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authorMarijn Haverbeke <marijnh@gmail.com>2011-05-06 22:13:13 +0200
committerMarijn Haverbeke <marijnh@gmail.com>2011-05-06 22:51:19 +0200
commita3ec0b1f643d00b9418e4884bd7caa07bf052201 (patch)
tree82000510ac9c9cf3f0c7cf4ae5f3c6b123b559cb
parent44c1621525cc9d4f7ff68e832493394d8ae565e9 (diff)
downloadrust-a3ec0b1f643d00b9418e4884bd7caa07bf052201.tar.gz
rust-a3ec0b1f643d00b9418e4884bd7caa07bf052201.zip
Rename std modules to be camelcased
(Have fun mergining your stuff with this.)
-rw-r--r--src/comp/back/Link.rs26
-rw-r--r--src/comp/back/x86.rs36
-rw-r--r--src/comp/driver/rustc.rs74
-rw-r--r--src/comp/driver/session.rs18
-rw-r--r--src/comp/front/ast.rs54
-rw-r--r--src/comp/front/codemap.rs8
-rw-r--r--src/comp/front/creader.rs202
-rw-r--r--src/comp/front/eval.rs30
-rw-r--r--src/comp/front/extenv.rs10
-rw-r--r--src/comp/front/extfmt.rs36
-rw-r--r--src/comp/front/lexer.rs80
-rw-r--r--src/comp/front/parser.rs74
-rw-r--r--src/comp/front/token.rs18
-rw-r--r--src/comp/lib/llvm.rs236
-rw-r--r--src/comp/middle/capture.rs30
-rw-r--r--src/comp/middle/fold.rs98
-rw-r--r--src/comp/middle/metadata.rs274
-rw-r--r--src/comp/middle/resolve.rs94
-rw-r--r--src/comp/middle/trans.rs402
-rw-r--r--src/comp/middle/ty.rs192
-rw-r--r--src/comp/middle/typeck.rs176
-rw-r--r--src/comp/middle/typestate_check.rs212
-rw-r--r--src/comp/middle/walk.rs10
-rw-r--r--src/comp/pretty/pp.rs36
-rw-r--r--src/comp/pretty/pprust.rs106
-rw-r--r--src/comp/util/common.rs50
-rw-r--r--src/comp/util/typestate_ann.rs60
-rw-r--r--src/lib/BitV.rs (renamed from src/lib/bitv.rs)26
-rw-r--r--src/lib/Dbg.rs (renamed from src/lib/dbg.rs)2
-rw-r--r--src/lib/Deque.rs (renamed from src/lib/deque.rs)36
-rw-r--r--src/lib/EBML.rs (renamed from src/lib/ebml.rs)26
-rw-r--r--src/lib/ExtFmt.rs76
-rw-r--r--src/lib/FS.rs (renamed from src/lib/fs.rs)22
-rw-r--r--src/lib/GenericOS.rs2
-rw-r--r--src/lib/GetOpts.rs80
-rw-r--r--src/lib/IO.rs (renamed from src/lib/io.rs)118
-rw-r--r--src/lib/Int.rs (renamed from src/lib/_int.rs)4
-rw-r--r--src/lib/List.rs (renamed from src/lib/list.rs)6
-rw-r--r--src/lib/Map.rs (renamed from src/lib/map.rs)38
-rw-r--r--src/lib/Option.rs (renamed from src/lib/option.rs)4
-rw-r--r--src/lib/Rand.rs (renamed from src/lib/rand.rs)0
-rw-r--r--src/lib/Run_Program.rs (renamed from src/lib/run_program.rs)54
-rw-r--r--src/lib/SHA1.rs (renamed from src/lib/sha1.rs)16
-rw-r--r--src/lib/Sort.rs (renamed from src/lib/sort.rs)4
-rw-r--r--src/lib/Str.rs (renamed from src/lib/_str.rs)12
-rw-r--r--src/lib/Sys.rs (renamed from src/lib/sys.rs)0
-rw-r--r--src/lib/Task.rs (renamed from src/lib/_task.rs)0
-rw-r--r--src/lib/Term.rs12
-rw-r--r--src/lib/U8.rs (renamed from src/lib/_u8.rs)0
-rw-r--r--src/lib/UFind.rs10
-rw-r--r--src/lib/UInt.rs (renamed from src/lib/_uint.rs)12
-rw-r--r--src/lib/Util.rs (renamed from src/lib/util.rs)2
-rw-r--r--src/lib/Vec.rs (renamed from src/lib/_vec.rs)24
-rw-r--r--src/lib/linux_OS.rs (renamed from src/lib/linux_os.rs)10
-rw-r--r--src/lib/macos_OS.rs (renamed from src/lib/macos_os.rs)10
-rw-r--r--src/lib/posix_FS.rs (renamed from src/lib/posix_fs.rs)12
-rw-r--r--src/lib/std.rc77
-rw-r--r--src/lib/win32_FS.rs (renamed from src/lib/win32_fs.rs)0
-rw-r--r--src/lib/win32_OS.rs (renamed from src/lib/win32_os.rs)8
-rw-r--r--src/test/bench/99-bottles/99bob-iter.rs10
-rw-r--r--src/test/bench/99-bottles/99bob-pattern.rs8
-rw-r--r--src/test/bench/99-bottles/99bob-simple.rs10
-rw-r--r--src/test/bench/99-bottles/99bob-tail.rs8
-rw-r--r--src/test/bench/shootout/binarytrees.rs4
-rw-r--r--src/test/bench/shootout/fannkuchredux.rs10
-rw-r--r--src/test/bench/shootout/fasta.rs30
-rw-r--r--src/test/run-pass/alt-join.rs10
-rw-r--r--src/test/run-pass/alt-pattern-drop.rs12
-rw-r--r--src/test/run-pass/lib-bitv.rs304
-rw-r--r--src/test/run-pass/lib-deque.rs8
-rw-r--r--src/test/run-pass/lib-int.rs30
-rw-r--r--src/test/run-pass/lib-io.rs10
-rw-r--r--src/test/run-pass/lib-map.rs132
-rw-r--r--src/test/run-pass/lib-option.rs2
-rw-r--r--src/test/run-pass/lib-qsort.rs4
-rw-r--r--src/test/run-pass/lib-rand.rs6
-rw-r--r--src/test/run-pass/lib-sha1.rs16
-rw-r--r--src/test/run-pass/lib-sort.rs4
-rw-r--r--src/test/run-pass/lib-str-buf.rs12
-rw-r--r--src/test/run-pass/lib-str.rs46
-rw-r--r--src/test/run-pass/lib-task.rs4
-rw-r--r--src/test/run-pass/lib-uint.rs82
-rw-r--r--src/test/run-pass/lib-vec-str-conversions.rs14
-rw-r--r--src/test/run-pass/lib-vec.rs18
-rw-r--r--src/test/run-pass/mlist-cycle.rs2
-rw-r--r--src/test/run-pass/mutable-alias-vec.rs2
-rw-r--r--src/test/run-pass/nested-pattern.rs8
-rw-r--r--src/test/run-pass/rt-circular-buffer.rs20
-rw-r--r--src/test/run-pass/str-append.rs6
-rw-r--r--src/test/run-pass/syntax-extension-fmt.rs4
-rw-r--r--src/test/run-pass/task-comm-12.rs4
-rw-r--r--src/test/run-pass/task-comm-13-thread.rs2
-rw-r--r--src/test/run-pass/task-comm-13.rs2
-rw-r--r--src/test/run-pass/type-sizes.rs2
-rw-r--r--src/test/run-pass/use.rs8
-rw-r--r--src/test/run-pass/user.rs4
-rw-r--r--src/test/run-pass/utf8_chars.rs44
-rw-r--r--src/test/run-pass/vec-alloc-append.rs2
-rw-r--r--src/test/run-pass/vec-append.rs40
-rw-r--r--src/test/run-pass/vec-ref-count.rs12
100 files changed, 2150 insertions, 2151 deletions
diff --git a/src/comp/back/Link.rs b/src/comp/back/Link.rs
index ebeda8dc36b..695d3202ff2 100644
--- a/src/comp/back/Link.rs
+++ b/src/comp/back/Link.rs
@@ -1,8 +1,8 @@
 import driver.session;
 import lib.llvm.llvm;
 import middle.trans;
-import std._str;
-import std.fs;
+import std.Str;
+import std.FS;
 
 import lib.llvm.llvm.ModuleRef;
 import lib.llvm.llvm.ValueRef;
@@ -19,14 +19,14 @@ tag output_type {
 }
 
 fn llvm_err(session.session sess, str msg) {
-    sess.err(msg + ": " + _str.str_from_cstr(llvm.LLVMRustGetLastError()));
+    sess.err(msg + ": " + Str.str_from_cstr(llvm.LLVMRustGetLastError()));
     fail;
 }
 
 fn link_intrinsics(session.session sess, ModuleRef llmod) {
-    auto path = fs.connect(sess.get_opts().sysroot, "intrinsics.bc");
+    auto path = FS.connect(sess.get_opts().sysroot, "intrinsics.bc");
     auto membuf =
-        llvm.LLVMRustCreateMemoryBufferWithContentsOfFile(_str.buf(path));
+        llvm.LLVMRustCreateMemoryBufferWithContentsOfFile(Str.buf(path));
     if ((membuf as uint) == 0u) {
         llvm_err(sess, "installation problem: couldn't open intrinstics.bc");
         fail;
@@ -58,12 +58,12 @@ mod Write {
     // Decides what to call an intermediate file, given the name of the output
     // and the extension to use.
     fn mk_intermediate_name(str output_path, str extension) -> str {
-        auto dot_pos = _str.index(output_path, '.' as u8);
+        auto dot_pos = Str.index(output_path, '.' as u8);
         auto stem;
         if (dot_pos < 0) {
             stem = output_path;
         } else {
-            stem = _str.substr(output_path, 0u, dot_pos as uint);
+            stem = Str.substr(output_path, 0u, dot_pos as uint);
         }
         ret stem + "." + extension;
     }
@@ -86,12 +86,12 @@ mod Write {
                         auto filename = mk_intermediate_name(output,
                                                              "no-opt.bc");
                         llvm.LLVMWriteBitcodeToFile(llmod,
-                                                    _str.buf(filename));
+                                                    Str.buf(filename));
                     }
                 }
                 case (_) {
                     auto filename = mk_intermediate_name(output, "bc");
-                    llvm.LLVMWriteBitcodeToFile(llmod, _str.buf(filename));
+                    llvm.LLVMWriteBitcodeToFile(llmod, Str.buf(filename));
                 }
             }
         }
@@ -183,15 +183,15 @@ mod Write {
                                                              "opt.bc");
                         llvm.LLVMRunPassManager(pm.llpm, llmod);
                         llvm.LLVMWriteBitcodeToFile(llmod,
-                                                    _str.buf(filename));
+                                                    Str.buf(filename));
                         pm = mk_pass_manager();
                     }
                 }
             }
 
             llvm.LLVMRustWriteOutputFile(pm.llpm, llmod,
-                                         _str.buf(x86.get_target_triple()),
-                                         _str.buf(output),
+                                         Str.buf(x86.get_target_triple()),
+                                         Str.buf(output),
                                          FileType);
             llvm.LLVMDisposeModule(llmod);
             ret;
@@ -199,7 +199,7 @@ mod Write {
 
         llvm.LLVMRunPassManager(pm.llpm, llmod);
 
-        llvm.LLVMWriteBitcodeToFile(llmod, _str.buf(output));
+        llvm.LLVMWriteBitcodeToFile(llmod, Str.buf(output));
         llvm.LLVMDisposeModule(llmod);
     }
 }
diff --git a/src/comp/back/x86.rs b/src/comp/back/x86.rs
index 855bd51b8ff..bad4eb3ec8e 100644
--- a/src/comp/back/x86.rs
+++ b/src/comp/back/x86.rs
@@ -1,8 +1,8 @@
 import lib.llvm.llvm;
 import lib.llvm.llvm.ModuleRef;
-import std._str;
-import std._vec;
-import std.os.target_os;
+import std.Str;
+import std.Vec;
+import std.OS.target_os;
 import util.common.istr;
 
 const int wordsz = 4;
@@ -241,7 +241,7 @@ fn native_glue(int n_args, abi.native_glue_type ngt) -> vec[str] {
         }
         auto m = vec("movl  " + src_off + "(%ebp),%eax",
                      "movl  %eax," + dst_off + "(%esp)");
-        ret _str.connect(m, "\n\t");
+        ret Str.connect(m, "\n\t");
     }
 
     auto carg = bind copy_arg(pass_task, _);
@@ -259,7 +259,7 @@ fn native_glue(int n_args, abi.native_glue_type ngt) -> vec[str] {
         + vec("subl  $" + wstr(n_args) + ", %esp   # esp -= args",
               "andl  $~0xf, %esp    # align esp down")
 
-        + _vec.init_fn[str](carg, (n_args) as uint)
+        + Vec.init_fn[str](carg, (n_args) as uint)
 
         +  vec("movl  %edx, %edi     # save task from edx to edi",
                "call  *%ecx          # call *%ecx",
@@ -278,7 +278,7 @@ fn decl_glue(int align, str prefix, str name, vec[str] insns) -> str {
     ret "\t.globl " + sym + "\n" +
         "\t.balign " + istr(align) + "\n" +
         sym + ":\n" +
-        "\t" + _str.connect(insns, "\n\t");
+        "\t" + Str.connect(insns, "\n\t");
 }
 
 
@@ -291,8 +291,8 @@ fn decl_native_glue(int align, str prefix, abi.native_glue_type ngt, uint n)
 }
 
 fn get_symbol_prefix() -> str {
-    if (_str.eq(target_os(), "macos") ||
-        _str.eq(target_os(), "win32")) {
+    if (Str.eq(target_os(), "macos") ||
+        Str.eq(target_os(), "win32")) {
         ret "_";
     } else {
         ret "";
@@ -313,44 +313,44 @@ fn get_module_asm() -> str {
                       abi.yield_glue_name(),
                       rust_yield_glue()))
 
-        + _vec.init_fn[str](bind decl_native_glue(align, prefix,
+        + Vec.init_fn[str](bind decl_native_glue(align, prefix,
             abi.ngt_rust, _), (abi.n_native_glues + 1) as uint)
-        + _vec.init_fn[str](bind decl_native_glue(align, prefix,
+        + Vec.init_fn[str](bind decl_native_glue(align, prefix,
             abi.ngt_pure_rust, _), (abi.n_native_glues + 1) as uint)
-        + _vec.init_fn[str](bind decl_native_glue(align, prefix,
+        + Vec.init_fn[str](bind decl_native_glue(align, prefix,
             abi.ngt_cdecl, _), (abi.n_native_glues + 1) as uint);
 
 
-    ret _str.connect(glues, "\n\n");
+    ret Str.connect(glues, "\n\n");
 }
 
 fn get_meta_sect_name() -> str {
-    if (_str.eq(target_os(), "macos")) {
+    if (Str.eq(target_os(), "macos")) {
         ret "__DATA,__note.rustc";
     }
-    if (_str.eq(target_os(), "win32")) {
+    if (Str.eq(target_os(), "win32")) {
         ret ".note.rustc";
     }
     ret ".note.rustc";
 }
 
 fn get_data_layout() -> str {
-    if (_str.eq(target_os(), "macos")) {
+    if (Str.eq(target_os(), "macos")) {
       ret "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64" +
         "-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128" +
         "-n8:16:32";
     }
-    if (_str.eq(target_os(), "win32")) {
+    if (Str.eq(target_os(), "win32")) {
       ret "e-p:32:32-f64:64:64-i64:64:64-f80:32:32-n8:16:32";
     }
     ret "e-p:32:32-f64:32:64-i64:32:64-f80:32:32-n8:16:32";
 }
 
 fn get_target_triple() -> str {
-    if (_str.eq(target_os(), "macos")) {
+    if (Str.eq(target_os(), "macos")) {
         ret "i686-apple-darwin";
     }
-    if (_str.eq(target_os(), "win32")) {
+    if (Str.eq(target_os(), "win32")) {
         ret "i686-pc-mingw32";
     }
     ret "i686-unknown-linux-gnu";
diff --git a/src/comp/driver/rustc.rs b/src/comp/driver/rustc.rs
index 9c6c352dd37..cb8b676d517 100644
--- a/src/comp/driver/rustc.rs
+++ b/src/comp/driver/rustc.rs
@@ -15,14 +15,14 @@ import back.Link;
 import lib.llvm;
 import util.common;
 
-import std.fs;
-import std.map.mk_hashmap;
-import std.option;
-import std.option.some;
-import std.option.none;
-import std._str;
-import std._vec;
-import std.io;
+import std.FS;
+import std.Map.mk_hashmap;
+import std.Option;
+import std.Option.some;
+import std.Option.none;
+import std.Str;
+import std.Vec;
+import std.IO;
 import std.Time;
 
 import std.GetOpts;
@@ -47,7 +47,7 @@ fn default_environment(session.session sess,
     ret
         vec(
             // Target bindings.
-            tup("target_os", eval.val_str(std.os.target_os())),
+            tup("target_os", eval.val_str(std.OS.target_os())),
             tup("target_arch", eval.val_str("x86")),
             tup("target_libc", eval.val_str(libc)),
 
@@ -60,9 +60,9 @@ fn default_environment(session.session sess,
 fn parse_input(session.session sess,
                       parser.parser p,
                       str input) -> @ast.crate {
-    if (_str.ends_with(input, ".rc")) {
+    if (Str.ends_with(input, ".rc")) {
         ret parser.parse_crate_from_crate_file(p);
-    } else if (_str.ends_with(input, ".rs")) {
+    } else if (Str.ends_with(input, ".rs")) {
         ret parser.parse_crate_from_source_file(p);
     }
     sess.err("unknown input file type: " + input);
@@ -123,20 +123,20 @@ fn pretty_print_input(session.session sess,
     auto def = tup(0, 0);
     auto p = front.parser.new_parser(sess, env, def, input, 0u);
     auto crate = front.parser.parse_crate_from_source_file(p);
-    pretty.pprust.print_file(crate.node.module, input, std.io.stdout());
+    pretty.pprust.print_file(crate.node.module, input, std.IO.stdout());
 }
 
 fn version(str argv0) {
     auto vers = "unknown version";
     auto env_vers = #env("CFG_VERSION");
-    if (_str.byte_len(env_vers) != 0u) {
+    if (Str.byte_len(env_vers) != 0u) {
         vers = env_vers;
     }
-    io.stdout().write_str(#fmt("%s %s\n", argv0, vers));
+    IO.stdout().write_str(#fmt("%s %s\n", argv0, vers));
 }
 
 fn usage(str argv0) {
-    io.stdout().write_str(#fmt("usage: %s [options] <input>\n", argv0) + "
+    IO.stdout().write_str(#fmt("usage: %s [options] <input>\n", argv0) + "
 options:
 
     -h --help          display this message
@@ -162,38 +162,38 @@ options:
 }
 
 fn get_os(str triple) -> session.os {
-    if (_str.find(triple, "win32") > 0 ||
-        _str.find(triple, "mingw32") > 0 ) {
+    if (Str.find(triple, "win32") > 0 ||
+        Str.find(triple, "mingw32") > 0 ) {
         ret session.os_win32;
-    } else if (_str.find(triple, "darwin") > 0) { ret session.os_macos; }
-    else if (_str.find(triple, "linux") > 0) { ret session.os_linux; }
+    } else if (Str.find(triple, "darwin") > 0) { ret session.os_macos; }
+    else if (Str.find(triple, "linux") > 0) { ret session.os_linux; }
 }
 
 fn get_arch(str triple) -> session.arch {
-    if (_str.find(triple, "i386") > 0 ||
-        _str.find(triple, "i486") > 0 ||
-        _str.find(triple, "i586") > 0 ||
-        _str.find(triple, "i686") > 0 ||
-        _str.find(triple, "i786") > 0 ) {
+    if (Str.find(triple, "i386") > 0 ||
+        Str.find(triple, "i486") > 0 ||
+        Str.find(triple, "i586") > 0 ||
+        Str.find(triple, "i686") > 0 ||
+        Str.find(triple, "i786") > 0 ) {
         ret session.arch_x86;
-    } else if (_str.find(triple, "x86_64") > 0) {
+    } else if (Str.find(triple, "x86_64") > 0) {
         ret session.arch_x64;
-    } else if (_str.find(triple, "arm") > 0 ||
-        _str.find(triple, "xscale") > 0 ) {
+    } else if (Str.find(triple, "arm") > 0 ||
+        Str.find(triple, "xscale") > 0 ) {
         ret session.arch_arm;
     }
 }
 
 fn get_default_sysroot(str binary) -> str {
-    auto dirname = fs.dirname(binary);
-    if (_str.eq(dirname, binary)) { ret "."; }
+    auto dirname = FS.dirname(binary);
+    if (Str.eq(dirname, binary)) { ret "."; }
     ret dirname;
 }
 
 fn main(vec[str] args) {
 
     let str triple =
-        std._str.rustrt.str_from_cstr(llvm.llvm.LLVMRustGetHostTriple());
+        std.Str.rustrt.str_from_cstr(llvm.llvm.LLVMRustGetHostTriple());
 
     let @session.config target_cfg =
         @rec(os = get_os(triple),
@@ -211,7 +211,7 @@ fn main(vec[str] args) {
                     optflag("save-temps"), optopt("sysroot"),
                     optflag("time-passes"), optflag("no-typestate"),
                     optflag("noverify"));
-    auto binary = _vec.shift[str](args);
+    auto binary = Vec.shift[str](args);
     auto match;
     alt (GetOpts.getopts(args, opts)) {
         case (GetOpts.failure(?f)) {
@@ -282,13 +282,13 @@ fn main(vec[str] args) {
         session.session(target_crate_num, target_cfg, sopts,
                         crate_cache, md, front.codemap.new_codemap());
 
-    auto n_inputs = _vec.len[str](match.free);
+    auto n_inputs = Vec.len[str](match.free);
 
     if (glue) {
         if (n_inputs > 0u) {
             sess.err("No input files allowed with --glue.");
         }
-        auto out = option.from_maybe[str]("glue.bc", output_file);
+        auto out = Option.from_maybe[str]("glue.bc", output_file);
         middle.trans.make_common_glue(sess, out);
         ret;
     }
@@ -304,19 +304,19 @@ fn main(vec[str] args) {
     if (pretty) {
         pretty_print_input(sess, env, ifile);
     } else if (ls) {
-        front.creader.list_file_metadata(ifile, std.io.stdout());
+        front.creader.list_file_metadata(ifile, std.IO.stdout());
     } else {
         alt (output_file) {
             case (none[str]) {
-                let vec[str] parts = _str.split(ifile, '.' as u8);
-                _vec.pop[str](parts);
+                let vec[str] parts = Str.split(ifile, '.' as u8);
+                Vec.pop[str](parts);
                 alt (output_type) {
                     case (Link.output_type_none) { parts += vec("pp"); }
                     case (Link.output_type_bitcode) { parts += vec("bc"); }
                     case (Link.output_type_assembly) { parts += vec("s"); }
                     case (Link.output_type_object) { parts += vec("o"); }
                 }
-                auto ofile = _str.connect(parts, ".");
+                auto ofile = Str.connect(parts, ".");
                 compile_input(sess, env, ifile, ofile);
             }
             case (some[str](?ofile)) {
diff --git a/src/comp/driver/session.rs b/src/comp/driver/session.rs
index cf34bb7cf8f..644846d06b1 100644
--- a/src/comp/driver/session.rs
+++ b/src/comp/driver/session.rs
@@ -2,10 +2,10 @@ import front.ast;
 import front.codemap;
 import util.common.span;
 import util.common.ty_mach;
-import std._uint;
+import std.UInt;
 import std.Term;
-import std.io;
-import std.map;
+import std.IO;
+import std.Map;
 
 tag os {
     os_win32;
@@ -42,25 +42,25 @@ type crate_metadata = rec(str name,
 fn emit_diagnostic(span sp, str msg, str kind, u8 color, codemap.codemap cm) {
     auto lo = codemap.lookup_pos(cm, sp.lo);
     auto hi = codemap.lookup_pos(cm, sp.hi);
-    io.stdout().write_str(#fmt("%s:%u:%u:%u:%u: ", lo.filename, lo.line,
+    IO.stdout().write_str(#fmt("%s:%u:%u:%u:%u: ", lo.filename, lo.line,
                                lo.col, hi.line, hi.col));
 
     if (Term.color_supported()) {
-        Term.fg(io.stdout().get_buf_writer(), color);
+        Term.fg(IO.stdout().get_buf_writer(), color);
     }
 
-    io.stdout().write_str(#fmt("%s:", kind));
+    IO.stdout().write_str(#fmt("%s:", kind));
 
     if (Term.color_supported()) {
-        Term.reset(io.stdout().get_buf_writer());
+        Term.reset(IO.stdout().get_buf_writer());
     }
 
