123_body(env* e, ty v) { body(*(e->p),*(e->q),v) }
+     *
+     *    foo([foreach123_body, env*], a, b);
+     *
+     */
+
+    // Step 1: walk body and figure out which references it makes
+    // escape. This could be determined upstream, and probably ought
+    // to be so, eventualy. For first cut, skip this. Null env.
+
+    auto env_ty = T_opaque_closure_ptr(cx.fcx.ccx.tn);
+
+
+    // Step 2: Declare foreach body function.
+
+    // FIXME: possibly support alias-mode here?
+    auto decl_ty = plain_ty(ty.ty_nil);
+    alt (decl.node) {
+        case (ast.decl_local(?local)) {
+            decl_ty = node_ann_type(cx.fcx.ccx, local.ann);
+        }
+    }
+
+    let str s =
+        cx.fcx.ccx.names.next("_rust_foreach")
+        + sep() + cx.fcx.ccx.path;
+
+    // The 'env' arg entering the body function is a fake env member (as in
+    // the env-part of the normal rust calling convention) that actually
+    // points to a stack allocated env in this frame. We bundle that env
+    // pointer along with the foreach-body-fn pointer into a 'normal' fn pair
+    // and pass it in as a first class fn-arg to the iterator.
+
+    auto iter_body_llty = type_of_fn_full(cx.fcx.ccx, ast.proto_fn,
+                                          none[TypeRef],
+                                          vec(rec(mode=ast.val, ty=decl_ty)),
+                                          plain_ty(ty.ty_nil));
+
+    let ValueRef lliterbody = decl_fastcall_fn(cx.fcx.ccx.llmod,
+                                               s, iter_body_llty);
+
+    // FIXME: handle ty params properly.
+    let vec[ast.ty_param] ty_params = vec();
+
+    auto fcx = new_fn_ctxt(cx.fcx.ccx, lliterbody);
+    auto bcx = new_top_block_ctxt(fcx);
+
+    // FIXME: populate lllocals from llenv here.
+    auto res = trans_block(bcx, body);
+    res.bcx.build.RetVoid();
+
+
+    // Step 3: Call iter passing [lliterbody, llenv], plus other args.
+
+    alt (seq.node) {
+
+        case (ast.expr_call(?f, ?args, ?ann)) {
+
+            auto pair = cx.build.Alloca(T_fn_pair(cx.fcx.ccx.tn,
+                                                  iter_body_llty));
+            auto code_cell = cx.build.GEP(pair,
+                                          vec(C_int(0),
+                                              C_int(abi.fn_field_code)));
+            cx.build.Store(lliterbody, code_cell);
+
+            // log "lliterbody: " + val_str(cx.fcx.ccx.tn, lliterbody);
+            ret trans_call(cx, f,
+                           some[ValueRef](cx.build.Load(pair)),
+                           args,
+                           ann);
+        }
+    }
+    fail;
+}
+
+
 fn trans_while(@block_ctxt cx, @ast.expr cond,
                &ast.block body) -> result {
 
@@ -2061,17 +2899,29 @@ fn trans_pat_match(@block_ctxt cx, @ast.pat pat, ValueRef llval,
     alt (pat.node) {
         case (ast.pat_wild(_)) { ret res(cx, llval); }
         case (ast.pat_bind(_, _, _)) { ret res(cx, llval); }
+
+        case (ast.pat_lit(?lt, ?ann)) {
+            auto lllit = trans_lit(cx.fcx.ccx, *lt, ann);
+            auto lltype = ty.ann_to_type(ann);
+            auto lleq = trans_compare(cx, ast.eq, lltype, llval, lllit);
+
+            auto matched_cx = new_sub_block_ctxt(lleq.bcx, "matched_cx");
+            lleq.bcx.build.CondBr(lleq.val, matched_cx.llbb, next_cx.llbb);
+            ret res(matched_cx, llval);
+        }
+
         case (ast.pat_tag(?id, ?subpats, ?vdef_opt, ?ann)) {
             auto lltagptr = cx.build.GEP(llval, vec(C_int(0), C_int(0)));
             auto lltag = cx.build.Load(lltagptr);
 
             auto vdef = option.get[ast.variant_def](vdef_opt);
             auto variant_id = vdef._1;
-            auto tinfo = cx.fcx.ccx.tags.get(vdef._0);
             auto variant_tag = 0;
+
+            auto variants = tag_variants(cx.fcx.ccx, vdef._0);
             auto i = 0;
-            for (tup(ast.def_id,arity) vinfo in tinfo.variants) {
-                auto this_variant_id = vinfo._0;
+            for (ast.variant v in variants) {
+                auto this_variant_id = v.id;
                 if (variant_id._0 == this_variant_id._0 &&
                     variant_id._1 == this_variant_id._1) {
                     variant_tag = i;
@@ -2113,6 +2963,7 @@ fn trans_pat_binding(@block_ctxt cx, @ast.pat pat, ValueRef llval)
     -> result {
     alt (pat.node) {
         case (ast.pat_wild(_)) { ret res(cx, llval); }
+        case (ast.pat_lit(_, _)) { ret res(cx, llval); }
         case (ast.pat_bind(?id, ?def_id, ?ann)) {
             auto ty = node_ann_type(cx.fcx.ccx, ann);
             auto llty = type_of(cx.fcx.ccx, ty);
@@ -2204,6 +3055,34 @@ fn lval_val(@block_ctxt cx, ValueRef val) -> lval_result {
             llobj=none[ValueRef]);
 }
 
+fn lval_generic_fn(@block_ctxt cx,
+                   ty.ty_params_and_ty tpt,
+                   ast.def_id fn_id,
+                   &ast.ann ann)
+    -> lval_result {
+
+    check (cx.fcx.ccx.fn_pairs.contains_key(fn_id));
+    auto lv = lval_val(cx, cx.fcx.ccx.fn_pairs.get(fn_id));
+    auto monoty = node_ann_type(cx.fcx.ccx, ann);
+    auto tys = ty.resolve_ty_params(tpt, monoty);
+
+    if (_vec.len[@ty.t](tys) != 0u) {
+        auto bcx = cx;
+        let vec[ValueRef] tydescs = vec();
+        for (@ty.t t in tys) {
+            auto td = get_tydesc(bcx, t);
+            bcx = td.bcx;
+            append[ValueRef](tydescs, td.val);
+        }
+        auto gen = rec( item_type = tpt._1,
+                        tydescs = tydescs );
+        lv = rec(res = res(bcx, lv.res.val),
+                 generic = some[generic_info](gen)
+                 with lv);
+    }
+    ret lv;
+}
+
 fn trans_path(@block_ctxt cx, &ast.path p, &option.t[ast.def] dopt,
               &ast.ann ann) -> lval_result {
     alt (dopt) {
@@ -2226,49 +3105,60 @@ fn trans_path(@block_ctxt cx, &ast.path p, &option.t[ast.def] dopt,
                     ret lval_mem(cx, cx.fcx.llobjfields.get(did));
                 }
                 case (ast.def_fn(?did)) {
-                    check (cx.fcx.ccx.fn_pairs.contains_key(did));
-                    check (cx.fcx.ccx.item_ids.contains_key(did));
-
+                    check (cx.fcx.ccx.items.contains_key(did));
                     auto fn_item = cx.fcx.ccx.items.get(did);
-                    auto lv = lval_val(cx, cx.fcx.ccx.fn_pairs.get(did));
-                    auto monoty = node_ann_type(cx.fcx.ccx, ann);
-                    auto tys = ty.resolve_ty_params(fn_item, monoty);
-
-                    if (_vec.len[@ty.t](tys) != 0u) {
-                        auto bcx = cx;
-                        let vec[ValueRef] tydescs = vec();
-                        for (@ty.t t in tys) {
-                            auto td = get_tydesc(bcx, t);
-                            bcx = td.bcx;
-                            append[ValueRef](tydescs, td.val);
-                        }
-                        auto gen = rec( item_type = ty.item_ty(fn_item)._1,
-                                        tydescs = tydescs );
-                        lv = rec(res = res(bcx, lv.res.val),
-                                 generic = some[generic_info](gen)
-                                 with lv);
-                    }
-
-                    ret lv;
+                    ret lval_generic_fn(cx, ty.item_ty(fn_item), did, ann);
                 }
                 case (ast.def_obj(?did)) {
-                    check (cx.fcx.ccx.fn_pairs.contains_key(did));
-                    ret lval_val(cx, cx.fcx.ccx.fn_pairs.get(did));
+                    check (cx.fcx.ccx.items.contains_key(did));
+                    auto fn_item = cx.fcx.ccx.items.get(did);
+                    ret lval_generic_fn(cx, ty.item_ty(fn_item), did, ann);
                 }
                 case (ast.def_variant(?tid, ?vid)) {
-                    check (cx.fcx.ccx.tags.contains_key(tid));
                     if (cx.fcx.ccx.fn_pairs.contains_key(vid)) {
-                        ret lval_val(cx, cx.fcx.ccx.fn_pairs.get(vid));
+                        check (cx.fcx.ccx.items.contains_key(tid));
+                        auto tag_item = cx.fcx.ccx.items.get(tid);
+                        auto params = ty.item_ty(tag_item)._0;
+                        auto fty = plain_ty(ty.ty_nil);
+                        alt (tag_item.node) {
+                            case (ast.item_tag(_, ?variants, _, _)) {
+                                for (ast.variant v in variants) {
+                                    if (v.id == vid) {
+                                        fty = node_ann_type(cx.fcx.ccx,
+                                                            v.ann);
+                                    }
+                                }
+                            }
+                        }
+                        ret lval_generic_fn(cx, tup(params, fty), vid, ann);
                     } else {
-                        // Nullary variants are just scalar constants.
-                        check (cx.fcx.ccx.item_ids.contains_key(vid));
-                        ret lval_val(cx, cx.fcx.ccx.item_ids.get(vid));
+                        // Nullary variant.
+                        auto tag_ty = node_ann_type(cx.fcx.ccx, ann);
+                        auto lldiscrim_gv = cx.fcx.ccx.discrims.get(vid);
+                        auto lldiscrim = cx.build.Load(lldiscrim_gv);
+
+                        auto alloc_result = alloc_ty(cx, tag_ty);
+                        auto lltagblob = alloc_result.val;
+                        auto lltagptr = alloc_result.bcx.build.PointerCast(
+                            lltagblob, T_ptr(type_of(cx.fcx.ccx, tag_ty)));
+
+                        auto lldiscrimptr = alloc_result.bcx.build.GEP(
+                            lltagptr, vec(C_int(0), C_int(0)));
+                        alloc_result.bcx.build.Store(lldiscrim, lldiscrimptr);
+
+                        ret lval_val(alloc_result.bcx, lltagptr);
                     }
                 }
                 case (ast.def_const(?did)) {
                     check (cx.fcx.ccx.consts.contains_key(did));
                     ret lval_mem(cx, cx.fcx.ccx.consts.get(did));
                 }
+                case (ast.def_native_fn(?did)) {
+                    check (cx.fcx.ccx.native_items.contains_key(did));
+                    auto fn_item = cx.fcx.ccx.native_items.get(did);
+                    ret lval_generic_fn(cx, ty.native_item_ty(fn_item),
+                                        did, ann);
+                }
                 case (_) {
                     cx.fcx.ccx.sess.unimpl("def variant in trans");
                 }
@@ -2283,11 +3173,10 @@ fn trans_path(@block_ctxt cx, &ast.path p, &option.t[ast.def] dopt,
 
 fn trans_field(@block_ctxt cx, &ast.span sp, @ast.expr base,
                &ast.ident field, &ast.ann ann) -> lval_result {
-    auto lv = trans_lval(cx, base);
-    auto r = lv.res;
-    r = autoderef(r.bcx, r.val, ty.expr_ty(base));
-    check (lv.is_mem);
+    auto r = trans_expr(cx, base);
     auto t = ty.expr_ty(base);
+    r = autoderef(r.bcx, r.val, t);
+    t = autoderefed_ty(t);
     alt (t.struct) {
         case (ty.ty_tup(?fields)) {
             let uint ix = ty.field_num(cx.fcx.ccx.sess, sp, field);
@@ -2325,10 +3214,23 @@ fn trans_index(@block_ctxt cx, &ast.span sp, @ast.expr base,
     auto v = lv.val;
     auto bcx = ix.bcx;
 
+    // Cast to an LLVM integer. Rust is less strict than LLVM in this regard.
+    auto ix_val;
+    auto ix_size = llsize_of_real(cx.fcx.ccx, val_ty(ix.val));
+    auto int_size = llsize_of_real(cx.fcx.ccx, T_int());
+    if (ix_size < int_size) {
+        ix_val = bcx.build.ZExt(ix.val, T_int());
+    } else if (ix_size > int_size) {
+        ix_val = bcx.build.Trunc(ix.val, T_int());
+    } else {
+        ix_val = ix.val;
+    }
+
     auto llunit_ty = node_type(cx.fcx.ccx, ann);
     auto unit_sz = size_of(bcx, node_ann_type(cx.fcx.ccx, ann));
     bcx = unit_sz.bcx;
-    auto scaled_ix = bcx.build.Mul(ix.val, unit_sz.val);
+
+    auto scaled_ix = bcx.build.Mul(ix_val, unit_sz.val);
 
     auto lim = bcx.build.GEP(v, vec(C_int(0), C_int(abi.vec_elt_fill)));
     lim = bcx.build.Load(lim);
@@ -2345,7 +3247,7 @@ fn trans_index(@block_ctxt cx, &ast.span sp, @ast.expr base,
     fail_res.bcx.build.Br(next_cx.llbb);
 
     auto body = next_cx.build.GEP(v, vec(C_int(0), C_int(abi.vec_elt_data)));
-    auto elt = next_cx.build.GEP(body, vec(C_int(0), ix.val));
+    auto elt = next_cx.build.GEP(body, vec(C_int(0), ix_val));
     ret lval_mem(next_cx, elt);
 }
 
@@ -2400,125 +3302,24 @@ fn trans_cast(@block_ctxt cx, @ast.expr e, &ast.ann ann) -> result {
     ret e_res;
 }
 
-
-// NB: this must match type_of_fn_full and create_llargs_for_fn_args.
-fn trans_args(@block_ctxt cx,
-              ValueRef llclosure,
-              option.t[ValueRef] llobj,
-              option.t[generic_info] gen,
-              &vec[@ast.expr] es,
-              @ty.t fn_ty)
-    -> tup(@block_ctxt, vec[ValueRef], option.t[ValueRef]) {
-    let vec[ValueRef] vs = vec(cx.fcx.lltaskptr);
-    let @block_ctxt bcx = cx;
-
-    let vec[ty.arg] args = ty.ty_fn_args(fn_ty);
-
-    let option.t[ValueRef] llretslot_opt = none[ValueRef];
-
-    alt (gen) {
-        case (some[generic_info](?g)) {
-            for (ValueRef t in g.tydescs) {
-                vs += t;
-            }
-            args = ty.ty_fn_args(g.item_type);
-            if (ty.type_has_dynamic_size(ty.ty_fn_ret(g.item_type))) {
-                auto retty = ty.ty_fn_ret(fn_ty);
-                auto llretty = type_of(cx.fcx.ccx, retty);
-                auto llretslot = cx.build.Alloca(llretty);
-                vs += cx.build.PointerCast(llretslot, T_ptr(T_i8()));
-                llretslot_opt = some[ValueRef](llretslot);
-            }
-        }
-        case (_) { }
-    }
-
-    alt (llobj) {
-        case (some[ValueRef](?ob)) {
-            // Every object is always found in memory,
-            // and not-yet-loaded (as part of an lval x.y
-            // doted method-call).
-            vs += cx.build.Load(ob);
-        }
-        case (_) {
-            vs += llclosure;
-        }
-    }
-
-    auto i = 0u;
-    for (@ast.expr e in es) {
-        auto mode = args.(i).mode;
-
-        auto val;
-        if (ty.type_is_structural(ty.expr_ty(e))) {
-            auto re = trans_expr(bcx, e);
-            val = re.val;
-            bcx = re.bcx;
-            if (mode == ast.val) {
-                // Until here we've been treating structures by pointer;
-                // we are now passing it as an arg, so need to load it.
-                val = bcx.build.Load(val);
-            }
-        } else if (mode == ast.alias) {
-            let lval_result lv;
-            if (ty.is_lval(e)) {
-                lv = trans_lval(bcx, e);
-            } else {
-                auto r = trans_expr(bcx, e);
-                lv = lval_val(r.bcx, r.val);
-            }
-            bcx = lv.res.bcx;
-
-            if (lv.is_mem) {
-                val = lv.res.val;
-            } else {
-                // Non-mem but we're trying to alias; synthesize an
-                // alloca, spill to it and pass its address.
-                auto llty = val_ty(lv.res.val);
-                auto llptr = lv.res.bcx.build.Alloca(llty);
-                lv.res.bcx.build.Store(lv.res.val, llptr);
-                val = llptr;
-            }
-
-        } else {
-            auto re = trans_expr(bcx, e);
-            val = re.val;
-            bcx = re.bcx;
-        }
-
-        if (ty.type_has_dynamic_size(args.(i).ty)) {
-            val = bcx.build.PointerCast(val, T_typaram_ptr());
-        }
-
-        vs += val;
-        i += 1u;
-    }
-
-    ret tup(bcx, vs, llretslot_opt);
-}
-
 fn trans_bind_thunk(@crate_ctxt cx,
                     @ty.t incoming_fty,
                     @ty.t outgoing_fty,
                     vec[option.t[@ast.expr]] args,
                     TypeRef llclosure_ty,
-                    vec[@ty.t] bound_tys) -> ValueRef {
+                    vec[@ty.t] bound_tys,
+                    uint ty_param_count) -> ValueRef {
     // Construct a thunk-call with signature incoming_fty, and that copies
     // args forward into a call to outgoing_fty.
 
-    let str s = cx.names.next("_rust_thunk") + "." + cx.path;
+    let str s = cx.names.next("_rust_thunk") + sep() + cx.path;
     let TypeRef llthunk_ty = get_pair_fn_ty(type_of(cx, incoming_fty));
     let ValueRef llthunk = decl_fastcall_fn(cx.llmod, s, llthunk_ty);
 
-    let @ty.t rty = ret_ty_of_fn_ty(incoming_fty);
-
-    // FIXME: handle ty params properly.
-    let vec[ast.ty_param] ty_params = vec();
-
-    auto fcx = new_fn_ctxt(cx, s, llthunk);
+    auto fcx = new_fn_ctxt(cx, llthunk);
     auto bcx = new_top_block_ctxt(fcx);
 
-    auto llclosure = bcx.build.PointerCast(fcx.llclosure, llclosure_ty);
+    auto llclosure = bcx.build.PointerCast(fcx.llenv, llclosure_ty);
 
     auto llbody = bcx.build.GEP(llclosure,
                                 vec(C_int(0),
@@ -2536,10 +3337,33 @@ fn trans_bind_thunk(@crate_ctxt cx,
                                          vec(C_int(0),
                                              C_int(abi.fn_field_box)));
     lltargetclosure = bcx.build.Load(lltargetclosure);
-    let vec[ValueRef] llargs = vec(fcx.lltaskptr,
+
+    auto outgoing_ret_ty = ty.ty_fn_ret(outgoing_fty);
+    auto outgoing_arg_tys = ty.ty_fn_args(outgoing_fty);
+
+    auto llretptr = fcx.llretptr;
+    if (ty.type_has_dynamic_size(outgoing_ret_ty)) {
+        llretptr = bcx.build.PointerCast(llretptr, T_typaram_ptr(cx.tn));
+    }
+
+    let vec[ValueRef] llargs = vec(llretptr,
+                                   fcx.lltaskptr,
                                    lltargetclosure);
-    let uint a = 0u;
+
+    // Copy in the type parameters.
+    let uint i = 0u;
+    while (i < ty_param_count) {
+        auto lltyparam_ptr =
+            bcx.build.GEP(llbody, vec(C_int(0),
+                                      C_int(abi.closure_elt_ty_params),
+                                      C_int(i as int)));
+        llargs += vec(bcx.build.Load(lltyparam_ptr));
+        i += 1u;
+    }
+
+    let uint a = 2u + i;    // retptr, task ptr, env come first
     let int b = 0;
+    let uint outgoing_arg_index = 0u;
     for (option.t[@ast.expr] arg in args) {
         alt (arg) {
 
@@ -2556,10 +3380,19 @@ fn trans_bind_thunk(@crate_ctxt cx,
             // Arg will be provided when the thunk is invoked.
             case (none[@ast.expr]) {
                 let ValueRef passed_arg = llvm.LLVMGetParam(llthunk, a);
+                if (ty.type_has_dynamic_size(outgoing_arg_tys.
+                        (outgoing_arg_index).ty)) {
+                    // Cast to a generic typaram pointer in order to make a
+                    // type-compatible call.
+                    passed_arg = bcx.build.PointerCast(passed_arg,
+                                                       T_typaram_ptr(cx.tn));
+                }
                 llargs += passed_arg;
                 a += 1u;
             }
         }
+
+        outgoing_arg_index += 0u;
     }
 
     // FIXME: turn this call + ret into a tail call.
@@ -2567,21 +3400,9 @@ fn trans_bind_thunk(@crate_ctxt cx,
                                     vec(C_int(0),
                                         C_int(abi.fn_field_code)));
     lltargetfn = bcx.build.Load(lltargetfn);
-    auto r = bcx.build.FastCall(lltargetfn, llargs);
 
-    alt (fcx.llretptr) {
-        case (some[ValueRef](?llptr)) {
-            bcx.build.Store(bcx.build.Load(r), llptr);
-            bcx.build.RetVoid();
-        }
-        case (none[ValueRef]) {
-            if (ty.type_is_nil(rty)) {
-                bcx.build.RetVoid();
-            } else {
-                bcx.build.Ret(r);
-            }
-        }
-    }
+    auto r = bcx.build.FastCall(lltargetfn, llargs);
+    bcx.build.RetVoid();
 
     ret llthunk;
 }
@@ -2604,7 +3425,23 @@ fn trans_bind(@block_ctxt cx, @ast.expr f,
                 }
             }
         }
-        if (_vec.len[@ast.expr](bound) == 0u) {
+
+        // Figure out which tydescs we need to pass, if any.
+        let @ty.t outgoing_fty;
+        let vec[ValueRef] lltydescs;
+        alt (f_res.generic) {
+            case (none[generic_info]) {
+                outgoing_fty = ty.expr_ty(f);
+                lltydescs = vec();
+            }
+            case (some[generic_info](?ginfo)) {
+                outgoing_fty = ginfo.item_type;
+                lltydescs = ginfo.tydescs;
+            }
+        }
+        auto ty_param_count = _vec.len[ValueRef](lltydescs);
+
+        if (_vec.len[@ast.expr](bound) == 0u && ty_param_count == 0u) {
             // Trivial 'binding': just return the static pair-ptr.
             ret f_res.res;
         } else {
@@ -2615,22 +3452,32 @@ fn trans_bind(@block_ctxt cx, @ast.expr f,
             // Translate the bound expressions.
             let vec[@ty.t] bound_tys = vec();
             let vec[ValueRef] bound_vals = vec();
+            auto i = 0u;
             for (@ast.expr e in bound) {
                 auto arg = trans_expr(bcx, e);
                 bcx = arg.bcx;
+
                 append[ValueRef](bound_vals, arg.val);
                 append[@ty.t](bound_tys, ty.expr_ty(e));
+
+                i += 1u;
             }
 
+            // Get the type of the bound function.
+            let TypeRef lltarget_ty = type_of(bcx.fcx.ccx, outgoing_fty);
+
             // Synthesize a closure type.
-            let @ty.t bindings_ty = ty.plain_ty(ty.ty_tup(bound_tys));
-            let TypeRef lltarget_ty = type_of(bcx.fcx.ccx, ty.expr_ty(f));
+            let @ty.t bindings_ty = plain_ty(ty.ty_tup(bound_tys));
             let TypeRef llbindings_ty = type_of(bcx.fcx.ccx, bindings_ty);
-            let TypeRef llclosure_ty = T_closure_ptr(lltarget_ty,
-                                                     llbindings_ty);
+            let TypeRef llclosure_ty = T_closure_ptr(cx.fcx.ccx.tn,
+                                                     lltarget_ty,
+                                                     llbindings_ty,
+                                                     ty_param_count);
 
             // Malloc a box for the body.
-            auto r = trans_malloc_inner(bcx, llclosure_ty);
+            // FIXME: this isn't generic-safe
+            auto r = trans_raw_malloc(bcx, llclosure_ty,
+                llsize_of(llvm.LLVMGetElementType(llclosure_ty)));
             auto box = r.val;
             bcx = r.bcx;
             auto rc = bcx.build.GEP(box,
@@ -2656,19 +3503,40 @@ fn trans_bind(@block_ctxt cx, @ast.expr f,
                 bcx.build.GEP(closure,
                               vec(C_int(0),
                                   C_int(abi.closure_elt_target)));
-            bcx.build.Store(bcx.build.Load(f_res.res.val), bound_target);
+            auto src = bcx.build.Load(f_res.res.val);
+            bcx.build.Store(src, bound_target);
 
             // Copy expr values into boxed bindings.
-            let int i = 0;
+            i = 0u;
             auto bindings =
                 bcx.build.GEP(closure,
                               vec(C_int(0),
                                   C_int(abi.closure_elt_bindings)));
             for (ValueRef v in bound_vals) {
                 auto bound = bcx.build.GEP(bindings,
-                                           vec(C_int(0),C_int(i)));
+                                           vec(C_int(0), C_int(i as int)));
                 bcx = copy_ty(r.bcx, INIT, bound, v, bound_tys.(i)).bcx;
-                i += 1;
+                i += 1u;
+            }
+
+            // If necessary, copy tydescs describing type parameters into the
+            // appropriate slot in the closure.
+            alt (f_res.generic) {
+                case (none[generic_info]) { /* nothing to do */ }
+                case (some[generic_info](?ginfo)) {
+                    auto ty_params_slot =
+                        bcx.build.GEP(closure,
+                                      vec(C_int(0),
+                                          C_int(abi.closure_elt_ty_params)));
+                    auto i = 0;
+                    for (ValueRef td in ginfo.tydescs) {
+                        auto ty_param_slot = bcx.build.GEP(ty_params_slot,
+                                                           vec(C_int(0),
+                                                               C_int(i)));
+                        bcx.build.Store(td, ty_param_slot);
+                        i += 1;
+                    }
+                }
             }
 
             // Make thunk and store thunk-ptr in outer pair's code slot.
@@ -2678,8 +3546,9 @@ fn trans_bind(@block_ctxt cx, @ast.expr f,
 
             let @ty.t pair_ty = node_ann_type(cx.fcx.ccx, ann);
             let ValueRef llthunk =
-                trans_bind_thunk(cx.fcx.ccx, pair_ty, ty.expr_ty(f),
-                                 args, llclosure_ty, bound_tys);
+                trans_bind_thunk(cx.fcx.ccx, pair_ty, outgoing_fty,
+                                 args, llclosure_ty, bound_tys,
+                                 ty_param_count);
 
             bcx.build.Store(llthunk, pair_code);
 
@@ -2687,9 +3556,11 @@ fn trans_bind(@block_ctxt cx, @ast.expr f,
             auto pair_box = bcx.build.GEP(pair_v,
                                           vec(C_int(0),
                                               C_int(abi.fn_field_box)));
-            bcx.build.Store(bcx.build.PointerCast(box,
-                                                  T_opaque_closure_ptr()),
-                            pair_box);
+            bcx.build.Store
+                (bcx.build.PointerCast
+                 (box,
+                  T_opaque_closure_ptr(bcx.fcx.ccx.tn)),
+                 pair_box);
 
             find_scope_cx(cx).cleanups +=
                 clean(bind drop_slot(_, pair_v, pair_ty));
@@ -2699,11 +3570,153 @@ fn trans_bind(@block_ctxt cx, @ast.expr f,
     }
 }
 