-    io.stdout().write_str(#fmt(" %s\n", msg));
+    IO.stdout().write_str(#fmt(" %s\n", msg));
 }
 
 state obj session(ast.crate_num cnum,
                   @config targ_cfg, @options opts,
-                  map.hashmap[int, crate_metadata] crates,
+                  Map.hashmap[int, crate_metadata] crates,
                   mutable vec[@ast.meta_item] metadata,
                   codemap.codemap cm) {
 
diff --git a/src/comp/front/ast.rs b/src/comp/front/ast.rs
index 574ebd4a63c..0e15c964aa6 100644
--- a/src/comp/front/ast.rs
+++ b/src/comp/front/ast.rs
@@ -1,8 +1,8 @@
 
-import std.map.hashmap;
-import std.option;
-import std._str;
-import std._vec;
+import std.Map.hashmap;
+import std.Option;
+import std.Str;
+import std.Vec;
 import util.common.span;
 import util.common.spanned;
 import util.common.ty_mach;
@@ -24,8 +24,8 @@ type ty_param = ident;
 tag ann {
     ann_none;
     ann_type(middle.ty.t,
-             option.t[vec[middle.ty.t]], /* ty param substs */
-             option.t[@ts_ann]); /* pre- and postcondition for typestate */
+             Option.t[vec[middle.ty.t]], /* ty param substs */
+             Option.t[@ts_ann]); /* pre- and postcondition for typestate */
 }
 
 tag def {
@@ -79,8 +79,8 @@ tag crate_directive_ {
     // 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_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);
@@ -100,7 +100,7 @@ tag block_index_entry {
     bie_tag_variant(@item /* tag item */, uint /* variant index */);
 }
 type block_ = rec(vec[@stmt] stmts,
-                  option.t[@expr] expr,
+                  Option.t[@expr] expr,
                   hashmap[ident,block_index_entry] index,
                   ann a); /* ann is only meaningful for the ts_ann field */
 
@@ -111,7 +111,7 @@ 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);
+    pat_tag(path, vec[@pat], Option.t[variant_def], ann);
 }
 
 tag mutability {
@@ -226,10 +226,10 @@ tag init_op {
 type initializer = rec(init_op op,
                        @expr expr);
 
-type local = rec(option.t[@ty] ty,
+type local = rec(Option.t[@ty] ty,
                  bool infer,
                  ident ident,
-                 option.t[initializer] init,
+                 Option.t[initializer] init,
                  def_id id,
                  ann ann);
 
@@ -253,16 +253,16 @@ type expr = spanned[expr_];
 tag expr_ {
     expr_vec(vec[@expr], mutability, ann);
     expr_tup(vec[elt], ann);
-    expr_rec(vec[field], option.t[@expr], ann);
+    expr_rec(vec[field], Option.t[@expr], ann);
     expr_call(@expr, vec[@expr], ann);
     expr_self_method(ident, ann);
-    expr_bind(@expr, vec[option.t[@expr]], ann);
-    expr_spawn(spawn_dom, option.t[str], @expr, vec[@expr], ann);
+    expr_bind(@expr, vec[Option.t[@expr]], ann);
+    expr_spawn(spawn_dom, Option.t[str], @expr, vec[@expr], ann);
     expr_binary(binop, @expr, @expr, ann);
     expr_unary(unop, @expr, ann);
     expr_lit(@lit, ann);
     expr_cast(@expr, @ty, ann);
-    expr_if(@expr, block, option.t[@expr], ann);
+    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);
@@ -275,13 +275,13 @@ tag expr_ {
     expr_recv(@expr /* TODO: @expr|is_lval */, @expr, ann);
     expr_field(@expr, ident, ann);
     expr_index(@expr, @expr, ann);
-    expr_path(path, option.t[def], ann);
-    expr_ext(path, vec[@expr], option.t[str], @expr, ann);
+    expr_path(path, Option.t[def], ann);
+    expr_ext(path, vec[@expr], Option.t[str], @expr, ann);
     expr_fail(ann);
     expr_break(ann);
     expr_cont(ann);
-    expr_ret(option.t[@expr], ann);
-    expr_put(option.t[@expr], ann);
+    expr_ret(Option.t[@expr], ann);
+    expr_put(Option.t[@expr], ann);
     expr_be(@expr, ann);
     expr_log(int, @expr, ann);
 /* just an assert, no significance to typestate */
@@ -331,7 +331,7 @@ tag ty_ {
     ty_rec(vec[ty_field]);
     ty_fn(proto, vec[ty_arg], @ty);
     ty_obj(vec[ty_method]);
-    ty_path(path, option.t[def]);
+    ty_path(path, Option.t[def]);
     ty_type;
     ty_constr(@ty, vec[@constr]);
 }
@@ -364,7 +364,7 @@ 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,
-                option.t[@method] dtor);
+                Option.t[@method] dtor);
 
 tag mod_index_entry {
     mie_view_item(@view_item);
@@ -402,8 +402,8 @@ type variant = spanned[variant_];
 
 type view_item = spanned[view_item_];
 tag view_item_ {
-    view_item_use(ident, vec[@meta_item], def_id, option.t[int]);
-    view_item_import(ident, vec[ident], def_id, option.t[def]);
+    view_item_use(ident, vec[@meta_item], def_id, Option.t[int]);
+    view_item_import(ident, vec[ident], def_id, Option.t[def]);
     view_item_export(ident);
 }
 
@@ -423,7 +423,7 @@ tag item_ {
 type native_item = spanned[native_item_];
 tag native_item_ {
     native_item_ty(ident, def_id);
-    native_item_fn(ident, option.t[str],
+    native_item_fn(ident, Option.t[str],
                    fn_decl, vec[ty_param], def_id, ann);
 }
 
@@ -542,7 +542,7 @@ fn is_exported(ident i, _mod m) -> bool {
     for (@ast.view_item vi in m.view_items) {
         alt (vi.node) {
             case (ast.view_item_export(?id)) {
-                if (_str.eq(i, id)) {
+                if (Str.eq(i, id)) {
                     ret true;
                 }
                 count += 1;
@@ -574,7 +574,7 @@ fn is_constraint_arg(@expr e) -> bool {
         case (expr_lit(_,_)) {
             ret true;
         }
-        case (expr_path(_, option.some[def](def_local(_)), _)) {
+        case (expr_path(_, Option.some[def](def_local(_)), _)) {
             ret true;
         }
         case (_) {
diff --git a/src/comp/front/codemap.rs b/src/comp/front/codemap.rs
index 402b488487e..578f574b2f2 100644
--- a/src/comp/front/codemap.rs
+++ b/src/comp/front/codemap.rs
@@ -1,4 +1,4 @@
-import std._vec;
+import std.Vec;
 
 /* A codemap is a thing that maps uints to file/line/column positions
  * in a crate. This to make it possible to represent the positions
@@ -24,18 +24,18 @@ fn new_filemap(str filename, uint start_pos) -> filemap {
 }
 
 fn next_line(filemap file, uint pos) {
-    _vec.push[uint](file.lines, pos);
+    Vec.push[uint](file.lines, pos);
 }
 
 fn lookup_pos(codemap map, uint pos) -> loc {
-    auto a = 0u; auto b = _vec.len[filemap](map.files);
+    auto a = 0u; auto b = Vec.len[filemap](map.files);
     while (b - a > 1u) {
         auto m = (a + b) / 2u;
         if (map.files.(m).start_pos > pos) { b = m; }
         else { a = m; }
     }
     auto f = map.files.(a);
-    a = 0u; b = _vec.len[uint](f.lines);
+    a = 0u; b = Vec.len[uint](f.lines);
     while (b - a > 1u) {
         auto m = (a + b) / 2u;
         if (f.lines.(m) > pos) { b = m; }
diff --git a/src/comp/front/creader.rs b/src/comp/front/creader.rs
index a9660bf52e5..d5067b2518b 100644
--- a/src/comp/front/creader.rs
+++ b/src/comp/front/creader.rs
@@ -14,17 +14,17 @@ import back.x86;
 import util.common;
 import util.common.span;
 
-import std._str;
-import std._uint;
-import std._vec;
-import std.ebml;
-import std.fs;
-import std.io;
-import std.option;
-import std.option.none;
-import std.option.some;
-import std.os;
-import std.map.hashmap;
+import std.Str;
+import std.UInt;
+import std.Vec;
+import std.EBML;
+import std.FS;
+import std.IO;
+import std.Option;
+import std.Option.none;
+import std.Option.some;
+import std.OS;
+import std.Map.hashmap;
 
 // TODO: map to a real type here.
 type env = @rec(
@@ -122,7 +122,7 @@ fn parse_ty(@pstate st, str_def sd) -> ty.t {
             while (peek(st) as char != ']') {
                 auto name = "";
                 while (peek(st) as char != '=') {
-                    name += _str.unsafe_from_byte(next(st));
+                    name += Str.unsafe_from_byte(next(st));
                 }
                 st.pos = st.pos + 1u;
                 fields += vec(rec(ident=name, mt=parse_mt(st, sd)));
@@ -160,7 +160,7 @@ fn parse_ty(@pstate st, str_def sd) -> ty.t {
                 }
                 auto name = "";
                 while (peek(st) as char != '[') {
-                    name += _str.unsafe_from_byte(next(st));
+                    name += Str.unsafe_from_byte(next(st));
                 }
                 auto func = parse_ty_fn(st, sd);
                 methods += vec(rec(proto=proto,
@@ -210,7 +210,7 @@ fn parse_mt(@pstate st, str_def sd) -> ty.mt {
 fn parse_def(@pstate st, str_def sd) -> ast.def_id {
     auto def = "";
     while (peek(st) as char != '|') {
-        def += _str.unsafe_from_byte(next(st));
+        def += Str.unsafe_from_byte(next(st));
     }
     st.pos = st.pos + 1u;
     ret sd(def);
@@ -265,7 +265,7 @@ fn parse_ty_fn(@pstate st, str_def sd) -> tup(vec[ty.arg], ty.t) {
 
 fn parse_def_id(vec[u8] buf) -> ast.def_id {
     auto colon_idx = 0u;
-    auto len = _vec.len[u8](buf);
+    auto len = Vec.len[u8](buf);
     while (colon_idx < len && buf.(colon_idx) != (':' as u8)) {
         colon_idx += 1u;
     }
@@ -274,30 +274,30 @@ fn parse_def_id(vec[u8] buf) -> ast.def_id {
         fail;
     }
 
-    auto crate_part = _vec.slice[u8](buf, 0u, colon_idx);
-    auto def_part = _vec.slice[u8](buf, colon_idx + 1u, len);
-    auto crate_num = _uint.parse_buf(crate_part, 10u) as int;
-    auto def_num = _uint.parse_buf(def_part, 10u) as int;
+    auto crate_part = Vec.slice[u8](buf, 0u, colon_idx);
+    auto def_part = Vec.slice[u8](buf, colon_idx + 1u, len);
+    auto crate_num = UInt.parse_buf(crate_part, 10u) as int;
+    auto def_num = UInt.parse_buf(def_part, 10u) as int;
     ret tup(crate_num, def_num);
 }
 
-fn lookup_hash(&ebml.doc d, fn(vec[u8]) -> bool eq_fn, uint hash)
-    -> option.t[ebml.doc] {
-    auto index = ebml.get_doc(d, metadata.tag_index);
-    auto table = ebml.get_doc(index, metadata.tag_index_table);
+fn lookup_hash(&EBML.doc d, fn(vec[u8]) -> bool eq_fn, uint hash)
+    -> Option.t[EBML.doc] {
+    auto index = EBML.get_doc(d, metadata.tag_index);
+    auto table = EBML.get_doc(index, metadata.tag_index_table);
 
     auto hash_pos = table.start + (hash % 256u) * 4u;
-    auto pos = ebml.be_uint_from_bytes(d.data, hash_pos, 4u);
-    auto bucket = ebml.doc_at(d.data, pos);
+    auto pos = EBML.be_uint_from_bytes(d.data, hash_pos, 4u);
+    auto bucket = EBML.doc_at(d.data, pos);
     // Awkward logic because we can't ret from foreach yet
-    auto result = option.none[ebml.doc];
+    auto result = Option.none[EBML.doc];
     auto belt = metadata.tag_index_buckets_bucket_elt;
-    for each (ebml.doc elt in ebml.tagged_docs(bucket, belt)) {
+    for each (EBML.doc elt in EBML.tagged_docs(bucket, belt)) {
         alt (result) {
-            case (option.none[ebml.doc]) {
-                auto pos = ebml.be_uint_from_bytes(elt.data, elt.start, 4u);
-                if (eq_fn(_vec.slice[u8](elt.data, elt.start+4u, elt.end))) {
-                    result = option.some[ebml.doc](ebml.doc_at(d.data, pos));
+            case (Option.none[EBML.doc]) {
+                auto pos = EBML.be_uint_from_bytes(elt.data, elt.start, 4u);
+                if (eq_fn(Vec.slice[u8](elt.data, elt.start+4u, elt.end))) {
+                    result = Option.some[EBML.doc](EBML.doc_at(d.data, pos));
                 }
             }
             case (_) {}
@@ -310,113 +310,113 @@ fn lookup_hash(&ebml.doc d, fn(vec[u8]) -> bool eq_fn, uint hash)
 // definition the path refers to.
 fn resolve_path(vec[ast.ident] path, vec[u8] data) -> resolve_result {
     fn eq_item(vec[u8] data, str s) -> bool {
-        ret _str.eq(_str.unsafe_from_bytes(data), s);
+        ret Str.eq(Str.unsafe_from_bytes(data), s);
     }
-    auto s = _str.connect(path, ".");
-    auto md = ebml.new_doc(data);
-    auto paths = ebml.get_doc(md, metadata.tag_paths);
+    auto s = Str.connect(path, ".");
+    auto md = EBML.new_doc(data);
+    auto paths = EBML.get_doc(md, metadata.tag_paths);
     auto eqer = bind eq_item(_, s);
     alt (lookup_hash(paths, eqer, metadata.hash_path(s))) {
-        case (option.some[ebml.doc](?d)) {
-            auto did_doc = ebml.get_doc(d, metadata.tag_def_id);
-            ret rr_ok(parse_def_id(ebml.doc_data(did_doc)));
+        case (Option.some[EBML.doc](?d)) {
+            auto did_doc = EBML.get_doc(d, metadata.tag_def_id);
+            ret rr_ok(parse_def_id(EBML.doc_data(did_doc)));
         }
-        case (option.none[ebml.doc]) {
+        case (Option.none[EBML.doc]) {
             ret rr_not_found(s);
         }
     }
 }
 
-fn maybe_find_item(int item_id, &ebml.doc items) -> option.t[ebml.doc] {
+fn maybe_find_item(int item_id, &EBML.doc items) -> Option.t[EBML.doc] {
     fn eq_item(vec[u8] bytes, int item_id) -> bool {
-        ret ebml.be_uint_from_bytes(bytes, 0u, 4u) as int == item_id;
+        ret EBML.be_uint_from_bytes(bytes, 0u, 4u) as int == item_id;
     }
     auto eqer = bind eq_item(_, item_id);
     ret lookup_hash(items, eqer, metadata.hash_def_num(item_id));
 }
 
-fn find_item(int item_id, &ebml.doc items) -> ebml.doc {
+fn find_item(int item_id, &EBML.doc items) -> EBML.doc {
     alt (maybe_find_item(item_id, items)) {
-        case (option.some[ebml.doc](?d)) {ret d;}
+        case (Option.some[EBML.doc](?d)) {ret d;}
     }
 }
 
 // Looks up an item in the given metadata and returns an EBML doc pointing
 // to the item data.
-fn lookup_item(int item_id, vec[u8] data) -> ebml.doc {
-    auto items = ebml.get_doc(ebml.new_doc(data), metadata.tag_items);
+fn lookup_item(int item_id, vec[u8] data) -> EBML.doc {
+    auto items = EBML.get_doc(EBML.new_doc(data), metadata.tag_items);
     ret find_item(item_id, items);
 }
 
-fn item_kind(&ebml.doc item) -> u8 {
-    auto kind = ebml.get_doc(item, metadata.tag_items_data_item_kind);
-    ret ebml.doc_as_uint(kind) as u8;
+fn item_kind(&EBML.doc item) -> u8 {
+    auto kind = EBML.get_doc(item, metadata.tag_items_data_item_kind);
+    ret EBML.doc_as_uint(kind) as u8;
 }
 
-fn item_symbol(&ebml.doc item) -> str {
-    auto sym = ebml.get_doc(item, metadata.tag_items_data_item_symbol);
-    ret _str.unsafe_from_bytes(ebml.doc_data(sym));
+fn item_symbol(&EBML.doc item) -> str {
+    auto sym = EBML.get_doc(item, metadata.tag_items_data_item_symbol);
+    ret Str.unsafe_from_bytes(EBML.doc_data(sym));
 }
 
-fn variant_tag_id(&ebml.doc d) -> ast.def_id {
-    auto tagdoc = ebml.get_doc(d, metadata.tag_items_data_item_tag_id);
-    ret parse_def_id(ebml.doc_data(tagdoc));
+fn variant_tag_id(&EBML.doc d) -> ast.def_id {
+    auto tagdoc = EBML.get_doc(d, metadata.tag_items_data_item_tag_id);
+    ret parse_def_id(EBML.doc_data(tagdoc));
 }
 
-fn item_type(&ebml.doc item, int this_cnum, ty.ctxt tcx) -> ty.t {
+fn item_type(&EBML.doc item, int this_cnum, ty.ctxt tcx) -> ty.t {
     fn parse_external_def_id(int this_cnum, str s) -> ast.def_id {
         // FIXME: This is completely wrong when linking against a crate
         // that, in turn, links against another crate. We need a mapping
         // from crate ID to crate "meta" attributes as part of the crate
         // metadata.
-        auto buf = _str.bytes(s);
+        auto buf = Str.bytes(s);
         auto external_def_id = parse_def_id(buf);
         ret tup(this_cnum, external_def_id._1);
     }
 
-    auto tp = ebml.get_doc(item, metadata.tag_items_data_item_type);
-    auto s = _str.unsafe_from_bytes(ebml.doc_data(tp));
+    auto tp = EBML.get_doc(item, metadata.tag_items_data_item_type);
+    auto s = Str.unsafe_from_bytes(EBML.doc_data(tp));
     ret parse_ty_data(item.data, this_cnum, tp.start, tp.end - tp.start,
                       bind parse_external_def_id(this_cnum, _), tcx);
 }
 
-fn item_ty_param_count(&ebml.doc item, int this_cnum) -> uint {
+fn item_ty_param_count(&EBML.doc item, int this_cnum) -> uint {
     let uint ty_param_count = 0u;
     auto tp = metadata.tag_items_data_item_ty_param_count;
-    for each (ebml.doc p in ebml.tagged_docs(item, tp)) {
-        ty_param_count = ebml.vint_at(ebml.doc_data(p), 0u)._0;
+    for each (EBML.doc p in EBML.tagged_docs(item, tp)) {
+        ty_param_count = EBML.vint_at(EBML.doc_data(p), 0u)._0;
     }
     ret ty_param_count;
 }
 
-fn tag_variant_ids(&ebml.doc item, int this_cnum) -> vec[ast.def_id] {
+fn tag_variant_ids(&EBML.doc item, int this_cnum) -> vec[ast.def_id] {
     let vec[ast.def_id] ids = vec();
     auto v = metadata.tag_items_data_item_variant;
-    for each (ebml.doc p in ebml.tagged_docs(item, v)) {
-        auto ext = parse_def_id(ebml.doc_data(p));
-        _vec.push[ast.def_id](ids, tup(this_cnum, ext._1));
+    for each (EBML.doc p in EBML.tagged_docs(item, v)) {
+        auto ext = parse_def_id(EBML.doc_data(p));
+        Vec.push[ast.def_id](ids, tup(this_cnum, ext._1));
     }
     ret ids;
 }
 
-fn get_metadata_section(str filename) -> option.t[vec[u8]] {
+fn get_metadata_section(str filename) -> Option.t[vec[u8]] {
     auto mb = llvm.LLVMRustCreateMemoryBufferWithContentsOfFile
-        (_str.buf(filename));
-    if (mb as int == 0) {ret option.none[vec[u8]];}
+        (Str.buf(filename));
+    if (mb as int == 0) {ret Option.none[vec[u8]];}
     auto of = mk_object_file(mb);
     auto si = mk_section_iter(of.llof);
     while (llvm.LLVMIsSectionIteratorAtEnd(of.llof, si.llsi) == False) {
         auto name_buf = llvm.LLVMGetSectionName(si.llsi);
-        auto name = _str.str_from_cstr(name_buf);
-        if (_str.eq(name, x86.get_meta_sect_name())) {
+        auto name = Str.str_from_cstr(name_buf);
+        if (Str.eq(name, x86.get_meta_sect_name())) {
             auto cbuf = llvm.LLVMGetSectionContents(si.llsi);
             auto csz = llvm.LLVMGetSectionSize(si.llsi);
-            auto cvbuf = cbuf as _vec.vbuf;
-            ret option.some[vec[u8]](_vec.vec_from_vbuf[u8](cvbuf, csz));
+            auto cvbuf = cbuf as Vec.vbuf;
+            ret Option.some[vec[u8]](Vec.vec_from_vbuf[u8](cvbuf, csz));
         }
         llvm.LLVMMoveToNextSection(si.llsi);
     }
-    ret option.none[vec[u8]];
+    ret Option.none[vec[u8]];
 }
 
 
@@ -426,9 +426,9 @@ fn load_crate(session.session sess,
               vec[str] library_search_paths) {
     auto filename = parser.default_native_name(sess, ident);
     for (str library_search_path in library_search_paths) {
-        auto path = fs.connect(library_search_path, filename);
+        auto path = FS.connect(library_search_path, filename);
         alt (get_metadata_section(path)) {
-            case (option.some[vec[u8]](?cvec)) {
+            case (Option.some[vec[u8]](?cvec)) {
                 sess.set_external_crate(cnum, rec(name=ident, data=cvec));
                 ret;
             }
@@ -442,7 +442,7 @@ fn load_crate(session.session sess,
 }
 
 fn fold_view_item_use(&env e, &span sp, ast.ident ident,
-        vec[@ast.meta_item] meta_items, ast.def_id id, option.t[int] cnum_opt)
+        vec[@ast.meta_item] meta_items, ast.def_id id, Option.t[int] cnum_opt)
         -> @ast.view_item {
     auto cnum;
     if (!e.crate_cache.contains_key(ident)) {
@@ -497,7 +497,7 @@ fn kind_has_type_params(u8 kind_ch) -> bool {
 // Crate metadata queries
 
 fn lookup_def(session.session sess, int cnum, vec[ast.ident] path)
-        -> option.t[ast.def] {
+        -> Option.t[ast.def] {
     auto data = sess.get_external_crate(cnum).data;
 
     auto did;
@@ -568,7 +568,7 @@ fn get_tag_variants(session.session sess, ty.ctxt tcx, ast.def_id def)
         -> vec[trans.variant_info] {
     auto external_crate_id = def._0;
     auto data = sess.get_external_crate(external_crate_id).data;
-    auto items = ebml.get_doc(ebml.new_doc(data), metadata.tag_items);
+    auto items = EBML.get_doc(EBML.new_doc(data), metadata.tag_items);
     auto item = find_item(def._1, items);
 
     let vec[trans.variant_info] infos = vec();
@@ -593,52 +593,52 @@ fn get_tag_variants(session.session sess, ty.ctxt tcx, ast.def_id def)
     ret infos;
 }
 
-fn list_file_metadata(str path, io.writer out) {
+fn list_file_metadata(str path, IO.writer out) {
     alt (get_metadata_section(path)) {
-        case (option.some[vec[u8]](?bytes)) {
+        case (Option.some[vec[u8]](?bytes)) {
             list_crate_metadata(bytes, out);
         }
-        case (option.none[vec[u8]]) {
+        case (Option.none[vec[u8]]) {
             out.write_str("Could not find metadata in " + path + ".\n");
         }
     }
 }
 
-fn read_path(&ebml.doc d) -> tup(str, uint) {
-    auto desc = ebml.doc_data(d);
-    auto pos = ebml.be_uint_from_bytes(desc, 0u, 4u);
-    auto pathbytes = _vec.slice[u8](desc, 4u, _vec.len[u8](desc));
-    auto path = _str.unsafe_from_bytes(pathbytes);
+fn read_path(&EBML.doc d) -> tup(str, uint) {
+    auto desc = EBML.doc_data(d);
+    auto pos = EBML.be_uint_from_bytes(desc, 0u, 4u);
+    auto pathbytes = Vec.slice[u8](desc, 4u, Vec.len[u8](desc));
+    auto path = Str.unsafe_from_bytes(pathbytes);
     ret tup(path, pos);
 }
 