+// NB: must keep 4 fns in sync:
+//
+//  - type_of_fn_full
+//  - create_llargs_for_fn_args.
+//  - new_fn_ctxt
+//  - trans_args
+
+fn trans_args(@block_ctxt cx,
+              ValueRef llenv,
+              option.t[ValueRef] llobj,
+              option.t[generic_info] gen,
+              option.t[ValueRef] lliterbody,
+              &vec[@ast.expr] es,
+              @ty.t fn_ty)
+    -> tup(@block_ctxt, vec[ValueRef], ValueRef) {
+
+    let vec[ty.arg] args = ty.ty_fn_args(fn_ty);
+    let vec[ValueRef] llargs = vec();
+    let vec[ValueRef] lltydescs = vec();
+    let @block_ctxt bcx = cx;
+
+
+    // Arg 0: Output pointer.
+    auto retty = ty.ty_fn_ret(fn_ty);
+    auto llretslot_res = alloc_ty(bcx, retty);
+    bcx = llretslot_res.bcx;
+    auto llretslot = llretslot_res.val;
+
+    alt (gen) {
+        case (some[generic_info](?g)) {
+            lltydescs = g.tydescs;
+            args = ty.ty_fn_args(g.item_type);
+            retty = ty.ty_fn_ret(g.item_type);
+        }
+        case (_) {
+        }
+    }
+    if (ty.type_has_dynamic_size(retty)) {
+        llargs += bcx.build.PointerCast(llretslot,
+                                        T_typaram_ptr(cx.fcx.ccx.tn));
+    } else if (ty.count_ty_params(retty) != 0u) {
+        // It's possible that the callee has some generic-ness somewhere in
+        // its return value -- say a method signature within an obj or a fn
+        // type deep in a structure -- which the caller has a concrete view
+        // of. If so, cast the caller's view of the restlot to the callee's
+        // view, for the sake of making a type-compatible call.
+        llargs += cx.build.PointerCast(llretslot,
+                                       T_ptr(type_of(bcx.fcx.ccx, retty)));
+    } else {
+        llargs += llretslot;
+    }
+
+
+    // Arg 1: Task pointer.
+    llargs += bcx.fcx.lltaskptr;
+
+    // Arg 2: Env (closure-bindings / self-obj)
+    alt (llobj) {
+        case (some[ValueRef](?ob)) {
+            // Every object is always found in memory,
+            // and not-yet-loaded (as part of an lval x.y
+            // doted method-call).
+            llargs += bcx.build.Load(ob);
+        }
+        case (_) {
+            llargs += llenv;
+        }
+    }
+
+    // Args >3: ty_params ...
+    llargs += lltydescs;
+
+    // ... then possibly an lliterbody argument.
+    alt (lliterbody) {
+        case (none[ValueRef]) {}
+        case (some[ValueRef](?lli)) {
+            llargs += lli;
+        }
+    }
+
+    // ... then explicit args.
+
+    // First we figure out the caller's view of the types of the arguments.
+    // This will be needed if this is a generic call, because the callee has
+    // to cast her view of the arguments to the caller's view.
+    auto arg_tys = type_of_explicit_args(cx.fcx.ccx, args);
+
+    auto i = 0u;
+    for (@ast.expr e in es) {
+        auto mode = args.(i).mode;
+
+        auto val;
+        if (ty.type_is_structural(ty.expr_ty(e))) {
+            auto re = trans_expr(bcx, e);
+            val = re.val;
+            bcx = re.bcx;
+            if (mode == ast.val) {
+                // Until here we've been treating structures by pointer;
+                // we are now passing it as an arg, so need to load it.
+                val = bcx.build.Load(val);
+            }
+        } else if (mode == ast.alias) {
+            let lval_result lv;
+            if (ty.is_lval(e)) {
+                lv = trans_lval(bcx, e);
+            } else {
+                auto r = trans_expr(bcx, e);
+                lv = lval_val(r.bcx, r.val);
+            }
+            bcx = lv.res.bcx;
+
+            if (lv.is_mem) {
+                val = lv.res.val;
+            } else {
+                // Non-mem but we're trying to alias; synthesize an
+                // alloca, spill to it and pass its address.
+                auto llty = val_ty(lv.res.val);
+                auto llptr = lv.res.bcx.build.Alloca(llty);
+                lv.res.bcx.build.Store(lv.res.val, llptr);
+                val = llptr;
+            }
+
+        } else {
+            auto re = trans_expr(bcx, e);
+            val = re.val;
+            bcx = re.bcx;
+        }
+
+        if (ty.count_ty_params(args.(i).ty) > 0u) {
+            auto lldestty = arg_tys.(i);
+            val = bcx.build.PointerCast(val, lldestty);
+        }
+
+        llargs += val;
+        i += 1u;
+    }
+
+    ret tup(bcx, llargs, llretslot);
+}
+
 fn trans_call(@block_ctxt cx, @ast.expr f,
-              vec[@ast.expr] args, &ast.ann ann) -> result {
+              option.t[ValueRef] lliterbody,
+              vec[@ast.expr] args,
+              &ast.ann ann) -> result {
     auto f_res = trans_lval(cx, f);
     auto faddr = f_res.res.val;
-    auto llclosure = C_null(T_opaque_closure_ptr());
+    auto llenv = C_null(T_opaque_closure_ptr(cx.fcx.ccx.tn));
 
     alt (f_res.llobj) {
         case (some[ValueRef](_)) {
@@ -2718,71 +3731,67 @@ fn trans_call(@block_ctxt cx, @ast.expr f,
                                             C_int(abi.fn_field_code)));
             faddr = bcx.build.Load(faddr);
 
-            llclosure = bcx.build.GEP(pair, vec(C_int(0),
-                                                C_int(abi.fn_field_box)));
-            llclosure = bcx.build.Load(llclosure);
+            auto llclosure = bcx.build.GEP(pair,
+                                           vec(C_int(0),
+                                               C_int(abi.fn_field_box)));
+            llenv = bcx.build.Load(llclosure);
         }
     }
     auto fn_ty = ty.expr_ty(f);
     auto ret_ty = ty.ann_to_type(ann);
     auto args_res = trans_args(f_res.res.bcx,
-                               llclosure, f_res.llobj,
+                               llenv, f_res.llobj,
                                f_res.generic,
+                               lliterbody,
                                args, fn_ty);
 
     auto bcx = args_res._0;
-    auto real_retval = bcx.build.FastCall(faddr, args_res._1);
-    auto retval = real_retval;
+    auto llargs = args_res._1;
+    auto llretslot = args_res._2;
 
-    if (ty.type_is_nil(ret_ty)) {
-        retval = C_nil();
-    }
+    /*
+    log "calling: " + val_str(cx.fcx.ccx.tn, faddr);
 
-    // Check for a generic retslot.
-    alt (args_res._2) {
+    for (ValueRef arg in llargs) {
+        log "arg: " + val_str(cx.fcx.ccx.tn, arg);
+    }
+    */
 
-        case (some[ValueRef](?llretslot)) {
-            retval = load_scalar_or_boxed(bcx, llretslot, ret_ty);
-        }
+    bcx.build.FastCall(faddr, llargs);
+    auto retval = C_nil();
 
-        case (none[ValueRef]) {
-            if (! (ty.type_is_scalar(ret_ty) ||
-                   ty.type_is_boxed(ret_ty))) {
-                // Structured returns come back as first-class values. This is
-                // nice for LLVM but wrong for us; we treat structured values
-                // by pointer in most of our code here. So spill it to an
-                // alloca.
-                auto local = bcx.build.Alloca(type_of(cx.fcx.ccx, ret_ty));
-                bcx.build.Store(retval, local);
-                retval = local;
-            }
-        }
+    if (!ty.type_is_nil(ret_ty)) {
+        retval = load_scalar_or_boxed(bcx, llretslot, ret_ty);
+        // Retval doesn't correspond to anything really tangible in the frame,
+        // but it's a ref all the same, so we put a note here to drop it when
+        // we're done in this scope.
+        find_scope_cx(cx).cleanups += clean(bind drop_ty(_, retval, ret_ty));
     }
 
-    // Retval doesn't correspond to anything really tangible in the frame, but
-    // it's a ref all the same, so we put a note here to drop it when we're
-    // done in this scope.
-    find_scope_cx(cx).cleanups += clean(bind drop_ty(_, retval, ret_ty));
-
     ret res(bcx, retval);
 }
 
 fn trans_tup(@block_ctxt cx, vec[ast.elt] elts,
              &ast.ann ann) -> result {
-    auto t = node_ann_type(cx.fcx.ccx, ann);
-    auto llty = type_of(cx.fcx.ccx, t);
-    auto tup_val = cx.build.Alloca(llty);
+    auto bcx = cx;
+    auto t = node_ann_type(bcx.fcx.ccx, ann);
+    auto tup_res = alloc_ty(bcx, t);
+    auto tup_val = tup_res.val;
+    bcx = tup_res.bcx;
+
     find_scope_cx(cx).cleanups += clean(bind drop_ty(_, tup_val, t));
     let int i = 0;
-    auto r = res(cx, C_nil());
+
     for (ast.elt e in elts) {
-        auto t = ty.expr_ty(e.expr);
-        auto src_res = trans_expr(r.bcx, e.expr);
-        auto dst_elt = r.bcx.build.GEP(tup_val, vec(C_int(0), C_int(i)));
-        r = copy_ty(src_res.bcx, INIT, dst_elt, src_res.val, t);
+        auto e_ty = ty.expr_ty(e.expr);
+        auto src_res = trans_expr(bcx, e.expr);
+        bcx = src_res.bcx;
+        auto dst_res = GEP_tup_like(bcx, t, tup_val, vec(0, i));
+        bcx = dst_res.bcx;
+        bcx = copy_ty(src_res.bcx, INIT, dst_res.val, src_res.val, e_ty).bcx;
         i += 1;
     }
-    ret res(r.bcx, tup_val);
+    ret res(bcx, tup_val);
 }
 
 fn trans_vec(@block_ctxt cx, vec[@ast.expr] args,
@@ -2807,44 +3816,89 @@ fn trans_vec(@block_ctxt cx, vec[@ast.expr] args,
 
     // FIXME: pass tydesc properly.
     auto sub = trans_upcall(bcx, "upcall_new_vec", vec(data_sz, C_int(0)));
+    bcx = sub.bcx;
 
     auto llty = type_of(bcx.fcx.ccx, t);
-    auto vec_val = sub.bcx.build.IntToPtr(sub.val, llty);
+    auto vec_val = vi2p(bcx, sub.val, llty);
     find_scope_cx(bcx).cleanups += clean(bind drop_ty(_, vec_val, t));
 
-    auto body = sub.bcx.build.GEP(vec_val, vec(C_int(0),
-                                               C_int(abi.vec_elt_data)));
+    auto body = bcx.build.GEP(vec_val, vec(C_int(0),
+                                           C_int(abi.vec_elt_data)));
+
+    auto pseudo_tup_ty =
+        plain_ty(ty.ty_tup(_vec.init_elt[@ty.t](unit_ty,
+                                                _vec.len[@ast.expr](args))));
     let int i = 0;
+
     for (@ast.expr e in args) {
-        auto src_res = trans_expr(sub.bcx, e);
-        auto dst_elt = sub.bcx.build.GEP(body, vec(C_int(0), C_int(i)));
-        sub = copy_ty(src_res.bcx, INIT, dst_elt, src_res.val, unit_ty);
+        auto src_res = trans_expr(bcx, e);
+        bcx = src_res.bcx;
+        auto dst_res = GEP_tup_like(bcx, pseudo_tup_ty, body, vec(0, i));
+        bcx = dst_res.bcx;
+        bcx = copy_ty(bcx, INIT, dst_res.val, src_res.val, unit_ty).bcx;
         i += 1;
     }
-    auto fill = sub.bcx.build.GEP(vec_val,
-                                  vec(C_int(0), C_int(abi.vec_elt_fill)));
-    sub.bcx.build.Store(data_sz, fill);
+    auto fill = bcx.build.GEP(vec_val,
+                              vec(C_int(0), C_int(abi.vec_elt_fill)));
+    bcx.build.Store(data_sz, fill);
 
-    ret res(sub.bcx, vec_val);
+    ret res(bcx, vec_val);
 }
 
 fn trans_rec(@block_ctxt cx, vec[ast.field] fields,
-             &ast.ann ann) -> result {
-    auto t = node_ann_type(cx.fcx.ccx, ann);
-    auto llty = type_of(cx.fcx.ccx, t);
-    auto rec_val = cx.build.Alloca(llty);
+             option.t[@ast.expr] base, &ast.ann ann) -> result {
+
+    auto bcx = cx;
+    auto t = node_ann_type(bcx.fcx.ccx, ann);
+    auto llty = type_of(bcx.fcx.ccx, t);
+    auto rec_res = alloc_ty(bcx, t);
+    auto rec_val = rec_res.val;
+    bcx = rec_res.bcx;
+
     find_scope_cx(cx).cleanups += clean(bind drop_ty(_, rec_val, t));
     let int i = 0;
-    auto r = res(cx, C_nil());
-    for (ast.field f in fields) {
-        auto t = ty.expr_ty(f.expr);
-        auto src_res = trans_expr(r.bcx, f.expr);
-        auto dst_elt = r.bcx.build.GEP(rec_val, vec(C_int(0), C_int(i)));
-        // FIXME: calculate copy init-ness in typestate.
-        r = copy_ty(src_res.bcx, INIT, dst_elt, src_res.val, t);
+
+    auto base_val = C_nil();
+
+    alt (base) {
+        case (none[@ast.expr]) { }
+        case (some[@ast.expr](?bexp)) {
+            auto base_res = trans_expr(bcx, bexp);
+            bcx = base_res.bcx;
+            base_val = base_res.val;
+        }
+    }
+
+    let vec[ty.field] ty_fields = vec();
+    alt (t.struct) {
+        case (ty.ty_rec(?flds)) { ty_fields = flds; }
+    }
+
+    for (ty.field tf in ty_fields) {
+        auto e_ty = tf.ty;
+        auto dst_res = GEP_tup_like(bcx, t, rec_val, vec(0, i));
+        bcx = dst_res.bcx;
+
+        auto expr_provided = false;
+        auto src_res = res(bcx, C_nil());
+
+        for (ast.field f in fields) {
+            if (_str.eq(f.ident, tf.ident)) {
+                expr_provided = true;
+                src_res = trans_expr(bcx, f.expr);
+            }
+        }
+        if (!expr_provided) {
+            src_res = GEP_tup_like(bcx, t, base_val, vec(0, i));
+            src_res = res(src_res.bcx,
+                          load_scalar_or_boxed(bcx, src_res.val, e_ty));
+        }
+
+        bcx = src_res.bcx;
+        bcx = copy_ty(bcx, INIT, dst_res.val, src_res.val, e_ty).bcx;
         i += 1;
     }
-    ret res(r.bcx, rec_val);
+    ret res(bcx, rec_val);
 }
 
 
@@ -2871,6 +3925,10 @@ fn trans_expr(@block_ctxt cx, @ast.expr e) -> result {
             ret trans_for(cx, decl, seq, body);
         }
 
+        case (ast.expr_for_each(?decl, ?seq, ?body, _)) {
+            ret trans_for_each(cx, decl, seq, body);
+        }
+
         case (ast.expr_while(?cond, ?body, _)) {
             ret trans_while(cx, cond, body);
         }
@@ -2911,10 +3969,11 @@ fn trans_expr(@block_ctxt cx, @ast.expr e) -> result {
             auto lhs_val = load_scalar_or_boxed(lhs_res.res.bcx,
                                                 lhs_res.res.val, t);
             auto rhs_res = trans_expr(lhs_res.res.bcx, src);
-            auto v = trans_eager_binop(rhs_res.bcx, op, lhs_val, rhs_res.val);
+            auto v = trans_eager_binop(rhs_res.bcx, op, t,
+                                       lhs_val, rhs_res.val);
             // FIXME: calculate copy init-ness in typestate.
-            ret copy_ty(rhs_res.bcx, DROP_EXISTING,
-                        lhs_res.res.val, v, t);
+            ret copy_ty(v.bcx, DROP_EXISTING,
+                        lhs_res.res.val, v.val, t);
         }
 
         case (ast.expr_bind(?f, ?args, ?ann)) {
@@ -2922,7 +3981,7 @@ fn trans_expr(@block_ctxt cx, @ast.expr e) -> result {
         }
 
         case (ast.expr_call(?f, ?args, ?ann)) {
-            ret trans_call(cx, f, args, ann);
+            ret trans_call(cx, f, none[ValueRef], args, ann);
         }
 
         case (ast.expr_cast(?e, _, ?ann)) {
@@ -2937,8 +3996,36 @@ fn trans_expr(@block_ctxt cx, @ast.expr e) -> result {
             ret trans_tup(cx, args, ann);
         }
 
-        case (ast.expr_rec(?args, ?ann)) {
-            ret trans_rec(cx, args, ann);
+        case (ast.expr_rec(?args, ?base, ?ann)) {
+            ret trans_rec(cx, args, base, ann);
+        }
+
+        case (ast.expr_ext(_, _, _, ?expanded, _)) {
+            ret trans_expr(cx, expanded);
+        }
+
+        case (ast.expr_fail) {
+            ret trans_fail(cx, e.span, "explicit failure");
+        }
+
+        case (ast.expr_log(?a)) {
+            ret trans_log(cx, a);
+        }
+
+        case (ast.expr_check_expr(?a)) {
+            ret trans_check_expr(cx, a);
+        }
+
+        case (ast.expr_ret(?e)) {
+            ret trans_ret(cx, e);
+        }
+
+        case (ast.expr_put(?e)) {
+            ret trans_put(cx, e);
+        }
+
+        case (ast.expr_be(?e)) {
+            ret trans_be(cx, e);
         }
 
         // lval cases fall through to trans_lval and then
@@ -2962,7 +4049,7 @@ fn trans_expr(@block_ctxt cx, @ast.expr e) -> result {
 fn load_scalar_or_boxed(@block_ctxt cx,
                         ValueRef v,
                         @ty.t t) -> ValueRef {
-    if (ty.type_is_scalar(t) || ty.type_is_boxed(t)) {
+    if (ty.type_is_scalar(t) || ty.type_is_boxed(t) || ty.type_is_native(t)) {
         ret cx.build.Load(v);
     } else {
         ret v;
@@ -2975,7 +4062,7 @@ fn trans_log(@block_ctxt cx, @ast.expr e) -> result {
     auto e_ty = ty.expr_ty(e);
     alt (e_ty.struct) {
         case (ty.ty_str) {
-            auto v = sub.bcx.build.PtrToInt(sub.val, T_int());
+            auto v = vp2i(sub.bcx, sub.val);
             ret trans_upcall(sub.bcx,
                              "upcall_log_str",
                              vec(v));
@@ -3014,6 +4101,38 @@ fn trans_fail(@block_ctxt cx, common.span sp, str fail_str) -> result {
     ret trans_upcall(cx, "upcall_fail", args);
 }
 
+fn trans_put(@block_ctxt cx, &option.t[@ast.expr] e) -> result {
+    auto llcallee = C_nil();
+    auto llenv = C_nil();
+
+    alt (cx.fcx.lliterbody) {
+        case (some[ValueRef](?lli)) {
+            auto slot = cx.build.Alloca(val_ty(lli));
+            cx.build.Store(lli, slot);
+
+            llcallee = cx.build.GEP(slot, vec(C_int(0),
+                                              C_int(abi.fn_field_code)));
+            llcallee = cx.build.Load(llcallee);
+
+            llenv = cx.build.GEP(slot, vec(C_int(0),
+                                           C_int(abi.fn_field_box)));
+            llenv = cx.build.Load(llenv);
+        }
+    }
+    auto bcx = cx;
+    auto dummy_retslot = bcx.build.Alloca(T_nil());
+    let vec[ValueRef] llargs = vec(dummy_retslot, cx.fcx.lltaskptr, llenv);
+    alt (e) {
+        case (none[@ast.expr]) { }
+        case (some[@ast.expr](?x)) {
+            auto r = trans_expr(bcx, x);
+            llargs += r.val;
+            bcx = r.bcx;
+        }
+    }
+    ret res(bcx, bcx.build.FastCall(llcallee, llargs));
+}
+
 fn trans_ret(@block_ctxt cx, &option.t[@ast.expr] e) -> result {
     auto bcx = cx;
     auto val = C_nil();
@@ -3024,18 +4143,7 @@ fn trans_ret(@block_ctxt cx, &option.t[@ast.expr] e) -> result {
             auto r = trans_expr(cx, x);
             bcx = r.bcx;
             val = r.val;
-
-            // A return is an implicit copy into a newborn anonymous
-            // 'return value' in the caller frame.
-            bcx = incr_all_refcnts(bcx, val, t).bcx;
-
-            if (ty.type_is_structural(t)) {
-                // We usually treat structurals by-pointer; in particular,
-                // trans_expr will have given us a structure pointer. But in
-                // this case we're about to return. LLVM wants a first-class
-                // value here (which makes sense; the frame is going away!)
-                val = r.bcx.build.Load(val);
-            }
+            bcx = copy_ty(bcx, INIT, cx.fcx.llretptr, val, t).bcx;
         }
         case (_) { /* fall through */  }
     }
@@ -3055,38 +4163,18 @@ fn trans_ret(@block_ctxt cx, &option.t[@ast.expr] e) -> result {
         }
     }
 
-    alt (e) {
-        case (some[@ast.expr](?ex)) {
-            auto t = ty.expr_ty(ex);
-
-            if (ty.type_is_nil(t)) {
-                bcx.build.RetVoid();
-                val = C_nil();
-                ret res(bcx, val);  // FIXME: early return needed due to
-                                    // typestate bug
-            }
-
-            alt (cx.fcx.llretptr) {
-                case (some[ValueRef](?llptr)) {
-                    // Generic return via tydesc + retptr.
-                    bcx = copy_ty(bcx, INIT, llptr, val, t).bcx;
-                    bcx.build.RetVoid();
-                }
-                case (none[ValueRef]) {
-                    val = bcx.build.Ret(val);
-                }
-            }
-            ret res(bcx, val);
-        }
-        case (_) { /* fall through */  }
-    }
-
-    // FIXME: until LLVM has a unit type, we are moving around
-    // C_nil values rather than their void type.
     bcx.build.RetVoid();
     ret res(bcx, C_nil());
 }
 
+fn trans_be(@block_ctxt cx, @ast.expr e) -> result {
+    // FIXME: This should be a typestate precondition
+    check (ast.is_call_expr(e));
+    // FIXME: Turn this into a real tail call once
+    // calling convention issues are settled
+    ret trans_ret(cx, some(e));
+}
+
 fn init_local(@block_ctxt cx, @ast.local local) -> result {
 
     // Make a note to drop this slot on the way out.
@@ -3121,22 +4209,6 @@ fn init_local(@block_ctxt cx, @ast.local local) -> result {
 fn trans_stmt(@block_ctxt cx, &ast.stmt s) -> result {
     auto bcx = cx;
     alt (s.node) {
-        case (ast.stmt_log(?a)) {
-            bcx = trans_log(cx, a).bcx;
-        }
-
-        case (ast.stmt_check_expr(?a)) {
-            bcx = trans_check_expr(cx, a).bcx;
-        }
-
-        case (ast.stmt_fail) {
-            bcx = trans_fail(cx, s.span, "explicit failure").bcx;
-        }
-
-        case (ast.stmt_ret(?e)) {
-            bcx = trans_ret(cx, e).bcx;
-        }
-
         case (ast.stmt_expr(?e)) {
             bcx = trans_expr(cx, e).bcx;
         }
@@ -3184,7 +4256,13 @@ fn new_block_ctxt(@fn_ctxt cx, block_parent parent,
 
 // Use this when you're at the top block of a function or the like.
 fn new_top_block_ctxt(@fn_ctxt fcx) -> @block_ctxt {
-    ret new_block_ctxt(fcx, parent_none, SCOPE_BLOCK, "function top level");
+    auto cx = new_block_ctxt(fcx, parent_none, SCOPE_BLOCK,
+                             "function top level");
+
+    // FIXME: hack to give us some spill room to make up for an LLVM
+    // bug where it destroys its own callee-saves.
+    cx.build.Alloca(T_array(T_int(), 10u));
+    ret cx;
 }
 
 // Use this when you're at a curly-brace or similar lexical scope.
@@ -3237,8 +4315,7 @@ iter block_locals(&ast.block b) -> @ast.local {
     }
 }
 
-fn alloc_local(@block_ctxt cx, @ast.local local) -> result {
-    auto t = node_ann_type(cx.fcx.ccx, local.ann);
+fn alloc_ty(@block_ctxt cx, @ty.t t) -> result {
     auto val = C_int(0);
     auto bcx = cx;
     if (ty.type_has_dynamic_size(t)) {
@@ -3248,10 +4325,16 @@ fn alloc_local(@block_ctxt cx, @ast.local local) -> result {
     } else {
         val = bcx.build.Alloca(type_of(cx.fcx.ccx, t));
     }
-    bcx.fcx.lllocals.insert(local.id, val);
     ret res(bcx, val);
 }
 
+fn alloc_local(@block_ctxt cx, @ast.local local) -> result {
+    auto t = node_ann_type(cx.fcx.ccx, local.ann);
+    auto r = alloc_ty(cx, t);
+    r.bcx.fcx.lllocals.insert(local.id, r.val);
+    ret r;
+}
+
 fn trans_block(@block_ctxt cx, &ast.block b) -> result {
     auto bcx = cx;
 
@@ -3287,12 +4370,19 @@ fn trans_block(@block_ctxt cx, &ast.block b) -> result {
     ret res(bcx, r.val);
 }
 
+// NB: must keep 4 fns in sync:
+//
+//  - type_of_fn_full
+//  - create_llargs_for_fn_args.
+//  - new_fn_ctxt
+//  - trans_args
+
 fn new_fn_ctxt(@crate_ctxt cx,
-               str name,
                ValueRef llfndecl) -> @fn_ctxt {
 
-    let ValueRef lltaskptr = llvm.LLVMGetParam(llfndecl, 0u);
-    let ValueRef llclosure = llvm.LLVMGetParam(llfndecl, 1u);
+    let ValueRef llretptr = llvm.LLVMGetParam(llfndecl, 0u);
+    let ValueRef lltaskptr = llvm.LLVMGetParam(llfndecl, 1u);
+    let ValueRef llenv = llvm.LLVMGetParam(llfndecl, 2u);
 
     let hashmap[ast.def_id, ValueRef] llargs = new_def_hash[ValueRef]();
     let hashmap[ast.def_id, ValueRef] llobjfields = new_def_hash[ValueRef]();
@@ -3301,9 +4391,10 @@ fn new_fn_ctxt(@crate_ctxt cx,
 
     ret @rec(llfn=llfndecl,
              lltaskptr=lltaskptr,
-             llclosure=llclosure,
+             llenv=llenv,
+             llretptr=llretptr,
              mutable llself=none[ValueRef],
-             mutable llretptr=none[ValueRef],
+             mutable lliterbody=none[ValueRef],
              llargs=llargs,
              llobjfields=llobjfields,
              lllocals=lllocals,
@@ -3311,39 +4402,46 @@ fn new_fn_ctxt(@crate_ctxt cx,
              ccx=cx);
 }
 
-// NB: this must match trans_args and type_of_fn_full.
+// NB: must keep 4 fns in sync:
+//
+//  - type_of_fn_full
+//  - create_llargs_for_fn_args.
+//  - new_fn_ctxt
+//  - trans_args
+
 fn create_llargs_for_fn_args(&@fn_ctxt cx,
+                             ast.proto proto,
                              option.t[TypeRef] ty_self,
                              @ty.t ret_ty,
                              &vec[ast.arg] args,
                              &vec[ast.ty_param] ty_params) {
-    let uint arg_n = 1u;
-
-    for (ast.ty_param tp in ty_params) {
-        auto llarg = llvm.LLVMGetParam(cx.llfn, arg_n);
-        check (llarg as int != 0);
-        cx.lltydescs.insert(tp.id, llarg);
-        arg_n += 1u;
-    }
-
-    if (ty.type_has_dynamic_size(ret_ty)) {
-        cx.llretptr = some[ValueRef](llvm.LLVMGetParam(cx.llfn, arg_n));
-        arg_n += 1u;
-    }
 
     alt (ty_self) {
         case (some[TypeRef](_)) {
-            auto llself = llvm.LLVMGetParam(cx.llfn, arg_n);
-            check (llself as int != 0);
-            cx.llself = some[ValueRef](llself);
-            arg_n += 1u;
+            cx.llself = some[ValueRef](cx.llenv);
         }
         case (_) {
-            // llclosure, we don't know what it is.
+        }
+    }
+
+    auto arg_n = 3u;
+
+    if (ty_self == none[TypeRef]) {
+        for (ast.ty_param tp in ty_params) {
+            auto llarg = llvm.LLVMGetParam(cx.llfn, arg_n);
+            check (llarg as int != 0);
+            cx.lltydescs.insert(tp.id, llarg);
             arg_n += 1u;
         }
     }
 
+    if (proto == ast.proto_iter) {
+        auto llarg = llvm.LLVMGetParam(cx.llfn, arg_n);
+        check (llarg as int != 0);
+        cx.lliterbody = some[ValueRef](llarg);
+        arg_n += 1u;
+    }
+
     for (ast.arg arg in args) {
         auto llarg = llvm.LLVMGetParam(cx.llfn, arg_n);
         check (llarg as int != 0);
@@ -3398,7 +4496,7 @@ fn is_terminated(@block_ctxt cx) -> bool {
 
 fn arg_tys_of_fn(ast.ann ann) -> vec[ty.arg] {
     alt (ty.ann_to_type(ann).struct) {
-        case (ty.ty_fn(?arg_tys, _)) {
+        case (ty.ty_fn(_, ?arg_tys, _)) {
             ret arg_tys;
         }
     }
@@ -3407,7 +4505,7 @@ fn arg_tys_of_fn(ast.ann ann) -> vec[ty.arg] {
 
 fn ret_ty_of_fn_ty(@ty.t t) -> @ty.t {
     alt (t.struct) {
-        case (ty.ty_fn(_, ?ret_ty)) {
+        case (ty.ty_fn(_, _, ?ret_ty)) {
             ret ret_ty;
         }
     }
@@ -3419,42 +4517,73 @@ fn ret_ty_of_fn(ast.ann ann) -> @ty.t {
     ret ret_ty_of_fn_ty(ty.ann_to_type(ann));
 }
 
-fn create_llobjfields_for_fields(@block_ctxt cx, ValueRef llself) {
+fn populate_fn_ctxt_from_llself(@block_ctxt cx, ValueRef llself) -> result {
+    auto bcx = cx;
 
-    let vec[TypeRef] llfield_tys = vec();
+    let vec[@ty.t] field_tys = vec();
 
-    for (ast.obj_field f in cx.fcx.ccx.obj_fields) {
-        llfield_tys += node_type(cx.fcx.ccx, f.ann);
+    for (ast.obj_field f in bcx.fcx.ccx.obj_fields) {
+        field_tys += vec(node_ann_type(bcx.fcx.ccx, f.ann));
     }
 