-fn list_crate_metadata(vec[u8] bytes, io.writer out) {
-    auto md = ebml.new_doc(bytes);
-    auto paths = ebml.get_doc(md, metadata.tag_paths);
-    auto items = ebml.get_doc(md, metadata.tag_items);
-    auto index = ebml.get_doc(paths, metadata.tag_index);
-    auto bs = ebml.get_doc(index, metadata.tag_index_buckets);
-    for each (ebml.doc bucket in
-              ebml.tagged_docs(bs, metadata.tag_index_buckets_bucket)) {
+fn list_crate_metadata(vec[u8] bytes, IO.writer out) {
+    auto md = EBML.new_doc(bytes);
+    auto paths = EBML.get_doc(md, metadata.tag_paths);
+    auto items = EBML.get_doc(md, metadata.tag_items);
+    auto index = EBML.get_doc(paths, metadata.tag_index);
+    auto bs = EBML.get_doc(index, metadata.tag_index_buckets);
+    for each (EBML.doc bucket in
+              EBML.tagged_docs(bs, metadata.tag_index_buckets_bucket)) {
         auto et = metadata.tag_index_buckets_bucket_elt;
-        for each (ebml.doc elt in ebml.tagged_docs(bucket, et)) {
+        for each (EBML.doc elt in EBML.tagged_docs(bucket, et)) {
             auto data = read_path(elt);
-            auto def = ebml.doc_at(bytes, data._1);
-            auto did_doc = ebml.get_doc(def, metadata.tag_def_id);
-            auto did = parse_def_id(ebml.doc_data(did_doc));
+            auto def = EBML.doc_at(bytes, data._1);
+            auto did_doc = EBML.get_doc(def, metadata.tag_def_id);
+            auto did = parse_def_id(EBML.doc_data(did_doc));
             out.write_str(#fmt("%s (%s)\n", data._0,
                                describe_def(items, did)));
         }
     }
 }
 
-fn describe_def(&ebml.doc items, ast.def_id id) -> str {
+fn describe_def(&EBML.doc items, ast.def_id id) -> str {
     if (id._0 != 0) {ret "external";}
     alt (maybe_find_item(id._1 as int, items)) {
-        case (option.some[ebml.doc](?item)) {
+        case (Option.some[EBML.doc](?item)) {
             ret item_kind_to_str(item_kind(item));
         }
-        case (option.none[ebml.doc]) {
+        case (Option.none[EBML.doc]) {
             ret "??"; // Native modules don't seem to get item entries.
         }
     }
diff --git a/src/comp/front/eval.rs b/src/comp/front/eval.rs
index a1b3392c609..e1ad59bc5b7 100644
--- a/src/comp/front/eval.rs
+++ b/src/comp/front/eval.rs
@@ -1,9 +1,9 @@
-import std._vec;
-import std._str;
-import std.option;
-import std.option.some;
-import std.option.none;
-import std.map.hashmap;
+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;
@@ -91,7 +91,7 @@ fn val_as_str(val v) -> str {
 
 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)) {
+        if (Str.eq(i, pair._0)) {
             ret pair._1;
         }
     }
@@ -114,8 +114,8 @@ fn eval_lit(ctx cx, span sp, @ast.lit lit) -> val {
 fn eval_expr(ctx cx, 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) {
+            if (Vec.len[ident](pth.node.idents) == 1u &&
+                Vec.len[@ast.ty](pth.node.types) == 0u) {
                 ret lookup(cx.sess, e, x.span, pth.node.idents.(0));
             }
             cx.sess.span_err(x.span, "evaluating structured path-name");
@@ -224,7 +224,7 @@ fn val_eq(session.session sess, span sp, val av, val bv) -> bool {
         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),
+        ret Str.eq(val_as_str(av),
                     val_as_str(bv));
     }
     sess.span_err(sp, "bad types in comparison");
@@ -388,7 +388,7 @@ fn eval_crate_directive(ctx cx,
                 case (none[filename]) {}
             }
 
-            auto full_path = prefix + std.fs.path_sep() + file_path;
+            auto full_path = prefix + std.FS.path_sep() + file_path;
 
             if (cx.mode == mode_depend) {
                 cx.deps += vec(full_path);
@@ -405,7 +405,7 @@ fn eval_crate_directive(ctx cx,
             auto im = ast.item_mod(id, m0, next_id);
             auto i = @spanned(cdir.span.lo, cdir.span.hi, im);
             ast.index_item(index, i);
-            _vec.push[@ast.item](items, i);
+            Vec.push[@ast.item](items, i);
         }
 
         case (ast.cdir_dir_mod(?id, ?dir_opt, ?cdirs)) {
@@ -418,16 +418,16 @@ fn eval_crate_directive(ctx cx,
                 case (none[filename]) {}
             }
 
-            auto full_path = prefix + std.fs.path_sep() + path;
+            auto full_path = prefix + std.FS.path_sep() + path;
             auto m0 = eval_crate_directives_to_mod(cx, e, cdirs, full_path);
             auto im = ast.item_mod(id, m0, cx.p.next_def_id());
             auto i = @spanned(cdir.span.lo, cdir.span.hi, im);
             ast.index_item(index, i);
-            _vec.push[@ast.item](items, i);
+            Vec.push[@ast.item](items, i);
         }
 
         case (ast.cdir_view_item(?vi)) {
-            _vec.push[@ast.view_item](view_items, vi);
+            Vec.push[@ast.view_item](view_items, vi);
             ast.index_view_item(index, vi);
         }
 
diff --git a/src/comp/front/extenv.rs b/src/comp/front/extenv.rs
index 6dc9c5ec021..a3fdde955d5 100644
--- a/src/comp/front/extenv.rs
+++ b/src/comp/front/extenv.rs
@@ -6,9 +6,9 @@
 
 import util.common;
 
-import std._str;
-import std._vec;
-import std.option;
+import std.Str;
+import std.Vec;
+import std.Option;
 import std.GenericOS;
 
 export expand_syntax_ext;
@@ -17,9 +17,9 @@ export expand_syntax_ext;
 fn expand_syntax_ext(parser.parser p,
                      common.span sp,
                      vec[@ast.expr] args,
-                     option.t[str] body) -> @ast.expr {
+                     Option.t[str] body) -> @ast.expr {
 
-    if (_vec.len[@ast.expr](args) != 1u) {
+    if (Vec.len[@ast.expr](args) != 1u) {
         p.err("malformed #env call");
     }
 
diff --git a/src/comp/front/extfmt.rs b/src/comp/front/extfmt.rs
index aea3e7df9c4..8aedf587236 100644
--- a/src/comp/front/extfmt.rs
+++ b/src/comp/front/extfmt.rs
@@ -6,11 +6,11 @@
 
 import util.common;
 
-import std._str;
-import std._vec;
-import std.option;
-import std.option.none;
-import std.option.some;
+import std.Str;
+import std.Vec;
+import std.Option;
+import std.Option.none;
+import std.Option.some;
 
 import std.ExtFmt.CT.signedness;
 import std.ExtFmt.CT.signed;
@@ -47,9 +47,9 @@ export expand_syntax_ext;
 
 // FIXME: Need to thread parser through here to handle errors correctly
 fn expand_syntax_ext(vec[@ast.expr] args,
-                     option.t[str] body) -> @ast.expr {
+                     Option.t[str] body) -> @ast.expr {
 
-    if (_vec.len[@ast.expr](args) == 0u) {
+    if (Vec.len[@ast.expr](args) == 0u) {
         log_err "malformed #fmt call";
         fail;
     }
@@ -60,8 +60,8 @@ fn expand_syntax_ext(vec[@ast.expr] args,
     // 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);
+    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);
 }
 
@@ -148,7 +148,7 @@ fn pieces_to_expr(vec[piece] pieces, vec[@ast.expr] args) -> @ast.expr {
         }
 
         auto recexpr = ast.expr_rec(astfields,
-                                    option.none[@ast.expr],
+                                    Option.none[@ast.expr],
                                     ast.ann_none);
         auto sp_recexpr = @rec(node=recexpr, span=sp);
         ret sp_recexpr;
@@ -196,7 +196,7 @@ fn pieces_to_expr(vec[piece] pieces, vec[@ast.expr] args) -> @ast.expr {
             // FIXME: 0-length vectors can't have their type inferred
             // through the rec that these flags are a member of, so
             // this is a hack placeholder flag
-            if (_vec.len[@ast.expr](flagexprs) == 0u) {
+            if (Vec.len[@ast.expr](flagexprs) == 0u) {
                 flagexprs += vec(make_rt_path_expr(sp, "flag_none"));
             }
 
@@ -303,7 +303,7 @@ fn pieces_to_expr(vec[piece] pieces, vec[@ast.expr] args) -> @ast.expr {
         auto unsupported = "conversion not supported in #fmt string";
 
         alt (cnv.param) {
-            case (option.none[int]) {
+            case (Option.none[int]) {
             }
             case (_) {
                 log_err unsupported;
@@ -398,7 +398,7 @@ fn pieces_to_expr(vec[piece] pieces, vec[@ast.expr] args) -> @ast.expr {
     fn log_conv(conv c) {
         alt (c.param) {
             case (some[int](?p)) {
-                log "param: " + std._int.to_str(p, 10u);
+                log "param: " + std.Int.to_str(p, 10u);
             }
             case (_) {
                 log "param: none";
@@ -425,10 +425,10 @@ fn pieces_to_expr(vec[piece] pieces, vec[@ast.expr] args) -> @ast.expr {
         }
         alt (c.width) {
             case (count_is(?i)) {
-                log "width: count is " + std._int.to_str(i, 10u);
+                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);
+                log "width: count is param " + std.Int.to_str(i, 10u);
             }
             case (count_is_next_param) {
                 log "width: count is next param";
@@ -439,10 +439,10 @@ fn pieces_to_expr(vec[piece] pieces, vec[@ast.expr] args) -> @ast.expr {
         }
         alt (c.precision) {
             case (count_is(?i)) {
-                log "prec: count is " + std._int.to_str(i, 10u);
+                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);
+                log "prec: count is param " + std.Int.to_str(i, 10u);
             }
             case (count_is_next_param) {
                 log "prec: count is next param";
@@ -498,7 +498,7 @@ fn pieces_to_expr(vec[piece] pieces, vec[@ast.expr] args) -> @ast.expr {
                 tmp_expr = make_add_expr(sp, tmp_expr, s_expr);
             }
             case (piece_conv(?conv)) {
-                if (n >= _vec.len[@ast.expr](args)) {
+                if (n >= Vec.len[@ast.expr](args)) {
                     log_err "too many conversions in #fmt string";
                     fail;
                 }
diff --git a/src/comp/front/lexer.rs b/src/comp/front/lexer.rs
index 4153533afee..a17dd514951 100644
--- a/src/comp/front/lexer.rs
+++ b/src/comp/front/lexer.rs
@@ -1,12 +1,12 @@
-import std.io;
-import std._str;
-import std._vec;
-import std._int;
-import std.map;
-import std.map.hashmap;
-import std.option;
-import std.option.some;
-import std.option.none;
+import std.IO;
+import std.Str;
+import std.Vec;
+import std.Int;
+import std.Map;
+import std.Map.hashmap;
+import std.Option;
+import std.Option.some;
+import std.Option.none;
 import util.common;
 import util.common.new_str_hash;
 
@@ -24,7 +24,7 @@ state type reader = state obj {
     fn get_filemap() -> codemap.filemap;
 };
 
-fn new_reader(io.reader rdr, str filename, codemap.filemap filemap)
+fn new_reader(IO.reader rdr, str filename, codemap.filemap filemap)
     -> reader {
     state obj reader(str file,
                      uint len,
@@ -49,13 +49,13 @@ fn new_reader(io.reader rdr, str filename, codemap.filemap filemap)
         }
 
         fn next() -> char {
-            if (pos < len) {ret _str.char_at(file, pos);}
+            if (pos < len) {ret Str.char_at(file, pos);}
             else {ret -1 as char;}
         }
 
         fn init() {
             if (pos < len) {
-                auto next = _str.char_range_at(file, pos);
+                auto next = Str.char_range_at(file, pos);
                 pos = next._1;
                 ch = next._0;
             }
@@ -67,7 +67,7 @@ fn new_reader(io.reader rdr, str filename, codemap.filemap filemap)
                 if (ch == '\n') {
                     codemap.next_line(fm, chpos);
                 }
-                auto next = _str.char_range_at(file, pos);
+                auto next = Str.char_range_at(file, pos);
                 pos = next._1;
                 ch = next._0;
             } else {
@@ -87,8 +87,8 @@ fn new_reader(io.reader rdr, str filename, codemap.filemap filemap)
             ret fm;
         }
     }
-    auto file = _str.unsafe_from_bytes(rdr.read_whole_stream());
-    auto rd = reader(file, _str.byte_len(file), 0u, -1 as char,
+    auto file = Str.unsafe_from_bytes(rdr.read_whole_stream());
+    auto rd = reader(file, Str.byte_len(file), 0u, -1 as char,
                      filemap.start_pos, filemap.start_pos,
                      keyword_table(),
                      reserved_word_table(),
@@ -97,7 +97,7 @@ fn new_reader(io.reader rdr, str filename, codemap.filemap filemap)
     ret rd;
 }
 
-fn keyword_table() -> std.map.hashmap[str, token.token] {
+fn keyword_table() -> std.Map.hashmap[str, token.token] {
     auto keywords = new_str_hash[token.token]();
 
     keywords.insert("mod", token.MOD);
@@ -205,7 +205,7 @@ fn keyword_table() -> std.map.hashmap[str, token.token] {
     ret keywords;
 }
 
-fn reserved_word_table() -> std.map.hashmap[str, ()] {
+fn reserved_word_table() -> std.Map.hashmap[str, ()] {
     auto reserved = new_str_hash[()]();
     reserved.insert("f16", ());  // IEEE 754-2008 'binary16' interchange fmt
     reserved.insert("f80", ());  // IEEE 754-1985 'extended'
@@ -341,20 +341,20 @@ fn digits_to_string(str s) -> int {
     ret accum_int;
 }
 
-fn scan_exponent(reader rdr) -> option.t[str] {
+fn scan_exponent(reader rdr) -> Option.t[str] {
     auto c = rdr.curr();
     auto res = "";
 
     if (c == 'e' || c == 'E') {
-        res += _str.from_bytes(vec(c as u8));
+        res += Str.from_bytes(vec(c as u8));
         rdr.bump();
         c = rdr.curr();
         if (c == '-' || c == '+') {
-            res += _str.from_bytes(vec(c as u8));
+            res += Str.from_bytes(vec(c as u8));
             rdr.bump();
         }
         auto exponent = scan_dec_digits(rdr);
-        if (_str.byte_len(exponent) > 0u) {
+        if (Str.byte_len(exponent) > 0u) {
             ret(some(res + exponent));
         }
         else {
@@ -374,7 +374,7 @@ fn scan_dec_digits(reader rdr) -> str {
 
     while (is_dec_digit (c) || c == '_') {
         if (c != '_') {
-            res += _str.from_bytes(vec(c as u8));
+            res += Str.from_bytes(vec(c as u8));
         }
         rdr.bump();
         c = rdr.curr();
@@ -574,12 +574,12 @@ fn next_token(reader rdr) -> token.token {
 
     if (is_alpha(c) || c == '_') {
         while (is_alnum(c) || c == '_') {
-            _str.push_char(accum_str, c);
+            Str.push_char(accum_str, c);
             rdr.bump();
             c = rdr.curr();
         }
 
-        if (_str.eq(accum_str, "_")) {
+        if (Str.eq(accum_str, "_")) {
             ret token.UNDERSCORE;
         }
 
@@ -738,37 +738,37 @@ fn next_token(reader rdr) -> token.token {
                         alt (rdr.next()) {
                             case ('n') {
                                 rdr.bump();
-                                _str.push_byte(accum_str, '\n' as u8);
+                                Str.push_byte(accum_str, '\n' as u8);
                             }
                             case ('r') {
                                 rdr.bump();
-                                _str.push_byte(accum_str, '\r' as u8);
+                                Str.push_byte(accum_str, '\r' as u8);
                             }
                             case ('t') {
                                 rdr.bump();
-                                _str.push_byte(accum_str, '\t' as u8);
+                                Str.push_byte(accum_str, '\t' as u8);
                             }
                             case ('\\') {
                                 rdr.bump();
-                                _str.push_byte(accum_str, '\\' as u8);
+                                Str.push_byte(accum_str, '\\' as u8);
                             }
                             case ('"') {
                                 rdr.bump();
-                                _str.push_byte(accum_str, '"' as u8);
+                                Str.push_byte(accum_str, '"' as u8);
                             }
 
                             case ('x') {
-                                _str.push_char(accum_str,
+                                Str.push_char(accum_str,
                                                scan_numeric_escape(rdr));
                             }
 
                             case ('u') {
-                                _str.push_char(accum_str,
+                                Str.push_char(accum_str,
                                                scan_numeric_escape(rdr));
                             }
 
                             case ('U') {
-                                _str.push_char(accum_str,
+                                Str.push_char(accum_str,
                                                scan_numeric_escape(rdr));
                             }
 
@@ -780,7 +780,7 @@ fn next_token(reader rdr) -> token.token {
                         }
                     }
                     case (_) {
-                        _str.push_char(accum_str, rdr.curr());
+                        Str.push_char(accum_str, rdr.curr());
                     }
                 }
                 rdr.bump();
@@ -870,7 +870,7 @@ fn read_line_comment(reader rdr) -> cmnt {
     while (rdr.curr() == ' ') {rdr.bump();}
     auto val = "";
     while (rdr.curr() != '\n' && !rdr.is_eof()) {
-        _str.push_char(val, rdr.curr());
+        Str.push_char(val, rdr.curr());
         rdr.bump();
     }
     ret rec(val=cmnt_line(val),
@@ -887,7 +887,7 @@ fn read_block_comment(reader rdr) -> cmnt {
     auto level = 1;
     while (true) {
         if (rdr.curr() == '\n') {
-            _vec.push[str](lines, val);
+            Vec.push[str](lines, val);
             val = "";
             consume_whitespace(rdr);
         } else {
@@ -895,13 +895,13 @@ fn read_block_comment(reader rdr) -> cmnt {
                 level -= 1;
                 if (level == 0) {
                     rdr.bump(); rdr.bump();
-                    _vec.push[str](lines, val);
+                    Vec.push[str](lines, val);
                     break;
                 }
             } else if (rdr.curr() == '/' && rdr.next() == '*') {
                 level += 1;
             }
-            _str.push_char(val, rdr.curr());
+            Str.push_char(val, rdr.curr());
             rdr.bump();
         }
         if (rdr.is_eof()) {fail;}
@@ -912,16 +912,16 @@ fn read_block_comment(reader rdr) -> cmnt {
 }
 
 fn gather_comments(str path) -> vec[cmnt] {
-    auto srdr = io.file_reader(path);
+    auto srdr = IO.file_reader(path);
     auto rdr = new_reader(srdr, path, codemap.new_filemap(path, 0u));
     let vec[cmnt] comments = vec();
     while (!rdr.is_eof()) {
         while (true) {
             consume_whitespace(rdr);
             if (rdr.curr() == '/' && rdr.next() == '/') {
-                _vec.push[cmnt](comments, read_line_comment(rdr));
+                Vec.push[cmnt](comments, read_line_comment(rdr));
             } else if (rdr.curr() == '/' && rdr.next() == '*') {
-                _vec.push[cmnt](comments, read_block_comment(rdr));
+                Vec.push[cmnt](comments, read_block_comment(rdr));
             } else { break; }
         }
         next_token(rdr);
diff --git a/src/comp/front/parser.rs b/src/comp/front/parser.rs
index e355290d7b0..bcde167157e 100644
--- a/src/comp/front/parser.rs
+++ b/src/comp/front/parser.rs
@@ -1,10 +1,10 @@
-import std.io;
-import std._vec;
-import std._str;
-import std.option;
-import std.option.some;
-import std.option.none;
-import std.map.hashmap;
+import std.IO;
+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 util.common;
@@ -118,12 +118,12 @@ fn new_parser(session.session sess,
             fn get_chpos() -> uint {ret rdr.get_chpos();}
         }
     auto ftype = SOURCE_FILE;
-    if (_str.ends_with(path, ".rc")) {
+    if (Str.ends_with(path, ".rc")) {
         ftype = CRATE_FILE;
     }
-    auto srdr = io.file_reader(path);
+    auto srdr = IO.file_reader(path);
     auto filemap = codemap.new_filemap(path, pos);
-    _vec.push[codemap.filemap](sess.get_codemap().files, filemap);
+    Vec.push[codemap.filemap](sess.get_codemap().files, filemap);
     auto rdr = lexer.new_reader(srdr, path, filemap);
     // Make sure npos points at first actual token.
     lexer.consume_any_whitespace(rdr);
@@ -320,7 +320,7 @@ fn parse_constrs(parser p) -> common.spanned[vec[@ast.constr]] {
                 case (token.IDENT(_)) {
                     auto constr = parse_ty_constr(p);
                     hi = constr.span.hi;
-                    _vec.push[@ast.constr](constrs, constr);
+                    Vec.push[@ast.constr](constrs, constr);
                     if (p.peek() == token.COMMA) {
                         p.bump();
                         more = false;
@@ -496,7 +496,7 @@ fn parse_arg(parser p) -> ast.arg {
 }
 
 fn parse_seq_to_end[T](token.token ket,
-                              option.t[token.token] sep,
+                              Option.t[token.token] sep,
                               (fn(parser) -> T) f,
                               uint hi,
                               parser p) -> vec[T] {
@@ -525,7 +525,7 @@ fn parse_seq_to_end[T](token.token ket,
 
 fn parse_seq[T](token.token bra,
                        token.token ket,
-                       option.t[token.token] sep,
+                       Option.t[token.token] sep,
                        (fn(parser) -> T) f,
                        parser p) -> util.common.spanned[vec[T]] {
     auto lo = p.get_lo_pos();
@@ -764,7 +764,7 @@ fn parse_bottom_expr(parser p) -> @ast.expr {
         case (token.BIND) {
             p.bump();
             auto e = parse_expr_res(p, RESTRICT_NO_CALL_EXPRS);
-            fn parse_expr_opt(parser p) -> option.t[@ast.expr] {
+            fn parse_expr_opt(parser p) -> Option.t[@ast.expr] {
                 alt (p.peek()) {
                     case (token.UNDERSCORE) {
                         p.bump();
@@ -777,7 +777,7 @@ fn parse_bottom_expr(parser p) -> @ast.expr {
             }
 
             auto pf = parse_expr_opt;
-            auto es = parse_seq[option.t[@ast.expr]](token.LPAREN,
+            auto es = parse_seq[Option.t[@ast.expr]](token.LPAREN,
                                                      token.RPAREN,
                                                      some(token.COMMA),
                                                      pf, p);
@@ -939,18 +939,18 @@ fn parse_bottom_expr(parser p) -> @ast.expr {
 
 fn expand_syntax_ext(parser p, ast.span sp,
                      &ast.path path, vec[@ast.expr] args,
-                     option.t[str] body) -> ast.expr_ {
+                     Option.t[str] body) -> ast.expr_ {
 
-    assert (_vec.len[ast.ident](path.node.idents) > 0u);
+    assert (Vec.len[ast.ident](path.node.idents) > 0u);
     auto extname = path.node.idents.(0);
-    if (_str.eq(extname, "fmt")) {
+    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 if (_str.eq(extname, "env")) {
+    } else if (Str.eq(extname, "env")) {
         auto expanded = extenv.expand_syntax_ext(p, sp, args, body);
         auto newexpr = ast.expr_ext(path, args, body,
                                     expanded,
@@ -968,7 +968,7 @@ fn extend_expr_by_ident(parser p, uint lo, uint hi,
     auto e_ = e.node;
     alt (e.node) {
         case (ast.expr_path(?pth, ?def, ?ann)) {
-            if (_vec.len[@ast.ty](pth.node.types) == 0u) {
+            if (Vec.len[@ast.ty](pth.node.types) == 0u) {
                 auto idents_ = pth.node.idents;
                 idents_ += vec(i);
                 auto tys = parse_ty_args(p, hi);
@@ -1238,7 +1238,7 @@ fn parse_if_expr(parser p) -> @ast.expr {
     auto cond = parse_expr(p);
     expect(p, token.RPAREN);
     auto thn = parse_block(p);
-    let option.t[@ast.expr] els = none[@ast.expr];
+    let Option.t[@ast.expr] els = none[@ast.expr];
     auto hi = thn.span.hi;
     alt (p.peek()) {
         case (token.ELSE) {
@@ -1398,7 +1398,7 @@ fn parse_spawn_expr(parser p) -> @ast.expr {
                                    pf, p);
     auto hi = es.span.hi;
     auto spawn_expr = ast.expr_spawn(ast.dom_implicit,
-                                     option.none[str],
+                                     Option.none[str],
                                      fn_expr,
                                      es.node,
                                      ast.ann_none);
@@ -1449,7 +1449,7 @@ fn parse_expr_inner(parser p) -> @ast.expr {
     }
 }
 
-fn parse_initializer(parser p) -> option.t[ast.initializer] {
+fn parse_initializer(parser p) -> Option.t[ast.initializer] {
     alt (p.peek()) {
         case (token.EQ) {
             p.bump();
@@ -1521,7 +1521,7 @@ fn parse_pat(parser p) -> @ast.pat {
     ret @spanned(lo, hi, pat);
 }
 
-fn parse_local_full(&option.t[@ast.ty] tyopt,
+fn parse_local_full(&Option.t[@ast.ty] tyopt,
                            parser p) -> @ast.local {
     auto ident = parse_ident(p);
     auto init = parse_initializer(p);
@@ -1607,7 +1607,7 @@ fn parse_source_stmt(parser p) -> @ast.stmt {
     fail;
 }
 
-fn index_block(vec[@ast.stmt] stmts, option.t[@ast.expr] expr) -> ast.block_ {
+fn index_block(vec[@ast.stmt] stmts, Option.t[@ast.expr] expr) -> ast.block_ {
     auto index = new_str_hash[ast.block_index_entry]();
     for (@ast.stmt s in stmts) {
         ast.index_stmt(index, s);
@@ -1634,7 +1634,7 @@ fn index_arm(@ast.pat pat) -> hashmap[ast.ident,ast.def_id] {
     ret index;
 }
 
-fn stmt_to_expr(@ast.stmt stmt) -> option.t[@ast.expr] {
+fn stmt_to_expr(@ast.stmt stmt) -> Option.t[@ast.expr] {
     alt (stmt.node) {
         case (ast.stmt_expr(?e,_)) { ret some[@ast.expr](e); }
         case (_) { /* fall through */ }
@@ -1697,7 +1697,7 @@ fn parse_block(parser p) -> ast.block {
     auto lo = p.get_lo_pos();
 
     let vec[@ast.stmt] stmts = vec();
-    let option.t[@ast.expr] expr = none[@ast.expr];
+    let Option.t[@ast.expr] expr = none[@ast.expr];
 
     expect(p, token.LBRACE);
     while (p.peek() != token.RBRACE) {
@@ -1871,7 +1871,7 @@ fn parse_item_obj(parser p, ast.layer lyr) -> @ast.item {
          pf, p);
 
     let vec[@ast.method] meths = vec();
-    let option.t[@ast.method] dtor = none[@ast.method];
+    let Option.t[@ast.method] dtor = none[@ast.method];
 
     expect(p, token.LBRACE);
     while (p.peek() != token.RBRACE) {
@@ -1880,7 +1880,7 @@ fn parse_item_obj(parser p, ast.layer lyr) -> @ast.item {
                 dtor = some[@ast.method](parse_dtor(p));
             }
             case (_) {
-                _vec.push[@ast.method](meths,
+                Vec.push[@ast.method](meths,
                                        parse_method(p));
             }
         }
@@ -2020,12 +2020,12 @@ fn parse_item_native_mod(parser p) -> @ast.item {
     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")) {
+        if (Str.eq(t, "cdecl")) {
+        } else if (Str.eq(t, "rust")) {
             abi = ast.native_abi_rust;
-        } else if (_str.eq(t, "llvm")) {
+        } else if (Str.eq(t, "llvm")) {
             abi = ast.native_abi_llvm;
-        } else if (_str.eq(t, "rust-intrinsic")) {
+        } else if (Str.eq(t, "rust-intrinsic")) {
             abi = ast.native_abi_rust_intrinsic;
         } else {
             p.err("unsupported abi: " + t);
@@ -2264,7 +2264,7 @@ fn parse_use(parser p) -> @ast.view_item {
 }
 
 fn parse_rest_import_name(parser p, ast.ident first,
-                                 option.t[ast.ident] def_ident)
+                                 Option.t[ast.ident] def_ident)
         -> @ast.view_item {
     auto lo = p.get_lo_pos();
     let vec[ast.ident] identifiers = vec(first);
@@ -2281,7 +2281,7 @@ fn parse_rest_import_name(parser p, ast.ident first,
             defined_id = i;
         }
         case (_) {
-            auto len = _vec.len[ast.ident](identifiers);
+            auto len = Vec.len[ast.ident](identifiers);
             defined_id = identifiers.(len - 1u);
         }
     }
@@ -2506,7 +2506,7 @@ fn parse_crate_directives(parser p, token.token term)
 
     while (p.peek() != term) {
         auto cdir = @parse_crate_directive(p);
-        _vec.push[@ast.crate_directive](cdirs, cdir);
+        Vec.push[@ast.crate_directive](cdirs, cdir);
     }
 
     ret cdirs;
@@ -2514,7 +2514,7 @@ fn parse_crate_directives(parser p, token.token term)
 
 fn parse_crate_from_crate_file(parser p) -> @ast.crate {
     auto lo = p.get_lo_pos();
-    auto prefix = std.fs.dirname(p.get_filemap().name);
+    auto prefix = std.FS.dirname(p.get_filemap().name);
     auto cdirs = parse_crate_directives(p, token.EOF);
     let vec[str] deps = vec();
     auto cx = @rec(p=p,
diff --git a/src/comp/front/token.rs b/src/comp/front/token.rs
index b0fa0588cfa..f0b6c4be352 100644
--- a/src/comp/front/token.rs
+++ b/src/comp/front/token.rs
@@ -1,9 +1,9 @@
 import util.common.ty_mach;
 import util.common.ty_mach_to_str;
 import util.common.new_str_hash;
-import std._int;
-import std._uint;
-import std._str;
+import std.Int;
+import std.UInt;
+import std.Str;
 
 tag binop {
     PLUS;
@@ -295,10 +295,10 @@ fn to_str(token t) -> str {
         case (JOIN) { ret "join"; }
 
         /* Literals */
-        case (LIT_INT(?i)) { ret _int.to_str(i, 10u); }
-        case (LIT_UINT(?u)) { ret _uint.to_str(u, 10u); }
+        case (LIT_INT(?i)) { ret Int.to_str(i, 10u); }
+        case (LIT_UINT(?u)) { ret UInt.to_str(u, 10u); }
         case (LIT_MACH_INT(?tm, ?i)) {
-            ret  _int.to_str(i, 10u)
+            ret  Int.to_str(i, 10u)
                 + "_" + ty_mach_to_str(tm);
         }
         case (LIT_FLOAT(?s)) { ret s; }
@@ -309,8 +309,8 @@ fn to_str(token t) -> str {
         case (LIT_CHAR(?c)) {
             // FIXME: escape.
             auto tmp = "'";
-            _str.push_char(tmp, c);
-            _str.push_byte(tmp, '\'' as u8);
+            Str.push_char(tmp, c);
+            Str.push_byte(tmp, '\'' as u8);
             ret tmp;
         }
 
@@ -320,7 +320,7 @@ fn to_str(token t) -> str {
 
         /* Name components */
         case (IDENT(?s)) { auto si = "ident:"; si += s; ret si; }
-        case (IDX(?i)) { ret "_" + _int.to_str(i, 10u); }
+        case (IDX(?i)) { ret "_" + Int.to_str(i, 10u); }
         case (UNDERSCORE) { ret "_"; }
 
         /* Reserved type names */
diff --git a/src/comp/lib/llvm.rs b/src/comp/lib/llvm.rs
index 1d2529ccf00..2c0ac2fcbe4 100644
--- a/src/comp/lib/llvm.rs
+++ b/src/comp/lib/llvm.rs
@@ -1,7 +1,7 @@
-import std._vec;
-import std._str;
-import std._str.rustrt.sbuf;
-import std._vec.rustrt.vbuf;
+import std.Vec;
+import std.Str;
+import std.Str.rustrt.sbuf;
+import std.Vec.rustrt.vbuf;
 
 import llvm.ModuleRef;
 import llvm.ContextRef;
@@ -831,7 +831,7 @@ native mod llvm = llvm_lib {
     /** Destroys a section iterator. */
     fn LLVMDisposeSectionIterator(SectionIteratorRef SI);
     /** Returns true if the section iterator is at the end of the section
-        list. */
+        List. */
     fn LLVMIsSectionIteratorAtEnd(ObjectFileRef ObjectFile,
                                   SectionIteratorRef SI) -> Bool;
     /** Moves the section iterator to point to the next section. */
@@ -894,8 +894,8 @@ obj builder(BuilderRef B, @mutable bool terminated) {
         assert (!*terminated);
         *terminated = true;
         ret llvm.LLVMBuildAggregateRet(B,
-                                       _vec.buf[ValueRef](RetVals),
-                                       _vec.len[ValueRef](RetVals));
+                                       Vec.buf[ValueRef](RetVals),
+                                       Vec.len[ValueRef](RetVals));
     }
 
     fn Br(BasicBlockRef Dest) -> ValueRef {
@@ -930,10 +930,10 @@ obj builder(BuilderRef B, @mutable bool terminated) {
         assert (!*terminated);
         *terminated = true;
         ret llvm.LLVMBuildInvoke(B, Fn,
-                                 _vec.buf[ValueRef](Args),
-                                 _vec.len[ValueRef](Args),
+                                 Vec.buf[ValueRef](Args),
+                                 Vec.len[ValueRef](Args),
                                  Then, Catch,
-                                 _str.buf(""));
+                                 Str.buf(""));
     }
 
     fn Unwind() -> ValueRef {
@@ -951,176 +951,176 @@ obj builder(BuilderRef B, @mutable bool terminated) {
     /* Arithmetic */
     fn Add(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildAdd(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildAdd(B, LHS, RHS, Str.buf(""));
     }
 
     fn NSWAdd(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildNSWAdd(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildNSWAdd(B, LHS, RHS, Str.buf(""));
     }
 
     fn NUWAdd(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildNUWAdd(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildNUWAdd(B, LHS, RHS, Str.buf(""));
     }
 
     fn FAdd(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildFAdd(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildFAdd(B, LHS, RHS, Str.buf(""));
     }
 
     fn Sub(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildSub(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildSub(B, LHS, RHS, Str.buf(""));
     }
 
     fn NSWSub(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildNSWSub(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildNSWSub(B, LHS, RHS, Str.buf(""));
     }
 
     fn NUWSub(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildNUWSub(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildNUWSub(B, LHS, RHS, Str.buf(""));
     }
 
     fn FSub(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildFSub(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildFSub(B, LHS, RHS, Str.buf(""));
     }
 
     fn Mul(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildMul(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildMul(B, LHS, RHS, Str.buf(""));
     }
 
     fn NSWMul(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildNSWMul(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildNSWMul(B, LHS, RHS, Str.buf(""));
     }
 
     fn NUWMul(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildNUWMul(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildNUWMul(B, LHS, RHS, Str.buf(""));
     }
 
     fn FMul(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildFMul(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildFMul(B, LHS, RHS, Str.buf(""));
     }
 
     fn UDiv(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildUDiv(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildUDiv(B, LHS, RHS, Str.buf(""));
     }
 
     fn SDiv(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildSDiv(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildSDiv(B, LHS, RHS, Str.buf(""));
     }
 
     fn ExactSDiv(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildExactSDiv(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildExactSDiv(B, LHS, RHS, Str.buf(""));
     }
 
     fn FDiv(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildFDiv(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildFDiv(B, LHS, RHS, Str.buf(""));
     }
 
     fn URem(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildURem(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildURem(B, LHS, RHS, Str.buf(""));
     }
 
     fn SRem(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildSRem(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildSRem(B, LHS, RHS, Str.buf(""));
     }
 
     fn FRem(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildFRem(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildFRem(B, LHS, RHS, Str.buf(""));
     }
 
     fn Shl(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildShl(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildShl(B, LHS, RHS, Str.buf(""));
     }
 
     fn LShr(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildLShr(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildLShr(B, LHS, RHS, Str.buf(""));
     }
 
     fn AShr(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildAShr(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildAShr(B, LHS, RHS, Str.buf(""));
     }
 
     fn And(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildAnd(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildAnd(B, LHS, RHS, Str.buf(""));
     }
 
     fn Or(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildOr(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildOr(B, LHS, RHS, Str.buf(""));
     }
 
     fn Xor(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildXor(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildXor(B, LHS, RHS, Str.buf(""));
     }
 
     fn BinOp(Opcode Op, ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildBinOp(B, Op, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildBinOp(B, Op, LHS, RHS, Str.buf(""));
     }
 
     fn Neg(ValueRef V) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildNeg(B, V, _str.buf(""));
+        ret llvm.LLVMBuildNeg(B, V, Str.buf(""));
     }
 
     fn NSWNeg(ValueRef V) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildNSWNeg(B, V, _str.buf(""));
+        ret llvm.LLVMBuildNSWNeg(B, V, Str.buf(""));
     }
 
     fn NUWNeg(ValueRef V) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildNUWNeg(B, V, _str.buf(""));
+        ret llvm.LLVMBuildNUWNeg(B, V, Str.buf(""));
     }
     fn FNeg(ValueRef V) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildFNeg(B, V, _str.buf(""));
+        ret llvm.LLVMBuildFNeg(B, V, Str.buf(""));
     }
     fn Not(ValueRef V) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildNot(B, V, _str.buf(""));
+        ret llvm.LLVMBuildNot(B, V, Str.buf(""));
     }
 
     /* Memory */
     fn Malloc(TypeRef Ty) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildMalloc(B, Ty, _str.buf(""));
+        ret llvm.LLVMBuildMalloc(B, Ty, Str.buf(""));
     }
 
     fn ArrayMalloc(TypeRef Ty, ValueRef Val) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildArrayMalloc(B, Ty, Val, _str.buf(""));
+        ret llvm.LLVMBuildArrayMalloc(B, Ty, Val, Str.buf(""));
     }
 
     fn Alloca(TypeRef Ty) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildAlloca(B, Ty, _str.buf(""));
+        ret llvm.LLVMBuildAlloca(B, Ty, Str.buf(""));
     }
 
     fn ArrayAlloca(TypeRef Ty, ValueRef Val) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildArrayAlloca(B, Ty, Val, _str.buf(""));
+        ret llvm.LLVMBuildArrayAlloca(B, Ty, Val, Str.buf(""));
     }
 
     fn Free(ValueRef PointerVal) -> ValueRef {
@@ -1130,7 +1130,7 @@ obj builder(BuilderRef B, @mutable bool terminated) {
 
     fn Load(ValueRef PointerVal) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildLoad(B, PointerVal, _str.buf(""));
+        ret llvm.LLVMBuildLoad(B, PointerVal, Str.buf(""));
     }
 
     fn Store(ValueRef Val, ValueRef Ptr) -> ValueRef {
@@ -1141,140 +1141,140 @@ obj builder(BuilderRef B, @mutable bool terminated) {
     fn GEP(ValueRef Pointer, vec[ValueRef] Indices) -> ValueRef {
         assert (!*terminated);
         ret llvm.LLVMBuildGEP(B, Pointer,
-                              _vec.buf[ValueRef](Indices),
-                              _vec.len[ValueRef](Indices),
-                              _str.buf(""));
+                              Vec.buf[ValueRef](Indices),
+                              Vec.len[ValueRef](Indices),
+                              Str.buf(""));
     }
 
     fn InBoundsGEP(ValueRef Pointer, vec[ValueRef] Indices) -> ValueRef {
         assert (!*terminated);
         ret llvm.LLVMBuildInBoundsGEP(B, Pointer,
-                                      _vec.buf[ValueRef](Indices),
-                                      _vec.len[ValueRef](Indices),
-                                      _str.buf(""));
+                                      Vec.buf[ValueRef](Indices),
+                                      Vec.len[ValueRef](Indices),
+                                      Str.buf(""));
     }
 
     fn StructGEP(ValueRef Pointer, uint Idx) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildStructGEP(B, Pointer, Idx, _str.buf(""));
+        ret llvm.LLVMBuildStructGEP(B, Pointer, Idx, Str.buf(""));
     }
 
-    fn GlobalString(sbuf Str) -> ValueRef {
+    fn GlobalString(sbuf _Str) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildGlobalString(B, Str, _str.buf(""));
+        ret llvm.LLVMBuildGlobalString(B, _Str, Str.buf(""));
     }
 
-    fn GlobalStringPtr(sbuf Str) -> ValueRef {
+    fn GlobalStringPtr(sbuf _Str) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildGlobalStringPtr(B, Str, _str.buf(""));
+        ret llvm.LLVMBuildGlobalStringPtr(B, _Str, Str.buf(""));
     }
 
     /* Casts */
     fn Trunc(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildTrunc(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildTrunc(B, Val, DestTy, Str.buf(""));
     }
 
     fn ZExt(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildZExt(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildZExt(B, Val, DestTy, Str.buf(""));
     }
 
     fn SExt(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildSExt(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildSExt(B, Val, DestTy, Str.buf(""));
     }
 
     fn FPToUI(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildFPToUI(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildFPToUI(B, Val, DestTy, Str.buf(""));
     }
 
     fn FPToSI(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildFPToSI(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildFPToSI(B, Val, DestTy, Str.buf(""));
     }
 
     fn UIToFP(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildUIToFP(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildUIToFP(B, Val, DestTy, Str.buf(""));
     }
 
     fn SIToFP(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildSIToFP(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildSIToFP(B, Val, DestTy, Str.buf(""));
     }
 
     fn FPTrunc(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildFPTrunc(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildFPTrunc(B, Val, DestTy, Str.buf(""));
     }
 
     fn FPExt(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildFPExt(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildFPExt(B, Val, DestTy, Str.buf(""));
     }
 
     fn PtrToInt(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildPtrToInt(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildPtrToInt(B, Val, DestTy, Str.buf(""));
     }
 
     fn IntToPtr(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildIntToPtr(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildIntToPtr(B, Val, DestTy, Str.buf(""));
     }
 
     fn BitCast(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildBitCast(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildBitCast(B, Val, DestTy, Str.buf(""));
     }
 
     fn ZExtOrBitCast(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildZExtOrBitCast(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildZExtOrBitCast(B, Val, DestTy, Str.buf(""));
     }
 
     fn SExtOrBitCast(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildSExtOrBitCast(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildSExtOrBitCast(B, Val, DestTy, Str.buf(""));
     }
 
     fn TruncOrBitCast(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildTruncOrBitCast(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildTruncOrBitCast(B, Val, DestTy, Str.buf(""));
     }
 
     fn Cast(Opcode Op, ValueRef Val, TypeRef DestTy, sbuf Name) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildCast(B, Op, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildCast(B, Op, Val, DestTy, Str.buf(""));
     }
 
     fn PointerCast(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildPointerCast(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildPointerCast(B, Val, DestTy, Str.buf(""));
     }
 
     fn IntCast(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildIntCast(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildIntCast(B, Val, DestTy, Str.buf(""));
     }
 
     fn FPCast(ValueRef Val, TypeRef DestTy) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildFPCast(B, Val, DestTy, _str.buf(""));
+        ret llvm.LLVMBuildFPCast(B, Val, DestTy, Str.buf(""));
     }
 
 
     /* Comparisons */
     fn ICmp(uint Op, ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildICmp(B, Op, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildICmp(B, Op, LHS, RHS, Str.buf(""));
     }
 
     fn FCmp(uint Op, ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildFCmp(B, Op, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildFCmp(B, Op, LHS, RHS, Str.buf(""));
     }
 
 
@@ -1282,94 +1282,94 @@ obj builder(BuilderRef B, @mutable bool terminated) {
     fn Phi(TypeRef Ty, vec[ValueRef] vals,
            vec[BasicBlockRef] bbs) -> ValueRef {
         assert (!*terminated);
-        auto phi = llvm.LLVMBuildPhi(B, Ty, _str.buf(""));
-        assert (_vec.len[ValueRef](vals) == _vec.len[BasicBlockRef](bbs));
+        auto phi = llvm.LLVMBuildPhi(B, Ty, Str.buf(""));
+        assert (Vec.len[ValueRef](vals) == Vec.len[BasicBlockRef](bbs));
         llvm.LLVMAddIncoming(phi,
-                             _vec.buf[ValueRef](vals),
-                             _vec.buf[BasicBlockRef](bbs),
-                             _vec.len[ValueRef](vals));
+                             Vec.buf[ValueRef](vals),
+                             Vec.buf[BasicBlockRef](bbs),
+                             Vec.len[ValueRef](vals));
         ret phi;
     }
 
     fn AddIncomingToPhi(ValueRef phi,
                         vec[ValueRef] vals,
                         vec[BasicBlockRef] bbs) {
-        assert (_vec.len[ValueRef](vals) == _vec.len[BasicBlockRef](bbs));
+        assert (Vec.len[ValueRef](vals) == Vec.len[BasicBlockRef](bbs));
         llvm.LLVMAddIncoming(phi,
-                             _vec.buf[ValueRef](vals),
-                             _vec.buf[BasicBlockRef](bbs),
-                             _vec.len[ValueRef](vals));
+                             Vec.buf[ValueRef](vals),
+                             Vec.buf[BasicBlockRef](bbs),
+                             Vec.len[ValueRef](vals));
     }
 
     fn Call(ValueRef Fn, vec[ValueRef] Args) -> ValueRef {
         assert (!*terminated);
         ret llvm.LLVMBuildCall(B, Fn,
-                               _vec.buf[ValueRef](Args),
-                               _vec.len[ValueRef](Args),
-                               _str.buf(""));
+                               Vec.buf[ValueRef](Args),
+                               Vec.len[ValueRef](Args),
+                               Str.buf(""));
     }
 
     fn FastCall(ValueRef Fn, vec[ValueRef] Args) -> ValueRef {
         assert (!*terminated);
         auto v = llvm.LLVMBuildCall(B, Fn,
-                                    _vec.buf[ValueRef](Args),
-                                    _vec.len[ValueRef](Args),
-                                    _str.buf(""));
+                                    Vec.buf[ValueRef](Args),
+                                    Vec.len[ValueRef](Args),
+                                    Str.buf(""));
         llvm.LLVMSetInstructionCallConv(v, LLVMFastCallConv);
         ret v;
     }
 
     fn Select(ValueRef If, ValueRef Then, ValueRef Else) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildSelect(B, If, Then, Else, _str.buf(""));
+        ret llvm.LLVMBuildSelect(B, If, Then, Else, Str.buf(""));
     }
 
     fn VAArg(ValueRef List, TypeRef Ty) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildVAArg(B, List, Ty, _str.buf(""));
+        ret llvm.LLVMBuildVAArg(B, List, Ty, Str.buf(""));
     }
 
     fn ExtractElement(ValueRef VecVal, ValueRef Index) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildExtractElement(B, VecVal, Index, _str.buf(""));
+        ret llvm.LLVMBuildExtractElement(B, VecVal, Index, Str.buf(""));
     }
 
     fn InsertElement(ValueRef VecVal, ValueRef EltVal,
                      ValueRef Index) -> ValueRef {
         assert (!*terminated);
         ret llvm.LLVMBuildInsertElement(B, VecVal, EltVal, Index,
-                                        _str.buf(""));
+                                        Str.buf(""));
     }
 
     fn ShuffleVector(ValueRef V1, ValueRef V2, ValueRef Mask) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildShuffleVector(B, V1, V2, Mask, _str.buf(""));
+        ret llvm.LLVMBuildShuffleVector(B, V1, V2, Mask, Str.buf(""));
     }
 
     fn ExtractValue(ValueRef AggVal, uint Index) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildExtractValue(B, AggVal, Index, _str.buf(""));
+        ret llvm.LLVMBuildExtractValue(B, AggVal, Index, Str.buf(""));
     }
 
     fn InsertValue(ValueRef AggVal, ValueRef EltVal,
                    uint Index) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildInsertValue(B, AggVal, EltVal, Index, _str.buf(""));
+        ret llvm.LLVMBuildInsertValue(B, AggVal, EltVal, Index, Str.buf(""));
     }
 
     fn IsNull(ValueRef Val) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildIsNull(B, Val, _str.buf(""));
+        ret llvm.LLVMBuildIsNull(B, Val, Str.buf(""));
     }
 
     fn IsNotNull(ValueRef Val) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildIsNotNull(B, Val, _str.buf(""));
+        ret llvm.LLVMBuildIsNotNull(B, Val, Str.buf(""));
     }
 
     fn PtrDiff(ValueRef LHS, ValueRef RHS) -> ValueRef {
         assert (!*terminated);
-        ret llvm.LLVMBuildPtrDiff(B, LHS, RHS, _str.buf(""));
+        ret llvm.LLVMBuildPtrDiff(B, LHS, RHS, Str.buf(""));
     }
 
     fn Trap() -> ValueRef {
@@ -1377,13 +1377,13 @@ obj builder(BuilderRef B, @mutable bool terminated) {
         let BasicBlockRef BB = llvm.LLVMGetInsertBlock(B);
         let ValueRef FN = llvm.LLVMGetBasicBlockParent(BB);
         let ModuleRef M = llvm.LLVMGetGlobalParent(FN);
-        let ValueRef T = llvm.LLVMGetNamedFunction(M, _str.buf("llvm.trap"));
+        let ValueRef T = llvm.LLVMGetNamedFunction(M, Str.buf("llvm.trap"));
         assert (T as int != 0);
         let vec[ValueRef] Args = vec();
         ret llvm.LLVMBuildCall(B, T,
-                               _vec.buf[ValueRef](Args),
-                               _vec.len[ValueRef](Args),
-                               _str.buf(""));
+                               Vec.buf[ValueRef](Args),
+                               Vec.len[ValueRef](Args),
+                               Str.buf(""));
     }
 
     drop {
@@ -1405,8 +1405,8 @@ fn mk_type_handle() -> type_handle {
 }
 
 
-state obj type_names(std.map.hashmap[TypeRef, str] type_names,
-                    std.map.hashmap[str, TypeRef] named_types) {
+state obj type_names(std.Map.hashmap[TypeRef, str] type_names,
+                    std.Map.hashmap[str, TypeRef] named_types) {
 
     fn associate(str s, TypeRef t) {
         assert (!named_types.contains_key(s));
@@ -1443,9 +1443,9 @@ fn mk_type_names() -> type_names {
         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);
+    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);
 }
@@ -1503,8 +1503,8 @@ fn type_to_str_inner(type_names names,
             let TypeRef out_ty = llvm.LLVMGetReturnType(ty);
             let uint n_args = llvm.LLVMCountParamTypes(ty);
             let vec[TypeRef] args =
-                _vec.init_elt[TypeRef](0 as TypeRef, n_args);
-            llvm.LLVMGetParamTypes(ty, _vec.buf[TypeRef](args));
+                Vec.init_elt[TypeRef](0 as TypeRef, n_args);
+            llvm.LLVMGetParamTypes(ty, Vec.buf[TypeRef](args));
             s += tys_str(names, outer, args);
             s += ") -> ";
             s += type_to_str_inner(names, outer, out_ty);
@@ -1515,8 +1515,8 @@ fn type_to_str_inner(type_names names,
             let str s = "{";
             let uint n_elts = llvm.LLVMCountStructElementTypes(ty);
             let vec[TypeRef] elts =
-                _vec.init_elt[TypeRef](0 as TypeRef, n_elts);
-            llvm.LLVMGetStructElementTypes(ty, _vec.buf[TypeRef](elts));
+                Vec.init_elt[TypeRef](0 as TypeRef, n_elts);
+            llvm.LLVMGetStructElementTypes(ty, Vec.buf[TypeRef](elts));
             s += tys_str(names, outer, elts);
             s += "}";
             ret s;
@@ -1529,7 +1529,7 @@ fn type_to_str_inner(type_names names,
             for (TypeRef tout in outer0) {
                 i += 1u;
                 if (tout as int == ty as int) {
-                    let uint n = _vec.len[TypeRef](outer0) - i;
+                    let uint n = Vec.len[TypeRef](outer0) - i;
                     ret "*\\" + util.common.istr(n as int);
                 }
             }
@@ -1556,7 +1556,7 @@ obj target_data_dtor(TargetDataRef TD) {
 type target_data = rec(TargetDataRef lltd, target_data_dtor dtor);
 
 fn mk_target_data(str string_rep) -> target_data {
-    auto lltd = llvm.LLVMCreateTargetData(_str.buf(string_rep));
+    auto lltd = llvm.LLVMCreateTargetData(Str.buf(string_rep));
     ret rec(lltd=lltd, dtor=target_data_dtor(lltd));
 }
 
diff --git a/src/comp/middle/capture.rs b/src/comp/middle/capture.rs
index 024315805dd..003c38972f8 100644
--- a/src/comp/middle/capture.rs
+++ b/src/comp/middle/capture.rs
@@ -1,29 +1,29 @@
 import driver.session;
 import front.ast;
-import std.map.hashmap;
-import std.option;
-import std.option.some;
-import std.option.none;
-import std._int;
-import std._vec;
+import std.Map.hashmap;
+import std.Option;
+import std.Option.some;
+import std.Option.none;
+import std.Int;
+import std.Vec;
 import util.common;
 