-    let TypeRef llfields_ty = T_struct(llfield_tys);
-    let TypeRef lltydesc_ty = T_ptr(T_tydesc());
-    let TypeRef llobj_body_ty = T_struct(vec(lltydesc_ty,
-                                             llfields_ty));
-    let TypeRef llobj_box_ty = T_ptr(T_box(llobj_body_ty));
+    // Synthesize a tuple type for the fields so that GEP_tup_like() can work
+    // its magic.
+    auto fields_tup_ty = ty.plain_ty(ty.ty_tup(field_tys));
+
+    auto n_typarams = _vec.len[ast.ty_param](bcx.fcx.ccx.obj_typarams);
+    let TypeRef llobj_box_ty = T_obj_ptr(bcx.fcx.ccx.tn, n_typarams);
 
     auto box_cell =
-        cx.build.GEP(llself,
-                     vec(C_int(0),
-                         C_int(abi.obj_field_box)));
+        bcx.build.GEP(llself,
+                      vec(C_int(0),
+                          C_int(abi.obj_field_box)));
+
+    auto box_ptr = bcx.build.Load(box_cell);
+
+    box_ptr = bcx.build.PointerCast(box_ptr, llobj_box_ty);
+
+    auto obj_typarams = bcx.build.GEP(box_ptr,
+                                     vec(C_int(0),
+                                         C_int(abi.box_rc_field_body),
+                                         C_int(abi.obj_body_elt_typarams)));
+
+    // The object fields immediately follow the type parameters, so we skip
+    // over them to get the pointer.
+    auto obj_fields = bcx.build.Add(vp2i(bcx, obj_typarams),
+        llsize_of(llvm.LLVMGetElementType(val_ty(obj_typarams))));
+
+    // If we can (i.e. the type is statically sized), then cast the resulting
+    // fields pointer to the appropriate LLVM type. If not, just leave it as
+    // i8 *.
+    if (!ty.type_has_dynamic_size(fields_tup_ty)) {
+        auto llfields_ty = type_of(bcx.fcx.ccx, fields_tup_ty);
+        obj_fields = vi2p(bcx, obj_fields, T_ptr(llfields_ty));
+    } else {
+        obj_fields = vi2p(bcx, obj_fields, T_ptr(T_i8()));
+    }
 
-    auto box_ptr = cx.build.Load(box_cell);
 
-    box_ptr = cx.build.PointerCast(box_ptr, llobj_box_ty);
+    let int i = 0;
 
-    auto obj_fields = cx.build.GEP(box_ptr,
-                                   vec(C_int(0),
-                                       C_int(abi.box_rc_field_body),
-                                       C_int(abi.obj_body_elt_fields)));
+    for (ast.ty_param p in bcx.fcx.ccx.obj_typarams) {
+        let ValueRef lltyparam = bcx.build.GEP(obj_typarams,
+                                               vec(C_int(0),
+                                                   C_int(i)));
+        lltyparam = bcx.build.Load(lltyparam);
+        bcx.fcx.lltydescs.insert(p.id, lltyparam);
+        i += 1;
+    }
 
-    let int i = 0;
-    for (ast.obj_field f in cx.fcx.ccx.obj_fields) {
-        let ValueRef llfield = cx.build.GEP(obj_fields,
-                                            vec(C_int(0),
-                                                C_int(i)));
+    i = 0;
+    for (ast.obj_field f in bcx.fcx.ccx.obj_fields) {
+        auto rslt = GEP_tup_like(bcx, fields_tup_ty, obj_fields, vec(0, i));
+        bcx = rslt.bcx;
+        auto llfield = rslt.val;
         cx.fcx.llobjfields.insert(f.id, llfield);
         i += 1;
     }
+
+    ret res(bcx, C_nil());
 }
 
 fn trans_fn(@crate_ctxt cx, &ast._fn f, ast.def_id fid,
@@ -3464,17 +4593,18 @@ fn trans_fn(@crate_ctxt cx, &ast._fn f, ast.def_id fid,
     auto llfndecl = cx.item_ids.get(fid);
     cx.item_names.insert(cx.path, llfndecl);
 
-    auto fcx = new_fn_ctxt(cx, cx.path, llfndecl);
-    create_llargs_for_fn_args(fcx, ty_self, ret_ty_of_fn(ann),
-                              f.inputs, ty_params);
+    auto fcx = new_fn_ctxt(cx, llfndecl);
+    create_llargs_for_fn_args(fcx, f.proto,
+                              ty_self, ret_ty_of_fn(ann),
+                              f.decl.inputs, ty_params);
     auto bcx = new_top_block_ctxt(fcx);
 
-    copy_args_to_allocas(bcx, ty_self, f.inputs,
+    copy_args_to_allocas(bcx, ty_self, f.decl.inputs,
                          arg_tys_of_fn(ann));
 
     alt (fcx.llself) {
         case (some[ValueRef](?llself)) {
-            create_llobjfields_for_fields(bcx, llself);
+            bcx = populate_fn_ctxt_from_llself(bcx, llself).bcx;
         }
         case (_) {
         }
@@ -3504,17 +4634,17 @@ fn trans_vtbl(@crate_ctxt cx, TypeRef self_ty,
 
         auto llfnty = T_nil();
         alt (node_ann_type(cx, m.node.ann).struct) {
-            case (ty.ty_fn(?inputs, ?output)) {
-                llfnty = type_of_fn_full(cx,
+            case (ty.ty_fn(?proto, ?inputs, ?output)) {
+                llfnty = type_of_fn_full(cx, proto,
                                          some[TypeRef](self_ty),
                                          inputs, output);
             }
         }
 
-        let @crate_ctxt mcx = @rec(path=cx.path + "." + m.node.ident
+        let @crate_ctxt mcx = @rec(path=cx.path + sep() + m.node.ident
                                    with *cx);
 
-        let str s = cx.names.next("_rust_method") + "." + mcx.path;
+        let str s = cx.names.next("_rust_method") + sep() + mcx.path;
         let ValueRef llfn = decl_fastcall_fn(cx.llmod, s, llfnty);
         cx.item_ids.insert(m.node.id, llfn);
 
@@ -3525,7 +4655,7 @@ fn trans_vtbl(@crate_ctxt cx, TypeRef self_ty,
     auto vtbl = C_struct(methods);
     auto gvar = llvm.LLVMAddGlobal(cx.llmod,
                                    val_ty(vtbl),
-                                   _str.buf("_rust_vtbl" + "." + cx.path));
+                                   _str.buf("_rust_vtbl" + sep() + cx.path));
     llvm.LLVMSetInitializer(gvar, vtbl);
     llvm.LLVMSetGlobalConstant(gvar, True);
     llvm.LLVMSetLinkage(gvar, lib.llvm.LLVMPrivateLinkage
@@ -3548,8 +4678,9 @@ fn trans_obj(@crate_ctxt cx, &ast._obj ob, ast.def_id oid,
                            id=f.id));
     }
 
-    auto fcx = new_fn_ctxt(cx, cx.path, llctor_decl);
-    create_llargs_for_fn_args(fcx, none[TypeRef], ret_ty_of_fn(ann),
+    auto fcx = new_fn_ctxt(cx, llctor_decl);
+    create_llargs_for_fn_args(fcx, ast.proto_fn,
+                              none[TypeRef], ret_ty_of_fn(ann),
                               fn_args, ty_params);
 
     auto bcx = new_top_block_ctxt(fcx);
@@ -3558,7 +4689,7 @@ fn trans_obj(@crate_ctxt cx, &ast._obj ob, ast.def_id oid,
     copy_args_to_allocas(bcx, none[TypeRef], fn_args, arg_tys);
 
     auto llself_ty = type_of(cx, ret_ty_of_fn(ann));
-    auto pair = bcx.build.Alloca(llself_ty);
+    auto pair = bcx.fcx.llretptr;
     auto vtbl = trans_vtbl(cx, llself_ty, ob, ty_params);
     auto pair_vtbl = bcx.build.GEP(pair,
                                    vec(C_int(0),
@@ -3568,10 +4699,11 @@ fn trans_obj(@crate_ctxt cx, &ast._obj ob, ast.def_id oid,
                                       C_int(abi.obj_field_box)));
     bcx.build.Store(vtbl, pair_vtbl);
 
-    let TypeRef llbox_ty = T_ptr(T_box(T_struct(vec(T_ptr(T_tydesc()),
-                                                    T_nil()))));
-    if (_vec.len[ty.arg](arg_tys) == 0u) {
-        // Store null into pair, if no args.
+    let TypeRef llbox_ty = T_opaque_obj_ptr(cx.tn);
+
+    if (_vec.len[ast.ty_param](ty_params) == 0u &&
+        _vec.len[ty.arg](arg_tys) == 0u) {
+        // Store null into pair, if no args or typarams.
         bcx.build.Store(C_null(llbox_ty), pair_box);
     } else {
         // Malloc a box for the body and copy args in.
@@ -3581,55 +4713,76 @@ fn trans_obj(@crate_ctxt cx, &ast._obj ob, ast.def_id oid,
         }
 
         // Synthesize an obj body type.
-        let @ty.t fields_ty = ty.plain_ty(ty.ty_tup(obj_fields));
-        let TypeRef llfields_ty = type_of(bcx.fcx.ccx, fields_ty);
-        let TypeRef llobj_body_ty =
-            T_ptr(T_box(T_struct(vec(T_ptr(T_tydesc()),
-                                     llfields_ty))));
+        auto tydesc_ty = plain_ty(ty.ty_type);
+        let vec[@ty.t] tps = vec();
+        for (ast.ty_param tp in ty_params) {
+            append[@ty.t](tps, tydesc_ty);
+        }
+
+        let @ty.t typarams_ty = plain_ty(ty.ty_tup(tps));
+        let @ty.t fields_ty = plain_ty(ty.ty_tup(obj_fields));
+        let @ty.t body_ty = plain_ty(ty.ty_tup(vec(tydesc_ty,
+                                                   typarams_ty,
+                                                   fields_ty)));
+        let @ty.t boxed_body_ty = plain_ty(ty.ty_box(body_ty));
 
         // Malloc a box for the body.
-        auto r = trans_malloc_inner(bcx, llobj_body_ty);
-        bcx = r.bcx;
-        auto box = r.val;
-        auto rc = bcx.build.GEP(box,
-                                vec(C_int(0),
-                                    C_int(abi.box_rc_field_refcnt)));
-        auto body = bcx.build.GEP(box,
-                                  vec(C_int(0),
-                                      C_int(abi.box_rc_field_body)));
-        bcx.build.Store(C_int(1), rc);
+        auto box = trans_malloc_boxed(bcx, body_ty);
+        bcx = box.bcx;
+        auto rc = GEP_tup_like(bcx, boxed_body_ty, box.val,
+                               vec(0, abi.box_rc_field_refcnt));
+        bcx = rc.bcx;
+        auto body = GEP_tup_like(bcx, boxed_body_ty, box.val,
+                                 vec(0, abi.box_rc_field_body));
+        bcx = body.bcx;
+        bcx.build.Store(C_int(1), rc.val);
 
         // Store body tydesc.
         auto body_tydesc =
-            bcx.build.GEP(body,
-                          vec(C_int(0),
-                              C_int(abi.obj_body_elt_tydesc)));
-
-        auto fields_tydesc = get_tydesc(r.bcx, fields_ty);
-        bcx = fields_tydesc.bcx;
-        bcx.build.Store(fields_tydesc.val, body_tydesc);
+            GEP_tup_like(bcx, body_ty, body.val,
+                         vec(0, abi.obj_body_elt_tydesc));
+        bcx = body_tydesc.bcx;
+
+        auto body_td = get_tydesc(bcx, body_ty);
+        bcx = body_td.bcx;
+        bcx.build.Store(body_td.val, body_tydesc.val);
+
+        // Copy typarams into captured typarams.
+        auto body_typarams =
+            GEP_tup_like(bcx, body_ty, body.val,
+                         vec(0, abi.obj_body_elt_typarams));
+        bcx = body_typarams.bcx;
+        let int i = 0;
+        for (ast.ty_param tp in ty_params) {
+            auto typaram = bcx.fcx.lltydescs.get(tp.id);
+            auto capture = GEP_tup_like(bcx, typarams_ty, body_typarams.val,
+                                        vec(0, i));
+            bcx = capture.bcx;
+            bcx = copy_ty(bcx, INIT, capture.val, typaram, tydesc_ty).bcx;
+            i += 1;
+        }
 
         // Copy args into body fields.
         auto body_fields =
-            bcx.build.GEP(body,
-                          vec(C_int(0),
-                              C_int(abi.obj_body_elt_fields)));
+            GEP_tup_like(bcx, body_ty, body.val,
+                         vec(0, abi.obj_body_elt_fields));
+        bcx = body_fields.bcx;
 
-        let int i = 0;
+        i = 0;
         for (ast.obj_field f in ob.fields) {
             auto arg = bcx.fcx.llargs.get(f.id);
             arg = load_scalar_or_boxed(bcx, arg, arg_tys.(i).ty);
-            auto field = bcx.build.GEP(body_fields,
-                                         vec(C_int(0),C_int(i)));
-            bcx = copy_ty(bcx, INIT, field, arg, arg_tys.(i).ty).bcx;
+            auto field = GEP_tup_like(bcx, fields_ty, body_fields.val,
+                                      vec(0, i));
+            bcx = field.bcx;
+            bcx = copy_ty(bcx, INIT, field.val, arg, arg_tys.(i).ty).bcx;
             i += 1;
         }
-
         // Store box ptr in outer pair.
-        auto p = bcx.build.PointerCast(box, llbox_ty);
+        auto p = bcx.build.PointerCast(box.val, llbox_ty);
         bcx.build.Store(p, pair_box);
     }
-    bcx.build.Ret(bcx.build.Load(pair));
+    bcx.build.RetVoid();
 }
 
 fn trans_tag_variant(@crate_ctxt cx, ast.def_id tag_id,
@@ -3652,8 +4805,9 @@ fn trans_tag_variant(@crate_ctxt cx, ast.def_id tag_id,
     check (cx.item_ids.contains_key(variant.id));
     let ValueRef llfndecl = cx.item_ids.get(variant.id);
 
-    auto fcx = new_fn_ctxt(cx, cx.path, llfndecl);
-    create_llargs_for_fn_args(fcx, none[TypeRef], ret_ty_of_fn(variant.ann),
+    auto fcx = new_fn_ctxt(cx, llfndecl);
+    create_llargs_for_fn_args(fcx, ast.proto_fn,
+                              none[TypeRef], ret_ty_of_fn(variant.ann),
                               fn_args, ty_params);
 
     auto bcx = new_top_block_ctxt(fcx);
@@ -3661,41 +4815,45 @@ fn trans_tag_variant(@crate_ctxt cx, ast.def_id tag_id,
     auto arg_tys = arg_tys_of_fn(variant.ann);
     copy_args_to_allocas(bcx, none[TypeRef], fn_args, arg_tys);
 
-    auto info = cx.tags.get(tag_id);
+    // Cast the tag to a type we can GEP into.
+    auto lltagptr = bcx.build.PointerCast(fcx.llretptr,
+                                          T_opaque_tag_ptr(fcx.ccx.tn));
 
-    auto lltagty = T_struct(vec(T_int(), T_array(T_i8(), info.size)));
-
-    // FIXME: better name.
-    llvm.LLVMAddTypeName(cx.llmod, _str.buf("tag"), lltagty);
-
-    auto lltagptr = bcx.build.Alloca(lltagty);
-    auto lldiscrimptr = bcx.build.GEP(lltagptr, vec(C_int(0), C_int(0)));
+    auto lldiscrimptr = bcx.build.GEP(lltagptr,
+                                      vec(C_int(0), C_int(0)));
     bcx.build.Store(C_int(index), lldiscrimptr);
 
-    auto llblobptr = bcx.build.GEP(lltagptr, vec(C_int(0), C_int(1)));
-
-    // First, generate the union type.
-    let vec[TypeRef] llargtys = vec();
-    for (ty.arg arg in arg_tys) {
-        llargtys += vec(type_of(cx, arg.ty));
-    }
-
-    auto llunionty = T_struct(llargtys);
-    auto llunionptr = bcx.build.TruncOrBitCast(llblobptr, T_ptr(llunionty));
+    auto llblobptr = bcx.build.GEP(lltagptr,
+                                   vec(C_int(0), C_int(1)));
 
     i = 0u;
     for (ast.variant_arg va in variant.args) {
-        auto llargval = bcx.build.Load(fcx.llargs.get(va.id));
-        auto lldestptr = bcx.build.GEP(llunionptr,
-                                       vec(C_int(0), C_int(i as int)));
+        auto rslt = GEP_tag(bcx, llblobptr, variant, i as int);
+        bcx = rslt.bcx;
+        auto lldestptr = rslt.val;
+
+        // If this argument to this function is a tag, it'll have come in to
+        // this function as an opaque blob due to the way that type_of()
+        // works. So we have to cast to the destination's view of the type.
+        auto llargptr = bcx.build.PointerCast(fcx.llargs.get(va.id),
+            val_ty(lldestptr));
+
+        auto arg_ty = arg_tys.(i).ty;
+        auto llargval;
+        if (ty.type_is_structural(arg_ty)) {
+            llargval = llargptr;
+        } else {
+            llargval = bcx.build.Load(llargptr);
+        }
+
+        rslt = copy_ty(bcx, INIT, lldestptr, llargval, arg_ty);
+        bcx = rslt.bcx;
 
-        bcx.build.Store(llargval, lldestptr);
         i += 1u;
     }
 
-    auto lltagval = bcx.build.Load(lltagptr);
     bcx = trans_block_cleanups(bcx, find_scope_cx(bcx));
-    bcx.build.Ret(lltagval);
+    bcx.build.RetVoid();
 }
 
 // FIXME: this should do some structural hash-consing to avoid
@@ -3732,20 +4890,21 @@ fn trans_const(@crate_ctxt cx, @ast.expr e,
 fn trans_item(@crate_ctxt cx, &ast.item item) {
     alt (item.node) {
         case (ast.item_fn(?name, ?f, ?tps, ?fid, ?ann)) {
-            auto sub_cx = @rec(path=cx.path + "." + name with *cx);
+            auto sub_cx = @rec(path=cx.path + sep() + name with *cx);
             trans_fn(sub_cx, f, fid, none[TypeRef], tps, ann);
         }
         case (ast.item_obj(?name, ?ob, ?tps, ?oid, ?ann)) {
-            auto sub_cx = @rec(path=cx.path + "." + name,
+            auto sub_cx = @rec(path=cx.path + sep() + name,
+                               obj_typarams=tps,
                                obj_fields=ob.fields with *cx);
             trans_obj(sub_cx, ob, oid, tps, ann);
         }
         case (ast.item_mod(?name, ?m, _)) {
-            auto sub_cx = @rec(path=cx.path + "." + name with *cx);
+            auto sub_cx = @rec(path=cx.path + sep() + name with *cx);
             trans_mod(sub_cx, m);
         }
         case (ast.item_tag(?name, ?variants, ?tps, ?tag_id)) {
-            auto sub_cx = @rec(path=cx.path + "." + name with *cx);
+            auto sub_cx = @rec(path=cx.path + sep() + name with *cx);
             auto i = 0;
             for (ast.variant variant in variants) {
                 trans_tag_variant(sub_cx, tag_id, variant, i, tps);
@@ -3753,7 +4912,7 @@ fn trans_item(@crate_ctxt cx, &ast.item item) {
             }
         }
         case (ast.item_const(?name, _, ?expr, ?cid, ?ann)) {
-            auto sub_cx = @rec(path=cx.path + "." + name with *cx);
+            auto sub_cx = @rec(path=cx.path + sep() + name with *cx);
             trans_const(sub_cx, expr, cid, ann);
         }
         case (_) { /* fall through */ }
@@ -3784,15 +4943,21 @@ fn decl_fn_and_pair(@crate_ctxt cx,
     auto llfty = get_pair_fn_ty(llpairty);
 
     // Declare the function itself.
-    let str s = cx.names.next("_rust_" + kind) + "." + name;
+    let str s = cx.names.next("_rust_" + kind) + sep() + name;
     let ValueRef llfn = decl_fastcall_fn(cx.llmod, s, llfty);
 
     // Declare the global constant pair that points to it.
-    let str ps = cx.names.next("_rust_" + kind + "_pair") + "." + name;
+    let str ps = cx.names.next("_rust_" + kind + "_pair") + sep() + name;
+
+    register_fn_pair(cx, ps, llpairty, llfn, id);
+}
+
+fn register_fn_pair(@crate_ctxt cx, str ps, TypeRef llpairty, ValueRef llfn,
+                    ast.def_id id) {
     let ValueRef gvar = llvm.LLVMAddGlobal(cx.llmod, llpairty,
                                            _str.buf(ps));
     auto pair = C_struct(vec(llfn,
-                             C_null(T_opaque_closure_ptr())));
+                             C_null(T_opaque_closure_ptr(cx.tn))));
 
     llvm.LLVMSetInitializer(gvar, pair);
     llvm.LLVMSetGlobalConstant(gvar, True);
@@ -3804,12 +4969,86 @@ fn decl_fn_and_pair(@crate_ctxt cx,
     cx.fn_pairs.insert(id, gvar);
 }
 
+fn native_fn_wrapper_type(@crate_ctxt cx, &ast.ann ann) -> TypeRef {
+    auto x = node_ann_type(cx, ann);
+    alt (x.struct) {
+        case (ty.ty_native_fn(?abi, ?args, ?out)) {
+            ret type_of_fn(cx, ast.proto_fn, args, out);
+        }
+    }
+    fail;
+}
+
+fn decl_native_fn_and_pair(@crate_ctxt cx,
+                           str name,
+                           &ast.ann ann,
+                           ast.def_id id) {
+    // Declare the wrapper.
+    auto wrapper_type = native_fn_wrapper_type(cx, ann);
+    let str s = cx.names.next("_rust_wrapper") + sep() + name;
+    let ValueRef wrapper_fn = decl_fastcall_fn(cx.llmod, s, wrapper_type);
+
+    // Declare the global constant pair that points to it.
+    auto wrapper_pair_type = T_fn_pair(cx.tn, wrapper_type);
+    let str ps = cx.names.next("_rust_wrapper_pair") + sep() + name;
+
+    register_fn_pair(cx, ps, wrapper_pair_type, wrapper_fn, id);
+
+    // Declare the function itself.
+    auto llfty = get_pair_fn_ty(node_type(cx, ann));
+    auto function = decl_cdecl_fn(cx.llmod, name, llfty);
+
+    // Build the wrapper.
+    auto fcx = new_fn_ctxt(cx, wrapper_fn);
+    auto bcx = new_top_block_ctxt(fcx);
+    auto fn_type = node_ann_type(cx, ann);
+
+    let vec[ValueRef] call_args = vec();
+    auto abi = ty.ty_fn_abi(fn_type);
+    auto arg_n = 3u;
+    alt (abi) {
+        case (ast.native_abi_rust) {
+            call_args += vec(fcx.lltaskptr);
+            auto num_ty_param = ty.count_ty_params(plain_ty(fn_type.struct));
+            for each (uint i in _uint.range(0u, num_ty_param)) {
+                auto llarg = llvm.LLVMGetParam(fcx.llfn, arg_n);
+                check (llarg as int != 0);
+                call_args += vec(llarg);
+                arg_n += 1u;
+            }
+        }
+        case (ast.native_abi_cdecl) {
+        }
+    }
+    auto args = ty.ty_fn_args(fn_type);
+    for (ty.arg arg in args) {
+        auto llarg = llvm.LLVMGetParam(fcx.llfn, arg_n);
+        check (llarg as int != 0);
+        call_args += vec(llarg);
+        arg_n += 1u;
+    }
+    auto r = bcx.build.Call(function, call_args);
+    bcx.build.Store(r, fcx.llretptr);
+    bcx.build.RetVoid();
+}
+
+fn collect_native_item(&@crate_ctxt cx, @ast.native_item i) -> @crate_ctxt {
+    alt (i.node) {
+        case (ast.native_item_fn(?name, _, _, ?fid, ?ann)) {
+            cx.native_items.insert(fid, i);
+            if (! cx.obj_methods.contains_key(fid)) {
+                decl_native_fn_and_pair(cx, name, ann, fid);
+            }
+        }
+        case (_) { /* fall through */ }
+    }
+    ret cx;
+}
 
 fn collect_item(&@crate_ctxt cx, @ast.item i) -> @crate_ctxt {
 
     alt (i.node) {
         case (ast.item_fn(?name, ?f, _, ?fid, ?ann)) {
-            // TODO: type-params
             cx.items.insert(fid, i);
             if (! cx.obj_methods.contains_key(fid)) {
                 decl_fn_and_pair(cx, "fn", name, ann, fid);
@@ -3817,7 +5056,6 @@ fn collect_item(&@crate_ctxt cx, @ast.item i) -> @crate_ctxt {
         }
 
         case (ast.item_obj(?name, ?ob, _, ?oid, ?ann)) {
-            // TODO: type-params
             cx.items.insert(oid, i);
             decl_fn_and_pair(cx, "obj_ctor", name, ann, oid);
             for (@ast.method m in ob.methods) {
@@ -3833,13 +5071,7 @@ fn collect_item(&@crate_ctxt cx, @ast.item i) -> @crate_ctxt {
             cx.items.insert(mid, i);
         }
 
-        case (ast.item_tag(_, ?variants, _, ?tag_id)) {
-            auto vi = new_def_hash[uint]();
-            auto navi = new_def_hash[uint]();
-            let vec[tup(ast.def_id,arity)] variant_info = vec();
-            cx.tags.insert(tag_id, @rec(th=mk_type_handle(),
-                                        mutable variants=variant_info,
-                                        mutable size=0u));
+        case (ast.item_tag(_, ?variants, ?tps, ?tag_id)) {
             cx.items.insert(tag_id, i);
         }
 
@@ -3854,7 +5086,8 @@ fn collect_items(@crate_ctxt cx, @ast.crate crate) {
     let fold.ast_fold[@crate_ctxt] fld =
         fold.new_identity_fold[@crate_ctxt]();
 
-    fld = @rec( update_env_for_item = bind collect_item(_,_)
+    fld = @rec( update_env_for_item = bind collect_item(_,_),
+                update_env_for_native_item = bind collect_native_item(_,_)
                 with *fld );
 
     fold.fold_crate[@crate_ctxt](cx, fld, crate);
@@ -3890,103 +5123,30 @@ fn collect_tag_ctors(@crate_ctxt cx, @ast.crate crate) {
 }
 
 
-// The tag type resolution pass, which determines all the LLVM types that
-// correspond to each tag type in the crate.
-
-fn resolve_tag_types_for_item(&@crate_ctxt cx, @ast.item i) -> @crate_ctxt {
-    alt (i.node) {
-        case (ast.item_tag(_, ?variants, _, ?tag_id)) {
-            auto max_align = 0u;
-            auto max_size = 0u;
-
-            auto info = cx.tags.get(tag_id);
-            let vec[tup(ast.def_id,arity)] variant_info = vec();
-
-            for (ast.variant variant in variants) {
-                auto arity_info;
-                if (_vec.len[ast.variant_arg](variant.args) > 0u) {
-                    auto llvariantty = type_of_variant(cx, variant);
-                    auto align =
-                        llvm.LLVMPreferredAlignmentOfType(cx.td.lltd,
-                                                          llvariantty);
-                    auto size =
-                        llvm.LLVMStoreSizeOfType(cx.td.lltd,
-                                                 llvariantty) as uint;
-                    if (max_align < align) { max_align = align; }
-                    if (max_size < size) { max_size = size; }
-
-                    arity_info = n_ary;
-                } else {
-                    arity_info = nullary;
-                }
-
-                variant_info += vec(tup(variant.id, arity_info));
-            }
-
-            info.variants = variant_info;
-            info.size = max_size;
-
-            // FIXME: alignment is wrong here, manually insert padding I
-            // guess :(
-            auto tag_ty = T_struct(vec(T_int(), T_array(T_i8(), max_size)));
-            auto th = cx.tags.get(tag_id).th.llth;
-            llvm.LLVMRefineType(llvm.LLVMResolveTypeHandle(th), tag_ty);
-        }
-        case (_) {
-            // fall through
-        }
-    }
-
-    ret cx;
-}
-
-fn resolve_tag_types(@crate_ctxt cx, @ast.crate crate) {
-    let fold.ast_fold[@crate_ctxt] fld =
-        fold.new_identity_fold[@crate_ctxt]();
-
-    fld = @rec( update_env_for_item = bind resolve_tag_types_for_item(_,_)
-                with *fld );
-
-    fold.fold_crate[@crate_ctxt](cx, fld, crate);
-}
-
 // The constant translation pass.
 
 fn trans_constant(&@crate_ctxt cx, @ast.item it) -> @crate_ctxt {
     alt (it.node) {
         case (ast.item_tag(_, ?variants, _, ?tag_id)) {
-            auto info = cx.tags.get(tag_id);
+            auto i = 0u;
+            auto n_variants = _vec.len[ast.variant](variants);
+            while (i < n_variants) {
+                auto variant = variants.(i);
 
-            auto tag_ty = llvm.LLVMResolveTypeHandle(info.th.llth);
-            check (llvm.LLVMCountStructElementTypes(tag_ty) == 2u);
-            auto elts = vec(0 as TypeRef, 0 as TypeRef);
-            llvm.LLVMGetStructElementTypes(tag_ty, _vec.buf[TypeRef](elts));
-            auto union_ty = elts.(1);
+                auto discrim_val = C_int(i as int);
 
-            auto i = 0u;
-            while (i < _vec.len[tup(ast.def_id,arity)](info.variants)) {
-                auto variant_info = info.variants.(i);
-                alt (variant_info._1) {
-                    case (nullary) {
-                        // Nullary tags become constants.
-                        auto union_val = C_zero_byte_arr(info.size as uint);
-                        auto val = C_struct(vec(C_int(i as int), union_val));
-
-                        // FIXME: better name
-                        auto gvar = llvm.LLVMAddGlobal(cx.llmod, val_ty(val),
-                                                       _str.buf("tag"));
-                        llvm.LLVMSetInitializer(gvar, val);
-                        llvm.LLVMSetGlobalConstant(gvar, True);
-                        llvm.LLVMSetLinkage(gvar,
-                                            lib.llvm.LLVMPrivateLinkage
-                                            as llvm.Linkage);
-                        cx.item_ids.insert(variant_info._0, gvar);
-                    }
-                    case (n_ary) {
-                        // N-ary tags are treated as functions and generated
-                        // later.
-                    }
-                }
+                // FIXME: better name.
+                auto discrim_gvar = llvm.LLVMAddGlobal(cx.llmod, T_int(),
+                    _str.buf("tag_discrim"));
+
+                // FIXME: Eventually we do want to export these, but we need
+                // to figure out what name they get first!
+                llvm.LLVMSetInitializer(discrim_gvar, discrim_val);
+                llvm.LLVMSetGlobalConstant(discrim_gvar, True);
+                llvm.LLVMSetLinkage(discrim_gvar, lib.llvm.LLVMPrivateLinkage
+                                    as llvm.Linkage);
+
+                cx.discrims.insert(variant.id, discrim_gvar);
 
                 i += 1u;
             }
@@ -4016,21 +5176,36 @@ fn trans_constants(@crate_ctxt cx, @ast.crate crate) {
     fold.fold_crate[@crate_ctxt](cx, fld, crate);
 }
 
+
+fn vp2i(@block_ctxt cx, ValueRef v) -> ValueRef {
+    ret cx.build.PtrToInt(v, T_int());
+}
+
+
+fn vi2p(@block_ctxt cx, ValueRef v, TypeRef t) -> ValueRef {
+    ret cx.build.IntToPtr(v, t);
+}
+
 fn p2i(ValueRef v) -> ValueRef {
     ret llvm.LLVMConstPtrToInt(v, T_int());
 }
 
+fn i2p(ValueRef v, TypeRef t) -> ValueRef {
+    ret llvm.LLVMConstIntToPtr(v, t);
+}
+
 fn trans_exit_task_glue(@crate_ctxt cx) {
     let vec[TypeRef] T_args = vec();
     let vec[ValueRef] V_args = vec();
 
     auto llfn = cx.glues.exit_task_glue;
-    let ValueRef lltaskptr = llvm.LLVMGetParam(llfn, 0u);
+    let ValueRef lltaskptr = llvm.LLVMGetParam(llfn, 3u);
     auto fcx = @rec(llfn=llfn,
                     lltaskptr=lltaskptr,
-                    llclosure=C_null(T_opaque_closure_ptr()),
+                    llenv=C_null(T_opaque_closure_ptr(cx.tn)),
+                    llretptr=C_null(T_ptr(T_nil())),
                     mutable llself=none[ValueRef],
-                    mutable llretptr=none[ValueRef],
+                    mutable lliterbody=none[ValueRef],
                     llargs=new_def_hash[ValueRef](),
                     llobjfields=new_def_hash[ValueRef](),
                     lllocals=new_def_hash[ValueRef](),
@@ -4043,9 +5218,9 @@ fn trans_exit_task_glue(@crate_ctxt cx) {
 }
 
 fn create_typedefs(@crate_ctxt cx) {
-    llvm.LLVMAddTypeName(cx.llmod, _str.buf("rust_crate"), T_crate());
-    llvm.LLVMAddTypeName(cx.llmod, _str.buf("rust_task"), T_task());
-    llvm.LLVMAddTypeName(cx.llmod, _str.buf("rust_tydesc"), T_tydesc());
+    llvm.LLVMAddTypeName(cx.llmod, _str.buf("crate"), T_crate(cx.tn));
+    llvm.LLVMAddTypeName(cx.llmod, _str.buf("task"), T_task(cx.tn));
+    llvm.LLVMAddTypeName(cx.llmod, _str.buf("tydesc"), T_tydesc(cx.tn));
 }
 
 fn create_crate_constant(@crate_ctxt cx) {
@@ -4075,12 +5250,37 @@ fn create_crate_constant(@crate_ctxt cx) {
                      exit_task_glue_off,  // size_t main_exit_task_glue_off
                      C_null(T_int()),     // int n_rust_syms
                      C_null(T_int()),     // int n_c_syms
-                     C_null(T_int())      // int n_libs
+                     C_null(T_int()),     // int n_libs
+                     C_int(abi.abi_x86_rustc_fastcall) // uintptr_t abi_tag
                      ));
 
     llvm.LLVMSetInitializer(cx.crate_ptr, crate_val);
 }
 
+fn find_main_fn(@crate_ctxt cx) -> ValueRef {
+    auto e = sep() + "main";
+    let ValueRef v = C_nil();
+    let uint n = 0u;
+    for each (tup(str,ValueRef) i in cx.item_names.items()) {
+        if (_str.ends_with(i._0, e)) {
+            n += 1u;
+            v = i._1;
+        }
+    }
+    alt (n) {
+        case (0u) {
+            cx.sess.err("main fn not found");
+        }
+        case (1u) {
+            ret v;
+        }
+        case (_) {
+            cx.sess.err("multiple main fns found");
+        }
+    }
+    fail;
+}
+
 fn trans_main_fn(@crate_ctxt cx, ValueRef llcrate) {
     auto T_main_args = vec(T_int(), T_int());
     auto T_rust_start_args = vec(T_int(), T_int(), T_int(), T_int());
@@ -4100,8 +5300,7 @@ fn trans_main_fn(@crate_ctxt cx, ValueRef llcrate) {
 
     auto llargc = llvm.LLVMGetParam(llmain, 0u);
     auto llargv = llvm.LLVMGetParam(llmain, 1u);
-    check (cx.item_names.contains_key("_rust.main"));
-    auto llrust_main = cx.item_names.get("_rust.main");
+    auto llrust_main = find_main_fn(cx);
 
     //
     // Emit the moral equivalent of:
@@ -4131,6 +5330,24 @@ fn declare_intrinsics(ModuleRef llmod) -> hashmap[str,ValueRef] {
     ret intrinsics;
 }
 
+
+fn trace_str(@block_ctxt cx, str s) {
+    trans_upcall(cx, "upcall_trace_str", vec(p2i(C_cstr(cx.fcx.ccx, s))));
+}
+
+fn trace_word(@block_ctxt cx, ValueRef v) {
+    trans_upcall(cx, "upcall_trace_word", vec(v));
+}
+
+fn trace_ptr(@block_ctxt cx, ValueRef v) {
+    trace_word(cx, cx.build.PtrToInt(v, T_int()));
+}
+
+fn trap(@block_ctxt bcx) {
+    let vec[ValueRef] v = vec();
+    bcx.build.Call(bcx.fcx.ccx.intrinsics.get("llvm.trap"), v);
+}
+
 fn check_module(ModuleRef llmod) {
     auto pm = mk_pass_manager();
     llvm.LLVMAddVerifierPass(pm.llpm);
@@ -4139,8 +5356,8 @@ fn check_module(ModuleRef llmod) {
     // TODO: run the linter here also, once there are llvm-c bindings for it.
 }
 
-fn make_no_op_type_glue(ModuleRef llmod) -> ValueRef {
-    auto ty = T_fn(vec(T_taskptr(), T_ptr(T_i8())), T_void());
+fn make_no_op_type_glue(ModuleRef llmod, type_names tn) -> ValueRef {
+    auto ty = T_fn(vec(T_taskptr(tn), T_ptr(T_i8())), T_void());
     auto fun = decl_fastcall_fn(llmod, abi.no_op_type_glue_name(), ty);
     auto bb_name = _str.buf("_rust_no_op_type_glue_bb");
     auto llbb = llvm.LLVMAppendBasicBlock(fun, bb_name);
@@ -4234,9 +5451,197 @@ fn make_bzero_glue(ModuleRef llmod) -> ValueRef {
     ret fun;
 }
 
-fn make_glues(ModuleRef llmod) -> @glue_fns {
-    ret @rec(activate_glue = decl_glue(llmod, abi.activate_glue_name()),
-             yield_glue = decl_glue(llmod, abi.yield_glue_name()),
+fn make_vec_append_glue(ModuleRef llmod, type_names tn) -> ValueRef {
+    /*
+     * Args to vec_append_glue:
+     *
+     *   0. (Implicit) task ptr
+     *
+     *   1. Pointer to the tydesc of the vec, so that we can tell if it's gc
+     *      mem, and have a tydesc to pass to malloc if we're allocating anew.
+     *
+     *   2. Pointer to the tydesc of the vec's stored element type, so that
+     *      elements can be copied to a newly alloc'ed vec if one must be
+     *      created.
+     *
+     *   3. Dst vec ptr (i.e. ptr to ptr to rust_vec).
+     *
+     *   4. Src vec (i.e. ptr to rust_vec).
+     *
+     *   5. Flag indicating whether to skip trailing null on dst.
+     *
+     */
+
+    auto ty = T_fn(vec(T_taskptr(tn),
+                       T_ptr(T_tydesc(tn)),
+                       T_ptr(T_tydesc(tn)),
+                       T_ptr(T_opaque_vec_ptr()),
+                       T_opaque_vec_ptr(), T_bool()),
+                   T_void());
+
+    auto llfn = decl_fastcall_fn(llmod, abi.vec_append_glue_name(), ty);
+    ret llfn;
+}
+
+fn trans_vec_append_glue(@crate_ctxt cx) {
+
+    auto llfn = cx.glues.vec_append_glue;
+
+    let ValueRef lltaskptr = llvm.LLVMGetParam(llfn, 0u);
+    let ValueRef llvec_tydesc = llvm.LLVMGetParam(llfn, 1u);
+    let ValueRef llelt_tydesc = llvm.LLVMGetParam(llfn, 2u);
+    let ValueRef lldst_vec_ptr = llvm.LLVMGetParam(llfn, 3u);
+    let ValueRef llsrc_vec = llvm.LLVMGetParam(llfn, 4u);
+    let ValueRef llskipnull = llvm.LLVMGetParam(llfn, 5u);
+
+    auto fcx = @rec(llfn=llfn,
+                    lltaskptr=lltaskptr,
+                    llenv=C_null(T_ptr(T_nil())),
+                    llretptr=C_null(T_ptr(T_nil())),
+                    mutable llself=none[ValueRef],
+                    mutable lliterbody=none[ValueRef],
+                    llargs=new_def_hash[ValueRef](),
+                    llobjfields=new_def_hash[ValueRef](),
+                    lllocals=new_def_hash[ValueRef](),
+                    lltydescs=new_def_hash[ValueRef](),
+                    ccx=cx);
+
+    auto bcx = new_top_block_ctxt(fcx);
+
+    auto lldst_vec = bcx.build.Load(lldst_vec_ptr);
+
+    // First the dst vec needs to grow to accommodate the src vec.
+    // To do this we have to figure out how many bytes to add.
+
+    fn vec_fill(@block_ctxt bcx, ValueRef v) -> ValueRef {
+        ret bcx.build.Load(bcx.build.GEP(v, vec(C_int(0),
+                                                C_int(abi.vec_elt_fill))));
+    }
+
+    fn put_vec_fill(@block_ctxt bcx, ValueRef v, ValueRef fill) -> ValueRef {
+        ret bcx.build.Store(fill,
+                            bcx.build.GEP(v,
+                                          vec(C_int(0),
+                                              C_int(abi.vec_elt_fill))));
+    }
+
+    fn vec_fill_adjusted(@block_ctxt bcx, ValueRef v,
+                         ValueRef skipnull) -> ValueRef {
+        auto f = bcx.build.Load(bcx.build.GEP(v,
+                                              vec(C_int(0),
+                                                  C_int(abi.vec_elt_fill))));
+        ret bcx.build.Select(skipnull, bcx.build.Sub(f, C_int(1)), f);
+    }
+
+    fn vec_p0(@block_ctxt bcx, ValueRef v) -> ValueRef {
+        auto p = bcx.build.GEP(v, vec(C_int(0),
+                                      C_int(abi.vec_elt_data)));
+        ret bcx.build.PointerCast(p, T_ptr(T_i8()));
+    }
+
+
+    fn vec_p1(@block_ctxt bcx, ValueRef v) -> ValueRef {
+        auto len = vec_fill(bcx, v);
+        ret bcx.build.GEP(vec_p0(bcx, v), vec(len));
+    }
+
+    fn vec_p1_adjusted(@block_ctxt bcx, ValueRef v,
+                       ValueRef skipnull) -> ValueRef {
+        auto len = vec_fill_adjusted(bcx, v, skipnull);
+        ret bcx.build.GEP(vec_p0(bcx, v), vec(len));
+    }
+
+
+    auto llcopy_dst_ptr = bcx.build.Alloca(T_int());
+    auto llnew_vec_res =
+        trans_upcall(bcx, "upcall_vec_grow",
+                     vec(vp2i(bcx, lldst_vec),
+                         vec_fill_adjusted(bcx, llsrc_vec, llskipnull),
+                         vp2i(bcx, llcopy_dst_ptr),
+                         vp2i(bcx, llvec_tydesc)));
+
+    bcx = llnew_vec_res.bcx;
+    auto llnew_vec = vi2p(bcx, llnew_vec_res.val,
+                          T_opaque_vec_ptr());
+
+    put_vec_fill(bcx, llnew_vec, C_int(0));
+
+    auto copy_dst_cx = new_sub_block_ctxt(bcx, "copy new <- dst");
+    auto copy_src_cx = new_sub_block_ctxt(bcx, "copy new <- src");
+
+    auto pp0 = bcx.build.Alloca(T_ptr(T_i8()));
+    bcx.build.Store(vec_p0(bcx, llnew_vec), pp0);
+
+    bcx.build.CondBr(bcx.build.TruncOrBitCast
+                     (bcx.build.Load(llcopy_dst_ptr),
+                      T_i1()),
+                     copy_dst_cx.llbb,
+                     copy_src_cx.llbb);
+
+
+    fn copy_elts(@block_ctxt cx,
+                 ValueRef elt_tydesc,
+                 ValueRef dst,
+                 ValueRef src,
+                 ValueRef n_bytes) -> result {
+
+        auto src_lim = cx.build.GEP(src, vec(n_bytes));
+
+        auto elt_llsz =
+            cx.build.Load(cx.build.GEP(elt_tydesc,
+                                       vec(C_int(0),
+                                           C_int(abi.tydesc_field_size))));
+
+        fn take_one(ValueRef elt_tydesc,
+                    @block_ctxt cx, ValueRef v) -> result {
+            call_tydesc_glue_full(cx, v,
+                                  elt_tydesc,
+                                  abi.tydesc_field_take_glue_off);
+            ret res(cx, v);
+        }
+
+        auto bcx = iter_sequence_raw(cx, src, src_lim,
+                                     elt_llsz, bind take_one(elt_tydesc,
+                                                             _, _)).bcx;
+
+        ret call_memcpy(bcx, dst, src, n_bytes);
+    }
+
+    // Copy any dst elements in, omitting null if doing str.
+    auto n_bytes = vec_fill_adjusted(copy_dst_cx, lldst_vec, llskipnull);
+    copy_dst_cx = copy_elts(copy_dst_cx,
+                            llelt_tydesc,
+                            copy_dst_cx.build.Load(pp0),
+                            vec_p0(copy_dst_cx, lldst_vec),
+                            n_bytes).bcx;
+
+    put_vec_fill(copy_dst_cx, llnew_vec, n_bytes);
+    copy_dst_cx.build.Store(vec_p1(copy_dst_cx, llnew_vec), pp0);
+    copy_dst_cx.build.Br(copy_src_cx.llbb);
+
+
+    // Copy any src elements in, carrying along null if doing str.
+    n_bytes = vec_fill(copy_src_cx, llsrc_vec);
+    copy_src_cx = copy_elts(copy_src_cx,
+                            llelt_tydesc,
+                            copy_src_cx.build.Load(pp0),
+                            vec_p0(copy_src_cx, llsrc_vec),
+                            n_bytes).bcx;
+
+    put_vec_fill(copy_src_cx, llnew_vec,
+                 copy_src_cx.build.Add(vec_fill(copy_src_cx,
+                                                llnew_vec),
+                                        n_bytes));
+
+    // Write new_vec back through the alias we were given.
+    copy_src_cx.build.Store(llnew_vec, lldst_vec_ptr);
+    copy_src_cx.build.RetVoid();
+}
+
+
+fn make_glues(ModuleRef llmod, type_names tn) -> @glue_fns {
+    ret @rec(activate_glue = decl_glue(llmod, tn, abi.activate_glue_name()),
+             yield_glue = decl_glue(llmod, tn, abi.yield_glue_name()),
              /*
               * Note: the signature passed to decl_cdecl_fn here looks unusual
               * because it is. It corresponds neither to an upcall signature
@@ -4248,14 +5653,19 @@ fn make_glues(ModuleRef llmod) -> @glue_fns {
               * this is the signature required to retrieve it.
               */
              exit_task_glue = decl_cdecl_fn(llmod, abi.exit_task_glue_name(),
-                                            T_fn(vec(T_taskptr()), T_void())),
+                                            T_fn(vec(T_int(),
+                                                     T_int(),
+                                                     T_int(),
+                                                     T_taskptr(tn)),
+                                                 T_void())),
 
              upcall_glues =
-             _vec.init_fn[ValueRef](bind decl_upcall(llmod, _),
+             _vec.init_fn[ValueRef](bind decl_upcall_glue(llmod, tn, _),
                                     abi.n_upcall_glues as uint),
-             no_op_type_glue = make_no_op_type_glue(llmod),
+             no_op_type_glue = make_no_op_type_glue(llmod, tn),
              memcpy_glue = make_memcpy_glue(llmod),
-             bzero_glue = make_bzero_glue(llmod));
+             bzero_glue = make_bzero_glue(llmod),
+             vec_append_glue = make_vec_append_glue(llmod, tn));
 }
 
 fn trans_crate(session.session sess, @ast.crate crate, str output,
@@ -4267,33 +5677,40 @@ fn trans_crate(session.session sess, @ast.crate crate, str output,
     llvm.LLVMSetDataLayout(llmod, _str.buf(x86.get_data_layout()));
     llvm.LLVMSetTarget(llmod, _str.buf(x86.get_target_triple()));
     auto td = mk_target_data(x86.get_data_layout());
+    auto tn = mk_type_names();
     let ValueRef crate_ptr =
-        llvm.LLVMAddGlobal(llmod, T_crate(), _str.buf("rust_crate"));
+        llvm.LLVMAddGlobal(llmod, T_crate(tn), _str.buf("rust_crate"));
 
     llvm.LLVMSetModuleInlineAsm(llmod, _str.buf(x86.get_module_asm()));
 
     auto intrinsics = declare_intrinsics(llmod);
 
-    auto glues = make_glues(llmod);
+    auto glues = make_glues(llmod, tn);
     auto hasher = ty.hash_ty;
     auto eqer = ty.eq_ty;
-    auto tydescs = map.mk_hashmap[@ty.t,ValueRef](hasher, eqer);
+    auto tag_sizes = map.mk_hashmap[@ty.t,uint](hasher, eqer);
+    auto tydescs = map.mk_hashmap[@ty.t,@tydesc_info](hasher, eqer);
+    let vec[ast.ty_param] obj_typarams = vec();
     let vec[ast.obj_field] obj_fields = vec();
 
     auto cx = @rec(sess = sess,
                    llmod = llmod,
                    td = td,
+                   tn = tn,
                    crate_ptr = crate_ptr,
                    upcalls = new_str_hash[ValueRef](),
                    intrinsics = intrinsics,
                    item_names = new_str_hash[ValueRef](),
                    item_ids = new_def_hash[ValueRef](),
                    items = new_def_hash[@ast.item](),
-                   tags = new_def_hash[@tag_info](),
+                   native_items = new_def_hash[@ast.native_item](),
+                   tag_sizes = tag_sizes,
+                   discrims = new_def_hash[ValueRef](),
                    fn_pairs = new_def_hash[ValueRef](),
                    consts = new_def_hash[ValueRef](),
                    obj_methods = new_def_hash[()](),
                    tydescs = tydescs,
+                   obj_typarams = obj_typarams,
                    obj_fields = obj_fields,
                    glues = glues,
                    names = namegen(0),
@@ -4302,12 +5719,12 @@ fn trans_crate(session.session sess, @ast.crate crate, str output,
     create_typedefs(cx);
 
     collect_items(cx, crate);
-    resolve_tag_types(cx, crate);
     collect_tag_ctors(cx, crate);
     trans_constants(cx, crate);
 
     trans_mod(cx, crate.node.module);
     trans_exit_task_glue(cx);
+    trans_vec_append_glue(cx);
     create_crate_constant(cx);
     if (!shared) {
         trans_main_fn(cx, cx.crate_ptr);
diff --git a/src/comp/middle/ty.rs b/src/comp/middle/ty.rs
index f27595a157c..5a595db6ea5 100644
--- a/src/comp/middle/ty.rs
+++ b/src/comp/middle/ty.rs
@@ -19,7 +19,10 @@ import util.common.span;
 
 type arg = rec(ast.mode mode, @t ty);
 type field = rec(ast.ident ident, @t ty);
-type method = rec(ast.ident ident, vec[arg] inputs, @t output);
+type method = rec(ast.proto proto,
+                  ast.ident ident,
+                  vec[arg] inputs,
+                  @t output);
 
 // NB: If you change this, you'll probably want to change the corresponding
 // AST structure in front/ast.rs as well.
@@ -32,16 +35,19 @@ tag sty {
     ty_machine(util.common.ty_mach);
     ty_char;
     ty_str;
-    ty_tag(ast.def_id);
+    ty_tag(ast.def_id, vec[@t]);
     ty_box(@t);
     ty_vec(@t);
     ty_tup(vec[@t]);
     ty_rec(vec[field]);
-    ty_fn(vec[arg], @t);                            // TODO: effect
+    ty_fn(ast.proto, vec[arg], @t);                 // TODO: effect
+    ty_native_fn(ast.native_abi, vec[arg], @t);     // TODO: effect
     ty_obj(vec[method]);
     ty_var(int);                                    // ephemeral type var
     ty_local(ast.def_id);                           // type of a local var
-    ty_param(ast.def_id);                           // fn type param
+    ty_param(ast.def_id);                           // fn/tag type param
+    ty_type;
+    ty_native;
     // TODO: ty_fn_arg(@t), for a possibly-aliased function argument
 }
 
@@ -103,6 +109,7 @@ fn ast_ty_to_str(&@ast.ty ty) -> str {
         case (ast.ty_str)          { s = "str";                           }
         case (ast.ty_box(?t))      { s = "@" + ast_ty_to_str(t);          }
         case (ast.ty_vec(?t))      { s = "vec[" + ast_ty_to_str(t) + "]"; }
+        case (ast.ty_type)         { s = "type";                          }
 
         case (ast.ty_tup(?elts)) {
             auto f = ast_ty_to_str;
@@ -118,9 +125,13 @@ fn ast_ty_to_str(&@ast.ty ty) -> str {
             s += ")";
         }
 
-        case (ast.ty_fn(?inputs, ?output)) {
+        case (ast.ty_fn(?proto, ?inputs, ?output)) {
             auto f = ast_fn_input_to_str;
-            s = "fn(";
+            if (proto == ast.proto_fn) {
+                s = "fn(";
+            } else {
+                s = "iter(";
+            }
             auto is = _vec.map[rec(ast.mode mode, @ast.ty ty),str](f, inputs);
             s += _str.connect(is, ", ");
             s += ")";
@@ -138,6 +149,7 @@ fn ast_ty_to_str(&@ast.ty ty) -> str {
             s = "mutable " + ast_ty_to_str(t);
         }
 
+
         case (_) {
             fail;   // FIXME: typestate bug
         }
@@ -157,6 +169,8 @@ fn path_to_str(&ast.path pth) -> str {
     ret result;
 }
 
+// FIXME use the pretty-printer for this once it has a concept of an
+// abstract stream
 fn ty_to_str(&@t typ) -> str {
 
     fn fn_input_to_str(&rec(ast.mode mode, @t ty) input) -> str {
@@ -170,10 +184,14 @@ fn ty_to_str(&@t typ) -> str {
         ret s + ty_to_str(input.ty);
     }
 
-    fn fn_to_str(option.t[ast.ident] ident,
+    fn fn_to_str(ast.proto proto,
+                 option.t[ast.ident] ident,
                  vec[arg] inputs, @t output) -> str {
             auto f = fn_input_to_str;
             auto s = "fn";
+            if (proto == ast.proto_iter) {
+                s = "iter";
+            }
             alt (ident) {
                 case (some[ast.ident](?i)) {
                     s += " ";
@@ -193,7 +211,8 @@ fn ty_to_str(&@t typ) -> str {
     }
 
     fn method_to_str(&method m) -> str {
-        ret fn_to_str(some[ast.ident](m.ident), m.inputs, m.output) + ";";
+        ret fn_to_str(m.proto, some[ast.ident](m.ident),
+                      m.inputs, m.output) + ";";
     }
 
     fn field_to_str(&field f) -> str {
@@ -206,6 +225,7 @@ fn ty_to_str(&@t typ) -> str {
     }
 
     alt (typ.struct) {
+        case (ty_native)       { s = "native";                    }
         case (ty_nil)          { s = "()";                        }
         case (ty_bool)         { s = "bool";                      }
         case (ty_int)          { s = "int";                       }
@@ -215,6 +235,7 @@ fn ty_to_str(&@t typ) -> str {
         case (ty_str)          { s = "str";                       }
         case (ty_box(?t))      { s = "@" + ty_to_str(t);          }
         case (ty_vec(?t))      { s = "vec[" + ty_to_str(t) + "]"; }
+        case (ty_type)         { s = "type";                      }
 
         case (ty_tup(?elems)) {
             auto f = ty_to_str;
@@ -228,13 +249,23 @@ fn ty_to_str(&@t typ) -> str {
             s = "rec(" + _str.connect(strs, ",") + ")";
         }
 
-        case (ty_tag(_)) {
+        case (ty_tag(?id, ?tps)) {
             // The user should never see this if the cname is set properly!
-            s = "<tag>";
+            s = "<tag#" + util.common.istr(id._0) + ":" +
+                util.common.istr(id._1) + ">";
+            if (_vec.len[@t](tps) > 0u) {
+                auto f = ty_to_str;
+                auto strs = _vec.map[@t,str](f, tps);
+                s += "[" + _str.connect(strs, ",") + "]";
+            }
+        }
+
+        case (ty_fn(?proto, ?inputs, ?output)) {
+            s = fn_to_str(proto, none[ast.ident], inputs, output);
         }
 
-        case (ty_fn(?inputs, ?output)) {
-            s = fn_to_str(none[ast.ident], inputs, output);
+        case (ty_native_fn(_, ?inputs, ?output)) {
+            s = fn_to_str(ast.proto_fn, none[ast.ident], inputs, output);
         }
 
         case (ty_obj(?meths)) {
@@ -280,13 +311,21 @@ fn fold_ty(ty_fold fld, @t ty) -> @t {
         case (ty_machine(_))    { ret fld.fold_simple_ty(ty); }
         case (ty_char)          { ret fld.fold_simple_ty(ty); }
         case (ty_str)           { ret fld.fold_simple_ty(ty); }
-        case (ty_tag(_))        { ret fld.fold_simple_ty(ty); }
+        case (ty_type)          { ret fld.fold_simple_ty(ty); }
+        case (ty_native)        { ret fld.fold_simple_ty(ty); }
         case (ty_box(?subty)) {
             ret rewrap(ty, ty_box(fold_ty(fld, subty)));
         }
         case (ty_vec(?subty)) {
             ret rewrap(ty, ty_vec(fold_ty(fld, subty)));
         }
+        case (ty_tag(?tid, ?subtys)) {
+            let vec[@t] new_subtys = vec();
+            for (@t subty in subtys) {
+                new_subtys += vec(fold_ty(fld, subty));
+            }
+            ret rewrap(ty, ty_tag(tid, new_subtys));
+        }
         case (ty_tup(?subtys)) {
             let vec[@t] new_subtys = vec();
             for (@t subty in subtys) {
@@ -302,13 +341,21 @@ fn fold_ty(ty_fold fld, @t ty) -> @t {
             }
             ret rewrap(ty, ty_rec(new_fields));
         }
-        case (ty_fn(?args, ?ret_ty)) {
+        case (ty_fn(?proto, ?args, ?ret_ty)) {
             let vec[arg] new_args = vec();
             for (arg a in args) {
                 auto new_ty = fold_ty(fld, a.ty);
                 new_args += vec(rec(mode=a.mode, ty=new_ty));
             }
-            ret rewrap(ty, ty_fn(new_args, fold_ty(fld, ret_ty)));
+            ret rewrap(ty, ty_fn(proto, new_args, fold_ty(fld, ret_ty)));
+        }
+        case (ty_native_fn(?abi, ?args, ?ret_ty)) {
+            let vec[arg] new_args = vec();
+            for (arg a in args) {
+                auto new_ty = fold_ty(fld, a.ty);
+                new_args += vec(rec(mode=a.mode, ty=new_ty));
+            }
+            ret rewrap(ty, ty_native_fn(abi, new_args, fold_ty(fld, ret_ty)));
         }
         case (ty_obj(?methods)) {
             let vec[method] new_methods = vec();
@@ -317,7 +364,8 @@ fn fold_ty(ty_fold fld, @t ty) -> @t {
                 for (arg a in m.inputs) {
                     new_args += vec(rec(mode=a.mode, ty=fold_ty(fld, a.ty)));
                 }
-                new_methods += vec(rec(ident=m.ident, inputs=new_args,
+                new_methods += vec(rec(proto=m.proto, ident=m.ident,
+                                       inputs=new_args,
                                        output=fold_ty(fld, m.output)));
             }
             ret rewrap(ty, ty_obj(new_methods));
@@ -327,7 +375,7 @@ fn fold_ty(ty_fold fld, @t ty) -> @t {
         case (ty_param(_))      { ret fld.fold_simple_ty(ty); }
     }
 