-type fn_id_of_local = std.map.hashmap[ast.def_id, ast.def_id];
+type fn_id_of_local = std.Map.hashmap[ast.def_id, ast.def_id];
 type env = rec(mutable vec[ast.def_id] current_context, // fn or obj
                fn_id_of_local idmap,
                session.session sess);
 
 fn current_context(&env e) -> ast.def_id {
-    ret e.current_context.(_vec.len(e.current_context) - 1u);
+    ret e.current_context.(Vec.len(e.current_context) - 1u);
 }
 
 fn enter_item(@env e, @ast.item i) {
     alt (i.node) {
         case (ast.item_fn(?name, _, _, ?id, _)) {
-            _vec.push(e.current_context, id);
+            Vec.push(e.current_context, id);
         }
         case (ast.item_obj(_, _, _, ?ids, _)) {
-            _vec.push(e.current_context, ids.ty);
+            Vec.push(e.current_context, ids.ty);
         }
         case (_) {}
     }
@@ -32,10 +32,10 @@ fn enter_item(@env e, @ast.item i) {
 fn leave_item(@env e, @ast.item i) {
     alt (i.node) {
         case (ast.item_fn(?name, _, _, ?id, _)) {
-            _vec.pop(e.current_context);
+            Vec.pop(e.current_context);
         }
         case (ast.item_obj(_, _, _, ?ids, _)) {
-            _vec.pop(e.current_context);
+            Vec.pop(e.current_context);
         }
         case (_) {}
     }
@@ -61,13 +61,13 @@ fn walk_expr(@env e, @ast.expr x) {
         }
         case (ast.expr_path(_, ?def, _)) {
             auto local_id;
-            alt (option.get(def)) {
+            alt (Option.get(def)) {
                 case (ast.def_local(?id)) { local_id = id; }
                 case (_) { ret; }
             }
 
-            auto df = ast.def_id_of_def(option.get(def));
-            auto def_context = option.get(e.idmap.find(df));
+            auto df = ast.def_id_of_def(Option.get(def));
+            auto def_context = Option.get(e.idmap.find(df));
 
             if (current_context(*e) != def_context) {
                 e.sess.span_err(x.span,
diff --git a/src/comp/middle/fold.rs b/src/comp/middle/fold.rs
index b37f7be835e..ace45c2f9a5 100644
--- a/src/comp/middle/fold.rs
+++ b/src/comp/middle/fold.rs
@@ -1,7 +1,7 @@
-import std.map.hashmap;
-import std.option;
-import std.option.some;
-import std.option.none;
+import std.Map.hashmap;
+import std.Option;
+import std.Option.some;
+import std.Option.none;
 
 import util.common.new_str_hash;
 import util.common.spanned;
@@ -32,8 +32,8 @@ import front.ast.ann;
 import front.ast.mt;
 import front.ast.purity;
 
-import std._uint;
-import std._vec;
+import std.UInt;
+import std.Vec;
 
 type ast_fold[ENV] =
     @rec
@@ -67,7 +67,7 @@ type ast_fold[ENV] =
          @ty output) -> @ty)                      fold_ty_fn,
 
      (fn(&ENV e, &span sp, ast.path p,
-         &option.t[def] d) -> @ty)                fold_ty_path,
+         &Option.t[def] d) -> @ty)                fold_ty_path,
 
      (fn(&ENV e, &span sp, @ty t) -> @ty)         fold_ty_chan,
      (fn(&ENV e, &span sp, @ty t) -> @ty)         fold_ty_port,
@@ -82,7 +82,7 @@ type ast_fold[ENV] =
 
      (fn(&ENV e, &span sp,
          vec[ast.field] fields,
-         option.t[@expr] base, ann a) -> @expr)   fold_expr_rec,
+         Option.t[@expr] base, ann a) -> @expr)   fold_expr_rec,
 
      (fn(&ENV e, &span sp,
          @expr f, vec[@expr] args,
@@ -92,11 +92,11 @@ type ast_fold[ENV] =
          ident id, ann a) -> @expr)               fold_expr_self_method,
 
      (fn(&ENV e, &span sp,
-         @expr f, vec[option.t[@expr]] args,
+         @expr f, vec[Option.t[@expr]] args,
          ann a) -> @expr)                         fold_expr_bind,
 
      (fn(&ENV e, &span sp,
-         ast.spawn_dom dom, option.t[str] name,
+         ast.spawn_dom dom, Option.t[str] name,
          @expr f, vec[@expr] args,
          ann a) -> @expr)                         fold_expr_spawn,
 
@@ -118,7 +118,7 @@ type ast_fold[ENV] =
 
      (fn(&ENV e, &span sp,
          @expr cond, &block thn,
-         &option.t[@expr] els,
+         &Option.t[@expr] els,
          ann a) -> @expr)                         fold_expr_if,
 
      (fn(&ENV e, &span sp,
@@ -169,12 +169,12 @@ type ast_fold[ENV] =
 
      (fn(&ENV e, &span sp,
          &path p,
-         &option.t[def] d,
+         &Option.t[def] d,
          ann a) -> @expr)                         fold_expr_path,
 
      (fn(&ENV e, &span sp,
          &path p, vec[@expr] args,
-         option.t[str] body,
+         Option.t[str] body,
          @expr expanded,
          ann a) -> @expr)                         fold_expr_ext,
 
@@ -185,10 +185,10 @@ type ast_fold[ENV] =
      (fn(&ENV e, &span sp, ann a) -> @expr)       fold_expr_cont,
 
      (fn(&ENV e, &span sp,
-         &option.t[@expr] rv, ann a) -> @expr)    fold_expr_ret,
+         &Option.t[@expr] rv, ann a) -> @expr)    fold_expr_ret,
 
      (fn(&ENV e, &span sp,
-         &option.t[@expr] rv, ann a) -> @expr)    fold_expr_put,
+         &Option.t[@expr] rv, ann a) -> @expr)    fold_expr_put,
 
      (fn(&ENV e, &span sp,
          @expr e, ann a) -> @expr)                fold_expr_be,
@@ -229,7 +229,7 @@ type ast_fold[ENV] =
 
      (fn(&ENV e, &span sp,
          path p, vec[@pat] args,
-         option.t[ast.variant_def] d,
+         Option.t[ast.variant_def] d,
          ann a) -> @pat)                          fold_pat_tag,
 
 
@@ -253,7 +253,7 @@ type ast_fold[ENV] =
          def_id id, ann a) -> @item)              fold_item_fn,
 
      (fn(&ENV e, &span sp, ident ident,
-         option.t[str] link_name,
+         Option.t[str] link_name,
          &ast.fn_decl decl,
          vec[ast.ty_param] ty_params,
          def_id id, ann a) -> @native_item)       fold_native_item_fn,
@@ -284,10 +284,10 @@ type ast_fold[ENV] =
      // View Item folds.
      (fn(&ENV e, &span sp, ident ident,
          vec[@meta_item] meta_items,
-         def_id id, option.t[int]) -> @view_item) fold_view_item_use,
+         def_id id, Option.t[int]) -> @view_item) fold_view_item_use,
 
      (fn(&ENV e, &span sp, ident i, vec[ident] idents,
-         def_id id, option.t[def]) -> @view_item) fold_view_item_import,
+         def_id id, Option.t[def]) -> @view_item) fold_view_item_import,
 
      (fn(&ENV e, &span sp, ident i) -> @view_item) fold_view_item_export,
 
@@ -316,7 +316,7 @@ type ast_fold[ENV] =
      (fn(&ENV e,
          vec[ast.obj_field] fields,
          vec[@ast.method] methods,
-         option.t[@ast.method] dtor) -> ast._obj) fold_obj,
+         Option.t[@ast.method] dtor) -> ast._obj) fold_obj,
 
      // Env updates.
      (fn(&ENV e, @ast.crate c) -> ENV) update_env_for_crate,
@@ -341,7 +341,7 @@ type ast_fold[ENV] =
 fn fold_path[ENV](&ENV env, ast_fold[ENV] fld, &path p) -> path {
     let vec[@ast.ty] tys_ = vec();
     for (@ast.ty t in p.node.types) {
-        _vec.push[@ast.ty](tys_, fold_ty(env, fld, t));
+        Vec.push[@ast.ty](tys_, fold_ty(env, fld, t));
     }
     let ast.path_ p_ = rec(idents=p.node.idents, types=tys_);
     ret fld.fold_path(env, p.span, p_);
@@ -382,7 +382,7 @@ fn fold_ty[ENV](&ENV env, ast_fold[ENV] fld, @ty t) -> @ty {
             let vec[mt] elts_ = vec();
             for (mt elt in elts) {
                 auto ty_ = fold_ty(env, fld, elt.ty);
-                _vec.push[mt](elts_, rec(ty=ty_, mut=elt.mut));
+                Vec.push[mt](elts_, rec(ty=ty_, mut=elt.mut));
             }
             ret fld.fold_ty_tup(env_, t.span, elts_);
         }
@@ -391,7 +391,7 @@ fn fold_ty[ENV](&ENV env, ast_fold[ENV] fld, @ty t) -> @ty {
             let vec[ast.ty_field] flds_ = vec();
             for (ast.ty_field f in flds) {
                 auto ty_ = fold_ty(env, fld, f.mt.ty);
-                _vec.push[ast.ty_field]
+                Vec.push[ast.ty_field]
                     (flds_, rec(mt=rec(ty=ty_, mut=f.mt.mut) with f));
             }
             ret fld.fold_ty_rec(env_, t.span, flds_);
@@ -404,7 +404,7 @@ fn fold_ty[ENV](&ENV env, ast_fold[ENV] fld, @ty t) -> @ty {
                                       m.inputs, m.output);
                 alt (tfn.node) {
                     case (ast.ty_fn(?p, ?ins, ?out)) {
-                        _vec.push[ast.ty_method]
+                        Vec.push[ast.ty_method]
                             (meths_, rec(proto=p, inputs=ins,
                                          output=out with m));
                     }
@@ -518,7 +518,7 @@ fn fold_pat[ENV](&ENV env, ast_fold[ENV] fld, @ast.pat p) -> @ast.pat {
 fn fold_exprs[ENV](&ENV env, ast_fold[ENV] fld, vec[@expr] es) -> vec[@expr] {
     let vec[@expr] exprs = vec();
     for (@expr e in es) {
-        _vec.push[@expr](exprs, fold_expr(env, fld, e));
+        Vec.push[@expr](exprs, fold_expr(env, fld, e));
     }
     ret exprs;
 }
@@ -558,7 +558,7 @@ fn fold_expr[ENV](&ENV env, ast_fold[ENV] fld, &@expr e) -> @expr {
 
         case (ast.expr_rec(?fs, ?base, ?t)) {
             let vec[ast.field] fields = vec();
-            let option.t[@expr] b = none[@expr];
+            let Option.t[@expr] b = none[@expr];
             for (ast.field f in fs) {
                 fields += vec(fold_rec_field(env, fld, f));
             }
@@ -586,8 +586,8 @@ fn fold_expr[ENV](&ENV env, ast_fold[ENV] fld, &@expr e) -> @expr {
 
         case (ast.expr_bind(?f, ?args_opt, ?t)) {
             auto ff = fold_expr(env_, fld, f);
-            let vec[option.t[@ast.expr]] aargs_opt = vec();
-            for (option.t[@ast.expr] t_opt in args_opt) {
+            let vec[Option.t[@ast.expr]] aargs_opt = vec();
+            for (Option.t[@ast.expr] t_opt in args_opt) {
                 alt (t_opt) {
                     case (none[@ast.expr]) {
                         aargs_opt += vec(none[@ast.expr]);
@@ -865,7 +865,7 @@ fn fold_block[ENV](&ENV env, ast_fold[ENV] fld, &block blk) -> block {
     let vec[@ast.stmt] stmts = vec();
     for (@ast.stmt s in blk.node.stmts) {
         auto new_stmt = fold_stmt[ENV](env_, fld, s);
-        _vec.push[@ast.stmt](stmts, new_stmt);
+        Vec.push[@ast.stmt](stmts, new_stmt);
         ast.index_stmt(index, new_stmt);
     }
 
@@ -935,7 +935,7 @@ fn fold_obj[ENV](&ENV env, ast_fold[ENV] fld, &ast._obj ob) -> ast._obj {
     for (ast.obj_field f in ob.fields) {
         fields += vec(fold_obj_field(env, fld, f));
     }
-    let option.t[@ast.method] dtor = none[@ast.method];
+    let Option.t[@ast.method] dtor = none[@ast.method];
     alt (ob.dtor) {
         case (none[@ast.method]) { }
         case (some[@ast.method](?m)) {
@@ -954,7 +954,7 @@ fn fold_obj[ENV](&ENV env, ast_fold[ENV] fld, &ast._obj ob) -> ast._obj {
                                                 m.node.ann),
                                span=m.span);
         let ENV _env = fld.update_env_for_item(env, i);
-        _vec.push[@ast.method](meths, fold_method(_env, fld, m));
+        Vec.push[@ast.method](meths, fold_method(_env, fld, m));
     }
     ret fld.fold_obj(env, fields, meths, dtor);
 }
@@ -1057,13 +1057,13 @@ fn fold_mod[ENV](&ENV e, ast_fold[ENV] fld, &ast._mod m) -> ast._mod {
 
     for (@view_item vi in m.view_items) {
         auto new_vi = fold_view_item[ENV](e, fld, vi);
-        _vec.push[@view_item](view_items, new_vi);
+        Vec.push[@view_item](view_items, new_vi);
         ast.index_view_item(index, new_vi);
     }
 
     for (@item i in m.items) {
         auto new_item = fold_item[ENV](e, fld, i);
-        _vec.push[@item](items, new_item);
+        Vec.push[@item](items, new_item);
         ast.index_item(index, new_item);
     }
 
@@ -1098,12 +1098,12 @@ fn fold_native_mod[ENV](&ENV e, ast_fold[ENV] fld,
 
     for (@view_item vi in m.view_items) {
         auto new_vi = fold_view_item[ENV](e, fld, vi);
-        _vec.push[@view_item](view_items, new_vi);
+        Vec.push[@view_item](view_items, new_vi);
     }
 
     for (@native_item i in m.items) {
         auto new_item = fold_native_item[ENV](e, fld, i);
-        _vec.push[@native_item](items, new_item);
+        Vec.push[@native_item](items, new_item);
         ast.index_native_item(index, new_item);
     }
 
@@ -1202,7 +1202,7 @@ fn identity_fold_ty_fn[ENV](&ENV env, &span sp,
 }
 
 fn identity_fold_ty_path[ENV](&ENV env, &span sp, ast.path p,
-                        &option.t[def] d) -> @ty {
+                        &Option.t[def] d) -> @ty {
     ret @respan(sp, ast.ty_path(p, d));
 }
 
@@ -1228,7 +1228,7 @@ fn identity_fold_expr_tup[ENV](&ENV env, &span sp,
 
 fn identity_fold_expr_rec[ENV](&ENV env, &span sp,
                                vec[ast.field] fields,
-                               option.t[@expr] base, ann a) -> @expr {
+                               Option.t[@expr] base, ann a) -> @expr {
     ret @respan(sp, ast.expr_rec(fields, base, a));
 }
 
@@ -1243,13 +1243,13 @@ fn identity_fold_expr_self_method[ENV](&ENV env, &span sp, ident id,
 }
 
 fn identity_fold_expr_bind[ENV](&ENV env, &span sp, @expr f,
-                                vec[option.t[@expr]] args_opt, ann a)
+                                vec[Option.t[@expr]] args_opt, ann a)
         -> @expr {
     ret @respan(sp, ast.expr_bind(f, args_opt, a));
 }
 
 fn identity_fold_expr_spawn[ENV](&ENV env, &span sp,
-                                 ast.spawn_dom dom, option.t[str] name,
+                                 ast.spawn_dom dom, Option.t[str] name,
                                  @expr f, vec[@expr] args, ann a) -> @expr {
     ret @respan(sp, ast.expr_spawn(dom, name, f, args, a));
 }
@@ -1278,7 +1278,7 @@ fn identity_fold_expr_cast[ENV](&ENV env, &span sp, @ast.expr e,
 
 fn identity_fold_expr_if[ENV](&ENV env, &span sp,
                               @expr cond, &block thn,
-                              &option.t[@expr] els, ann a) -> @expr {
+                              &Option.t[@expr] els, ann a) -> @expr {
     ret @respan(sp, ast.expr_if(cond, thn, els, a));
 }
 
@@ -1347,14 +1347,14 @@ fn identity_fold_expr_index[ENV](&ENV env, &span sp,
 }
 
 fn identity_fold_expr_path[ENV](&ENV env, &span sp,
-                                &path p, &option.t[def] d,
+                                &path p, &Option.t[def] d,
                                 ann a) -> @expr {
     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[str] body,
+                               Option.t[str] body,
                                @expr expanded,
                                ann a) -> @expr {
     ret @respan(sp, ast.expr_ext(p, args, body, expanded, a));
@@ -1373,12 +1373,12 @@ fn identity_fold_expr_cont[ENV](&ENV env, &span sp, ann a) -> @expr {
 }
 
 fn identity_fold_expr_ret[ENV](&ENV env, &span sp,
-                               &option.t[@expr] rv, ann a) -> @expr {
+                               &Option.t[@expr] rv, ann a) -> @expr {
     ret @respan(sp, ast.expr_ret(rv, a));
 }
 
 fn identity_fold_expr_put[ENV](&ENV env, &span sp,
-                               &option.t[@expr] rv, ann a) -> @expr {
+                               &Option.t[@expr] rv, ann a) -> @expr {
     ret @respan(sp, ast.expr_put(rv, a));
 }
 
@@ -1437,7 +1437,7 @@ fn identity_fold_pat_bind[ENV](&ENV e, &span sp, ident i, def_id did, ann a)
 }
 
 fn identity_fold_pat_tag[ENV](&ENV e, &span sp, path p, vec[@pat] args,
-                              option.t[ast.variant_def] d, ann a) -> @pat {
+                              Option.t[ast.variant_def] d, ann a) -> @pat {
     ret @respan(sp, ast.pat_tag(p, args, d, a));
 }
 
@@ -1468,7 +1468,7 @@ fn identity_fold_item_fn[ENV](&ENV e, &span sp, ident i,
 }
 
 fn identity_fold_native_item_fn[ENV](&ENV e, &span sp, ident i,
-                                     option.t[str] link_name,
+                                     Option.t[str] link_name,
                                      &ast.fn_decl decl,
                                      vec[ast.ty_param] ty_params,
                                      def_id id, ann a) -> @native_item {
@@ -1513,14 +1513,14 @@ fn identity_fold_item_obj[ENV](&ENV e, &span sp, ident i,
 
 fn identity_fold_view_item_use[ENV](&ENV e, &span sp, ident i,
                                     vec[@meta_item] meta_items,
-                                    def_id id, option.t[int] cnum)
+                                    def_id id, Option.t[int] cnum)
     -> @view_item {
     ret @respan(sp, ast.view_item_use(i, meta_items, id, cnum));
 }
 
 fn identity_fold_view_item_import[ENV](&ENV e, &span sp, ident i,
                                        vec[ident] is, def_id id,
-                                       option.t[def] target_def)
+                                       Option.t[def] target_def)
     -> @view_item {
     ret @respan(sp, ast.view_item_import(i, is, id, target_def));
 }
@@ -1574,7 +1574,7 @@ fn identity_fold_crate[ENV](&ENV e, &span sp,
 fn identity_fold_obj[ENV](&ENV e,
                           vec[ast.obj_field] fields,
                           vec[@ast.method] methods,
-                          option.t[@ast.method] dtor) -> ast._obj {
+                          Option.t[@ast.method] dtor) -> ast._obj {
     ret rec(fields=fields, methods=methods, dtor=dtor);
 }
 
diff --git a/src/comp/middle/metadata.rs b/src/comp/middle/metadata.rs
index ce37822d642..f8e7a96e7b0 100644
--- a/src/comp/middle/metadata.rs
+++ b/src/comp/middle/metadata.rs
@@ -1,12 +1,12 @@
-import std._str;
-import std._uint;
-import std._vec;
-import std.map.hashmap;
-import std.ebml;
-import std.io;
-import std.option;
-import std.option.some;
-import std.option.none;
+import std.Str;
+import std.UInt;
+import std.Vec;
+import std.Map.hashmap;
+import std.EBML;
+import std.IO;
+import std.Option;
+import std.Option.some;
+import std.Option.none;
 
 import front.ast;
 import middle.fold;
@@ -75,12 +75,12 @@ mod Encode {
 
     fn ty_str(@ctxt cx, ty.t t) -> str {
         assert (!cx_uses_abbrevs(cx));
-        auto sw = io.string_writer();
+        auto sw = IO.string_writer();
         enc_ty(sw.get_writer(), cx, t);
         ret sw.get_str();
     }
 
-    fn enc_ty(io.writer w, @ctxt cx, ty.t t) {
+    fn enc_ty(IO.writer w, @ctxt cx, ty.t t) {
         alt (cx.abbrevs) {
             case (ac_no_abbrevs) { enc_sty(w, cx, ty.struct(cx.tcx, t)); }
             case (ac_use_abbrevs(?abbrevs)) {
@@ -109,8 +109,8 @@ mod Encode {
                         if (abbrev_len < len) {
                             // I.e. it's actually an abbreviation.
                             auto s = ("#"
-                                      + _uint.to_str(pos, 16u) + ":"
-                                      + _uint.to_str(len, 16u) + "#");
+                                      + UInt.to_str(pos, 16u) + ":"
+                                      + UInt.to_str(len, 16u) + "#");
                             auto a = rec(pos=pos, len=len, s=s);
                             abbrevs.insert(t, a);
                         }
@@ -121,7 +121,7 @@ mod Encode {
         }
     }
 
-    fn enc_mt(io.writer w, @ctxt cx, &ty.mt mt) {
+    fn enc_mt(IO.writer w, @ctxt cx, &ty.mt mt) {
         alt (mt.mut) {
             case (ast.imm)       { }
             case (ast.mut)       { w.write_char('m'); }
@@ -130,7 +130,7 @@ mod Encode {
         enc_ty(w, cx, mt.ty);
     }
 
-    fn enc_sty(io.writer w, @ctxt cx, ty.sty st) {
+    fn enc_sty(IO.writer w, @ctxt cx, ty.sty st) {
         alt (st) {
             case (ty.ty_nil) { w.write_char('n'); }
             case (ty.ty_bool) { w.write_char('b'); }
@@ -231,14 +231,14 @@ mod Encode {
         }
     }
 