-    ret ty;
+    fail;
 }
 
 // Type utilities
@@ -349,24 +397,44 @@ fn type_is_nil(@t ty) -> bool {
     fail;
 }
 
+
 fn type_is_structural(@t ty) -> bool {
     alt (ty.struct) {
-        case (ty_tup(_)) { ret true; }
-        case (ty_rec(_)) { ret true; }
-        case (ty_tag(_)) { ret true; }
-        case (ty_fn(_,_)) { ret true; }
-        case (ty_obj(_)) { ret true; }
-        case (_) { ret false; }
+        case (ty_tup(_))    { ret true; }
+        case (ty_rec(_))    { ret true; }
+        case (ty_tag(_,_))  { ret true; }
+        case (ty_fn(_,_,_)) { ret true; }
+        case (ty_obj(_))    { ret true; }
+        case (_)            { ret false; }
+    }
+    fail;
+}
+
+fn type_is_sequence(@t ty) -> bool {
+    alt (ty.struct) {
+        case (ty_str)    { ret true; }
+        case (ty_vec(_))    { ret true; }
+        case (_)            { ret false; }
+    }
+    fail;
+}
+
+fn sequence_element_type(@t ty) -> @t {
+    alt (ty.struct) {
+        case (ty_str)     { ret plain_ty(ty_machine(common.ty_u8)); }
+        case (ty_vec(?e)) { ret e; }
     }
     fail;
 }
 
+
 fn type_is_tup_like(@t ty) -> bool {
     alt (ty.struct) {
-        case (ty_tup(_)) { ret true; }
-        case (ty_rec(_)) { ret true; }
-        case (ty_tag(_)) { ret true; }
-        case (_) { ret false; }
+        case (ty_box(_))    { ret true; }
+        case (ty_tup(_))    { ret true; }
+        case (ty_rec(_))    { ret true; }
+        case (ty_tag(_,_))  { ret true; }
+        case (_)            { ret false; }
     }
     fail;
 }
@@ -402,6 +470,17 @@ fn type_is_scalar(@t ty) -> bool {
         case (ty_uint) { ret true; }
         case (ty_machine(_)) { ret true; }
         case (ty_char) { ret true; }
+        case (ty_type) { ret true; }
+        case (_) { ret false; }
+    }
+    fail;
+}
+
+// FIXME: should we just return true for native types in
+// type_is_scalar?
+fn type_is_native(@t ty) -> bool {
+    alt (ty.struct) {
+        case (ty_native) { ret true; }
         case (_) { ret false; }
     }
     fail;
@@ -423,6 +502,13 @@ fn type_has_dynamic_size(@t ty) -> bool {
                 i += 1u;
             }
         }
+        case (ty_tag(_, ?subtys)) {
+            auto i = 0u;
+            while (i < _vec.len[@t](subtys)) {
+                if (type_has_dynamic_size(subtys.(i))) { ret true; }
+                i += 1u;
+            }
+        }
         case (ty_param(_)) { ret true; }
         case (_) { /* fall through */ }
     }
@@ -547,23 +633,42 @@ fn count_ty_params(@t ty) -> uint {
 // Type accessors for substructures of types
 
 fn ty_fn_args(@t fty) -> vec[arg] {
-  alt (fty.struct) {
-    case (ty.ty_fn(?a, _)) { ret a; }
-  }
+    alt (fty.struct) {
+        case (ty.ty_fn(_, ?a, _)) { ret a; }
+        case (ty.ty_native_fn(_, ?a, _)) { ret a; }
+    }
+    fail;
+}
+
+fn ty_fn_proto(@t fty) -> ast.proto {
+    alt (fty.struct) {
+        case (ty.ty_fn(?p, _, _)) { ret p; }
+    }
+    fail;
+}
+
+fn ty_fn_abi(@t fty) -> ast.native_abi {
+    alt (fty.struct) {
+        case (ty.ty_native_fn(?a, _, _)) { ret a; }
+    }
+    fail;
 }
 
 fn ty_fn_ret(@t fty) -> @t {
-  alt (fty.struct) {
-    case (ty.ty_fn(_, ?r)) { ret r; }
-  }
+    alt (fty.struct) {
+        case (ty.ty_fn(_, _, ?r)) { ret r; }
+        case (ty.ty_native_fn(_, _, ?r)) { ret r; }
+    }
+    fail;
 }
 
 fn is_fn_ty(@t fty) -> bool {
-  alt (fty.struct) {
-    case (ty.ty_fn(_, _)) { ret true; }
-    case (_) { ret false; }
-  }
-  ret false;
+    alt (fty.struct) {
+        case (ty.ty_fn(_, _, _)) { ret true; }
+        case (ty.ty_native_fn(_, _, _)) { ret true; }
+        case (_) { ret false; }
+    }
+    ret false;
 }
 
 
@@ -571,7 +676,24 @@ fn is_fn_ty(@t fty) -> bool {
 
 // Given an item, returns the associated type as well as a list of the IDs of
 // its type parameters.
-fn item_ty(@ast.item it) -> tup(vec[ast.def_id], @t) {
+type ty_params_and_ty = tup(vec[ast.def_id], @t);
+fn native_item_ty(@ast.native_item it) -> ty_params_and_ty {
+    auto ty_params;
+    auto result_ty;
+    alt (it.node) {
+        case (ast.native_item_fn(_, _, ?tps, _, ?ann)) {
+            ty_params = tps;
+            result_ty = ann_to_type(ann);
+        }
+    }
+    let vec[ast.def_id] ty_param_ids = vec();
+    for (ast.ty_param tp in ty_params) {
+        ty_param_ids += vec(tp.id);
+    }
+    ret tup(ty_param_ids, result_ty);
+}
+
+fn item_ty(@ast.item it) -> ty_params_and_ty {
     let vec[ast.ty_param] ty_params;
     auto result_ty;
     alt (it.node) {
@@ -591,8 +713,13 @@ fn item_ty(@ast.item it) -> tup(vec[ast.def_id], @t) {
             result_ty = ann_to_type(ann);
         }
         case (ast.item_tag(_, _, ?tps, ?did)) {
+            // Create a new generic polytype.
             ty_params = tps;
-            result_ty = plain_ty(ty_tag(did));
+            let vec[@t] subtys = vec();
+            for (ast.ty_param tp in tps) {
+                subtys += vec(plain_ty(ty_param(tp.id)));
+            }
+            result_ty = plain_ty(ty_tag(did, subtys));
         }
         case (ast.item_obj(_, _, ?tps, _, ?ann)) {
             ty_params = tps;
@@ -628,6 +755,7 @@ fn block_ty(&ast.block b) -> @t {
 fn pat_ty(@ast.pat pat) -> @t {
     alt (pat.node) {
         case (ast.pat_wild(?ann))           { ret ann_to_type(ann); }
+        case (ast.pat_lit(_, ?ann))         { ret ann_to_type(ann); }
         case (ast.pat_bind(_, _, ?ann))     { ret ann_to_type(ann); }
         case (ast.pat_tag(_, _, _, ?ann))   { ret ann_to_type(ann); }
     }
@@ -638,7 +766,7 @@ fn expr_ty(@ast.expr expr) -> @t {
     alt (expr.node) {
         case (ast.expr_vec(_, ?ann))          { ret ann_to_type(ann); }
         case (ast.expr_tup(_, ?ann))          { ret ann_to_type(ann); }
-        case (ast.expr_rec(_, ?ann))          { ret ann_to_type(ann); }
+        case (ast.expr_rec(_, _, ?ann))       { ret ann_to_type(ann); }
         case (ast.expr_bind(_, _, ?ann))      { ret ann_to_type(ann); }
         case (ast.expr_call(_, _, ?ann))      { ret ann_to_type(ann); }
         case (ast.expr_binary(_, _, _, ?ann)) { ret ann_to_type(ann); }
@@ -647,6 +775,8 @@ fn expr_ty(@ast.expr expr) -> @t {
         case (ast.expr_cast(_, _, ?ann))      { ret ann_to_type(ann); }
         case (ast.expr_if(_, _, _, ?ann))     { ret ann_to_type(ann); }
         case (ast.expr_for(_, _, _, ?ann))    { ret ann_to_type(ann); }
+        case (ast.expr_for_each(_, _, _, ?ann))
+                                              { ret ann_to_type(ann); }
         case (ast.expr_while(_, _, ?ann))     { ret ann_to_type(ann); }
         case (ast.expr_do_while(_, _, ?ann))  { ret ann_to_type(ann); }
         case (ast.expr_alt(_, _, ?ann))       { ret ann_to_type(ann); }
@@ -657,6 +787,14 @@ fn expr_ty(@ast.expr expr) -> @t {
         case (ast.expr_field(_, _, ?ann))     { ret ann_to_type(ann); }
         case (ast.expr_index(_, _, ?ann))     { ret ann_to_type(ann); }
         case (ast.expr_path(_, _, ?ann))      { ret ann_to_type(ann); }
+        case (ast.expr_ext(_, _, _, _, ?ann)) { ret ann_to_type(ann); }
+
+        case (ast.expr_fail)                  { ret plain_ty(ty_nil); }
+        case (ast.expr_log(_))                { ret plain_ty(ty_nil); }
+        case (ast.expr_check_expr(_))         { ret plain_ty(ty_nil); }
+        case (ast.expr_ret(_))                { ret plain_ty(ty_nil); }
+        case (ast.expr_put(_))                { ret plain_ty(ty_nil); }
+        case (ast.expr_be(_))                 { ret plain_ty(ty_nil); }
     }
     fail;
 }
@@ -726,7 +864,10 @@ fn is_lval(@ast.expr expr) -> bool {
     }
 }
 
-// Type unification
+// Type unification via Robinson's algorithm (Robinson 1965). Implemented as
+// described in Hoder and Voronkov:
+//
+//     http://www.cs.man.ac.uk/~hoderk/ubench/unification_full.pdf
 
 fn unify(@ty.t expected, @ty.t actual, &unify_handler handler)
         -> unify_result {
@@ -746,81 +887,137 @@ fn unify(@ty.t expected, @ty.t actual, &unify_handler handler)
         ret ures_err(terr_mismatch, expected, actual);
     }
 
-    fn unify_fn(&hashmap[int,@ty.t] bindings,
-                @ty.t expected,
-                @ty.t actual,
-                &unify_handler handler,
-                vec[arg] expected_inputs, @t expected_output,
-                vec[arg] actual_inputs, @t actual_output)
-      -> unify_result {
-      auto expected_len = _vec.len[arg](expected_inputs);
-      auto actual_len = _vec.len[arg](actual_inputs);
-      if (expected_len != actual_len) {
-        ret ures_err(terr_arg_count, expected, actual);
-      }
+    tag fn_common_res {
+        fn_common_res_err(unify_result);
+        fn_common_res_ok(vec[arg], @t);
+    }
 
-      // TODO: as above, we should have an iter2 iterator.
-      let vec[arg] result_ins = vec();
-      auto i = 0u;
-      while (i < expected_len) {
-        auto expected_input = expected_inputs.(i);
-        auto actual_input = actual_inputs.(i);
-
-        // This should be safe, I think?
-        auto result_mode;
-        if (mode_is_alias(expected_input.mode) ||
-            mode_is_alias(actual_input.mode)) {
-          result_mode = ast.alias;
-        } else {
-          result_mode = ast.val;
+    fn unify_fn_common(@hashmap[int,@ty.t] bindings,
+                       @ty.t expected,
+                       @ty.t actual,
+                       &unify_handler handler,
+                       vec[arg] expected_inputs, @t expected_output,
+                       vec[arg] actual_inputs, @t actual_output)
+        -> fn_common_res {
+        auto expected_len = _vec.len[arg](expected_inputs);
+        auto actual_len = _vec.len[arg](actual_inputs);
+        if (expected_len != actual_len) {
+            ret fn_common_res_err(ures_err(terr_arg_count,
+                                           expected, actual));
+        }
+
+        // TODO: as above, we should have an iter2 iterator.
+        let vec[arg] result_ins = vec();
+        auto i = 0u;
+        while (i < expected_len) {
+            auto expected_input = expected_inputs.(i);
+            auto actual_input = actual_inputs.(i);
+
+            // This should be safe, I think?
+            auto result_mode;
+            if (mode_is_alias(expected_input.mode) ||
+                mode_is_alias(actual_input.mode)) {
+                result_mode = ast.alias;
+            } else {
+                result_mode = ast.val;
+            }
+
+            auto result = unify_step(bindings,
+                                     actual_input.ty,
+                                     expected_input.ty,
+                                     handler);
+
+            alt (result) {
+                case (ures_ok(?rty)) {
+                    result_ins += vec(rec(mode=result_mode,
+                                          ty=rty));
+                }
+
+                case (_) {
+                    ret fn_common_res_err(result);
+                }
+            }
+
+            i += 1u;
         }
 
+        // Check the output.
         auto result = unify_step(bindings,
-                                 actual_input.ty,
-                                 expected_input.ty,
+                                 expected_output,
+                                 actual_output,
                                  handler);
-
         alt (result) {
-          case (ures_ok(?rty)) {
-            result_ins += vec(rec(mode=result_mode,
-                                  ty=rty));
-          }
+            case (ures_ok(?rty)) {
+                ret fn_common_res_ok(result_ins, rty);
+            }
 
-          case (_) {
-            ret result;
-          }
+            case (_) {
+                ret fn_common_res_err(result);
+            }
         }
+    }
 
-        i += 1u;
-      }
+    fn unify_fn(@hashmap[int,@ty.t] bindings,
+                ast.proto e_proto,
+                ast.proto a_proto,
+                @ty.t expected,
+                @ty.t actual,
+                &unify_handler handler,
+                vec[arg] expected_inputs, @t expected_output,
+                vec[arg] actual_inputs, @t actual_output)
+        -> unify_result {
 
-      // Check the output.
-      auto result_out;
-      auto result = unify_step(bindings,
-                               expected_output,
-                               actual_output,
-                               handler);
-      alt (result) {
-        case (ures_ok(?rty)) {
-          result_out = rty;
+        if (e_proto != a_proto) {
+            ret ures_err(terr_mismatch, expected, actual);
         }
-
-        case (_) {
-          ret result;
+        auto t = unify_fn_common(bindings, expected, actual,
+                                 handler, expected_inputs, expected_output,
+                                 actual_inputs, actual_output);
+        alt (t) {
+            case (fn_common_res_err(?r)) {
+                ret r;
+            }
+            case (fn_common_res_ok(?result_ins, ?result_out)) {
+                auto t2 = plain_ty(ty.ty_fn(e_proto, result_ins, result_out));
+                ret ures_ok(t2);
+            }
         }
-      }
+    }
 
-      auto t = plain_ty(ty.ty_fn(result_ins, result_out));
-      ret ures_ok(t);
+    fn unify_native_fn(@hashmap[int,@ty.t] bindings,
+                       ast.native_abi e_abi,
+                       ast.native_abi a_abi,
+                       @ty.t expected,
+                       @ty.t actual,
+                       &unify_handler handler,
+                       vec[arg] expected_inputs, @t expected_output,
+                       vec[arg] actual_inputs, @t actual_output)
+        -> unify_result {
+        if (e_abi != a_abi) {
+            ret ures_err(terr_mismatch, expected, actual);
+        }
 
+        auto t = unify_fn_common(bindings, expected, actual,
+                                 handler, expected_inputs, expected_output,
+                                 actual_inputs, actual_output);
+        alt (t) {
+            case (fn_common_res_err(?r)) {
+                ret r;
+            }
+            case (fn_common_res_ok(?result_ins, ?result_out)) {
+                auto t2 = plain_ty(ty.ty_native_fn(e_abi, result_ins,
+                                                   result_out));
+                ret ures_ok(t2);
+            }
+        }
     }
 
-    fn unify_obj(&hashmap[int,@ty.t] bindings,
-                @ty.t expected,
-                @ty.t actual,
-                &unify_handler handler,
-                vec[method] expected_meths,
-                vec[method] actual_meths) -> unify_result {
+    fn unify_obj(@hashmap[int,@ty.t] bindings,
+                 @ty.t expected,
+                 @ty.t actual,
+                 &unify_handler handler,
+                 vec[method] expected_meths,
+                 vec[method] actual_meths) -> unify_result {
       let vec[method] result_meths = vec();
       let uint i = 0u;
       let uint expected_len = _vec.len[method](expected_meths);
@@ -830,32 +1027,6 @@ fn unify(@ty.t expected, @ty.t actual, &unify_handler handler)
         ret ures_err(terr_meth_count, expected, actual);
       }
 
-      // FIXME: work around buggy typestate logic for 'alt', sigh.
-      fn is_ok(&unify_result r) -> bool {
-        alt (r) {
-          case (ures_ok(?tfn)) {
-            ret true;
-          }
-          case (_) {}
-        }
-        ret false;
-      }
-
-      fn append_if_ok(&method e_meth,
-                      &unify_result r, &mutable vec[method] result_meths) {
-        alt (r) {
-          case (ures_ok(?tfn)) {
-            alt (tfn.struct) {
-              case (ty_fn(?ins, ?out)) {
-                result_meths += vec(rec(inputs = ins,
-                                        output = out
-                                        with e_meth));
-              }
-            }
-          }
-        }
-      }
-
       while (i < expected_len) {
         auto e_meth = expected_meths.(i);
         auto a_meth = actual_meths.(i);
@@ -863,40 +1034,69 @@ fn unify(@ty.t expected, @ty.t actual, &unify_handler handler)
           ret ures_err(terr_obj_meths(e_meth.ident, a_meth.ident),
                        expected, actual);
         }
-        auto r = unify_fn(bindings, expected, actual, handler,
+        auto r = unify_fn(bindings,
+                          e_meth.proto, a_meth.proto,
+                          expected, actual, handler,
                           e_meth.inputs, e_meth.output,
                           a_meth.inputs, a_meth.output);
-        if (!is_ok(r)) {
-          ret r;
+        alt (r) {
+            case (ures_ok(?tfn)) {
+                alt (tfn.struct) {
+                    case (ty_fn(?proto, ?ins, ?out)) {
+                        result_meths += vec(rec(inputs = ins,
+                                                output = out
+                                                with e_meth));
+                    }
+                }
+            }
+            case (_) {
+                ret r;
+            }
         }
-        append_if_ok(e_meth, r, result_meths);
         i += 1u;
       }
       auto t = plain_ty(ty_obj(result_meths));
       ret ures_ok(t);
     }
 
-    fn unify_step(&hashmap[int,@ty.t] bindings, @ty.t expected, @ty.t actual,
-                  &unify_handler handler) -> unify_result {
+    fn resolve(@hashmap[int,@t] bindings, @t typ) -> @t {
+        alt (typ.struct) {
+            case (ty_var(?id)) {
+                alt (bindings.find(id)) {
+                    case (some[@t](?typ2)) {
+                        ret resolve(bindings, typ2);
+                    }
+                    case (none[@t]) {
+                        // fall through
+                    }
+                }
+            }
+            case (_) {
+                // fall through
+            }
+        }
+        ret typ;
+    }
+
+    fn unify_step(@hashmap[int,@ty.t] bindings, @ty.t in_expected,
+                  @ty.t in_actual, &unify_handler handler) -> unify_result {
+
+        // Resolve any bindings.
+        auto expected = resolve(bindings, in_expected);
+        auto actual = resolve(bindings, in_actual);
+
         // TODO: rewrite this using tuple pattern matching when available, to
         // avoid all this rightward drift and spikiness.
 
+        // TODO: occurs check, to make sure we don't loop forever when
+        // unifying e.g. 'a and option['a]
+
         alt (actual.struct) {
             // If the RHS is a variable type, then just do the appropriate
             // binding.
             case (ty.ty_var(?actual_id)) {
-                alt (bindings.find(actual_id)) {
-                    case (some[@ty.t](?actual_ty)) {
-                        // FIXME: change the binding here?
-                        // FIXME: "be"
-                        ret unify_step(bindings, expected, actual_ty,
-                                       handler);
-                    }
-                    case (none[@ty.t]) {
-                        bindings.insert(actual_id, expected);
-                        ret ures_ok(expected);
-                    }
-                }
+                bindings.insert(actual_id, expected);
+                ret ures_ok(expected);
             }
             case (ty.ty_local(?actual_id)) {
                 auto actual_ty = handler.resolve_local(actual_id);
@@ -938,14 +1138,45 @@ fn unify(@ty.t expected, @ty.t actual, &unify_handler handler)
             case (ty.ty_machine(_)) { ret struct_cmp(expected, actual); }
             case (ty.ty_char)       { ret struct_cmp(expected, actual); }
             case (ty.ty_str)        { ret struct_cmp(expected, actual); }
+            case (ty.ty_type)       { ret struct_cmp(expected, actual); }
+            case (ty.ty_native)     { ret struct_cmp(expected, actual); }
 
-            case (ty.ty_tag(?expected_id)) {
+            case (ty.ty_tag(?expected_id, ?expected_tps)) {
                 alt (actual.struct) {
-                    case (ty.ty_tag(?actual_id)) {
-                        if (expected_id._0 == actual_id._0 &&
-                                expected_id._1 == actual_id._1) {
-                            ret ures_ok(expected);
+                    case (ty.ty_tag(?actual_id, ?actual_tps)) {
+                        if (expected_id._0 != actual_id._0 ||
+                                expected_id._1 != actual_id._1) {
+                            ret ures_err(terr_mismatch, expected, actual);
                         }
+
+                        // TODO: factor this cruft out, see the TODO in the
+                        // ty.ty_tup case
+                        let vec[@ty.t] result_tps = vec();
+                        auto i = 0u;
+                        auto expected_len = _vec.len[@ty.t](expected_tps);
+                        while (i < expected_len) {
+                            auto expected_tp = expected_tps.(i);
+                            auto actual_tp = actual_tps.(i);
+
+                            auto result = unify_step(bindings,
+                                                     expected_tp,
+                                                     actual_tp,
+                                                     handler);
+
+                            alt (result) {
+                                case (ures_ok(?rty)) {
+                                    append[@ty.t](result_tps, rty);
+                                }
+                                case (_) {
+                                    ret result;
+                                }
+                            }
+
+                            i += 1u;
+                        }
+
+                        ret ures_ok(plain_ty(ty.ty_tag(expected_id,
+                                                       result_tps)));
                     }
                     case (_) { /* fall through */ }
                 }
@@ -970,8 +1201,6 @@ fn unify(@ty.t expected, @ty.t actual, &unify_handler handler)
                         }
                     }
 
-                    // TODO: ty_var
-
                     case (_) {
                         ret ures_err(terr_mismatch, expected, actual);
                     }
@@ -995,8 +1224,6 @@ fn unify(@ty.t expected, @ty.t actual, &unify_handler handler)
                         }
                     }
 
-                    // TODO: ty_var
-
                     case (_) {
                         ret ures_err(terr_mismatch, expected, actual);
                    }
@@ -1045,8 +1272,6 @@ fn unify(@ty.t expected, @ty.t actual, &unify_handler handler)
                         ret ures_ok(plain_ty(ty.ty_tup(result_elems)));
                     }
 
-                    // TODO: ty_var
-
                     case (_) {
                         ret ures_err(terr_mismatch, expected, actual);
                     }
@@ -1106,20 +1331,19 @@ fn unify(@ty.t expected, @ty.t actual, &unify_handler handler)
                         ret ures_ok(plain_ty(ty.ty_rec(result_fields)));
                     }
 
-                    // TODO: ty_var
-
                     case (_) {
                         ret ures_err(terr_mismatch, expected, actual);
                     }
                 }
             }
 
-            case (ty.ty_fn(?expected_inputs, ?expected_output)) {
+            case (ty.ty_fn(?ep, ?expected_inputs, ?expected_output)) {
                 alt (actual.struct) {
-                    case (ty.ty_fn(?actual_inputs, ?actual_output)) {
-                      ret unify_fn(bindings, expected, actual, handler,
-                                   expected_inputs, expected_output,
-                                   actual_inputs, actual_output);
+                    case (ty.ty_fn(?ap, ?actual_inputs, ?actual_output)) {
+                        ret unify_fn(bindings, ep, ap,
+                                     expected, actual, handler,
+                                     expected_inputs, expected_output,
+                                     actual_inputs, actual_output);
                     }
 
                     case (_) {
@@ -1128,35 +1352,40 @@ fn unify(@ty.t expected, @ty.t actual, &unify_handler handler)
                 }
             }
 
-            case (ty.ty_obj(?expected_meths)) {
-              alt (actual.struct) {
-                case (ty.ty_obj(?actual_meths)) {
-                  ret unify_obj(bindings, expected, actual, handler,
-                                expected_meths, actual_meths);
-                }
-                case (_) {
-                  ret ures_err(terr_mismatch, expected, actual);
+            case (ty.ty_native_fn(?e_abi, ?expected_inputs,
+                                  ?expected_output)) {
+                alt (actual.struct) {
+                    case (ty.ty_native_fn(?a_abi, ?actual_inputs,
+                                          ?actual_output)) {
+                        ret unify_native_fn(bindings, e_abi, a_abi,
+                                            expected, actual, handler,
+                                            expected_inputs, expected_output,
+                                            actual_inputs, actual_output);
+                    }
+                    case (_) {
+                        ret ures_err(terr_mismatch, expected, actual);
+                    }
                 }
-              }
             }
 
-            case (ty.ty_var(?expected_id)) {
-                alt (bindings.find(expected_id)) {
-                    case (some[@ty.t](?expected_ty)) {
-                        // FIXME: change the binding here?
-                        // FIXME: "be"
-                        ret unify_step(bindings,
-                                       expected_ty,
-                                       actual,
-                                       handler);
+            case (ty.ty_obj(?expected_meths)) {
+                alt (actual.struct) {
+                    case (ty.ty_obj(?actual_meths)) {
+                        ret unify_obj(bindings, expected, actual, handler,
+                                      expected_meths, actual_meths);
                     }
-                    case (none[@ty.t]) {
-                        bindings.insert(expected_id, actual);
-                        ret ures_ok(actual);
+                    case (_) {
+                        ret ures_err(terr_mismatch, expected, actual);
                     }
                 }
             }
 
+            case (ty.ty_var(?expected_id)) {
+                // Add a binding.
+                bindings.insert(expected_id, actual);
+                ret ures_ok(actual);
+            }
+
             case (ty.ty_local(?expected_id)) {
                 auto expected_ty = handler.resolve_local(expected_id);
                 auto result = unify_step(bindings,
@@ -1182,13 +1411,43 @@ fn unify(@ty.t expected, @ty.t actual, &unify_handler handler)
         fail;
     }
 
+    // Performs type binding substitution.
+    fn substitute(@hashmap[int,@t] bindings, @t typ) -> @t {
+        state obj folder(@hashmap[int,@t] bindings) {
+            fn fold_simple_ty(@t typ) -> @t {
+                alt (typ.struct) {
+                    case (ty_var(?id)) {
+                        alt (bindings.find(id)) {
+                            case (some[@t](?typ2)) {
+                                ret substitute(bindings, typ2);
+                            }
+                            case (none[@t]) {
+                                ret typ;
+                            }
+                        }
+                    }
+                    case (_) {
+                        ret typ;
+                    }
+                }
+            }
+        }
+
+        ret ty.fold_ty(folder(bindings), typ);
+    }
+
     fn hash_int(&int x) -> uint { ret x as uint; }
     fn eq_int(&int a, &int b) -> bool { ret a == b; }
     auto hasher = hash_int;
     auto eqer = eq_int;
-    auto bindings = map.mk_hashmap[int,@ty.t](hasher, eqer);
+    auto bindings = @map.mk_hashmap[int,@ty.t](hasher, eqer);
 
-    ret unify_step(bindings, expected, actual, handler);
+    auto ures = unify_step(bindings, expected, actual, handler);
+    alt (ures) {
+        case (ures_ok(?t))  { ret ures_ok(substitute(bindings, t)); }
+        case (_)            { ret ures;                             }
+    }
+    fail;   // not reached
 }
 
 fn type_err_to_str(&ty.type_err err) -> str {
@@ -1231,9 +1490,10 @@ fn type_err_to_str(&ty.type_err err) -> str {
     }
 }
 
-// Type parameter resolution, used in translation
+// Type parameter resolution, used in translation and typechecking
 
-fn resolve_ty_params(@ast.item item, @t monoty) -> vec[@t] {
+fn resolve_ty_params(ty_params_and_ty ty_params_and_polyty,
+                     @t monoty) -> vec[@t] {
     obj resolve_ty_params_handler(@hashmap[ast.def_id,@t] bindings) {
         fn resolve_local(ast.def_id id) -> @t { log "resolve local"; fail; }
         fn record_local(ast.def_id id, @t ty) { log "record local"; fail; }
@@ -1249,8 +1509,6 @@ fn resolve_ty_params(@ast.item item, @t monoty) -> vec[@t] {
         }
     }
 