-    fn enc_proto(io.writer w, ast.proto proto) {
+    fn enc_proto(IO.writer w, ast.proto proto) {
         alt (proto) {
             case (ast.proto_iter) { w.write_char('W'); }
             case (ast.proto_fn) { w.write_char('F'); }
         }
     }
 
-    fn enc_ty_fn(io.writer w, @ctxt cx, vec[ty.arg] args, ty.t out) {
+    fn enc_ty_fn(IO.writer w, @ctxt cx, vec[ty.arg] args, ty.t out) {
         w.write_char('[');
         for (ty.arg arg in args) {
             if (arg.mode == ast.alias) { w.write_char('&'); }
@@ -253,46 +253,46 @@ mod Encode {
 
 // Returns a Plain Old LLVM String.
 fn C_postr(str s) -> ValueRef {
-    ret llvm.LLVMConstString(_str.buf(s), _str.byte_len(s), False);
+    ret llvm.LLVMConstString(Str.buf(s), Str.byte_len(s), False);
 }
 
 
 // Path table encoding
 
-fn encode_name(&ebml.writer ebml_w, str name) {
-    ebml.start_tag(ebml_w, tag_paths_data_name);
-    ebml_w.writer.write(_str.bytes(name));
-    ebml.end_tag(ebml_w);
+fn encode_name(&EBML.writer ebml_w, str name) {
+    EBML.start_tag(ebml_w, tag_paths_data_name);
+    ebml_w.writer.write(Str.bytes(name));
+    EBML.end_tag(ebml_w);
 }
 
-fn encode_def_id(&ebml.writer ebml_w, &ast.def_id id) {
-    ebml.start_tag(ebml_w, tag_def_id);
-    ebml_w.writer.write(_str.bytes(def_to_str(id)));
-    ebml.end_tag(ebml_w);
+fn encode_def_id(&EBML.writer ebml_w, &ast.def_id id) {
+    EBML.start_tag(ebml_w, tag_def_id);
+    ebml_w.writer.write(Str.bytes(def_to_str(id)));
+    EBML.end_tag(ebml_w);
 }
 
-fn encode_tag_variant_paths(&ebml.writer ebml_w,
+fn encode_tag_variant_paths(&EBML.writer ebml_w,
                             vec[ast.variant] variants,
                             vec[str] path,
                             &mutable vec[tup(str, uint)] index) {
     for (ast.variant variant in variants) {
         add_to_index(ebml_w, path, index, variant.node.name);
-        ebml.start_tag(ebml_w, tag_paths_data_item);
+        EBML.start_tag(ebml_w, tag_paths_data_item);
         encode_name(ebml_w, variant.node.name);
         encode_def_id(ebml_w, variant.node.id);
-        ebml.end_tag(ebml_w);
+        EBML.end_tag(ebml_w);
     }
 }
 
-fn add_to_index(&ebml.writer ebml_w,
+fn add_to_index(&EBML.writer ebml_w,
                 vec[str] path,
                 &mutable vec[tup(str, uint)] index,
                 str name) {
     auto full_path = path + vec(name);
-    index += vec(tup(_str.connect(full_path, "."), ebml_w.writer.tell()));
+    index += vec(tup(Str.connect(full_path, "."), ebml_w.writer.tell()));
 }
 
-fn encode_native_module_item_paths(&ebml.writer ebml_w,
+fn encode_native_module_item_paths(&EBML.writer ebml_w,
                                    &ast.native_mod nmod,
                                    vec[str] path,
                                    &mutable vec[tup(str, uint)] index) {
@@ -300,23 +300,23 @@ fn encode_native_module_item_paths(&ebml.writer ebml_w,
         alt (nitem.node) {
             case (ast.native_item_ty(?id, ?did)) {
                 add_to_index(ebml_w, path, index, id);
-                ebml.start_tag(ebml_w, tag_paths_data_item);
+                EBML.start_tag(ebml_w, tag_paths_data_item);
                 encode_name(ebml_w, id);
                 encode_def_id(ebml_w, did);
-                ebml.end_tag(ebml_w);
+                EBML.end_tag(ebml_w);
             }
             case (ast.native_item_fn(?id, _, _, _, ?did, _)) {
                 add_to_index(ebml_w, path, index, id);
-                ebml.start_tag(ebml_w, tag_paths_data_item);
+                EBML.start_tag(ebml_w, tag_paths_data_item);
                 encode_name(ebml_w, id);
                 encode_def_id(ebml_w, did);
-                ebml.end_tag(ebml_w);
+                EBML.end_tag(ebml_w);
             }
         }
     }
 }
 
-fn encode_module_item_paths(&ebml.writer ebml_w,
+fn encode_module_item_paths(&EBML.writer ebml_w,
                             &ast._mod module,
                             vec[str] path,
                             &mutable vec[tup(str, uint)] index) {
@@ -325,197 +325,197 @@ fn encode_module_item_paths(&ebml.writer ebml_w,
         alt (it.node) {
             case (ast.item_const(?id, _, ?tps, ?did, ?ann)) {
                 add_to_index(ebml_w, path, index, id);
-                ebml.start_tag(ebml_w, tag_paths_data_item);
+                EBML.start_tag(ebml_w, tag_paths_data_item);
                 encode_name(ebml_w, id);
                 encode_def_id(ebml_w, did);
-                ebml.end_tag(ebml_w);
+                EBML.end_tag(ebml_w);
             }
             case (ast.item_fn(?id, _, ?tps, ?did, ?ann)) {
                 add_to_index(ebml_w, path, index, id);
-                ebml.start_tag(ebml_w, tag_paths_data_item);
+                EBML.start_tag(ebml_w, tag_paths_data_item);
                 encode_name(ebml_w, id);
                 encode_def_id(ebml_w, did);
-                ebml.end_tag(ebml_w);
+                EBML.end_tag(ebml_w);
             }
             case (ast.item_mod(?id, ?_mod, ?did)) {
                 add_to_index(ebml_w, path, index, id);
-                ebml.start_tag(ebml_w, tag_paths_data_mod);
+                EBML.start_tag(ebml_w, tag_paths_data_mod);
                 encode_name(ebml_w, id);
                 encode_def_id(ebml_w, did);
                 encode_module_item_paths(ebml_w, _mod, path + vec(id), index);
-                ebml.end_tag(ebml_w);
+                EBML.end_tag(ebml_w);
             }
             case (ast.item_native_mod(?id, ?nmod, ?did)) {
                 add_to_index(ebml_w, path, index, id);
-                ebml.start_tag(ebml_w, tag_paths_data_mod);
+                EBML.start_tag(ebml_w, tag_paths_data_mod);
                 encode_name(ebml_w, id);
                 encode_def_id(ebml_w, did);
                 encode_native_module_item_paths(ebml_w, nmod, path + vec(id),
                                                 index);
-                ebml.end_tag(ebml_w);
+                EBML.end_tag(ebml_w);
             }
             case (ast.item_ty(?id, _, ?tps, ?did, ?ann)) {
                 add_to_index(ebml_w, path, index, id);
-                ebml.start_tag(ebml_w, tag_paths_data_item);
+                EBML.start_tag(ebml_w, tag_paths_data_item);
                 encode_name(ebml_w, id);
                 encode_def_id(ebml_w, did);
-                ebml.end_tag(ebml_w);
+                EBML.end_tag(ebml_w);
             }
             case (ast.item_tag(?id, ?variants, ?tps, ?did, _)) {
                 add_to_index(ebml_w, path, index, id);
-                ebml.start_tag(ebml_w, tag_paths_data_item);
+                EBML.start_tag(ebml_w, tag_paths_data_item);
                 encode_name(ebml_w, id);
                 encode_def_id(ebml_w, did);
-                ebml.end_tag(ebml_w);
+                EBML.end_tag(ebml_w);
 
                 encode_tag_variant_paths(ebml_w, variants, path, index);
             }
             case (ast.item_obj(?id, _, ?tps, ?odid, ?ann)) {
                 add_to_index(ebml_w, path, index, id);
-                ebml.start_tag(ebml_w, tag_paths_data_item);
+                EBML.start_tag(ebml_w, tag_paths_data_item);
                 encode_name(ebml_w, id);
                 encode_def_id(ebml_w, odid.ctor);
                 encode_obj_type_id(ebml_w, odid.ty);
-                ebml.end_tag(ebml_w);
+                EBML.end_tag(ebml_w);
             }
         }
     }
 }
 
-fn encode_item_paths(&ebml.writer ebml_w, @ast.crate crate)
+fn encode_item_paths(&EBML.writer ebml_w, @ast.crate crate)
         -> vec[tup(str, uint)] {
     let vec[tup(str, uint)] index = vec();
     let vec[str] path = vec();
-    ebml.start_tag(ebml_w, tag_paths);
+    EBML.start_tag(ebml_w, tag_paths);
     encode_module_item_paths(ebml_w, crate.node.module, path, index);
-    ebml.end_tag(ebml_w);
+    EBML.end_tag(ebml_w);
     ret index;
 }
 
 
 // Item info table encoding
 
-fn encode_kind(&ebml.writer ebml_w, u8 c) {
-    ebml.start_tag(ebml_w, tag_items_data_item_kind);
+fn encode_kind(&EBML.writer ebml_w, u8 c) {
+    EBML.start_tag(ebml_w, tag_items_data_item_kind);
     ebml_w.writer.write(vec(c));
-    ebml.end_tag(ebml_w);
+    EBML.end_tag(ebml_w);
 }
 
 fn def_to_str(ast.def_id did) -> str {
     ret #fmt("%d:%d", did._0, did._1);
 }
 
-fn encode_type_param_count(&ebml.writer ebml_w, vec[ast.ty_param] tps) {
-    ebml.start_tag(ebml_w, tag_items_data_item_ty_param_count);
-    ebml.write_vint(ebml_w.writer, _vec.len[ast.ty_param](tps));
-    ebml.end_tag(ebml_w);
+fn encode_type_param_count(&EBML.writer ebml_w, vec[ast.ty_param] tps) {
+    EBML.start_tag(ebml_w, tag_items_data_item_ty_param_count);
+    EBML.write_vint(ebml_w.writer, Vec.len[ast.ty_param](tps));
+    EBML.end_tag(ebml_w);
 }
 
-fn encode_variant_id(&ebml.writer ebml_w, ast.def_id vid) {
-    ebml.start_tag(ebml_w, tag_items_data_item_variant);
-    ebml_w.writer.write(_str.bytes(def_to_str(vid)));
-    ebml.end_tag(ebml_w);
+fn encode_variant_id(&EBML.writer ebml_w, ast.def_id vid) {
+    EBML.start_tag(ebml_w, tag_items_data_item_variant);
+    ebml_w.writer.write(Str.bytes(def_to_str(vid)));
+    EBML.end_tag(ebml_w);
 }
 
-fn encode_type(@trans.crate_ctxt cx, &ebml.writer ebml_w, ty.t typ) {
-    ebml.start_tag(ebml_w, tag_items_data_item_type);
+fn encode_type(@trans.crate_ctxt cx, &EBML.writer ebml_w, ty.t typ) {
+    EBML.start_tag(ebml_w, tag_items_data_item_type);
 
     auto f = def_to_str;
     auto ty_str_ctxt = @rec(ds=f, tcx=cx.tcx,
                             abbrevs=ac_use_abbrevs(cx.type_abbrevs));
-    Encode.enc_ty(io.new_writer_(ebml_w.writer), ty_str_ctxt, typ);
-    ebml.end_tag(ebml_w);
+    Encode.enc_ty(IO.new_writer_(ebml_w.writer), ty_str_ctxt, typ);
+    EBML.end_tag(ebml_w);
 }
 
-fn encode_symbol(@trans.crate_ctxt cx, &ebml.writer ebml_w, ast.def_id did) {
-    ebml.start_tag(ebml_w, tag_items_data_item_symbol);
-    ebml_w.writer.write(_str.bytes(cx.item_symbols.get(did)));
-    ebml.end_tag(ebml_w);
+fn encode_symbol(@trans.crate_ctxt cx, &EBML.writer ebml_w, ast.def_id did) {
+    EBML.start_tag(ebml_w, tag_items_data_item_symbol);
+    ebml_w.writer.write(Str.bytes(cx.item_symbols.get(did)));
+    EBML.end_tag(ebml_w);
 }
 
-fn encode_discriminant(@trans.crate_ctxt cx, &ebml.writer ebml_w,
+fn encode_discriminant(@trans.crate_ctxt cx, &EBML.writer ebml_w,
                        ast.def_id did) {
-    ebml.start_tag(ebml_w, tag_items_data_item_symbol);
-    ebml_w.writer.write(_str.bytes(cx.discrim_symbols.get(did)));
-    ebml.end_tag(ebml_w);
+    EBML.start_tag(ebml_w, tag_items_data_item_symbol);
+    ebml_w.writer.write(Str.bytes(cx.discrim_symbols.get(did)));
+    EBML.end_tag(ebml_w);
 }
 
-fn encode_tag_id(&ebml.writer ebml_w, &ast.def_id id) {
-    ebml.start_tag(ebml_w, tag_items_data_item_tag_id);
-    ebml_w.writer.write(_str.bytes(def_to_str(id)));
-    ebml.end_tag(ebml_w);
+fn encode_tag_id(&EBML.writer ebml_w, &ast.def_id id) {
+    EBML.start_tag(ebml_w, tag_items_data_item_tag_id);
+    ebml_w.writer.write(Str.bytes(def_to_str(id)));
+    EBML.end_tag(ebml_w);
 }
 
-fn encode_obj_type_id(&ebml.writer ebml_w, &ast.def_id id) {
-    ebml.start_tag(ebml_w, tag_items_data_item_obj_type_id);
-    ebml_w.writer.write(_str.bytes(def_to_str(id)));
-    ebml.end_tag(ebml_w);
+fn encode_obj_type_id(&EBML.writer ebml_w, &ast.def_id id) {
+    EBML.start_tag(ebml_w, tag_items_data_item_obj_type_id);
+    ebml_w.writer.write(Str.bytes(def_to_str(id)));
+    EBML.end_tag(ebml_w);
 }
 
 
-fn encode_tag_variant_info(@trans.crate_ctxt cx, &ebml.writer ebml_w,
+fn encode_tag_variant_info(@trans.crate_ctxt cx, &EBML.writer ebml_w,
                            ast.def_id did, vec[ast.variant] variants,
                            &mutable vec[tup(int, uint)] index,
                            vec[ast.ty_param] ty_params) {
     for (ast.variant variant in variants) {
         index += vec(tup(variant.node.id._1, ebml_w.writer.tell()));
 
-        ebml.start_tag(ebml_w, tag_items_data_item);
+        EBML.start_tag(ebml_w, tag_items_data_item);
         encode_def_id(ebml_w, variant.node.id);
         encode_kind(ebml_w, 'v' as u8);
         encode_tag_id(ebml_w, did);
         encode_type(cx, ebml_w, trans.node_ann_type(cx, variant.node.ann));
-        if (_vec.len[ast.variant_arg](variant.node.args) > 0u) {
+        if (Vec.len[ast.variant_arg](variant.node.args) > 0u) {
             encode_symbol(cx, ebml_w, variant.node.id);
         }
         encode_discriminant(cx, ebml_w, variant.node.id);
         encode_type_param_count(ebml_w, ty_params);
-        ebml.end_tag(ebml_w);
+        EBML.end_tag(ebml_w);
     }
 }
 
-fn encode_info_for_item(@trans.crate_ctxt cx, &ebml.writer ebml_w,
+fn encode_info_for_item(@trans.crate_ctxt cx, &EBML.writer ebml_w,
                         @ast.item item, &mutable vec[tup(int, uint)] index) {
     alt (item.node) {
         case (ast.item_const(_, _, _, ?did, ?ann)) {
-            ebml.start_tag(ebml_w, tag_items_data_item);
+            EBML.start_tag(ebml_w, tag_items_data_item);
             encode_def_id(ebml_w, did);
             encode_kind(ebml_w, 'c' as u8);
             encode_type(cx, ebml_w, trans.node_ann_type(cx, ann));
             encode_symbol(cx, ebml_w, did);
-            ebml.end_tag(ebml_w);
+            EBML.end_tag(ebml_w);
         }
         case (ast.item_fn(_, _, ?tps, ?did, ?ann)) {
-            ebml.start_tag(ebml_w, tag_items_data_item);
+            EBML.start_tag(ebml_w, tag_items_data_item);
             encode_def_id(ebml_w, did);
             encode_kind(ebml_w, 'f' as u8);
             encode_type_param_count(ebml_w, tps);
             encode_type(cx, ebml_w, trans.node_ann_type(cx, ann));
             encode_symbol(cx, ebml_w, did);
-            ebml.end_tag(ebml_w);
+            EBML.end_tag(ebml_w);
         }
         case (ast.item_mod(_, _, ?did)) {
-            ebml.start_tag(ebml_w, tag_items_data_item);
+            EBML.start_tag(ebml_w, tag_items_data_item);
             encode_def_id(ebml_w, did);
             encode_kind(ebml_w, 'm' as u8);
-            ebml.end_tag(ebml_w);
+            EBML.end_tag(ebml_w);
         }
         case (ast.item_native_mod(_, _, ?did)) {
-            ebml.start_tag(ebml_w, tag_items_data_item);
+            EBML.start_tag(ebml_w, tag_items_data_item);
             encode_def_id(ebml_w, did);
             encode_kind(ebml_w, 'n' as u8);
-            ebml.end_tag(ebml_w);
+            EBML.end_tag(ebml_w);
         }
         case (ast.item_ty(?id, _, ?tps, ?did, ?ann)) {
-            ebml.start_tag(ebml_w, tag_items_data_item);
+            EBML.start_tag(ebml_w, tag_items_data_item);
             encode_def_id(ebml_w, did);
             encode_kind(ebml_w, 'y' as u8);
             encode_type_param_count(ebml_w, tps);
             encode_type(cx, ebml_w, trans.node_ann_type(cx, ann));
-            ebml.end_tag(ebml_w);
+            EBML.end_tag(ebml_w);
         }
         case (ast.item_tag(?id, ?variants, ?tps, ?did, ?ann)) {
-            ebml.start_tag(ebml_w, tag_items_data_item);
+            EBML.start_tag(ebml_w, tag_items_data_item);
             encode_def_id(ebml_w, did);
             encode_kind(ebml_w, 't' as u8);
             encode_type_param_count(ebml_w, tps);
@@ -523,33 +523,33 @@ fn encode_info_for_item(@trans.crate_ctxt cx, &ebml.writer ebml_w,
             for (ast.variant v in variants) {
                 encode_variant_id(ebml_w, v.node.id);
             }
-            ebml.end_tag(ebml_w);
+            EBML.end_tag(ebml_w);
 
             encode_tag_variant_info(cx, ebml_w, did, variants, index, tps);
         }
         case (ast.item_obj(?id, _, ?tps, ?odid, ?ann)) {
-            ebml.start_tag(ebml_w, tag_items_data_item);
+            EBML.start_tag(ebml_w, tag_items_data_item);
             encode_def_id(ebml_w, odid.ctor);
             encode_kind(ebml_w, 'o' as u8);
             encode_type_param_count(ebml_w, tps);
             auto fn_ty = trans.node_ann_type(cx, ann);
             encode_type(cx, ebml_w, fn_ty);
             encode_symbol(cx, ebml_w, odid.ctor);
-            ebml.end_tag(ebml_w);
+            EBML.end_tag(ebml_w);
 
-            ebml.start_tag(ebml_w, tag_items_data_item);
+            EBML.start_tag(ebml_w, tag_items_data_item);
             encode_def_id(ebml_w, odid.ty);
             encode_kind(ebml_w, 'y' as u8);
             encode_type_param_count(ebml_w, tps);
             encode_type(cx, ebml_w, ty.ty_fn_ret(cx.tcx, fn_ty));
-            ebml.end_tag(ebml_w);
+            EBML.end_tag(ebml_w);
         }
     }
 }
 
-fn encode_info_for_native_item(@trans.crate_ctxt cx, &ebml.writer ebml_w,
+fn encode_info_for_native_item(@trans.crate_ctxt cx, &EBML.writer ebml_w,
                                @ast.native_item nitem) {
-    ebml.start_tag(ebml_w, tag_items_data_item);
+    EBML.start_tag(ebml_w, tag_items_data_item);
     alt (nitem.node) {
         case (ast.native_item_ty(_, ?did)) {
             encode_def_id(ebml_w, did);
@@ -564,14 +564,14 @@ fn encode_info_for_native_item(@trans.crate_ctxt cx, &ebml.writer ebml_w,
             encode_symbol(cx, ebml_w, did);
         }
     }
-    ebml.end_tag(ebml_w);
+    EBML.end_tag(ebml_w);
 }
 
-fn encode_info_for_items(@trans.crate_ctxt cx, &ebml.writer ebml_w)
+fn encode_info_for_items(@trans.crate_ctxt cx, &EBML.writer ebml_w)
         -> vec[tup(int, uint)] {
     let vec[tup(int, uint)] index = vec();
 
-    ebml.start_tag(ebml_w, tag_items_data);
+    EBML.start_tag(ebml_w, tag_items_data);
     for each (@tup(ast.def_id, @ast.item) kvp in cx.items.items()) {
         index += vec(tup(kvp._0._1, ebml_w.writer.tell()));
         encode_info_for_item(cx, ebml_w, kvp._1, index);
@@ -581,7 +581,7 @@ fn encode_info_for_items(@trans.crate_ctxt cx, &ebml.writer ebml_w)
         index += vec(tup(kvp._0._1, ebml_w.writer.tell()));
         encode_info_for_native_item(cx, ebml_w, kvp._1);
     }
-    ebml.end_tag(ebml_w);
+    EBML.end_tag(ebml_w);
 
     ret index;
 }
@@ -597,7 +597,7 @@ fn hash_def_num(&int def_num) -> uint {
 
 fn hash_path(&str s) -> uint {
     auto h = 5381u;
-    for (u8 ch in _str.bytes(s)) {
+    for (u8 ch in Str.bytes(s)) {
         h = ((h << 5u) + h) ^ (ch as uint);
     }
     ret h;
@@ -606,7 +606,7 @@ fn hash_path(&str s) -> uint {
 fn create_index[T](vec[tup(T, uint)] index, fn(&T) -> uint hash_fn)
         -> vec[vec[tup(T, uint)]] {
     let vec[vec[tup(T, uint)]] buckets = vec();
-    for each (uint i in _uint.range(0u, 256u)) {
+    for each (uint i in UInt.range(0u, 256u)) {
         let vec[tup(T, uint)] bucket = vec();
         buckets += vec(bucket);
     }
@@ -619,69 +619,69 @@ fn create_index[T](vec[tup(T, uint)] index, fn(&T) -> uint hash_fn)
     ret buckets;
 }
 
-fn encode_index[T](&ebml.writer ebml_w, vec[vec[tup(T, uint)]] buckets,
-                          fn(io.writer, &T) write_fn) {
-    auto writer = io.new_writer_(ebml_w.writer);
+fn encode_index[T](&EBML.writer ebml_w, vec[vec[tup(T, uint)]] buckets,
+                          fn(IO.writer, &T) write_fn) {
+    auto writer = IO.new_writer_(ebml_w.writer);
 
-    ebml.start_tag(ebml_w, tag_index);
+    EBML.start_tag(ebml_w, tag_index);
 
     let vec[uint] bucket_locs = vec();
-    ebml.start_tag(ebml_w, tag_index_buckets);
+    EBML.start_tag(ebml_w, tag_index_buckets);
     for (vec[tup(T, uint)] bucket in buckets) {
         bucket_locs += vec(ebml_w.writer.tell());
 
-        ebml.start_tag(ebml_w, tag_index_buckets_bucket);
+        EBML.start_tag(ebml_w, tag_index_buckets_bucket);
         for (tup(T, uint) elt in bucket) {
-            ebml.start_tag(ebml_w, tag_index_buckets_bucket_elt);
+            EBML.start_tag(ebml_w, tag_index_buckets_bucket_elt);
             writer.write_be_uint(elt._1, 4u);
             write_fn(writer, elt._0);
-            ebml.end_tag(ebml_w);
+            EBML.end_tag(ebml_w);
         }
-        ebml.end_tag(ebml_w);
+        EBML.end_tag(ebml_w);
     }
-    ebml.end_tag(ebml_w);
+    EBML.end_tag(ebml_w);
 
-    ebml.start_tag(ebml_w, tag_index_table);
+    EBML.start_tag(ebml_w, tag_index_table);
     for (uint pos in bucket_locs) {
         writer.write_be_uint(pos, 4u);
     }
-    ebml.end_tag(ebml_w);
+    EBML.end_tag(ebml_w);
 
-    ebml.end_tag(ebml_w);
+    EBML.end_tag(ebml_w);
 }
 
-fn write_str(io.writer writer, &str s) {
+fn write_str(IO.writer writer, &str s) {
     writer.write_str(s);
 }
 
-fn write_int(io.writer writer, &int n) {
+fn write_int(IO.writer writer, &int n) {
     writer.write_be_uint(n as uint, 4u);
 }
 
 
 fn encode_metadata(@trans.crate_ctxt cx, @ast.crate crate)
         -> ValueRef {
-    auto string_w = io.string_writer();
+    auto string_w = IO.string_writer();
     auto buf_w = string_w.get_writer().get_buf_writer();
-    auto ebml_w = ebml.create_writer(buf_w);
+    auto ebml_w = EBML.create_writer(buf_w);
 
     // Encode and index the paths.
-    ebml.start_tag(ebml_w, tag_paths);
+    EBML.start_tag(ebml_w, tag_paths);
     auto paths_index = encode_item_paths(ebml_w, crate);
     auto str_writer = write_str;
     auto path_hasher = hash_path;
     auto paths_buckets = create_index[str](paths_index, path_hasher);
     encode_index[str](ebml_w, paths_buckets, str_writer);
-    ebml.end_tag(ebml_w);
+    EBML.end_tag(ebml_w);
 
     // Encode and index the items.
-    ebml.start_tag(ebml_w, tag_items);
+    EBML.start_tag(ebml_w, tag_items);
     auto items_index = encode_info_for_items(cx, ebml_w);
     auto int_writer = write_int;
     auto item_hasher = hash_def_num;
     auto items_buckets = create_index[int](items_index, item_hasher);
     encode_index[int](ebml_w, items_buckets, int_writer);
-    ebml.end_tag(ebml_w);
+    EBML.end_tag(ebml_w);
 
     // Pad this, since something (LLVM, presumably) is cutting off the
     // remaining % 4 bytes.
@@ -698,9 +698,9 @@ fn write_metadata(@trans.crate_ctxt cx, @ast.crate crate) {
 
     auto llconst = trans.C_struct(vec(llmeta));
     auto llglobal = llvm.LLVMAddGlobal(cx.llmod, trans.val_ty(llconst),
-                                       _str.buf("rust_metadata"));
+                                       Str.buf("rust_metadata"));
     llvm.LLVMSetInitializer(llglobal, llconst);
-    llvm.LLVMSetSection(llglobal, _str.buf(x86.get_meta_sect_name()));
+    llvm.LLVMSetSection(llglobal, Str.buf(x86.get_meta_sect_name()));
 }
 
 //
diff --git a/src/comp/middle/resolve.rs b/src/comp/middle/resolve.rs
index 8b92cabd30e..433b4734052 100644
--- a/src/comp/middle/resolve.rs
+++ b/src/comp/middle/resolve.rs
@@ -7,15 +7,15 @@ import driver.session;
 import util.common.new_def_hash;
 import util.common.span;
 import util.typestate_ann.ts_ann;
-import std.map.hashmap;
-import std.list.list;
-import std.list.nil;
-import std.list.cons;
-import std.option;
-import std.option.some;
-import std.option.none;
-import std._str;
-import std._vec;
+import std.Map.hashmap;
+import std.List.list;
+import std.List.nil;
+import std.List.cons;
+import std.Option;
+import std.Option.some;
+import std.Option.none;
+import std.Str;
+import std.Vec;
 
 tag scope {
     scope_crate(@ast.crate);
@@ -43,7 +43,7 @@ tag direction {
     down;
 }
 
-type import_map = std.map.hashmap[ast.def_id,def_wrap];
+type import_map = std.Map.hashmap[ast.def_id,def_wrap];
 
 // A simple wrapper over defs that stores a bit more information about modules
 // and uses so that we can use the regular lookup_name when resolving imports.
@@ -112,7 +112,7 @@ fn unwrap_def(def_wrap d) -> def {
 }
 
 fn lookup_external_def(session.session sess, int cnum, vec[ident] idents)
-        -> option.t[def_wrap] {
+        -> Option.t[def_wrap] {
     alt (creader.lookup_def(sess, cnum, idents)) {
         case (none[ast.def]) {
             ret none[def_wrap];
@@ -141,7 +141,7 @@ fn lookup_external_def(session.session sess, int cnum, vec[ident] idents)
 
 fn find_final_def(&env e, import_map index,
                   &span sp, vec[ident] idents, namespace ns,
-                  option.t[ast.def_id] import_id) -> def_wrap {
+                  Option.t[ast.def_id] import_id) -> def_wrap {
 
     // We are given a series of identifiers (p.q.r) and we know that
     // in the environment 'e' the identifier 'p' was resolved to 'd'. We
@@ -153,8 +153,8 @@ fn find_final_def(&env e, import_map index,
         fn found_mod(&env e, &import_map index, &span sp,
                      vec[ident] idents, namespace ns,
                      @ast.item i) -> def_wrap {
-            auto len = _vec.len[ident](idents);
-            auto rest_idents = _vec.slice[ident](idents, 1u, len);
+            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);
@@ -178,8 +178,8 @@ fn find_final_def(&env e, import_map index,
                               vec[ident] idents, namespace ns,
                               ast.def_id mod_id)
                 -> def_wrap {
-            auto len = _vec.len[ident](idents);
-            auto rest_idents = _vec.slice[ident](idents, 1u, len);
+            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_external_mod(empty_e, mod_id, idents);
@@ -202,12 +202,12 @@ fn find_final_def(&env e, import_map index,
 
         fn found_crate(&env e, &import_map index, &span sp,
                        vec[ident] idents, int cnum) -> def_wrap {
-            auto len = _vec.len[ident](idents);
-            auto rest_idents = _vec.slice[ident](idents, 1u, len);
+            auto len = Vec.len[ident](idents);
+            auto rest_idents = Vec.slice[ident](idents, 1u, len);
             alt (lookup_external_def(e.sess, cnum, rest_idents)) {
                 case (none[def_wrap]) {
                     e.sess.span_err(sp, #fmt("unbound name '%s'",
-                                             _str.connect(idents, ".")));
+                                             Str.connect(idents, ".")));
                     fail;
                 }
                 case (some[def_wrap](?dw)) { ret dw; }
@@ -227,7 +227,7 @@ fn find_final_def(&env e, import_map index,
             case (_) {
             }
         }
-        auto len = _vec.len[ident](idents);
+        auto len = Vec.len[ident](idents);
         if (len == 1u) {
             ret d;
         }
@@ -247,13 +247,13 @@ fn find_final_def(&env e, import_map index,
             case (def_wrap_use(?vi)) {
                 alt (vi.node) {
                     case (ast.view_item_use(_, _, _, ?cnum_opt)) {
-                        auto cnum = option.get[int](cnum_opt);
+                        auto cnum = Option.get[int](cnum_opt);
                         ret found_crate(e, index, sp, idents, cnum);
                     }
                 }
             }
             case (def_wrap_other(?d)) {
-                let uint l = _vec.len[ident](idents);
+                let uint l = Vec.len[ident](idents);
                 ret def_wrap_expr_field(l, d);
             }
         }
@@ -261,7 +261,7 @@ fn find_final_def(&env e, import_map index,
     }
 
     if (import_id != none[ast.def_id]) {
-        alt (index.find(option.get[ast.def_id](import_id))) {
+        alt (index.find(Option.get[ast.def_id](import_id))) {
             case (some[def_wrap](?x)) {
                 alt (x) {
                     case (def_wrap_resolving) {
@@ -276,7 +276,7 @@ fn find_final_def(&env e, import_map index,
             case (none[def_wrap]) {
             }
         }
-        index.insert(option.get[ast.def_id](import_id), def_wrap_resolving);
+        index.insert(Option.get[ast.def_id](import_id), def_wrap_resolving);
     }
     auto first = idents.(0);
     auto d_ = lookup_name_wrapped(e, first, ns, up);
@@ -288,7 +288,7 @@ fn find_final_def(&env e, import_map index,
         case (some[tup(@env, def_wrap)](?d)) {
             auto x = found_something(*d._0, index, sp, idents, ns, d._1);
             if (import_id != none[ast.def_id]) {
-                index.insert(option.get[ast.def_id](import_id), x);
+                index.insert(Option.get[ast.def_id](import_id), x);
             }
             ret x;
         }
@@ -296,7 +296,7 @@ fn find_final_def(&env e, import_map index,
 }
 
 fn lookup_name_wrapped(&env e, ast.ident i, namespace ns, direction dir)
-    -> option.t[tup(@env, def_wrap)] {
+    -> Option.t[tup(@env, def_wrap)] {
 
     // log "resolving name " + i;
 
@@ -357,7 +357,7 @@ fn lookup_name_wrapped(&env e, ast.ident i, namespace ns, direction dir)
     }
 
     fn check_mod(ast.ident i, ast._mod m, namespace ns,
-                 direction dir) -> option.t[def_wrap] {
+                 direction dir) -> Option.t[def_wrap] {
 
         fn visible(ast.ident i, ast._mod m, direction dir) -> bool {
 
@@ -411,7 +411,7 @@ fn lookup_name_wrapped(&env e, ast.ident i, namespace ns, direction dir)
         }
     }
 
-    fn check_native_mod(ast.ident i, ast.native_mod m) -> option.t[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)) {
@@ -431,9 +431,9 @@ fn lookup_name_wrapped(&env e, ast.ident i, namespace ns, direction dir)
     }
 
     fn handle_fn_decl(ast.ident identifier, &ast.fn_decl decl,
-                      &vec[ast.ty_param] ty_params) -> option.t[def_wrap] {
+                      &vec[ast.ty_param] ty_params) -> Option.t[def_wrap] {
         for (ast.arg a in decl.inputs) {
-            if (_str.eq(a.ident, identifier)) {
+            if (Str.eq(a.ident, identifier)) {
                 auto t = ast.def_arg(a.id);
                 ret some(def_wrap_other(t));
             }
@@ -441,7 +441,7 @@ fn lookup_name_wrapped(&env e, ast.ident i, namespace ns, direction dir)
 
         auto i = 0u;
         for (ast.ty_param tp in ty_params) {
-            if (_str.eq(tp, identifier)) {
+            if (Str.eq(tp, identifier)) {
                 auto t = ast.def_ty_arg(i);
                 ret some(def_wrap_other(t));
             }
@@ -465,7 +465,7 @@ fn lookup_name_wrapped(&env e, ast.ident i, namespace ns, direction dir)
     }
 
     fn check_block(ast.ident i, &ast.block_ b, namespace ns)
-            -> option.t[def_wrap] {
+            -> Option.t[def_wrap] {
         alt (b.index.find(i)) {
             case (some[ast.block_index_entry](?ix)) {
                 alt(ix) {
@@ -486,7 +486,7 @@ fn lookup_name_wrapped(&env e, ast.ident i, namespace ns, direction dir)
     }
 
     fn in_scope(&session.session sess, ast.ident identifier, &scope s,
-                namespace ns, direction dir) -> option.t[def_wrap] {
+                namespace ns, direction dir) -> Option.t[def_wrap] {
         alt (s) {
 
             case (scope_crate(?c)) {
@@ -500,7 +500,7 @@ fn lookup_name_wrapped(&env e, ast.ident i, namespace ns, direction dir)
                     }
                     case (ast.item_obj(_, ?ob, ?ty_params, _, _)) {
                         for (ast.obj_field f in ob.fields) {
-                            if (_str.eq(f.ident, identifier)) {
+                            if (Str.eq(f.ident, identifier)) {
                                 auto t = ast.def_obj_field(f.id);
                                 ret some(def_wrap_other(t));
                             }
@@ -508,7 +508,7 @@ fn lookup_name_wrapped(&env e, ast.ident i, namespace ns, direction dir)
 
                         auto i = 0u;
                         for (ast.ty_param tp in ty_params) {
-                            if (_str.eq(tp, identifier)) {
+                            if (Str.eq(tp, identifier)) {
                                 auto t = ast.def_ty_arg(i);
                                 ret some(def_wrap_other(t));
                             }
@@ -518,7 +518,7 @@ fn lookup_name_wrapped(&env e, ast.ident i, namespace ns, direction dir)
                     case (ast.item_tag(_,?variants,?ty_params,?tag_id,_)) {
                         auto i = 0u;
                         for (ast.ty_param tp in ty_params) {
-                            if (_str.eq(tp, identifier)) {
+                            if (Str.eq(tp, identifier)) {
                                 auto t = ast.def_ty_arg(i);
                                 ret some(def_wrap_other(t));
                             }
@@ -534,7 +534,7 @@ fn lookup_name_wrapped(&env e, ast.ident i, namespace ns, direction dir)
                     case (ast.item_ty(_, _, ?ty_params, _, _)) {
                         auto i = 0u;
                         for (ast.ty_param tp in ty_params) {
-                            if (_str.eq(tp, identifier)) {
+                            if (Str.eq(tp, identifier)) {
                                 auto t = ast.def_ty_arg(i);
                                 ret some(def_wrap_other(t));
                             }
@@ -560,7 +560,7 @@ fn lookup_name_wrapped(&env e, ast.ident i, namespace ns, direction dir)
             case (scope_loop(?d)) {
                 alt (d.node) {
                     case (ast.decl_local(?local)) {
-                        if (_str.eq(local.ident, identifier)) {
+                        if (Str.eq(local.ident, identifier)) {
                             auto lc = ast.def_local(local.id);
                             ret some(def_wrap_other(lc));
                         }
@@ -605,9 +605,9 @@ fn lookup_name_wrapped(&env e, ast.ident i, namespace ns, direction dir)
 }
 
 fn fold_pat_tag(&env e, &span sp, ast.path p, vec[@ast.pat] args,
-                option.t[ast.variant_def] old_def,
+                Option.t[ast.variant_def] old_def,
                 ann a) -> @ast.pat {
-    auto len = _vec.len[ast.ident](p.node.idents);
+    auto len = Vec.len[ast.ident](p.node.idents);
     auto last_id = p.node.idents.(len - 1u);
     auto new_def;
     auto index = new_def_hash[def_wrap]();
@@ -646,9 +646,9 @@ fn fold_pat_tag(&env e, &span sp, ast.path p, vec[@ast.pat] args,
 // and split that off as the 'primary' expr_path, with secondary expr_field
 // expressions tacked on the end.
 
-fn fold_expr_path(&env e, &span sp, &ast.path p, &option.t[def] d,
+fn fold_expr_path(&env e, &span sp, &ast.path p, &Option.t[def] d,
                   ann a) -> @ast.expr {
-    auto n_idents = _vec.len[ast.ident](p.node.idents);
+    auto n_idents = Vec.len[ast.ident](p.node.idents);
     assert (n_idents != 0u);
 
     auto index = new_def_hash[def_wrap]();
@@ -669,7 +669,7 @@ fn fold_expr_path(&env e, &span sp, &ast.path p, &option.t[def] d,
         }
     }
     auto path_elems =
-        _vec.slice[ident](p.node.idents, 0u, path_len);
+        Vec.slice[ident](p.node.idents, 0u, path_len);
     auto p_ = rec(node=rec(idents = path_elems with p.node) with p);
     auto d_ = some(unwrap_def(d));
     auto ex = @fold.respan[ast.expr_](sp, ast.expr_path(p_, d_, a));
@@ -685,9 +685,9 @@ fn fold_expr_path(&env e, &span sp, &ast.path p, &option.t[def] d,
 fn fold_view_item_import(&env e, &span sp,
                          import_map index, ident i,
                          vec[ident] is, ast.def_id id,
-                         option.t[def] target_id) -> @ast.view_item {
+                         Option.t[def] target_id) -> @ast.view_item {
     // Produce errors for invalid imports
-    auto len = _vec.len[ast.ident](is);
+    auto len = Vec.len[ast.ident](is);
     auto last_id = is.(len - 1u);
     auto d = find_final_def(e, index, sp, is, ns_value, some(id));
     alt (d) {
@@ -698,12 +698,12 @@ fn fold_view_item_import(&env e, &span sp,
         case (_) {
         }
     }
-    let option.t[def] target_def = some(unwrap_def(d));
+    let Option.t[def] target_def = some(unwrap_def(d));
     ret @fold.respan[ast.view_item_](sp, ast.view_item_import(i, is, id,
                                                               target_def));
 }
 
-fn fold_ty_path(&env e, &span sp, ast.path p, &option.t[def] d) -> @ast.ty {
+fn fold_ty_path(&env e, &span sp, ast.path p, &Option.t[def] d) -> @ast.ty {
     auto index = new_def_hash[def_wrap]();
     auto d = find_final_def(e, index, sp, p.node.idents, ns_type,
                             none[ast.def_id]);
diff --git a/src/comp/middle/trans.rs b/src/comp/middle/trans.rs
index 86ddcddf28a..9f10097de3b 100644
--- a/src/comp/middle/trans.rs
+++ b/src/comp/middle/trans.rs
@@ -1,14 +1,14 @@
-import std._int;
-import std._str;
-import std._uint;
-import std._vec;
-import std._str.rustrt.sbuf;
-import std._vec.rustrt.vbuf;
-import std.map;
-import std.map.hashmap;
-import std.option;
-import std.option.some;
-import std.option.none;
+import std.Int;
+import std.Str;
+import std.UInt;
+import std.Vec;
+import std.Str.rustrt.sbuf;
+import std.Vec.rustrt.vbuf;
+import std.Map;
+import std.Map.hashmap;
+import std.Option;
+import std.Option.some;
+import std.Option.none;
 
 import front.ast;
 import front.creader;
@@ -110,7 +110,7 @@ state type crate_ctxt = rec(session.session sess,
                             hashmap[ty.t, TypeRef] lltypes,
                             @glue_fns glues,
                             namegen names,
-                            std.sha1.sha1 sha,
+                            std.SHA1.sha1 sha,
                             hashmap[ty.t, str] type_sha1s,
                             hashmap[ty.t, metadata.ty_abbrev] type_abbrevs,
                             ty.ctxt tcx);
@@ -129,8 +129,8 @@ state type fn_ctxt = rec(ValueRef llfn,
                          ValueRef llenv,
                          ValueRef llretptr,
                          mutable BasicBlockRef llallocas,
-                         mutable option.t[self_vt] llself,
-                         mutable option.t[ValueRef] lliterbody,
+                         mutable Option.t[self_vt] llself,
+                         mutable Option.t[ValueRef] lliterbody,
                          hashmap[ast.def_id, ValueRef] llargs,
                          hashmap[ast.def_id, ValueRef] llobjfields,
                          hashmap[ast.def_id, ValueRef] lllocals,
@@ -145,7 +145,7 @@ tag cleanup {
 
 tag block_kind {
     SCOPE_BLOCK;
-    LOOP_SCOPE_BLOCK(option.t[@block_ctxt], @block_ctxt);
+    LOOP_SCOPE_BLOCK(Option.t[@block_ctxt], @block_ctxt);
     NON_SCOPE_BLOCK;
 }
 
@@ -156,7 +156,7 @@ state type block_ctxt = rec(BasicBlockRef llbb,
                             mutable vec[cleanup] cleanups,
                             @fn_ctxt fcx);
 
-// FIXME: we should be able to use option.t[@block_parent] here but
+// FIXME: we should be able to use Option.t[@block_parent] here but
 // the infinite-tag check in rustboot gets upset.
 
 tag block_parent {
@@ -177,7 +177,7 @@ fn extend_path(@local_ctxt cx, str name) -> @local_ctxt {
 }
 
 fn path_name(vec[str] path) -> str {
-    ret _str.connect(path, sep());
+    ret Str.connect(path, sep());
 }
 
 
@@ -192,7 +192,7 @@ fn get_type_sha1(@crate_ctxt ccx, ty.t t) -> str {
             // to be independent of one another in the crate.
             auto cx = @rec(ds=f, tcx=ccx.tcx, abbrevs=metadata.ac_no_abbrevs);
             ccx.sha.input_str(metadata.Encode.ty_str(cx, t));
-            hash = _str.substr(ccx.sha.result_str(), 0u, 16u);
+            hash = Str.substr(ccx.sha.result_str(), 0u, 16u);
             ccx.type_sha1s.insert(t, hash);
         }
     }
@@ -306,8 +306,8 @@ fn T_char() -> TypeRef {
 
 fn T_fn(vec[TypeRef] inputs, TypeRef output) -> TypeRef {
     ret llvm.LLVMFunctionType(output,
-                              _vec.buf[TypeRef](inputs),
-                              _vec.len[TypeRef](inputs),
+                              Vec.buf[TypeRef](inputs),
+                              Vec.len[TypeRef](inputs),
                               False);
 }
 
@@ -321,8 +321,8 @@ fn T_ptr(TypeRef t) -> TypeRef {
 }
 
 fn T_struct(vec[TypeRef] elts) -> TypeRef {
-    ret llvm.LLVMStructType(_vec.buf[TypeRef](elts),
-                            _vec.len[TypeRef](elts),
+    ret llvm.LLVMStructType(Vec.buf[TypeRef](elts),
+                            Vec.len[TypeRef](elts),
                             False);
 }
 
@@ -352,9 +352,9 @@ fn T_task(type_names tn) -> TypeRef {
 fn T_tydesc_field(type_names tn, int field) -> TypeRef {
     // Bit of a kludge: pick the fn typeref out of the tydesc..
     let vec[TypeRef] tydesc_elts =
-        _vec.init_elt[TypeRef](T_nil(), abi.n_tydesc_fields as uint);
+        Vec.init_elt[TypeRef](T_nil(), abi.n_tydesc_fields as uint);
     llvm.LLVMGetStructElementTypes(T_tydesc(tn),
-                                   _vec.buf[TypeRef](tydesc_elts));
+                                   Vec.buf[TypeRef](tydesc_elts));
     auto t = llvm.LLVMGetElementType(tydesc_elts.(field));
     ret t;
 }
@@ -372,7 +372,7 @@ fn T_glue_fn(type_names tn) -> TypeRef {
 
 fn T_dtor(@crate_ctxt ccx, TypeRef llself_ty) -> TypeRef {
     ret type_of_fn_full(ccx, ast.proto_fn, some[TypeRef](llself_ty),
-                        _vec.empty[ty.arg](), ty.mk_nil(ccx.tcx), 0u);
+                        Vec.empty[ty.arg](), ty.mk_nil(ccx.tcx), 0u);
 }
 
 fn T_cmp_glue_fn(type_names tn) -> TypeRef {
@@ -535,7 +535,7 @@ fn T_opaque_closure_ptr(type_names tn) -> TypeRef {
 }
 
 fn T_tag(type_names tn, uint size) -> TypeRef {
-    auto s = "tag_" + _uint.to_str(size, 10u);
+    auto s = "tag_" + UInt.to_str(size, 10u);
     if (tn.name_has_type(s)) {
         ret tn.get_type(s);
     }
@@ -559,7 +559,7 @@ fn T_opaque_tag_ptr(type_names tn) -> TypeRef {
 }
 
 fn T_captured_tydescs(type_names tn, uint n) -> TypeRef {
-    ret T_struct(_vec.init_elt[TypeRef](T_ptr(T_tydesc(tn)), n));
+    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 {
@@ -623,7 +623,7 @@ fn type_of_explicit_args(@crate_ctxt cx, vec[ty.arg] inputs) -> vec[TypeRef] {
 
 fn type_of_fn_full(@crate_ctxt cx,
                    ast.proto proto,
-                   option.t[TypeRef] obj_self,
+                   Option.t[TypeRef] obj_self,
                    vec[ty.arg] inputs,
                    ty.t output,
                    uint ty_param_count) -> TypeRef {
@@ -811,7 +811,7 @@ fn type_of_inner(@crate_ctxt cx, ty.t t) -> TypeRef {
     }
 
     assert (llty as int != 0);
-    llvm.LLVMAddTypeName(cx.llmod, _str.buf(ty.ty_to_short_str(cx.tcx, t)),
+    llvm.LLVMAddTypeName(cx.llmod, Str.buf(ty.ty_to_short_str(cx.tcx, t)),
                          llty);
     cx.lltypes.insert(t, llty);
     ret llty;
@@ -872,7 +872,7 @@ fn sanitize(str s) -> str {
                         c != (' ' as u8) && c != ('\t' as u8) &&
                         c != (';' as u8)) {
                         auto v = vec(c);
-                        result += _str.from_bytes(v);
+                        result += Str.from_bytes(v);
                     }
                 }
             }
@@ -894,15 +894,15 @@ fn C_integral(int i, TypeRef t) -> ValueRef {
     //
     // ret llvm.LLVMConstInt(T_int(), t as LLVM.ULongLong, False);
     //
-    ret llvm.LLVMConstIntOfString(t, _str.buf(istr(i)), 10);
+    ret llvm.LLVMConstIntOfString(t, Str.buf(istr(i)), 10);
 }
 
 fn C_float(str s) -> ValueRef {
-    ret llvm.LLVMConstRealOfString(T_float(), _str.buf(s));
+    ret llvm.LLVMConstRealOfString(T_float(), Str.buf(s));
 }
 
 fn C_floating(str s, TypeRef t) -> ValueRef {
-    ret llvm.LLVMConstRealOfString(t, _str.buf(s));
+    ret llvm.LLVMConstRealOfString(t, Str.buf(s));
 }
 
 fn C_nil() -> ValueRef {
@@ -929,9 +929,9 @@ fn C_i8(uint i) -> ValueRef {
 // This is a 'c-like' raw string, which differs from
 // our boxed-and-length-annotated strings.
 fn C_cstr(@crate_ctxt cx, str s) -> ValueRef {
-    auto sc = llvm.LLVMConstString(_str.buf(s), _str.byte_len(s), False);
+    auto sc = llvm.LLVMConstString(Str.buf(s), Str.byte_len(s), False);
     auto g = llvm.LLVMAddGlobal(cx.llmod, val_ty(sc),
-                                _str.buf(cx.names.next("str")));
+                                Str.buf(cx.names.next("str")));
     llvm.LLVMSetInitializer(g, sc);
     llvm.LLVMSetGlobalConstant(g, True);
     llvm.LLVMSetLinkage(g, lib.llvm.LLVMInternalLinkage
@@ -941,15 +941,15 @@ fn C_cstr(@crate_ctxt cx, str s) -> ValueRef {
 