-    auto ty_params_and_polyty = item_ty(item);
-
     auto bindings = @new_def_hash[@t]();
     auto handler = resolve_ty_params_handler(bindings);
 
@@ -1274,6 +1532,47 @@ fn resolve_ty_params(@ast.item item, @t monoty) -> vec[@t] {
     ret result_tys;
 }
 
+// Performs type parameter replacement using the supplied mapping from
+// parameter IDs to types.
+fn replace_type_params(@t typ, hashmap[ast.def_id,@t] param_map) -> @t {
+    state obj param_replacer(hashmap[ast.def_id,@t] param_map) {
+        fn fold_simple_ty(@t typ) -> @t {
+            alt (typ.struct) {
+                case (ty_param(?param_def)) {
+                    if (param_map.contains_key(param_def)) {
+                        ret param_map.get(param_def);
+                    } else {
+                        ret typ;
+                    }
+                }
+                case (_) {
+                    ret typ;
+                }
+            }
+        }
+    }
+    auto replacer = param_replacer(param_map);
+    ret fold_ty(replacer, typ);
+}
+
+// Substitutes the type parameters specified by @ty_params with the
+// corresponding types in @bound in the given type. The two vectors must have
+// the same length.
+fn substitute_ty_params(vec[ast.ty_param] ty_params, vec[@t] bound, @t ty)
+        -> @t {
+    auto ty_param_len = _vec.len[ast.ty_param](ty_params);
+    check (ty_param_len == _vec.len[@t](bound));
+
+    auto bindings = common.new_def_hash[@t]();
+    auto i = 0u;
+    while (i < ty_param_len) {
+        bindings.insert(ty_params.(i).id, bound.(i));
+        i += 1u;
+    }
+
+    ret replace_type_params(ty, bindings);
+}
+
 // Local Variables:
 // mode: rust
 // fill-column: 78;
diff --git a/src/comp/middle/typeck.rs b/src/comp/middle/typeck.rs
index d778ffa96d0..5c7f963cb78 100644
--- a/src/comp/middle/typeck.rs
+++ b/src/comp/middle/typeck.rs
@@ -25,13 +25,20 @@ import middle.ty.type_is_scalar;
 import std._str;
 import std._uint;
 import std._vec;
+import std.map;
 import std.map.hashmap;
 import std.option;
 import std.option.none;
 import std.option.some;
 
 type ty_table = hashmap[ast.def_id, @ty.t];
-type ty_item_table = hashmap[ast.def_id,@ast.item];
+
+tag any_item {
+    any_item_rust(@ast.item);
+    any_item_native(@ast.native_item, ast.native_abi);
+}
+
+type ty_item_table = hashmap[ast.def_id,any_item];
 
 type crate_ctxt = rec(session.session sess,
                       @ty_table item_types,
@@ -72,6 +79,65 @@ fn generalize_ty(@crate_ctxt cx, @ty.t t) -> @ty.t {
     ret ty.fold_ty(generalizer, t);
 }
 
+// Substitutes the user's explicit types for the parameters in a path
+// expression.
+fn substitute_ty_params(&@crate_ctxt ccx,
+                        @ty.t typ,
+                        vec[@ast.ty] supplied,
+                        &span sp) -> @ty.t {
+    state obj ty_substituter(@crate_ctxt ccx,
+                             @mutable uint i,
+                             vec[@ast.ty] supplied,
+                             @hashmap[int,@ty.t] substs) {
+        fn fold_simple_ty(@ty.t typ) -> @ty.t {
+            alt (typ.struct) {
+                case (ty.ty_var(?vid)) {
+                    alt (substs.find(vid)) {
+                        case (some[@ty.t](?resolved_ty)) {
+                            ret resolved_ty;
+                        }
+                        case (none[@ty.t]) {
+                            if (i >= _vec.len[@ast.ty](supplied)) {
+                                // Just leave it as an unresolved parameter
+                                // for now. (We will error out later.)
+                                ret typ;
+                            }
+
+                            auto result = ast_ty_to_ty_crate(ccx,
+                                                             supplied.(*i));
+                            *i += 1u;
+                            substs.insert(vid, result);
+                            ret result;
+                        }
+                    }
+                }
+                case (_) { ret typ; }
+            }
+        }
+    }
+
+    fn hash_int(&int x) -> uint { ret x as uint; }
+    fn eq_int(&int a, &int b) -> bool { ret a == b; }
+    auto hasher = hash_int;
+    auto eqer = eq_int;
+    auto substs = @map.mk_hashmap[int,@ty.t](hasher, eqer);
+
+    auto subst_count = @mutable 0u;
+    auto substituter = ty_substituter(ccx, subst_count, supplied, substs);
+
+    auto result = ty.fold_ty(substituter, typ);
+
+    auto supplied_len = _vec.len[@ast.ty](supplied);
+    if ((*subst_count) != supplied_len) {
+        ccx.sess.span_err(sp, "expected " + _uint.to_str(*subst_count, 10u) +
+                          " type parameter(s) but found " +
+                          _uint.to_str(supplied_len, 10u) + " parameter(s)");
+        fail;
+    }
+
+    ret result;
+}
+
 // Parses the programmer's textual representation of a type into our internal
 // notion of a type. `getter` is a function that returns the type
 // corresponding to a definition ID.
@@ -81,23 +147,6 @@ fn ast_ty_to_ty(ty_getter getter, &@ast.ty ast_ty) -> @ty.t {
         ret rec(mode=arg.mode, ty=ast_ty_to_ty(getter, arg.ty));
     }
 
-    fn replace_type_params(@ty.t t, ty_table param_map) -> @ty.t {
-        state obj param_replacer(ty_table param_map) {
-            fn fold_simple_ty(@ty.t t) -> @ty.t {
-                alt (t.struct) {
-                    case (ty.ty_param(?param_def)) {
-                        ret param_map.get(param_def);
-                    }
-                    case (_) {
-                        ret t;
-                    }
-                }
-            }
-        }
-        auto replacer = param_replacer(param_map);
-        ret ty.fold_ty(replacer, t);
-    }
-
     fn instantiate(ty_getter getter, ast.def_id id,
                    vec[@ast.ty] args) -> @ty.t {
         // TODO: maybe record cname chains so we can do
@@ -113,7 +162,7 @@ fn ast_ty_to_ty(ty_getter getter, &@ast.ty ast_ty) -> @ty.t {
             auto param = params.(i);
             param_map.insert(param.id, ast_ty_to_ty(getter, arg));
         }
-        ret replace_type_params(ty_and_params.ty, param_map);
+        ret ty.replace_type_params(ty_and_params.ty, param_map);
     }
 
     auto mut = ast.imm;
@@ -145,10 +194,10 @@ fn ast_ty_to_ty(ty_getter getter, &@ast.ty ast_ty) -> @ty.t {
             sty = ty.ty_rec(flds);
         }
 
-        case (ast.ty_fn(?inputs, ?output)) {
+        case (ast.ty_fn(?proto, ?inputs, ?output)) {
             auto f = bind ast_arg_to_arg(getter, _);
             auto i = _vec.map[ast.ty_arg, arg](f, inputs);
-            sty = ty.ty_fn(i, ast_ty_to_ty(getter, output));
+            sty = ty.ty_fn(proto, i, ast_ty_to_ty(getter, output));
         }
 
         case (ast.ty_path(?path, ?def)) {
@@ -157,6 +206,9 @@ fn ast_ty_to_ty(ty_getter getter, &@ast.ty ast_ty) -> @ty.t {
                 case (ast.def_ty(?id)) {
                     sty = instantiate(getter, id, path.node.types).struct;
                 }
+                case (ast.def_native_ty(?id)) {
+                    sty = instantiate(getter, id, path.node.types).struct;
+                }
                 case (ast.def_obj(?id))     {
                     sty = instantiate(getter, id, path.node.types).struct;
                 }
@@ -181,7 +233,8 @@ fn ast_ty_to_ty(ty_getter getter, &@ast.ty ast_ty) -> @ty.t {
                 auto ins = _vec.map[ast.ty_arg, arg](f, m.inputs);
                 auto out = ast_ty_to_ty(getter, m.output);
                 append[ty.method](tmeths,
-                                  rec(ident=m.ident,
+                                  rec(proto=m.proto,
+                                      ident=m.ident,
                                       inputs=ins,
                                       output=out));
             }
@@ -192,23 +245,36 @@ fn ast_ty_to_ty(ty_getter getter, &@ast.ty ast_ty) -> @ty.t {
     ret @rec(struct=sty, mut=mut, cname=cname);
 }
 
+fn actual_type(@ty.t t, @ast.item item) -> @ty.t {
+    alt (item.node) {
+        case (ast.item_obj(_,_,_,_,_)) {
+            // An obj used as a type name refers to the output type of the
+            // item (constructor).
+            ret middle.ty.ty_fn_ret(t);
+        }
+        case (_) { }
+    }
+
+    ret t;
+}
+
 // A convenience function to use a crate_ctxt to resolve names for
 // ast_ty_to_ty.
 fn ast_ty_to_ty_crate(@crate_ctxt ccx, &@ast.ty ast_ty) -> @ty.t {
     fn getter(@crate_ctxt ccx, ast.def_id id) -> ty_and_params {
         check (ccx.item_items.contains_key(id));
         check (ccx.item_types.contains_key(id));
-        auto item = ccx.item_items.get(id);
+        auto it = ccx.item_items.get(id);
         auto ty = ccx.item_types.get(id);
-        auto params = ty_params_of_item(item);
-
-        alt (item.node) {
-            case (ast.item_obj(_,_,_,_,_)) {
-                // An obj used as a type name refers to the output type of the
-                // item (constructor).
-                ty = middle.ty.ty_fn_ret(ty);
+        auto params;
+        alt (it) {
+            case (any_item_rust(?item)) {
+                ty = actual_type(ty, item);
+                params = ty_params_of_item(item);
             }
-            case (_) { }
+            case (any_item_native(?native_item, _)) {
+                params = ty_params_of_native_item(native_item);
+           }
         }
 
         ret rec(params = params, ty = ty);
@@ -238,6 +304,18 @@ fn ty_params_of_item(@ast.item item) -> vec[ast.ty_param] {
     }
 }
 
+fn ty_params_of_native_item(@ast.native_item item) -> vec[ast.ty_param] {
+    alt (item.node) {
+        case (ast.native_item_fn(_, _, ?p, _, _)) {
+            ret p;
+        }
+        case (_) {
+            let vec[ast.ty_param] r = vec();
+            ret r;
+        }
+    }
+}
+
 // Item collection - a pair of bootstrap passes:
 //
 // 1. Collect the IDs of all type items (typedefs) and store them in a table.
@@ -249,6 +327,34 @@ fn ty_params_of_item(@ast.item item) -> vec[ast.ty_param] {
 // We then annotate the AST with the resulting types and return the annotated
 // AST, along with a table mapping item IDs to their types.
 
+fn ty_of_fn_decl(@ty_item_table id_to_ty_item,
+                 @ty_table item_to_ty,
+                 fn(&@ast.ty ast_ty) -> @ty.t convert,
+                 fn(&ast.arg a) -> arg ty_of_arg,
+                 &ast.fn_decl decl,
+                 ast.proto proto,
+                 ast.def_id def_id) -> @ty.t {
+    auto input_tys = _vec.map[ast.arg,arg](ty_of_arg, decl.inputs);
+    auto output_ty = convert(decl.output);
+    auto t_fn = plain_ty(ty.ty_fn(proto, input_tys, output_ty));
+    item_to_ty.insert(def_id, t_fn);
+    ret t_fn;
+}
+
+fn ty_of_native_fn_decl(@ty_item_table id_to_ty_item,
+                 @ty_table item_to_ty,
+                 fn(&@ast.ty ast_ty) -> @ty.t convert,
+                 fn(&ast.arg a) -> arg ty_of_arg,
+                 &ast.fn_decl decl,
+                 ast.native_abi abi,
+                 ast.def_id def_id) -> @ty.t {
+    auto input_tys = _vec.map[ast.arg,arg](ty_of_arg, decl.inputs);
+    auto output_ty = convert(decl.output);
+    auto t_fn = plain_ty(ty.ty_native_fn(abi, input_tys, output_ty));
+    item_to_ty.insert(def_id, t_fn);
+    ret t_fn;
+}
+
 fn collect_item_types(session.session sess, @ast.crate crate)
     -> tup(@ast.crate, @ty_table, @ty_item_table) {
 
@@ -256,17 +362,20 @@ fn collect_item_types(session.session sess, @ast.crate crate)
               @ty_table item_to_ty,
               ast.def_id id) -> ty_and_params {
         check (id_to_ty_item.contains_key(id));
-        auto item = id_to_ty_item.get(id);
-        auto ty = ty_of_item(id_to_ty_item, item_to_ty, item);
-        auto params = ty_params_of_item(item);
-
-        alt (item.node) {
-            case (ast.item_obj(_,_,_,_,_)) {
-                // An obj used as a type name refers to the output type of the
-                // item (constructor).
-                ty = middle.ty.ty_fn_ret(ty);
+        auto it = id_to_ty_item.get(id);
+        auto ty;
+        auto params;
+        alt (it) {
+            case (any_item_rust(?item)) {
+                ty = ty_of_item(id_to_ty_item, item_to_ty, item);
+                ty = actual_type(ty, item);
+                params = ty_params_of_item(item);
+            }
+            case (any_item_native(?native_item, ?abi)) {
+                ty = ty_of_native_item(id_to_ty_item, item_to_ty,
+                                       native_item, abi);
+                params = ty_params_of_native_item(native_item);
             }
-            case (_) { }
         }
 
         ret rec(params = params, ty = ty);
@@ -285,9 +394,10 @@ fn collect_item_types(session.session sess, @ast.crate crate)
         auto get = bind getter(id_to_ty_item, item_to_ty, _);
         auto convert = bind ast_ty_to_ty(get, _);
         auto f = bind ty_of_arg(id_to_ty_item, item_to_ty, _);
-        auto inputs = _vec.map[ast.arg,arg](f, m.node.meth.inputs);
-        auto output = convert(m.node.meth.output);
-        ret rec(ident=m.node.ident, inputs=inputs, output=output);
+        auto inputs = _vec.map[ast.arg,arg](f, m.node.meth.decl.inputs);
+        auto output = convert(m.node.meth.decl.output);
+        ret rec(proto=m.node.meth.proto, ident=m.node.ident,
+                inputs=inputs, output=output);
     }
 
     fn ty_of_obj(@ty_item_table id_to_ty_item,
@@ -318,7 +428,7 @@ fn collect_item_types(session.session sess, @ast.crate crate)
             auto t_field = ast_ty_to_ty(g, f.ty);
             append[arg](t_inputs, rec(mode=ast.alias, ty=t_field));
         }
-        auto t_fn = plain_ty(ty.ty_fn(t_inputs, t_obj));
+        auto t_fn = plain_ty(ty.ty_fn(ast.proto_fn, t_inputs, t_obj));
         ret t_fn;
     }
 
@@ -336,15 +446,9 @@ fn collect_item_types(session.session sess, @ast.crate crate)
             }
 
             case (ast.item_fn(?ident, ?fn_info, _, ?def_id, _)) {
-                // TODO: handle ty-params
-
                 auto f = bind ty_of_arg(id_to_ty_item, item_to_ty, _);
-                auto input_tys = _vec.map[ast.arg,arg](f, fn_info.inputs);
-                auto output_ty = convert(fn_info.output);
-
-                auto t_fn = plain_ty(ty.ty_fn(input_tys, output_ty));
-                item_to_ty.insert(def_id, t_fn);
-                ret t_fn;
+                ret ty_of_fn_decl(id_to_ty_item, item_to_ty, convert, f,
+                                  fn_info.decl, fn_info.proto, def_id);
             }
 
             case (ast.item_obj(?ident, ?obj_info, _, ?def_id, _)) {
@@ -369,28 +473,67 @@ fn collect_item_types(session.session sess, @ast.crate crate)
                 ret ty_;
             }
 
-            case (ast.item_tag(_, _, _, ?def_id)) {
-                auto t = plain_ty(ty.ty_tag(def_id));
+            case (ast.item_tag(_, _, ?tps, ?def_id)) {
+                // Create a new generic polytype.
+                let vec[@ty.t] subtys = vec();
+                for (ast.ty_param tp in tps) {
+                    subtys += vec(plain_ty(ty.ty_param(tp.id)));
+                }
+                auto t = plain_ty(ty.ty_tag(def_id, subtys));
                 item_to_ty.insert(def_id, t);
                 ret t;
             }
 
             case (ast.item_mod(_, _, _)) { fail; }
+            case (ast.item_native_mod(_, _, _)) { fail; }
+        }
+    }
+
+    fn ty_of_native_item(@ty_item_table id_to_ty_item,
+                         @ty_table item_to_ty,
+                         @ast.native_item it,
+                         ast.native_abi abi) -> @ty.t {
+        alt (it.node) {
+            case (ast.native_item_fn(?ident, ?fn_decl, ?params, ?def_id, _)) {
+                auto get = bind getter(id_to_ty_item, item_to_ty, _);
+                auto convert = bind ast_ty_to_ty(get, _);
+                auto f = bind ty_of_arg(id_to_ty_item, item_to_ty, _);
+                ret ty_of_native_fn_decl(id_to_ty_item, item_to_ty, convert,
+                                         f, fn_decl, abi, def_id);
+            }
+            case (ast.native_item_ty(_, ?def_id)) {
+                if (item_to_ty.contains_key(def_id)) {
+                    // Avoid repeating work.
+                    ret item_to_ty.get(def_id);
+                }
+                auto x =
+                    @rec(struct=ty.ty_native, mut=ast.imm, cname=none[str]);
+                item_to_ty.insert(def_id, x);
+                ret x;
+            }
         }
     }
 
     fn get_tag_variant_types(@ty_item_table id_to_ty_item,
                              @ty_table item_to_ty,
                              &ast.def_id tag_id,
-                             &vec[ast.variant] variants) -> vec[ast.variant] {
+                             &vec[ast.variant] variants,
+                             &vec[ast.ty_param] ty_params)
+            -> vec[ast.variant] {
         let vec[ast.variant] result = vec();
 
+        // Create a set of parameter types shared among all the variants.
+        let vec[@ty.t] ty_param_tys = vec();
+        for (ast.ty_param tp in ty_params) {
+            ty_param_tys += vec(plain_ty(ty.ty_param(tp.id)));
+        }
+
         for (ast.variant variant in variants) {
-            // Nullary tag constructors get truned into constants; n-ary tag
+            // Nullary tag constructors get turned into constants; n-ary tag
             // constructors get turned into functions.
             auto result_ty;
             if (_vec.len[ast.variant_arg](variant.args) == 0u) {
-                result_ty = plain_ty(ty.ty_tag(tag_id));
+                result_ty = plain_ty(ty.ty_tag(tag_id, ty_param_tys));
             } else {
                 // As above, tell ast_ty_to_ty() that trans_ty_item_to_ty()
                 // should be called to resolve named types.
@@ -401,8 +544,8 @@ fn collect_item_types(session.session sess, @ast.crate crate)
                     auto arg_ty = ast_ty_to_ty(f, va.ty);
                     args += vec(rec(mode=ast.alias, ty=arg_ty));
                 }
-                auto tag_t = plain_ty(ty.ty_tag(tag_id));
-                result_ty = plain_ty(ty.ty_fn(args, tag_t));
+                auto tag_t = plain_ty(ty.ty_tag(tag_id, ty_param_tys));
+                result_ty = plain_ty(ty.ty_fn(ast.proto_fn, args, tag_t));
             }
 
             item_to_ty.insert(variant.id, result_ty);
@@ -416,25 +559,40 @@ fn collect_item_types(session.session sess, @ast.crate crate)
 
     // First pass: collect all type item IDs.
     auto module = crate.node.module;
-    auto id_to_ty_item = @common.new_def_hash[@ast.item]();
+    auto id_to_ty_item = @common.new_def_hash[any_item]();
     fn collect(&@ty_item_table id_to_ty_item, @ast.item i)
         -> @ty_item_table {
         alt (i.node) {
             case (ast.item_ty(_, _, _, ?def_id, _)) {
-                id_to_ty_item.insert(def_id, i);
+                id_to_ty_item.insert(def_id, any_item_rust(i));
             }
             case (ast.item_tag(_, _, _, ?def_id)) {
-                id_to_ty_item.insert(def_id, i);
+                id_to_ty_item.insert(def_id, any_item_rust(i));
             }
             case (ast.item_obj(_, _, _, ?def_id, _)) {
-                id_to_ty_item.insert(def_id, i);
+                id_to_ty_item.insert(def_id, any_item_rust(i));
             }
             case (_) { /* empty */ }
         }
         ret id_to_ty_item;
     }
+    fn collect_native(&@ty_item_table id_to_ty_item, @ast.native_item i)
+        -> @ty_item_table {
+        alt (i.node) {
+            case (ast.native_item_ty(_, ?def_id)) {
+                // The abi of types is not used.
+                id_to_ty_item.insert(def_id,
+                                     any_item_native(i,
+                                                     ast.native_abi_cdecl));
+            }
+            case (_) {
+            }
+        }
+        ret id_to_ty_item;
+    }
     auto fld_1 = fold.new_identity_fold[@ty_item_table]();
-    fld_1 = @rec(update_env_for_item = bind collect(_, _)
+    fld_1 = @rec(update_env_for_item = bind collect(_, _),
+                 update_env_for_native_item = bind collect_native(_, _)
                  with *fld_1);
     fold.fold_crate[@ty_item_table](id_to_ty_item, fld_1, crate);
 
@@ -445,22 +603,34 @@ fn collect_item_types(session.session sess, @ast.crate crate)
 
     type env = rec(session.session sess,
                    @ty_item_table id_to_ty_item,
-                   @ty_table item_to_ty);
+                   @ty_table item_to_ty,
+                   ast.native_abi abi);
     let @env e = @rec(sess=sess,
                       id_to_ty_item=id_to_ty_item,
-                      item_to_ty=item_to_ty);
+                      item_to_ty=item_to_ty,
+                      abi=ast.native_abi_cdecl);
 
     fn convert(&@env e, @ast.item i) -> @env {
+        auto abi = e.abi;
         alt (i.node) {
             case (ast.item_mod(_, _, _)) {
                 // ignore item_mod, it has no type.
             }
+            case (ast.item_native_mod(_, ?native_mod, _)) {
+                // ignore item_native_mod, it has no type.
+                abi = native_mod.abi;
+            }
             case (_) {
                 // This call populates the ty_table with the converted type of
                 // the item in passing; we don't need to do anything else.
                 ty_of_item(e.id_to_ty_item, e.item_to_ty, i);
             }
         }
+        ret @rec(abi=abi with *e);
+    }
+
+    fn convert_native(&@env e, @ast.native_item i) -> @env {
+        ty_of_native_item(e.id_to_ty_item, e.item_to_ty, i, e.abi);
         ret e;
     }
 
@@ -484,9 +654,19 @@ fn collect_item_types(session.session sess, @ast.crate crate)
         ret @fold.respan[ast.item_](sp, item);
     }
 
+    fn fold_native_item_fn(&@env e, &span sp, ast.ident i,
+                           &ast.fn_decl d, vec[ast.ty_param] ty_params,
+                           ast.def_id id, ast.ann a) -> @ast.native_item {
+        check (e.item_to_ty.contains_key(id));
+        auto ty = e.item_to_ty.get(id);
+        auto item = ast.native_item_fn(i, d, ty_params, id,
+                                       ast.ann_type(ty));
+        ret @fold.respan[ast.native_item_](sp, item);
+    }
+
     fn get_ctor_obj_methods(@ty.t t) -> vec[method] {
         alt (t.struct) {
-            case (ty.ty_fn(_,?tobj)) {
+            case (ty.ty_fn(_,_,?tobj)) {
                 alt (tobj.struct) {
                     case (ty.ty_obj(?tm)) {
                         ret tm;
@@ -521,7 +701,8 @@ fn collect_item_types(session.session sess, @ast.crate crate)
             let method meth_ty = meth_tys.(ix);
             let ast.method_ m_;
             let @ast.method m;
-            auto meth_tfn = plain_ty(ty.ty_fn(meth_ty.inputs,
+            auto meth_tfn = plain_ty(ty.ty_fn(meth_ty.proto,
+                                              meth_ty.inputs,
                                               meth_ty.output));
             m_ = rec(ann=ast.ann_type(meth_tfn) with meth.node);
             m = @rec(node=m_ with *meth);
@@ -558,7 +739,9 @@ fn collect_item_types(session.session sess, @ast.crate crate)
                      ast.def_id id) -> @ast.item {
         auto variants_t = get_tag_variant_types(e.id_to_ty_item,
                                                 e.item_to_ty,
-                                                id, variants);
+                                                id,
+                                                variants,
+                                                ty_params);
         auto item = ast.item_tag(i, variants_t, ty_params, id);
         ret @fold.respan[ast.item_](sp, item);
     }
@@ -566,8 +749,10 @@ fn collect_item_types(session.session sess, @ast.crate crate)
     auto fld_2 = fold.new_identity_fold[@env]();
     fld_2 =
         @rec(update_env_for_item = bind convert(_,_),
+             update_env_for_native_item = bind convert_native(_,_),
              fold_item_const = bind fold_item_const(_,_,_,_,_,_,_),
              fold_item_fn    = bind fold_item_fn(_,_,_,_,_,_,_),
+             fold_native_item_fn = bind fold_native_item_fn(_,_,_,_,_,_,_),
              fold_item_obj   = bind fold_item_obj(_,_,_,_,_,_,_),
              fold_item_ty    = bind fold_item_ty(_,_,_,_,_,_,_),
              fold_item_tag   = bind fold_item_tag(_,_,_,_,_,_)
@@ -705,13 +890,17 @@ fn are_compatible(&@fn_ctxt fcx, @ty.t expected, @ty.t actual) -> bool {
 // TODO: enforce this via a predicate.
 
 fn demand_pat(&@fn_ctxt fcx, @ty.t expected, @ast.pat pat) -> @ast.pat {
-    auto p_1 = ast.pat_wild(ast.ann_none);  // FIXME: typestate botch
+    auto p_1;
 
     alt (pat.node) {
         case (ast.pat_wild(?ann)) {
             auto t = demand(fcx, pat.span, expected, ann_to_type(ann));
             p_1 = ast.pat_wild(ast.ann_type(t));
         }
+        case (ast.pat_lit(?lit, ?ann)) {
+            auto t = demand(fcx, pat.span, expected, ann_to_type(ann));
+            p_1 = ast.pat_lit(lit, ast.ann_type(t));
+        }
         case (ast.pat_bind(?id, ?did, ?ann)) {
             auto t = demand(fcx, pat.span, expected, ann_to_type(ann));
             fcx.locals.insert(did, t);
@@ -735,12 +924,12 @@ fn demand_pat(&@fn_ctxt fcx, @ty.t expected, @ast.pat pat) -> @ast.pat {
 
             auto subpats_len = _vec.len[@ast.pat](subpats);
             alt (variant_ty.struct) {
-                case (ty.ty_tag(_)) {
+                case (ty.ty_tag(_, _)) {
                     // Nullary tag variant.
                     check (subpats_len == 0u);
                     p_1 = ast.pat_tag(id, subpats, vdef_opt, ast.ann_type(t));
                 }
-                case (ty.ty_fn(?args, ?tag_ty)) {
+                case (ty.ty_fn(_, ?args, ?tag_ty)) {
                     let vec[@ast.pat] new_subpats = vec();
                     auto i = 0u;
                     for (arg a in args) {
@@ -771,9 +960,7 @@ fn demand_expr(&@fn_ctxt fcx, @ty.t expected, @ast.expr e) -> @ast.expr {
 
 fn demand_expr_full(&@fn_ctxt fcx, @ty.t expected, @ast.expr e,
                     autoderef_kind adk) -> @ast.expr {
-    // FIXME: botch to work around typestate bug in rustboot
-    let vec[@ast.expr] v = vec();
-    auto e_1 = ast.expr_vec(v, ast.ann_none);
+    auto e_1;
 
     alt (e.node) {
         case (ast.expr_vec(?es_0, ?ann)) {
@@ -811,20 +998,50 @@ fn demand_expr_full(&@fn_ctxt fcx, @ty.t expected, @ast.expr e,
             }
             e_1 = ast.expr_tup(elts_1, ast.ann_type(t));
         }
-        case (ast.expr_rec(?fields_0, ?ann)) {
+        case (ast.expr_rec(?fields_0, ?base_0, ?ann)) {
+
+            auto base_1 = base_0;
+
             auto t = demand(fcx, e.span, expected, ann_to_type(ann));
             let vec[ast.field] fields_1 = vec();
             alt (t.struct) {
                 case (ty.ty_rec(?field_tys)) {
-                    auto i = 0u;
-                    for (ast.field field_0 in fields_0) {
-                        check (_str.eq(field_0.ident, field_tys.(i).ident));
-                        auto e_1 = demand_expr(fcx, field_tys.(i).ty,
-                                               field_0.expr);
-                        fields_1 += vec(rec(mut=field_0.mut,
-                                            ident=field_0.ident,
-                                            expr=e_1));
-                        i += 1u;
+                    alt (base_0) {
+                        case (none[@ast.expr]) {
+                            auto i = 0u;
+                            for (ast.field field_0 in fields_0) {
+                                check (_str.eq(field_0.ident,
+                                               field_tys.(i).ident));
+                                auto e_1 = demand_expr(fcx,
+                                                       field_tys.(i).ty,
+                                                       field_0.expr);
+                                fields_1 += vec(rec(mut=field_0.mut,
+                                                    ident=field_0.ident,
+                                                    expr=e_1));
+                                i += 1u;
+                            }
+                        }
+                        case (some[@ast.expr](?bx)) {
+
+                            base_1 =
+                                some[@ast.expr](demand_expr(fcx, t, bx));
+
+                            let vec[field] base_fields = vec();
+
+                            for (ast.field field_0 in fields_0) {
+
+                                for (ty.field ft in field_tys) {
+                                    if (_str.eq(field_0.ident, ft.ident)) {
+                                        auto e_1 = demand_expr(fcx, ft.ty,
+                                                               field_0.expr);
+                                        fields_1 +=
+                                            vec(rec(mut=field_0.mut,
+                                                    ident=field_0.ident,
+                                                    expr=e_1));
+                                    }
+                                }
+                            }
+                        }
                     }
                 }
                 case (_) {
@@ -832,7 +1049,7 @@ fn demand_expr_full(&@fn_ctxt fcx, @ty.t expected, @ast.expr e,
                     fail;
                 }
             }
-            e_1 = ast.expr_rec(fields_1, ast.ann_type(t));
+            e_1 = ast.expr_rec(fields_1, base_1, ast.ann_type(t));
         }
         case (ast.expr_bind(?sube, ?es, ?ann)) {
             auto t = demand(fcx, e.span, expected, ann_to_type(ann));
@@ -868,6 +1085,7 @@ fn demand_expr_full(&@fn_ctxt fcx, @ty.t expected, @ast.expr e,
             auto t = demand_full(fcx, e.span, expected,
                                  ann_to_type(ann), adk);
             auto then_1 = demand_block(fcx, expected, then_0);
+
             auto else_1;
             alt (else_0) {
                 case (none[@ast.expr]) { else_1 = none[@ast.expr]; }
@@ -882,6 +1100,10 @@ fn demand_expr_full(&@fn_ctxt fcx, @ty.t expected, @ast.expr e,
             auto t = demand(fcx, e.span, expected, ann_to_type(ann));
             e_1 = ast.expr_for(decl, seq, bloc, ast.ann_type(t));
         }
+        case (ast.expr_for_each(?decl, ?seq, ?bloc, ?ann)) {
+            auto t = demand(fcx, e.span, expected, ann_to_type(ann));
+            e_1 = ast.expr_for_each(decl, seq, bloc, ast.ann_type(t));
+        }
         case (ast.expr_while(?cond, ?bloc, ?ann)) {
             auto t = demand(fcx, e.span, expected, ann_to_type(ann));
             e_1 = ast.expr_while(cond, bloc, ast.ann_type(t));
@@ -924,6 +1146,21 @@ fn demand_expr_full(&@fn_ctxt fcx, @ty.t expected, @ast.expr e,
                                  ann_to_type(ann), adk);
             e_1 = ast.expr_path(pth, d, ast.ann_type(t));
         }
+        case (ast.expr_ext(?p, ?args, ?body, ?expanded, ?ann)) {
+            auto t = demand_full(fcx, e.span, expected,
+                                 ann_to_type(ann), adk);
+            e_1 = ast.expr_ext(p, args, body, expanded, ast.ann_type(t));
+        }
+        case (ast.expr_fail) { e_1 = e.node; }
+        case (ast.expr_log(_)) { e_1 = e.node; }
+        case (ast.expr_ret(_)) { e_1 = e.node; }
+        case (ast.expr_put(_)) { e_1 = e.node; }
+        case (ast.expr_be(_)) { e_1 = e.node; }
+        case (ast.expr_check_expr(_)) { e_1 = e.node; }
+        case (_) {
+            fcx.ccx.sess.unimpl("type unification for expression variant");
+            fail;
+        }
     }
 
     ret @fold.respan[ast.expr_](e.span, e_1);
@@ -989,6 +1226,9 @@ fn check_pat(&@fn_ctxt fcx, @ast.pat pat) -> @ast.pat {
         case (ast.pat_wild(_)) {
             new_pat = ast.pat_wild(ast.ann_type(next_ty_var(fcx.ccx)));
         }
+        case (ast.pat_lit(?lt, _)) {
+            new_pat = ast.pat_lit(lt, ast.ann_type(check_lit(lt)));
+        }
         case (ast.pat_bind(?id, ?def_id, _)) {
             auto ann = ast.ann_type(next_ty_var(fcx.ccx));
             new_pat = ast.pat_bind(id, def_id, ann);
@@ -1000,7 +1240,7 @@ fn check_pat(&@fn_ctxt fcx, @ast.pat pat) -> @ast.pat {
             auto last_id = p.node.idents.(len - 1u);
             alt (t.struct) {
                 // N-ary variants have function types.
-                case (ty.ty_fn(?args, ?tag_ty)) {
+                case (ty.ty_fn(_, ?args, ?tag_ty)) {
                     auto arg_len = _vec.len[arg](args);
                     auto subpats_len = _vec.len[@ast.pat](subpats);
                     if (arg_len != subpats_len) {
@@ -1024,7 +1264,9 @@ fn check_pat(&@fn_ctxt fcx, @ast.pat pat) -> @ast.pat {
                 }
 
                 // Nullary variants have tag types.
-                case (ty.ty_tag(?tid)) {
+                case (ty.ty_tag(?tid, _)) {
+                    // TODO: ty params
+
                     auto subpats_len = _vec.len[@ast.pat](subpats);
                     if (subpats_len > 0u) {
                         // TODO: pluralize properly
@@ -1038,7 +1280,8 @@ fn check_pat(&@fn_ctxt fcx, @ast.pat pat) -> @ast.pat {
                         fail;   // TODO: recover
                     }
 
-                    auto ann = ast.ann_type(plain_ty(ty.ty_tag(tid)));
+                    let vec[@ty.t] tys = vec(); // FIXME
+                    auto ann = ast.ann_type(plain_ty(ty.ty_tag(tid, tys)));
                     new_pat = ast.pat_tag(p, subpats, vdef_opt, ann);
                 }
             }
@@ -1049,6 +1292,90 @@ fn check_pat(&@fn_ctxt fcx, @ast.pat pat) -> @ast.pat {
 }
 
 fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
+    // A generic function to factor out common logic from call and bind
+    // expressions.
+    fn check_call_or_bind(&@fn_ctxt fcx, &@ast.expr f,
+                          &vec[option.t[@ast.expr]] args)
+            -> tup(@ast.expr, vec[option.t[@ast.expr]]) {
+
+        // Check the function.
+        auto f_0 = check_expr(fcx, f);
+
+        // Check the arguments and generate the argument signature.
+        let vec[option.t[@ast.expr]] args_0 = vec();
+        let vec[arg] arg_tys_0 = vec();
+        for (option.t[@ast.expr] a_opt in args) {
+            alt (a_opt) {
+                case (some[@ast.expr](?a)) {
+                    auto a_0 = check_expr(fcx, a);
+                    args_0 += vec(some[@ast.expr](a_0));
+
+                    // FIXME: this breaks aliases. We need a ty_fn_arg.
+                    auto arg_ty = rec(mode=ast.val, ty=expr_ty(a_0));
+                    append[arg](arg_tys_0, arg_ty);
+                }
+                case (none[@ast.expr]) {
+                    args_0 += vec(none[@ast.expr]);
+
+                    // FIXME: breaks aliases too?
+                    auto typ = next_ty_var(fcx.ccx);
+                    append[arg](arg_tys_0, rec(mode=ast.val, ty=typ));
+                }
+            }
+        }
+
+        auto rt_0 = next_ty_var(fcx.ccx);
+        auto t_0;
+        alt (expr_ty(f_0).struct) {
+            case (ty.ty_fn(?proto, _, _))   {
+                t_0 = plain_ty(ty.ty_fn(proto, arg_tys_0, rt_0));
+            }
+            case (ty.ty_native_fn(?abi, _, _))   {
+                t_0 = plain_ty(ty.ty_native_fn(abi, arg_tys_0, rt_0));
+            }
+            case (_) {
+                log "check_call_or_bind(): fn expr doesn't have fn type";
+                fail;
+            }
+        }
+
+        // Unify and write back to the function.
+        auto f_1 = demand_expr(fcx, t_0, f_0);
+
+        // Take the argument types out of the resulting function type.
+        auto t_1 = expr_ty(f_1);
+
+        if (!ty.is_fn_ty(t_1)) {
+            fcx.ccx.sess.span_err(f_1.span,
+                                  "mismatched types: callee has " +
+                                  "non-function type: " +
+                                  ty_to_str(t_1));
+        }
+
+        let vec[arg] arg_tys_1 = ty.ty_fn_args(t_1);
+        let @ty.t rt_1 = ty.ty_fn_ret(t_1);
+
+        // Unify and write back to the arguments.
+        auto i = 0u;
+        let vec[option.t[@ast.expr]] args_1 = vec();
+        while (i < _vec.len[option.t[@ast.expr]](args_0)) {
+            alt (args_0.(i)) {
+                case (some[@ast.expr](?e_0)) {
+                    auto arg_ty_1 = arg_tys_1.(i);
+                    auto e_1 = demand_expr(fcx, arg_ty_1.ty, e_0);
+                    append[option.t[@ast.expr]](args_1, some[@ast.expr](e_1));
+                }
+                case (none[@ast.expr]) {
+                    append[option.t[@ast.expr]](args_1, none[@ast.expr]);
+                }
+            }
+
+            i += 1u;
+        }
+
+        ret tup(f_1, args_1);
+    }
+
     alt (expr.node) {
         case (ast.expr_lit(?lit, _)) {
             auto ty = check_lit(lit);
@@ -1103,6 +1430,9 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                         }
                     }
                 }
+                case (ast._mutable) {
+                    oper_t = @rec(mut=ast.mut with *oper_t);
+                }
                 case (_) { oper_t = strip_boxes(oper_t); }
             }
             ret @fold.respan[ast.expr_](expr.span,
@@ -1132,13 +1462,18 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                     check (fcx.ccx.item_types.contains_key(id));
                     t = generalize_ty(fcx.ccx, fcx.ccx.item_types.get(id));
                 }
+                case (ast.def_native_fn(?id)) {
+                    check (fcx.ccx.item_types.contains_key(id));
+                    t = generalize_ty(fcx.ccx, fcx.ccx.item_types.get(id));
+                }
                 case (ast.def_const(?id)) {
                     check (fcx.ccx.item_types.contains_key(id));
                     t = fcx.ccx.item_types.get(id);
                 }
                 case (ast.def_variant(_, ?variant_id)) {
                     check (fcx.ccx.item_types.contains_key(variant_id));
-                    t = fcx.ccx.item_types.get(variant_id);
+                    t = generalize_ty(fcx.ccx,
+                                      fcx.ccx.item_types.get(variant_id));
                 }
                 case (ast.def_binding(?id)) {
                     check (fcx.locals.contains_key(id));
@@ -1161,11 +1496,92 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                 }
             }
 
+            // Substitute type parameters if the user provided some.
+            if (_vec.len[@ast.ty](pth.node.types) > 0u) {
+                t = substitute_ty_params(fcx.ccx, t, pth.node.types,
+                                         expr.span);
+            }
+
             ret @fold.respan[ast.expr_](expr.span,
                                         ast.expr_path(pth, defopt,
                                                       ast.ann_type(t)));
         }
 
+        case (ast.expr_ext(?p, ?args, ?body, ?expanded, _)) {
+            auto exp_ = check_expr(fcx, expanded);
+            auto t = expr_ty(exp_);
+            ret @fold.respan[ast.expr_](expr.span,
+                                        ast.expr_ext(p, args, body, exp_,
+                                                     ast.ann_type(t)));
+        }
+
+        case (ast.expr_fail) {
+            ret expr;
+        }
+
+        case (ast.expr_ret(?expr_opt)) {
+            alt (expr_opt) {
+                case (none[@ast.expr]) {
+                    auto nil = plain_ty(ty.ty_nil);
+                    if (!are_compatible(fcx, fcx.ret_ty, nil)) {
+                        fcx.ccx.sess.err("ret; in function "
+                                         + "returning non-nil");
+                    }
+
+                    ret expr;
+                }
+
+                case (some[@ast.expr](?e)) {
+                    auto expr_0 = check_expr(fcx, e);
+                    auto expr_1 = demand_expr(fcx, fcx.ret_ty, expr_0);
+                    ret @fold.respan[ast.expr_](expr.span,
+                                                ast.expr_ret(some(expr_1)));
+                }
+            }
+        }
+
+        case (ast.expr_put(?expr_opt)) {
+            alt (expr_opt) {
+                case (none[@ast.expr]) {
+                    auto nil = plain_ty(ty.ty_nil);
+                    if (!are_compatible(fcx, fcx.ret_ty, nil)) {
+                        fcx.ccx.sess.err("put; in function "
+                                         + "putting non-nil");
+                    }
+
+                    ret expr;
+                }
+
+                case (some[@ast.expr](?e)) {
+                    auto expr_0 = check_expr(fcx, e);
+                    auto expr_1 = demand_expr(fcx, fcx.ret_ty, expr_0);
+                    ret @fold.respan[ast.expr_](expr.span,
+                                                ast.expr_put(some(expr_1)));
+                }
+            }
+        }
+
+        case (ast.expr_be(?e)) {
+            /* FIXME: prove instead of check */
+            check (ast.is_call_expr(e));
+            auto expr_0 = check_expr(fcx, e);
+            auto expr_1 = demand_expr(fcx, fcx.ret_ty, expr_0);
+            ret @fold.respan[ast.expr_](expr.span,
+                                        ast.expr_be(expr_1));
+        }
+
+        case (ast.expr_log(?e)) {
+            auto expr_t = check_expr(fcx, e);
+            ret @fold.respan[ast.expr_](expr.span, ast.expr_log(expr_t));
+        }
+
+        case (ast.expr_check_expr(?e)) {
+            auto expr_t = check_expr(fcx, e);
+            demand(fcx, expr.span, plain_ty(ty.ty_bool), expr_ty(expr_t));
+            ret @fold.respan[ast.expr_](expr.span,
+                                        ast.expr_check_expr(expr_t));
+        }
+
         case (ast.expr_assign(?lhs, ?rhs, _)) {
             auto lhs_0 = check_expr(fcx, lhs);
             auto rhs_0 = check_expr(fcx, rhs);
@@ -1238,6 +1654,17 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                                                      body_1, ann));
         }
 
+        case (ast.expr_for_each(?decl, ?seq, ?body, _)) {
+            auto decl_1 = check_decl_local(fcx, decl);
+            auto seq_1 = check_expr(fcx, seq);
+            auto body_1 = check_block(fcx, body);
+
+            auto ann = ast.ann_type(plain_ty(ty.ty_nil));
+            ret @fold.respan[ast.expr_](expr.span,
+                                        ast.expr_for_each(decl_1, seq_1,
+                                                          body_1, ann));
+        }
+
         case (ast.expr_while(?cond, ?body, _)) {
             auto cond_0 = check_expr(fcx, cond);
             auto cond_1 = demand_expr(fcx, plain_ty(ty.ty_bool), cond_0);
@@ -1324,96 +1751,71 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
         }
 
         case (ast.expr_bind(?f, ?args, _)) {
-            auto f_0 = check_expr(fcx, f);
-            auto t_0 = expr_ty(f_0);
-
-            if (!ty.is_fn_ty(t_0)) {
-                fcx.ccx.sess.span_err(f_0.span,
-                                      "mismatched types: bind callee has " +
-                                      "non-function type: " +
-                                      ty_to_str(t_0));
-            }
-
-            let vec[arg] arg_tys_0 = ty.ty_fn_args(t_0);
-            let @ty.t rt_0 = ty.ty_fn_ret(t_0);
-            let vec[option.t[@ast.expr]] args_1 = vec();
-
-            let uint i = 0u;
-
-            let vec[arg] residual_args = vec();
-            for (option.t[@ast.expr] a in args) {
-                alt (a) {
-                    case (none[@ast.expr]) {
-                        append[arg](residual_args,
-                                    arg_tys_0.(i));
-                        append[option.t[@ast.expr]](args_1,
-                                                    none[@ast.expr]);
-                    }
-                    case (some[@ast.expr](?sa)) {
-                        auto arg_1 = check_expr(fcx, sa);
-                        auto arg_t = expr_ty(arg_1);
-                        demand_expr(fcx, arg_tys_0.(i).ty, arg_1);
-                        append[option.t[@ast.expr]](args_1,
-                                                    some[@ast.expr](arg_1));
+            // Call the generic checker.
+            auto result = check_call_or_bind(fcx, f, args);
+
+            // Pull the argument and return types out.
+            auto proto_1;
+            let vec[ty.arg] arg_tys_1 = vec();
+            auto rt_1;
+            alt (expr_ty(result._0).struct) {
+                case (ty.ty_fn(?proto, ?arg_tys, ?rt)) {
+                    proto_1 = proto;
+                    rt_1 = rt;
+
+                    // For each blank argument, add the type of that argument
+                    // to the resulting function type.
+                    auto i = 0u;
+                    while (i < _vec.len[option.t[@ast.expr]](args)) {
+                        alt (args.(i)) {
+                            case (some[@ast.expr](_)) { /* no-op */ }
+                            case (none[@ast.expr]) {
+                                arg_tys_1 += vec(arg_tys.(i));
+                            }
+                        }
+                        i += 1u;
                     }
                 }
-                i += 1u;
+                case (_) {
+                    log "LHS of bind expr didn't have a function type?!";
+                    fail;
+                }
             }
 
-            let @ty.t t_1 = plain_ty(ty.ty_fn(residual_args, rt_0));
+            auto t_1 = plain_ty(ty.ty_fn(proto_1, arg_tys_1, rt_1));
             ret @fold.respan[ast.expr_](expr.span,
-                                        ast.expr_bind(f_0, args_1,
+                                        ast.expr_bind(result._0, result._1,
                                                       ast.ann_type(t_1)));
-
         }
 
         case (ast.expr_call(?f, ?args, _)) {
-
-            // Check the function.
-            auto f_0 = check_expr(fcx, f);
-
-            // Check the arguments and generate the argument signature.
-            let vec[@ast.expr] args_0 = vec();
-            let vec[arg] arg_tys_0 = vec();
-            for (@ast.expr a in args) {
-                auto a_0 = check_expr(fcx, a);
-                append[@ast.expr](args_0, a_0);
-
-                // FIXME: this breaks aliases. We need a ty_fn_arg.
-                append[arg](arg_tys_0, rec(mode=ast.val, ty=expr_ty(a_0)));
+            let vec[option.t[@ast.expr]] args_opt_0 = vec();
+            for (@ast.expr arg in args) {
+                args_opt_0 += vec(some[@ast.expr](arg));
             }
-            auto rt_0 = next_ty_var(fcx.ccx);
-            auto t_0 = plain_ty(ty.ty_fn(arg_tys_0, rt_0));
-
-            // Unify and write back to the function.
-            auto f_1 = demand_expr(fcx, t_0, f_0);
 
-            // Take the argument types out of the resulting function type.
-            auto t_1 = expr_ty(f_1);
+            // Call the generic checker.
+            auto result = check_call_or_bind(fcx, f, args_opt_0);
 
-            if (!ty.is_fn_ty(t_1)) {
-                fcx.ccx.sess.span_err(f_1.span,
-                                      "mismatched types: callee has " +
-                                      "non-function type: " +
-                                      ty_to_str(t_1));
-            }
-
-            let vec[arg] arg_tys_1 = ty.ty_fn_args(t_1);
-            let @ty.t rt_1 = ty.ty_fn_ret(t_1);
-
-            // Unify and write back to the arguments.
-            auto i = 0u;
+            // Pull out the arguments.
             let vec[@ast.expr] args_1 = vec();
-            while (i < _vec.len[@ast.expr](args_0)) {
-                auto arg_ty_1 = arg_tys_1.(i);
-                auto e = demand_expr(fcx, arg_ty_1.ty, args_0.(i));
-                append[@ast.expr](args_1, e);
+            for (option.t[@ast.expr] arg in result._1) {
+                args_1 += vec(option.get[@ast.expr](arg));
+            }
 
-                i += 1u;
+            // Pull the return type out of the type of the function.
+            auto rt_1 = plain_ty(ty.ty_nil);    // FIXME: typestate botch
+            alt (expr_ty(result._0).struct) {
+                case (ty.ty_fn(_,_,?rt))    { rt_1 = rt; }
+                case (ty.ty_native_fn(_, _, ?rt))    { rt_1 = rt; }
+                case (_) {
+                    log "LHS of call expr didn't have a function type?!";
+                    fail;
+                }
             }
 
             ret @fold.respan[ast.expr_](expr.span,
-                                        ast.expr_call(f_1, args_1,
+                                        ast.expr_call(result._0, args_1,
                                                       ast.ann_type(rt_1)));
         }
 
@@ -1478,7 +1880,10 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                                         ast.expr_tup(elts_1, ann));
         }
 
-        case (ast.expr_rec(?fields, _)) {
+        case (ast.expr_rec(?fields, ?base, _)) {
+
+            auto base_1 = base;
+
             let vec[ast.field] fields_1 = vec();
             let vec[field] fields_t = vec();
 
@@ -1492,9 +1897,52 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                 append[field](fields_t, rec(ident=f.ident, ty=expr_t));
             }
 
-            auto ann = ast.ann_type(plain_ty(ty.ty_rec(fields_t)));
+            auto ann = ast.ann_none;
+
+            alt (base) {
+                case (none[@ast.expr]) {
+                    ann = ast.ann_type(plain_ty(ty.ty_rec(fields_t)));
+                }
+
+                case (some[@ast.expr](?bexpr)) {
+                    auto bexpr_1 = check_expr(fcx, bexpr);
+                    auto bexpr_t = expr_ty(bexpr_1);
+
+                    let vec[field] base_fields = vec();
+
+                    alt (bexpr_t.struct) {
+                        case (ty.ty_rec(?flds)) {
+                            base_fields = flds;
+                        }
+                        case (_) {
+                            fcx.ccx.sess.span_err
+                                (expr.span,
+                                 "record update non-record base");
+                        }
+                    }
+
+                    ann = ast.ann_type(bexpr_t);
+
+                    for (ty.field f in fields_t) {
+                        auto found = false;
+                        for (ty.field bf in base_fields) {
+                            if (_str.eq(f.ident, bf.ident)) {
+                                demand(fcx, expr.span, f.ty, bf.ty);
+                                found = true;
+                            }
+                        }
+                        if (!found) {
+                            fcx.ccx.sess.span_err
+                                (expr.span,
+                                 "unknown field in record update: "
+                                 + f.ident);
+                        }
+                    }
+                }
+            }
+
             ret @fold.respan[ast.expr_](expr.span,
-                                        ast.expr_rec(fields_1, ann));
+                                        ast.expr_rec(fields_1, base_1, ann));
         }
 
         case (ast.expr_field(?base, ?field, _)) {
@@ -1537,7 +1985,8 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                                               "bad index on obj");
                     }
                     auto meth = methods.(ix);
-                    auto t = plain_ty(ty.ty_fn(meth.inputs, meth.output));
+                    auto t = plain_ty(ty.ty_fn(meth.proto,
+                                               meth.inputs, meth.output));
                     auto ann = ast.ann_type(t);
                     ret @fold.respan[ast.expr_](expr.span,
                                                 ast.expr_field(base_1,
@@ -1664,43 +2113,6 @@ fn check_stmt(&@fn_ctxt fcx, &@ast.stmt stmt) -> @ast.stmt {
             ret stmt;
         }
 
-        case (ast.stmt_ret(?expr_opt)) {
-            alt (expr_opt) {
-                case (none[@ast.expr]) {
-                    auto nil = plain_ty(ty.ty_nil);
-                    if (!are_compatible(fcx, fcx.ret_ty, nil)) {
-                        fcx.ccx.sess.err("ret; in function "
-                                         + "returning non-nil");
-                    }
-
-                    ret stmt;
-                }
-
-                case (some[@ast.expr](?expr)) {
-                    auto expr_0 = check_expr(fcx, expr);
-                    auto expr_1 = demand_expr(fcx, fcx.ret_ty, expr_0);
-                    ret @fold.respan[ast.stmt_](stmt.span,
-                                                ast.stmt_ret(some(expr_1)));
-                }
-            }
-        }
-
-        case (ast.stmt_log(?expr)) {
-            auto expr_t = check_expr(fcx, expr);
-            ret @fold.respan[ast.stmt_](stmt.span, ast.stmt_log(expr_t));
-        }
-
-        case (ast.stmt_check_expr(?expr)) {
-            auto expr_t = check_expr(fcx, expr);
-            demand(fcx, expr.span, plain_ty(ty.ty_bool), expr_ty(expr_t));
-            ret @fold.respan[ast.stmt_](stmt.span,
-                                        ast.stmt_check_expr(expr_t));
-        }
-
-        case (ast.stmt_fail) {
-            ret stmt;
-        }
-
         case (ast.stmt_expr(?expr)) {
             auto expr_t = check_expr(fcx, expr);
             ret @fold.respan[ast.stmt_](stmt.span, ast.stmt_expr(expr_t));
@@ -1744,9 +2156,8 @@ fn check_const(&@crate_ctxt ccx, &span sp, ast.ident ident, @ast.ty t,
     ret @fold.respan[ast.item_](sp, item);
 }
 
-fn check_fn(&@crate_ctxt ccx, ast.effect effect,
-            bool is_iter, vec[ast.arg] inputs,
-            @ast.ty output, &ast.block body) -> ast._fn {
+fn check_fn(&@crate_ctxt ccx, &ast.fn_decl decl, ast.proto proto,
+            &ast.block body) -> ast._fn {
     auto local_ty_table = @common.new_def_hash[@ty.t]();
 
     // FIXME: duplicate work: the item annotation already has the arg types
@@ -1760,12 +2171,12 @@ fn check_fn(&@crate_ctxt ccx, ast.effect effect,
     }
 
     // Store the type of each argument in the table.
-    for (ast.arg arg in inputs) {
+    for (ast.arg arg in decl.inputs) {
         auto input_ty = ast_ty_to_ty_crate(ccx, arg.ty);
         local_ty_table.insert(arg.id, input_ty);
     }
 
-    let @fn_ctxt fcx = @rec(ret_ty = ast_ty_to_ty_crate(ccx, output),
+    let @fn_ctxt fcx = @rec(ret_ty = ast_ty_to_ty_crate(ccx, decl.output),
                             locals = local_ty_table,
                             ccx = ccx);
 
@@ -1773,8 +2184,9 @@ fn check_fn(&@crate_ctxt ccx, ast.effect effect,
     auto block_t = check_block(fcx, body);
     auto block_wb = writeback(fcx, block_t);
 
-    auto fn_t = rec(effect=effect, is_iter=is_iter,
-                    inputs=inputs, output=output, body=block_wb);
+    auto fn_t = rec(decl=decl,
+                    proto=proto,
+                    body=block_wb);
     ret fn_t;
 }
 
@@ -1787,13 +2199,13 @@ fn check_item_fn(&@crate_ctxt ccx, &span sp, ast.ident ident, &ast._fn f,
     // again here, we can extract them.
 
     let vec[arg] inputs = vec();
-    for (ast.arg arg in f.inputs) {
+    for (ast.arg arg in f.decl.inputs) {
         auto input_ty = ast_ty_to_ty_crate(ccx, arg.ty);
         inputs += vec(rec(mode=arg.mode, ty=input_ty));
     }
 
-    auto output_ty = ast_ty_to_ty_crate(ccx, f.output);
-    auto fn_sty = ty.ty_fn(inputs, output_ty);
+    auto output_ty = ast_ty_to_ty_crate(ccx, f.decl.output);
+    auto fn_sty = ty.ty_fn(f.proto, inputs, output_ty);
     auto fn_ann = ast.ann_type(plain_ty(fn_sty));
 
     auto item = ast.item_fn(ident, f, ty_params, id, fn_ann);
@@ -1825,7 +2237,7 @@ fn check_crate(session.session sess, @ast.crate crate) -> @ast.crate {
     auto fld = fold.new_identity_fold[@crate_ctxt]();
 
     fld = @rec(update_env_for_item = bind update_obj_fields(_, _),
-               fold_fn      = bind check_fn(_,_,_,_,_,_),
+               fold_fn      = bind check_fn(_,_,_,_),
                fold_item_fn = bind check_item_fn(_,_,_,_,_,_,_)
                with *fld);
     ret fold.fold_crate[@crate_ctxt](ccx, fld, result._0);
diff --git a/src/comp/pretty/pp.rs b/src/comp/pretty/pp.rs
new file mode 100644
index 00000000000..43a9220f4e5
--- /dev/null
+++ b/src/comp/pretty/pp.rs
@@ -0,0 +1,207 @@
+import std.io;
+import std._vec;
+import std._str;
+
+tag boxtype {box_h; box_v; box_hv; box_align;}
+tag contexttype {cx_h; cx_v;}
+
+tag token {
+  brk(uint);
+  word(str);
+  cword(str); // closing token
+  open(boxtype, uint);
+  close;
+}
+
+type context = rec(contexttype tp, uint indent);
+
+type ps = @rec(mutable vec[context] context,
+               uint width,
+               mutable vec[token] buffered,
+               mutable uint scandepth,
+               mutable uint bufferedcol,
+               mutable uint col,
+               mutable bool start_of_line);
+
+fn mkstate(uint width) -> ps {
+  let vec[context] stack = vec(rec(tp=cx_v, indent=0u));
+  let vec[token] buff = vec();
+  ret @rec(mutable context=stack,
+           width=width,
+           mutable buffered=buff,
+           mutable scandepth=0u,
+           mutable bufferedcol=0u,
+           mutable col=0u,
+           mutable start_of_line=true);
+}
+
+impure fn push_context(ps p, contexttype tp, uint indent) {
+  before_print(p, false);
+  p.context = _vec.push[context](p.context, rec(tp=tp, indent=base_indent(p)
+                                                + indent));
+}
+
+impure fn pop_context(ps p) {
+  p.context = _vec.pop[context](p.context);
+}
+
+impure fn add_token(ps p, token tok) {
+  if (p.scandepth == 0u) {do_token(p, tok);}
+  else {buffer_token(p, tok);}
+}
+
+impure fn buffer_token(ps p, token tok) {
+  p.buffered += vec(tok);
+  p.bufferedcol += token_size(tok);
+  alt (p.buffered.(0)) {
+    case (brk(_)) {
+      alt (tok) {
+        case (brk(_)) {
+          if (p.scandepth == 1u) {finish_break_scan(p);}
+        }
+        case (open(box_h,_)) {p.scandepth += 1u;}
+        case (open(_,_)) {finish_break_scan(p);}
+        case (close) {
+          p.scandepth -= 1u;
+          if (p.scandepth == 0u) {finish_break_scan(p);}
+        }
+        case (_) {}
+      }
+    }
+    case (open(_,_)) {
+      if (p.bufferedcol > p.width) {finish_block_scan(p, cx_v);}
+      else {
+        alt (tok) {
+          case (open(_,_)) {p.scandepth += 1u;}
+          case (close) {
+            p.scandepth -= 1u;
+            if (p.scandepth == 0u) {finish_block_scan(p, cx_h);}
+          }
+          case (_) {}
+        }
+      }
+    }
+  }
+}
+
+impure fn finish_block_scan(ps p, contexttype tp) {
+  auto indent;
+  alt (p.buffered.(0)){
+    case (open(box_hv,?ind)) {
+      indent = ind;
+    }
+    case (open(box_align, _)) {
+      indent = p.col - base_indent(p);
+    }
+  }
+  p.scandepth = 0u;
+  push_context(p, tp, indent);
+  for (token t in _vec.shift[token](p.buffered)) {add_token(p, t);}
+}
+
+impure fn finish_break_scan(ps p) {
+  if (p.bufferedcol > p.width) {
+    write_str("\n");
+    p.col = 0u;
+  }
+  else {
+    auto width;
+    alt (p.buffered.(0)) {case(brk(?w)) {width = w;}}
+    auto i = 0u;
+    while (i < width) {write_str(" "); i+=1u;}
+    p.col += width;
+  }
+  p.scandepth = 0u;
+  for (token t in _vec.shift[token](p.buffered)) {add_token(p, t);}
+}
+
+impure fn start_scan(ps p, token tok) {
+  p.buffered = vec(tok);
+  p.scandepth = 1u;
+  p.bufferedcol = p.col;
+}
+
+fn cur_context(ps p) -> context {
+  ret p.context.(_vec.len[context](p.context)-1u);
+}
+fn base_indent(ps p) -> uint {
+  auto i = _vec.len[context](p.context);
+  while (i > 0u) {
+    i -= 1u;
+    auto cx = p.context.(i);
+    if (cx.tp == cx_v) {ret cx.indent;}
+  }
+}
+
+impure fn do_token(ps p, token tok) {
+  alt (tok) {
+    case (brk(?sz)) {
+      alt (cur_context(p).tp) {
+        case (cx_h) {
+          before_print(p, false);
+          start_scan(p, tok);
+        }
+        case (cx_v) {
+          write_str("\n");
+          p.col = 0u;
+          p.start_of_line = true;
+        }
+      }
+    }
+    case (word(?w)) {
+      before_print(p, false);
+      write_str(w);
+      p.col += _str.byte_len(w); // TODO char_len
+    }
+    case (cword(?w)) {
+      before_print(p, true);
+      write_str(w);
+      p.col += _str.byte_len(w); // TODO char_len
+    }
+    case (open(?tp, ?indent)) {
+      alt (tp) {
+        case (box_hv) {start_scan(p, tok);}
+        case (box_align) {start_scan(p, tok);}
+        case (box_h) {push_context(p, cx_h, indent);}
+        case (box_v) {push_context(p, cx_v, indent);}
+      }
+    }
+    case (close) {pop_context(p);}
+  }
+}
+
+impure fn before_print(ps p, bool closing) {
+  if (p.start_of_line) {
+    p.start_of_line = false;
+    auto ind;
+    if (closing) {ind = base_indent(p);}
+    else {ind = cur_context(p).indent;}
+    p.col = ind;
+    while (ind > 0u) {write_str(" "); ind -= 1u;}
+  }
+}
+
+fn write_str(str s) {
+  io.writefd(1, _str.bytes(s));
+}
+
+fn token_size(token tok) -> uint {
+  alt (tok) {
+    case (brk(?sz)) {ret sz;}
+    case (word(?w)) {ret _str.byte_len(w);}
+    case (cword(?w)) {ret _str.byte_len(w);}
+    case (open(_, _)) {ret 0u;} // TODO exception for V blocks?
+    case (close) {ret 0u;}
+  }
+}
+
+impure fn box(ps p, uint indent) {add_token(p, open(box_hv, indent));}
+impure fn abox(ps p) {add_token(p, open(box_align, 0u));}
+impure fn vbox(ps p, uint indent) {add_token(p, open(box_v, indent));}
+impure fn hbox(ps p, uint indent) {add_token(p, open(box_h, indent));}
+impure fn end(ps p) {add_token(p, close);}
+impure fn wrd(ps p, str wrd) {add_token(p, word(wrd));}
+impure fn cwrd(ps p, str wrd) {add_token(p, cword(wrd));}
+impure fn space(ps p) {add_token(p, brk(1u));}
+impure fn spaces(ps p, uint n) {add_token(p, brk(n));}
+impure fn line(ps p) {add_token(p, brk(0u));}
diff --git a/src/comp/pretty/pprust.rs b/src/comp/pretty/pprust.rs
new file mode 100644
index 00000000000..cab778f1732
--- /dev/null
+++ b/src/comp/pretty/pprust.rs
@@ -0,0 +1,708 @@
+import std._vec;
+import std._str;
+import std.option;
+import front.ast;
+import pp.box; import pp.abox; import pp.vbox;
+import pp.end; import pp.wrd; import pp.space; import pp.line;
+import pp.ps;
+
+import foo = std.io;
+
+const uint indent_unit = 2u;
+const int as_prec = 5;
+
+impure fn print_ast(ast._mod _mod) {
+  auto s = pp.mkstate(80u);
+  for (@ast.view_item vitem in _mod.view_items) {print_view_item(s, vitem);}
+  line(s);
+  for (@ast.item item in _mod.items) {print_item(s, item);}
+}
+
+impure fn hbox(ps s) {
+  pp.hbox(s, indent_unit);
+}
+impure fn wrd1(ps s, str word) {
+  wrd(s, word);
+  space(s);
+}
+impure fn popen(ps s) {
+  wrd(s, "(");
+  abox(s);
+}
+impure fn pclose(ps s) {
+  end(s);
+  wrd(s, ")");
+}
+impure fn bopen(ps s) {
+  wrd1(s, "{");
+  vbox(s, indent_unit);
+  line(s);
+}
+impure fn bclose(ps s) {
+  end(s);
+  pp.cwrd(s, "}");
+}
+impure fn commasep[IN](ps s, vec[IN] elts, impure fn (ps, IN) op) {
+  auto first = true;
+  for (IN elt in elts) {
+    if (first) {first = false;}
+    else {wrd1(s, ",");}
+    op(s, elt);
+  }
+}
+
+impure fn print_type(ps s, @ast.ty ty) {
+  hbox(s);
+  alt (ty.node) {
+    case (ast.ty_nil) {wrd(s, "()");}
+    case (ast.ty_bool) {wrd(s, "bool");}
+    case (ast.ty_int) {wrd(s, "int");}
+    case (ast.ty_uint) {wrd(s, "uint");}
+    case (ast.ty_machine(?tm)) {wrd(s, util.common.ty_mach_to_str(tm));}
+    case (ast.ty_char) {wrd(s, "char");}
+    case (ast.ty_str) {wrd(s, "str");}
+    case (ast.ty_box(?t)) {wrd(s, "@"); print_type(s, t);}
+    case (ast.ty_vec(?t)) {wrd(s, "vec["); print_type(s, t); wrd(s, "]");}
+    case (ast.ty_type) {wrd(s, "type");}
+    case (ast.ty_tup(?elts)) {
+      wrd(s, "tup");
+      popen(s);
+      auto f = print_type;
+      commasep[@ast.ty](s, elts, f);
+      pclose(s);
+    }
+    case (ast.ty_rec(?fields)) {
+      wrd(s, "rec");
+      popen(s);
+      impure fn print_field(ps s, ast.ty_field f) {
+        hbox(s);
+        print_type(s, f.ty);
+        space(s);
+        wrd(s, f.ident);
+        end(s);
+      }
+      auto f = print_field;
+      commasep[ast.ty_field](s, fields, f);
+      pclose(s);
+    }
+    case (ast.ty_fn(?proto,?inputs,?output)) {
+      if (proto == ast.proto_fn) {wrd(s, "fn");}
+      else {wrd(s, "iter");}
+      popen(s);
+      impure fn print_arg(ps s, ast.ty_arg input) {
+        if (middle.ty.mode_is_alias(input.mode)) {wrd(s, "&");}
+        print_type(s, input.ty);
+      }
+      auto f = print_arg;
+      commasep[ast.ty_arg](s, inputs, f);
+      pclose(s);
+      if (output.node != ast.ty_nil) {
+        space(s);
+        hbox(s);
+        wrd1(s, "->");
+        print_type(s, output);
+        end(s);
+      }
+    }
+    case (ast.ty_path(?path,_)) {
+      print_path(s, path);
+    }
+    case (ast.ty_mutable(?t)) {
+      wrd1(s, "mutable");
+      print_type(s, t);
+    }
+  }
+  end(s);
+}
+
+impure fn print_item(ps s, @ast.item item) {
+  hbox(s);
+  alt (item.node) {
+    case (ast.item_const(?id, ?ty, ?expr, _, _)) {
+      wrd1(s, "const");
+      print_type(s, ty);
+      space(s);
+      wrd1(s, id);
+      wrd1(s, "=");
+      print_expr(s, expr);
+      wrd(s, ";");
+    }
+    case (ast.item_fn(?name,?_fn,?typarams,_,_)) {
+      print_fn(s, _fn.decl, name, typarams);
+      space(s);
+      print_block(s, _fn.body);
+    }
+    case (ast.item_mod(?id,?_mod,_)) {
+      wrd1(s, "mod");
+      wrd1(s, id);
+      bopen(s);
+      for (@ast.item itm in _mod.items) {print_item(s, itm);}
+      bclose(s);
+    }
+    case (ast.item_native_mod(?id,?nmod,_)) {
+      wrd1(s, "native");
+      alt (nmod.abi) {
+        case (ast.native_abi_rust) {wrd1(s, "\"rust\"");}
+        case (ast.native_abi_cdecl) {wrd1(s, "\"cdecl\"");}
+      }
+      wrd1(s, "mod");
+      wrd1(s, id);
+      bopen(s);
+      for (@ast.native_item item in nmod.items) {
+        hbox(s);
+        alt (item.node) {
+          case (ast.native_item_ty(?id,_)) {
+            wrd1(s, "type");
+            wrd(s, id);
+          }
+          case (ast.native_item_fn(?id,?decl,?typarams,_,_)) {
+            print_fn(s, decl, id, typarams);
+          }
+        }
+        wrd(s, ";");
+        end(s);
+      }
+      bclose(s);
+    }
+    case (ast.item_ty(?id,?ty,?params,_,_)) {
+      wrd1(s, "type");
+      wrd(s, id);
+      print_type_params(s, params);
+      space(s);
+      wrd1(s, "=");
+      print_type(s, ty);
+      wrd(s, ";");
+    }
+    case (ast.item_tag(?id,?variants,?params,_)) {
+      wrd1(s, "tag");
+      wrd(s, id);
+      print_type_params(s, params);
+      space(s);
+      bopen(s);
+      for (ast.variant v in variants) {
+        wrd(s, v.name);
+        if (_vec.len[ast.variant_arg](v.args) > 0u) {
+          popen(s);
+          impure fn print_variant_arg(ps s, ast.variant_arg arg) {
+            print_type(s, arg.ty);
+          }
+          auto f = print_variant_arg;
+          commasep[ast.variant_arg](s, v.args, f);
+          pclose(s);
+        }
+        wrd(s, ";");
+        line(s);
+      }
+      bclose(s);
+    }
+    case (ast.item_obj(?id,?_obj,?params,_,_)) {
+      wrd1(s, "obj");
+      wrd(s, id);
+      print_type_params(s, params);
+      popen(s);
+      impure fn print_field(ps s, ast.obj_field field) {
+        hbox(s);
+        print_type(s, field.ty);
+        space(s);
+        wrd(s, field.ident);
+        end(s);
+      }
+      auto f = print_field;
+      commasep[ast.obj_field](s, _obj.fields, f);
+      pclose(s);
+      space(s);
+      bopen(s);
+      for (@ast.method meth in _obj.methods) {
+        hbox(s);
+        let vec[ast.ty_param] typarams = vec();
+        print_fn(s, meth.node.meth.decl, meth.node.ident, typarams);
+        space(s);
+        print_block(s, meth.node.meth.body);
+        end(s);
+        line(s);
+      }
+      alt (_obj.dtor) {
+        case (option.some[ast.block](?dtor)) {
+          hbox(s);
+          wrd1(s, "close");
+          print_block(s, dtor);
+          end(s);
+          line(s);
+        }
+        case (_) {}
+      }
+      bclose(s);
+    }
+  }
+  end(s);
+  line(s);
+  line(s);
+}
+
+impure fn print_block(ps s, ast.block blk) {
+  bopen(s);
+  for (@ast.stmt st in blk.node.stmts) {
+    alt (st.node) {
+      case (ast.stmt_decl(?decl)) {print_decl(s, decl);}
+      case (ast.stmt_expr(?expr)) {print_expr(s, expr);}
+    }
+    if (front.parser.stmt_ends_with_semi(st)) {wrd(s, ";");}
+    line(s);
+  }
+  alt (blk.node.expr) {
+    case (option.some[@ast.expr](?expr)) {
+      print_expr(s, expr);
+      line(s);
+    }
+    case (_) {}
+  }
+  bclose(s);
+}
+
+impure fn print_literal(ps s, @ast.lit lit) {
+  alt (lit.node) {
+    case (ast.lit_str(?st)) {print_string(s, st);}
+    case (ast.lit_char(?ch)) {
+      wrd(s, "'" + escape_str(_str.from_bytes(vec(ch as u8)), '\'') + "'");
+    }
+    case (ast.lit_int(?val)) {
+      wrd(s, util.common.istr(val));
+    }
+    case (ast.lit_uint(?val)) { // TODO clipping? uistr?
+      wrd(s, util.common.istr(val as int) + "u");
+    }
+    case (ast.lit_mach_int(?mach,?val)) {
+      wrd(s, util.common.istr(val as int));
+      wrd(s, util.common.ty_mach_to_str(mach));
+    }
+    case (ast.lit_nil) {wrd(s, "()");}
+    case (ast.lit_bool(?val)) {
+      if (val) {wrd(s, "true");} else {wrd(s, "false");}
+    }
+  }
+}
+
+impure fn print_expr(ps s, @ast.expr expr) {
+  auto pe = print_expr;
+  hbox(s);
+  alt (expr.node) {
+    case (ast.expr_vec(?exprs,_)) {
+      wrd(s, "vec");
+      popen(s);
+      commasep[@ast.expr](s, exprs, pe);
+      pclose(s);
+    }
+    case (ast.expr_tup(?exprs,_)) {
+      impure fn printElt(ps s, ast.elt elt) {
+        hbox(s);
+        if (elt.mut == ast.mut) {wrd1(s, "mutable");}
+        print_expr(s, elt.expr);
+        end(s);
+      }
+      wrd(s, "tup");
+      popen(s);
+      auto f = printElt;
+      commasep[ast.elt](s, exprs, f);
+      pclose(s);
+    }
+    case (ast.expr_rec(?fields,_,_)) {
+      impure fn print_field(ps s, ast.field field) {
+        hbox(s);
+        if (field.mut == ast.mut) {wrd1(s, "mutable");}
+        wrd(s, field.ident);
+        wrd(s, "=");
+        print_expr(s, field.expr);
+        end(s);
+      }
+      wrd(s, "rec");
+      popen(s);
+      auto f = print_field;
+      commasep[ast.field](s, fields, f);
+      pclose(s);
+    }
+    case (ast.expr_call(?func,?args,_)) {
+      print_expr(s, func);
+      popen(s);
+      commasep[@ast.expr](s, args, pe);
+      pclose(s);
+    }
+    case (ast.expr_bind(?func,?args,_)) {
+      impure fn print_opt(ps s, option.t[@ast.expr] expr) {
+        alt (expr) {
+          case (option.some[@ast.expr](?expr)) {
+            print_expr(s, expr);
+          }
+          case (_) {wrd(s, "_");}
+        }
+      }
+      wrd1(s, "bind");
+      print_expr(s, func);
+      popen(s);
+      auto f = print_opt;
+      commasep[option.t[@ast.expr]](s, args, f);
+      pclose(s);
+    }
+    case (ast.expr_binary(?op,?lhs,?rhs,_)) {
+      auto prec = operator_prec(op);
+      print_maybe_parens(s, lhs, prec);
+      space(s);
+      wrd1(s, ast.binop_to_str(op));
+      print_maybe_parens(s, rhs, prec + 1);
+    }
+    case (ast.expr_unary(?op,?expr,_)) {
+      wrd(s, ast.unop_to_str(op));
+      if (op == ast._mutable) {space(s);}
+      print_expr(s, expr);
+    }
+    case (ast.expr_lit(?lit,_)) {
+      print_literal(s, lit);
+    }
+    case (ast.expr_cast(?expr,?ty,_)) {
+      print_maybe_parens(s, expr, as_prec);
+      space(s);
+      wrd1(s, "as");
+      print_type(s, ty);
+    }
+    case (ast.expr_if(?test,?block,?elseopt,_)) {
+      wrd1(s, "if");
+      popen(s);
+      print_expr(s, test);
+      pclose(s);
+      space(s);
+      print_block(s, block);
+      alt (elseopt) {
+        case (option.some[@ast.expr](?_else)) {
+          space(s);
+          wrd1(s, "else");
+          print_expr(s, _else);
+        }
+      }
+    }
+    case (ast.expr_while(?test,?block,_)) {
+      wrd1(s, "while");
+      popen(s);
+      print_expr(s, test);
+      pclose(s);
+      space(s);
+      print_block(s, block);
+    }
+    case (ast.expr_for(?decl,?expr,?block,_)) {
+      wrd1(s, "for");
+      popen(s);
+      print_decl(s, decl);
+      space(s);
+      wrd1(s, "in");
+      print_expr(s, expr);
+      pclose(s);
+      space(s);
+      print_block(s, block);
+    }
+    case (ast.expr_for_each(?decl,?expr,?block,_)) {
+      wrd1(s, "for each");
+      popen(s);
+      print_decl(s, decl);
+      space(s);
+      wrd1(s, "in");
+      print_expr(s, expr);
+      space(s);
+      print_block(s, block);
+    }
+    case (ast.expr_do_while(?block,?expr,_)) {
+      wrd1(s, "do");
+      space(s);
+      print_block(s, block);
+      space(s);
+      wrd1(s, "while");
+      popen(s);
+      print_expr(s, expr);
+      pclose(s);
+    }
+    case (ast.expr_alt(?expr,?arms,_)) {
+      wrd1(s, "alt");
+      popen(s);
+      print_expr(s, expr);
+      pclose(s);
+      space(s);
+      bopen(s);
+      for (ast.arm arm in arms) {
+        hbox(s);
+        wrd1(s, "case");
+        popen(s);
+        print_pat(s, arm.pat);
+        pclose(s);
+        space(s);
+        print_block(s, arm.block);
+        end(s);
+        line(s);
+      }
+      bclose(s);
+    }
+    case (ast.expr_block(?block,_)) {
+      print_block(s, block);
+    }
+    case (ast.expr_assign(?lhs,?rhs,_)) {
+      print_expr(s, lhs);
+      space(s);
+      wrd1(s, "=");
+      print_expr(s, rhs);
+    }
+    case (ast.expr_assign_op(?op,?lhs,?rhs,_)) {
+      print_expr(s, lhs);
+      space(s);
+      wrd(s, ast.binop_to_str(op));
+      wrd1(s, "=");
+      print_expr(s, rhs);
+    }
+    case (ast.expr_field(?expr,?id,_)) {
+      print_expr(s, expr);
+      wrd(s, ".");
+      wrd(s, id);
+    }
+    case (ast.expr_index(?expr,?index,_)) {
+      print_expr(s, expr);
+      wrd(s, ".");
+      popen(s);
+      print_expr(s, index);
+      pclose(s);
+    }
+    case (ast.expr_path(?path,_,_)) {
+      print_path(s, path);
+    }
+    case (ast.expr_fail) {
+      wrd(s, "fail");
+    }
+    case (ast.expr_ret(?result)) {
+      wrd(s, "ret");
+      alt (result) {
+        case (option.some[@ast.expr](?expr)) {
+          space(s);
+          print_expr(s, expr);
+        }
+        case (_) {}
+      }
+    }
+    case (ast.expr_put(?result)) {
+      wrd(s, "put");
+      alt (result) {
+        case (option.some[@ast.expr](?expr)) {
+          space(s);
+          print_expr(s, expr);
+        }
+        case (_) {}
+      }
+    }
+    case (ast.expr_be(?result)) {
+      wrd1(s, "be");
+      print_expr(s, result);
+    }
+    case (ast.expr_log(?expr)) {
+      wrd1(s, "log");
+      print_expr(s, expr);
+    }
+    case (ast.expr_check_expr(?expr)) {
+      wrd1(s, "check");
+      print_expr(s, expr);
+    }
+    case (_) {wrd(s, "X");}
+    // TODO expr_ext(path, vec[@expr], option.t[@expr], @expr, ann);
+  }
+  end(s);
+}
+
+impure fn print_decl(ps s, @ast.decl decl) {
+  hbox(s);
+  alt (decl.node) {
+    case (ast.decl_local(?loc)) {
+      alt (loc.ty) {
+        case (option.some[@ast.ty](?ty)) {
+          wrd1(s, "let");
+          print_type(s, ty);
+          space(s);
+        }
+        case (_) {
+          wrd1(s, "auto");
+        }
+      }
+      wrd(s, loc.ident);
+      alt (loc.init) {
+        case (option.some[@ast.expr](?init)) {
+          space(s);
+          wrd1(s, "=");
+          print_expr(s, init);
+        }
+        case (_) {}
+      }
+    }
+    case (ast.decl_item(?item)) {
+      print_item(s, item);
+    }
+  }
+  end(s);
+}
+
+impure fn print_path(ps s, ast.path path) {
+  auto first = true;
+  for (str id in path.node.idents) {
+    if (first) {first = false;}
+    else {wrd(s, ".");}
+    wrd(s, id);
+  }
+  if (_vec.len[@ast.ty](path.node.types) > 0u) {
+    wrd(s, "[");
+    auto f = print_type;
+    commasep[@ast.ty](s, path.node.types, f);
+    wrd(s, "]");
+  }
+}
+
+impure fn print_pat(ps s, @ast.pat pat) {
+  alt (pat.node) {
+    case (ast.pat_wild(_)) {wrd(s, "_");}
+    case (ast.pat_bind(?id,_,_)) {wrd(s, "?" + id);}
+    case (ast.pat_lit(?lit,_)) {print_literal(s, lit);}
+    case (ast.pat_tag(?path,?args,_,_)) {
+      print_path(s, path);
+      if (_vec.len[@ast.pat](args) > 0u) {
+        popen(s);
+        auto f = print_pat;
+        commasep[@ast.pat](s, args, f);
+        pclose(s);
+      }
+    }
+  }
+}
+
+impure fn print_fn(ps s, ast.fn_decl decl, str name,
+                   vec[ast.ty_param] typarams) {
+  alt (decl.effect) {
+    case (ast.eff_impure) {wrd1(s, "impure");}
+    case (ast.eff_unsafe) {wrd1(s, "unsafe");}
+    case (_) {}
+  }
+  wrd1(s, "fn");
+  wrd(s, name);
+  print_type_params(s, typarams);
+  popen(s);
+  impure fn print_arg(ps s, ast.arg x) {
+    hbox(s);
+    print_type(s, x.ty);
+    space(s);
+    wrd(s, x.ident);
+    end(s);
+  }
+  auto f = print_arg;
+  commasep[ast.arg](s, decl.inputs, f);
+  pclose(s);
+  if (decl.output.node != ast.ty_nil) {
+    space(s);
+    hbox(s);
+    wrd1(s, "->");
+    print_type(s, decl.output);
+    end(s);
+  }
+}
+
+impure fn print_type_params(ps s, vec[ast.ty_param] params) {
+  if (_vec.len[ast.ty_param](params) > 0u) {
+    wrd(s, "[");
+    impure fn printParam(ps s, ast.ty_param param) {wrd(s, param.ident);}
+    auto f = printParam;
+    commasep[ast.ty_param](s, params, f);
+    wrd(s, "]");
+  }
+}
+
+impure fn print_view_item(ps s, @ast.view_item item) {
+  hbox(s);
+  alt (item.node) {
+    case (ast.view_item_use(?id,?mta,_)) {
+      wrd1(s, "use");
+      wrd(s, id);
+      if (_vec.len[@ast.meta_item](mta) > 0u) {
+        popen(s);
+        impure fn print_meta(ps s, @ast.meta_item item) {
+          hbox(s);
+          wrd1(s, item.node.name);
+          wrd1(s, "=");
+          print_string(s, item.node.value);
+          end(s);
+        }
+        auto f = print_meta;
+        commasep[@ast.meta_item](s, mta, f);
+        pclose(s);
+      }
+    }
+    case (ast.view_item_import(?id,?ids,_,_)) {
+      wrd1(s, "import");
+      if (!_str.eq(id, ids.(_vec.len[str](ids)-1u))) {
+        wrd1(s, id);
+        wrd1(s, "=");
+      }
+      auto first = true;
+      for (str elt in ids) {
+        if (first) {first = false;}
+        else {wrd(s, ".");}
+        wrd(s, elt);
+      }
+    }
+    case (ast.view_item_export(?id)) {
+      wrd1(s, "export");
+      wrd(s, id);
+    }
+  }
+  end(s);
+  wrd(s, ";");
+  line(s);
+}
+
+// FIXME: The fact that this builds up the table anew for every call is
+// not good. Eventually, table should be a const.
+fn operator_prec(ast.binop op) -> int {
+  for (front.parser.op_spec spec in front.parser.prec_table()) {
+    if (spec.op == op) {ret spec.prec;}
+  }
+  fail;
+}
+
+impure fn print_maybe_parens(ps s, @ast.expr expr, int outer_prec) {
+  auto add_them;
+  alt (expr.node) {
+    case (ast.expr_binary(?op,_,_,_)) {
+      add_them = operator_prec(op) < outer_prec;
+    }
+    case (ast.expr_cast(_,_,_)) {
+      add_them = as_prec < outer_prec;
+    }
+    case (_) {
+      add_them = false;
+    }
+  }
+  if (add_them) {popen(s);}
+  print_expr(s, expr);
+  if (add_them) {pclose(s);}
+}
+
+// TODO non-ascii
+fn escape_str(str st, char to_escape) -> str {
+  let str out = "";
+  auto len = _str.byte_len(st);
+  auto i = 0u;
+  while (i < len) {
+    alt (st.(i) as char) {
+      case ('\n') {out += "\\n";}
+      case ('\t') {out += "\\t";}
+      case ('\r') {out += "\\r";}
+      case ('\\') {out += "\\\\";}
+      case (?cur) {
+        if (cur == to_escape) {out += "\\";}
+        out += cur as u8;
+      }
+    }
+    i += 1u;
+  }
+  ret out;
+}
+
+impure fn print_string(ps s, str st) {
+  wrd(s, "\""); wrd(s, escape_str(st, '"')); wrd(s, "\"");
+}
diff --git a/src/comp/rustc.rc b/src/comp/rustc.rc
index b439632cfbc..e483340949e 100644
--- a/src/comp/rustc.rc
+++ b/src/comp/rustc.rc
@@ -5,9 +5,12 @@ use std;
 
 mod front {
     mod ast;
+    mod extfmt;
     mod lexer;
     mod parser;
+    mod pretty;
     mod token;
+    mod eval;
 }
 
 mod middle {
@@ -28,6 +31,11 @@ mod driver {
     mod session;
 }
 
+mod pretty {
+    mod pp;
+    mod pprust;
+}
+
 mod util {
     mod common;
 }
@@ -38,7 +46,6 @@ auth middle.trans.copy_args_to_allocas = impure;
 auth middle.trans.trans_block = impure;
 auth lib.llvm = unsafe;
 
-
 mod lib {
     alt (target_os) {
         case ("win32") {
diff --git a/src/comp/util/common.rs b/src/comp/util/common.rs
index 56f30e07117..071acea2ee2 100644
--- a/src/comp/util/common.rs
+++ b/src/comp/util/common.rs
@@ -2,8 +2,10 @@ import std._uint;
 import std._int;
 import front.ast;
 
+
+type filename = str;
 type pos = rec(uint line, uint col);
-type span = rec(str filename, pos lo, pos hi);
+type span = rec(filename filename, pos lo, pos hi);
 type spanned[T] = rec(T node, span span);
 
 tag ty_mach {