 // A rust boxed-and-length-annotated string.
 fn C_str(@crate_ctxt cx, str s) -> ValueRef {
-    auto len = _str.byte_len(s);
+    auto len = Str.byte_len(s);
     auto box = C_struct(vec(C_int(abi.const_refcount as int),
                             C_int(len + 1u as int), // 'alloc'
                             C_int(len + 1u as int), // 'fill'
                             C_int(0),               // 'pad'
-                            llvm.LLVMConstString(_str.buf(s),
+                            llvm.LLVMConstString(Str.buf(s),
                                                  len, False)));
     auto g = llvm.LLVMAddGlobal(cx.llmod, val_ty(box),
-                                _str.buf(cx.names.next("str")));
+                                Str.buf(cx.names.next("str")));
     llvm.LLVMSetInitializer(g, box);
     llvm.LLVMSetGlobalConstant(g, True);
     llvm.LLVMSetLinkage(g, lib.llvm.LLVMInternalLinkage
@@ -964,24 +964,24 @@ fn C_zero_byte_arr(uint size) -> ValueRef {
         elts += vec(C_integral(0, T_i8()));
         i += 1u;
     }
-    ret llvm.LLVMConstArray(T_i8(), _vec.buf[ValueRef](elts),
-                            _vec.len[ValueRef](elts));
+    ret llvm.LLVMConstArray(T_i8(), Vec.buf[ValueRef](elts),
+                            Vec.len[ValueRef](elts));
 }
 
 fn C_struct(vec[ValueRef] elts) -> ValueRef {
-    ret llvm.LLVMConstStruct(_vec.buf[ValueRef](elts),
-                             _vec.len[ValueRef](elts),
+    ret llvm.LLVMConstStruct(Vec.buf[ValueRef](elts),
+                             Vec.len[ValueRef](elts),
                              False);
 }
 
 fn C_array(TypeRef ty, vec[ValueRef] elts) -> ValueRef {
-    ret llvm.LLVMConstArray(ty, _vec.buf[ValueRef](elts),
-                            _vec.len[ValueRef](elts));
+    ret llvm.LLVMConstArray(ty, Vec.buf[ValueRef](elts),
+                            Vec.len[ValueRef](elts));
 }
 
 fn decl_fn(ModuleRef llmod, str name, uint cc, TypeRef llty) -> ValueRef {
     let ValueRef llfn =
-        llvm.LLVMAddFunction(llmod, _str.buf(name), llty);
+        llvm.LLVMAddFunction(llmod, Str.buf(name), llty);
     llvm.LLVMSetFunctionCallConv(llfn, cc);
     ret llfn;
 }
@@ -1026,7 +1026,7 @@ fn decl_native_glue(ModuleRef llmod, type_names tn,
         args += vec(T_int()); // taskptr, will not be passed
     }
 
-    args += _vec.init_elt[TypeRef](T_int(), n as uint);
+    args += Vec.init_elt[TypeRef](T_int(), n as uint);
 
     ret decl_fastcall_fn(llmod, s, T_fn(args, T_int()));
 }
@@ -1047,14 +1047,14 @@ fn get_extern_const(&hashmap[str, ValueRef] externs,
     if (externs.contains_key(name)) {
         ret externs.get(name);
     }
-    auto c = llvm.LLVMAddGlobal(llmod, ty, _str.buf(name));
+    auto c = llvm.LLVMAddGlobal(llmod, ty, Str.buf(name));
     externs.insert(name, c);
     ret c;
 }
 
 fn get_simple_extern_fn(&hashmap[str, ValueRef] externs,
                      ModuleRef llmod, str name, int n_args) -> ValueRef {
-    auto inputs = _vec.init_elt[TypeRef](T_int(), n_args as uint);
+    auto inputs = Vec.init_elt[TypeRef](T_int(), n_args as uint);
     auto output = T_int();
     auto t = T_fn(inputs, output);
     ret get_extern_fn(externs, llmod, name, lib.llvm.LLVMCCallConv, t);
@@ -1075,7 +1075,7 @@ fn trans_native_call(builder b, @glue_fns glues, ValueRef lltaskptr,
                      &hashmap[str, ValueRef] externs,
                      type_names tn, ModuleRef llmod, str name,
                      bool pass_task, vec[ValueRef] args) -> ValueRef {
-    let int n = (_vec.len[ValueRef](args) as int);
+    let int n = (Vec.len[ValueRef](args) as int);
     let ValueRef llnative = get_simple_extern_fn(externs, llmod, name, n);
     llnative = llvm.LLVMConstPointerCast(llnative, T_int());
 
@@ -1395,7 +1395,7 @@ fn GEP_tup_like(@block_ctxt cx, ty.t t,
     fn split_type(@crate_ctxt ccx, ty.t t, vec[int] ixs, uint n)
         -> rec(vec[ty.t] prefix, ty.t target) {
 
-        let uint len = _vec.len[int](ixs);
+        let uint len = Vec.len[int](ixs);
 
         // We don't support 0-index or 1-index GEPs. The former is nonsense
         // and the latter would only be meaningful if we supported non-0
@@ -1417,7 +1417,7 @@ fn GEP_tup_like(@block_ctxt cx, ty.t t,
         let vec[ty.t] prefix = vec();
         let int i = 0;
         while (i < ix) {
-            _vec.push[ty.t](prefix,
+            Vec.push[ty.t](prefix,
                             ty.get_element_type(ccx.tcx, t, i as uint));
             i += 1 ;
         }
@@ -1617,8 +1617,8 @@ fn mk_derived_tydesc(@block_ctxt cx, ty.t t, bool escapes) -> result {
     let uint n_params = ty.count_ty_params(cx.fcx.lcx.ccx.tcx, t);
     auto tys = linearize_ty_params(cx, t);
 
-    assert (n_params == _vec.len[uint](tys._0));
-    assert (n_params == _vec.len[ValueRef](tys._1));
+    assert (n_params == Vec.len[uint](tys._0));
+    assert (n_params == Vec.len[ValueRef](tys._1));
 
     auto root = get_static_tydesc(cx, t, tys._0).tydesc;
 
@@ -1746,7 +1746,7 @@ fn declare_tydesc(@local_ctxt cx, ty.t t) -> @tydesc_info {
 
     auto name = mangle_name_by_type_only(ccx, t, "tydesc");
     auto gvar = llvm.LLVMAddGlobal(ccx.llmod, T_tydesc(ccx.tn),
-                                   _str.buf(name));
+                                   Str.buf(name));
     auto tydesc = C_struct(vec(C_null(T_ptr(T_ptr(T_tydesc(ccx.tn)))),
                                llsize,
                                llalign,
@@ -1827,20 +1827,20 @@ fn make_generic_glue(@local_ctxt cx,
         llty = T_ptr(type_of(cx.ccx, t));
     }
 
-    auto ty_param_count = _vec.len[uint](ty_params);
+    auto ty_param_count = Vec.len[uint](ty_params);
 
     auto lltyparams = llvm.LLVMGetParam(llfn, 3u);
 
-    auto lltydescs = _vec.empty_mut[ValueRef]();
+    auto lltydescs = Vec.empty_mut[ValueRef]();
     auto p = 0u;
     while (p < ty_param_count) {
         auto llparam = bcx.build.GEP(lltyparams, vec(C_int(p as int)));
         llparam = bcx.build.Load(llparam);
-        _vec.grow_set[ValueRef](lltydescs, ty_params.(p), 0 as ValueRef,
+        Vec.grow_set[ValueRef](lltydescs, ty_params.(p), 0 as ValueRef,
                                 llparam);
         p += 1u;
     }
-    bcx.fcx.lltydescs = _vec.freeze[ValueRef](lltydescs);
+    bcx.fcx.lltydescs = Vec.freeze[ValueRef](lltydescs);
 
     auto llrawptr0 = llvm.LLVMGetParam(llfn, 4u);
     auto llval0 = bcx.build.BitCast(llrawptr0, llty);
@@ -2157,7 +2157,7 @@ fn make_cmp_glue(@block_ctxt cx,
          */
 
         auto flag = alloca(scx, T_i1());
-        llvm.LLVMSetValueName(flag, _str.buf("flag"));
+        llvm.LLVMSetValueName(flag, Str.buf("flag"));
 
         auto r;
         if (ty.type_is_sequence(cx.fcx.lcx.ccx.tcx, t)) {
@@ -2378,7 +2378,7 @@ fn tag_variants(@crate_ctxt cx, ast.def_id id) -> vec[variant_info] {
             for (ast.variant variant in variants) {
                 auto ctor_ty = node_ann_type(cx, variant.node.ann);
                 let vec[ty.t] arg_tys = vec();
-                if (_vec.len[ast.variant_arg](variant.node.args) > 0u) {
+                if (Vec.len[ast.variant_arg](variant.node.args) > 0u) {
                     for (ty.arg a in ty.ty_fn_args(cx.tcx, ctor_ty)) {
                         arg_tys += vec(a.ty);
                     }
@@ -2399,7 +2399,7 @@ fn tag_variant_with_id(@crate_ctxt cx,
     auto variants = tag_variants(cx, tag_id);
 
     auto i = 0u;
-    while (i < _vec.len[variant_info](variants)) {
+    while (i < Vec.len[variant_info](variants)) {
         auto variant = variants.(i);
         if (common.def_eq(variant.id, variant_id)) {
             ret variant;
@@ -2495,7 +2495,7 @@ fn iter_structural_ty_full(@block_ctxt cx,
         }
         case (ty.ty_tag(?tid, ?tps)) {
             auto variants = tag_variants(cx.fcx.lcx.ccx, tid);
-            auto n_variants = _vec.len[variant_info](variants);
+            auto n_variants = Vec.len[variant_info](variants);
 
             // Cast the tags to types we can GEP into.
             auto lltagty = T_opaque_tag_ptr(cx.fcx.lcx.ccx.tn);
@@ -2532,10 +2532,10 @@ fn iter_structural_ty_full(@block_ctxt cx,
             for (variant_info variant in variants) {
                 auto variant_cx = new_sub_block_ctxt(bcx,
                                                      "tag-iter-variant-" +
-                                                     _uint.to_str(i, 10u));
+                                                     UInt.to_str(i, 10u));
                 llvm.LLVMAddCase(llswitch, C_int(i as int), variant_cx.llbb);
 
-                if (_vec.len[ty.t](variant.args) > 0u) {
+                if (Vec.len[ty.t](variant.args) > 0u) {
                     // N-ary variant.
                     auto fn_ty = variant.ctor_ty;
                     alt (ty.struct(bcx.fcx.lcx.ccx.tcx, fn_ty)) {
@@ -3386,12 +3386,12 @@ fn join_results(@block_ctxt parent_cx,
         }
     }
 
-    alt (_vec.len[result](live)) {
+    alt (Vec.len[result](live)) {
         case (0u) {
             // No incoming edges are live, so we're in dead-code-land.
             // Arbitrarily pick the first dead edge, since the caller
             // is just going to propagate it outward.
-            assert (_vec.len[result](ins) >= 1u);
+            assert (Vec.len[result](ins) >= 1u);
             ret ins.(0);
         }
 
@@ -3408,7 +3408,7 @@ fn join_results(@block_ctxt parent_cx,
 }
 
 fn trans_if(@block_ctxt cx, @ast.expr cond,
-            &ast.block thn, &option.t[@ast.expr] els) -> result {
+            &ast.block thn, &Option.t[@ast.expr] els) -> result {
 
     auto cond_res = trans_expr(cx, cond);
 
@@ -3472,7 +3472,7 @@ fn trans_for(@block_ctxt cx,
 
         auto next_cx = new_sub_block_ctxt(cx, "next");
         auto scope_cx =
-            new_loop_scope_block_ctxt(cx, option.some[@block_ctxt](next_cx),
+            new_loop_scope_block_ctxt(cx, Option.some[@block_ctxt](next_cx),
                                       outer_next_cx, "for loop scope");
 
         cx.build.Br(scope_cx.llbb);
@@ -3517,15 +3517,15 @@ fn collect_upvars(@block_ctxt cx, &ast.block bloc, &ast.def_id initial_decl)
     fn walk_expr(env e, @ast.expr expr) {
         alt (expr.node) {
             case (ast.expr_path(?path, ?d, _)) {
-                alt (option.get[ast.def](d)) {
+                alt (Option.get[ast.def](d)) {
                     case (ast.def_arg(?did)) {
-                        _vec.push[ast.def_id](e.refs, did);
+                        Vec.push[ast.def_id](e.refs, did);
                     }
                     case (ast.def_local(?did)) {
-                        _vec.push[ast.def_id](e.refs, did);
+                        Vec.push[ast.def_id](e.refs, did);
                     }
                     case (ast.def_upvar(?did)) {
-                        _vec.push[ast.def_id](e.refs, did);
+                        Vec.push[ast.def_id](e.refs, did);
                     }
                     case (_) {}
                 }
@@ -3606,7 +3606,7 @@ fn trans_for_each(@block_ctxt cx,
     }
 
     auto upvars = collect_upvars(cx, body, decl_id);
-    auto upvar_count = _vec.len[ast.def_id](upvars);
+    auto upvar_count = Vec.len[ast.def_id](upvars);
 
     auto llbindingsptr;
     if (upvar_count > 0u) {
@@ -3645,7 +3645,7 @@ fn trans_for_each(@block_ctxt cx,
     }
 
     // Create an environment and populate it with the bindings.
-    auto tydesc_count = _vec.len[ValueRef](cx.fcx.lltydescs);
+    auto tydesc_count = Vec.len[ValueRef](cx.fcx.lltydescs);
     auto llenvptrty = T_closure_ptr(lcx.ccx.tn, T_ptr(T_nil()),
                                     val_ty(llbindingsptr), tydesc_count);
     auto llenvptr = alloca(cx, llvm.LLVMGetElementType(llenvptrty));
@@ -3776,7 +3776,7 @@ fn trans_while(@block_ctxt cx, @ast.expr cond,
 
     auto cond_cx = new_scope_block_ctxt(cx, "while cond");
     auto next_cx = new_sub_block_ctxt(cx, "next");
-    auto body_cx = new_loop_scope_block_ctxt(cx, option.none[@block_ctxt],
+    auto body_cx = new_loop_scope_block_ctxt(cx, Option.none[@block_ctxt],
                                              next_cx, "while loop body");
 
     auto body_res = trans_block(body_cx, body);
@@ -3795,7 +3795,7 @@ fn trans_do_while(@block_ctxt cx, &ast.block body,
                   @ast.expr cond) -> result {
 
     auto next_cx = new_sub_block_ctxt(cx, "next");
-    auto body_cx = new_loop_scope_block_ctxt(cx, option.none[@block_ctxt],
+    auto body_cx = new_loop_scope_block_ctxt(cx, Option.none[@block_ctxt],
                                              next_cx, "do-while loop body");
 
     auto body_res = trans_block(body_cx, body);
@@ -3834,7 +3834,7 @@ fn trans_pat_match(@block_ctxt cx, @ast.pat pat, ValueRef llval,
                                              vec(C_int(0), C_int(0)));
             auto lldiscrim = cx.build.Load(lldiscrimptr);
 
-            auto vdef = option.get[ast.variant_def](vdef_opt);
+            auto vdef = Option.get[ast.variant_def](vdef_opt);
             auto variant_id = vdef._1;
             auto variant_tag = 0;
 
@@ -3857,7 +3857,7 @@ fn trans_pat_match(@block_ctxt cx, @ast.pat pat, ValueRef llval,
 
             auto ty_params = node_ann_ty_params(ann);
 
-            if (_vec.len[@ast.pat](subpats) > 0u) {
+            if (Vec.len[@ast.pat](subpats) > 0u) {
                 auto llblobptr = matched_cx.build.GEP(lltagptr,
                     vec(C_int(0), C_int(1)));
                 auto i = 0;
@@ -3899,7 +3899,7 @@ fn trans_pat_binding(@block_ctxt cx, @ast.pat pat,
                 auto rslt = alloc_ty(cx, t);
                 auto dst = rslt.val;
                 auto bcx = rslt.bcx;
-                llvm.LLVMSetValueName(dst, _str.buf(id));
+                llvm.LLVMSetValueName(dst, Str.buf(id));
                 bcx.fcx.lllocals.insert(def_id, dst);
                 bcx.cleanups +=
                     vec(clean(bind drop_slot(_, dst, t)));
@@ -3907,10 +3907,10 @@ fn trans_pat_binding(@block_ctxt cx, @ast.pat pat,
             }
         }
         case (ast.pat_tag(_, ?subpats, ?vdef_opt, ?ann)) {
-            if (_vec.len[@ast.pat](subpats) == 0u) { ret res(cx, llval); }
+            if (Vec.len[@ast.pat](subpats) == 0u) { ret res(cx, llval); }
 
             // Get the appropriate variant for this tag.
-            auto vdef = option.get[ast.variant_def](vdef_opt);
+            auto vdef = Option.get[ast.variant_def](vdef_opt);
 
             auto lltagptr = cx.build.PointerCast(llval,
                 T_opaque_tag_ptr(cx.fcx.lcx.ccx.tn));
@@ -3982,9 +3982,9 @@ type generic_info = rec(ty.t item_type,
 
 type lval_result = rec(result res,
                        bool is_mem,
-                       option.t[generic_info] generic,
-                       option.t[ValueRef] llobj,
-                       option.t[ty.t] method_ty);
+                       Option.t[generic_info] generic,
+                       Option.t[ValueRef] llobj,
+                       Option.t[ty.t] method_ty);
 
 fn lval_mem(@block_ctxt cx, ValueRef val) -> lval_result {
     ret rec(res=res(cx, val),
@@ -4035,18 +4035,18 @@ fn lval_generic_fn(@block_ctxt cx,
         }
         case (ast.ann_type(?monoty_, ?tps, _)) {
             monoty = monoty_;
-            tys = option.get[vec[ty.t]](tps);
+            tys = Option.get[vec[ty.t]](tps);
         }
     }
 
-    if (_vec.len[ty.t](tys) != 0u) {
+    if (Vec.len[ty.t](tys) != 0u) {
         auto bcx = lv.res.bcx;
         let vec[ValueRef] tydescs = vec();
         for (ty.t t in tys) {
             // TODO: Doesn't always escape.
             auto td = get_tydesc(bcx, t, true);
             bcx = td.bcx;
-            _vec.push[ValueRef](tydescs, td.val);
+            Vec.push[ValueRef](tydescs, td.val);
         }
         auto gen = rec( item_type = tpt._1,
                         tydescs = tydescs );
@@ -4065,7 +4065,7 @@ fn lookup_discriminant(@local_ctxt lcx, ast.def_id tid, ast.def_id vid)
             assert (lcx.ccx.sess.get_targ_crate_num() != vid._0);
             auto sym = creader.get_symbol(lcx.ccx.sess, vid);
             auto gvar = llvm.LLVMAddGlobal(lcx.ccx.llmod, T_int(),
-                                           _str.buf(sym));
+                                           Str.buf(sym));
             llvm.LLVMSetLinkage(gvar,
                                 lib.llvm.LLVMExternalLinkage as llvm.Linkage);
             llvm.LLVMSetGlobalConstant(gvar, True);
@@ -4076,7 +4076,7 @@ fn lookup_discriminant(@local_ctxt lcx, ast.def_id tid, ast.def_id vid)
     }
 }
 
-fn trans_path(@block_ctxt cx, &ast.path p, &option.t[ast.def] dopt,
+fn trans_path(@block_ctxt cx, &ast.path p, &Option.t[ast.def] dopt,
               &ast.ann ann) -> lval_result {
     alt (dopt) {
         case (some[ast.def](?def)) {
@@ -4246,10 +4246,10 @@ fn trans_index(@block_ctxt cx, &ast.span sp, @ast.expr base,
     auto unit_ty = node_ann_type(cx.fcx.lcx.ccx, ann);
     auto unit_sz = size_of(bcx, unit_ty);
     bcx = unit_sz.bcx;
-    llvm.LLVMSetValueName(unit_sz.val, _str.buf("unit_sz"));
+    llvm.LLVMSetValueName(unit_sz.val, Str.buf("unit_sz"));
 
     auto scaled_ix = bcx.build.Mul(ix_val, unit_sz.val);
-    llvm.LLVMSetValueName(scaled_ix, _str.buf("scaled_ix"));
+    llvm.LLVMSetValueName(scaled_ix, Str.buf("scaled_ix"));
 
     auto lim = bcx.build.GEP(v, vec(C_int(0), C_int(abi.vec_elt_fill)));
     lim = bcx.build.Load(lim);
@@ -4369,7 +4369,7 @@ fn trans_cast(@block_ctxt cx, @ast.expr e, &ast.ann ann) -> result {
 fn trans_bind_thunk(@local_ctxt cx,
                     ty.t incoming_fty,
                     ty.t outgoing_fty,
-                    vec[option.t[@ast.expr]] args,
+                    vec[Option.t[@ast.expr]] args,
                     ty.t closure_ty,
                     vec[ty.t] bound_tys,
                     uint ty_param_count) -> ValueRef {
@@ -4433,7 +4433,7 @@ fn trans_bind_thunk(@local_ctxt cx,
     let vec[TypeRef] llout_arg_tys =
         type_of_explicit_args(cx.ccx, outgoing_args);
 
-    for (option.t[@ast.expr] arg in args) {
+    for (Option.t[@ast.expr] arg in args) {
 
         auto out_arg = outgoing_args.(outgoing_arg_index);
         auto llout_arg_ty = llout_arg_tys.(outgoing_arg_index);
@@ -4516,7 +4516,7 @@ fn trans_bind_thunk(@local_ctxt cx,
 }
 
 fn trans_bind(@block_ctxt cx, @ast.expr f,
-              vec[option.t[@ast.expr]] args,
+              vec[Option.t[@ast.expr]] args,
               &ast.ann ann) -> result {
     auto f_res = trans_lval(cx, f);
     if (f_res.is_mem) {
@@ -4524,12 +4524,12 @@ fn trans_bind(@block_ctxt cx, @ast.expr f,
     } else {
         let vec[@ast.expr] bound = vec();
 
-        for (option.t[@ast.expr] argopt in args) {
+        for (Option.t[@ast.expr] argopt in args) {
             alt (argopt) {
                 case (none[@ast.expr]) {
                 }
                 case (some[@ast.expr](?e)) {
-                    _vec.push[@ast.expr](bound, e);
+                    Vec.push[@ast.expr](bound, e);
                 }
             }
         }
@@ -4547,9 +4547,9 @@ fn trans_bind(@block_ctxt cx, @ast.expr f,
                 lltydescs = ginfo.tydescs;
             }
         }
-        auto ty_param_count = _vec.len[ValueRef](lltydescs);
+        auto ty_param_count = Vec.len[ValueRef](lltydescs);
 
-        if (_vec.len[@ast.expr](bound) == 0u && ty_param_count == 0u) {
+        if (Vec.len[@ast.expr](bound) == 0u && ty_param_count == 0u) {
             // Trivial 'binding': just return the static pair-ptr.
             ret f_res.res;
         } else {
@@ -4565,8 +4565,8 @@ fn trans_bind(@block_ctxt cx, @ast.expr f,
                 auto arg = trans_expr(bcx, e);
                 bcx = arg.bcx;
 
-                _vec.push[ValueRef](bound_vals, arg.val);
-                _vec.push[ty.t](bound_tys,
+                Vec.push[ValueRef](bound_vals, arg.val);
+                Vec.push[ty.t](bound_tys,
                                  ty.expr_ty(cx.fcx.lcx.ccx.tcx, e));
 
                 i += 1u;
@@ -4582,7 +4582,7 @@ fn trans_bind(@block_ctxt cx, @ast.expr f,
             let ty.t tydesc_ty = ty.mk_type(cx.fcx.lcx.ccx.tcx);
 
             let vec[ty.t] captured_tys =
-                _vec.init_elt[ty.t](tydesc_ty, ty_param_count);
+                Vec.init_elt[ty.t](tydesc_ty, ty_param_count);
 
             let vec[ty.t] closure_tys =
                 vec(tydesc_ty,
@@ -4778,9 +4778,9 @@ fn trans_arg_expr(@block_ctxt cx,
 
 fn trans_args(@block_ctxt cx,
               ValueRef llenv,
-              option.t[ValueRef] llobj,
-              option.t[generic_info] gen,
-              option.t[ValueRef] lliterbody,
+              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) {
@@ -4869,7 +4869,7 @@ fn trans_args(@block_ctxt cx,
 }
 
 fn trans_call(@block_ctxt cx, @ast.expr f,
-              option.t[ValueRef] lliterbody,
+              Option.t[ValueRef] lliterbody,
               vec[@ast.expr] args,
               &ast.ann ann) -> result {
 
@@ -4997,7 +4997,7 @@ fn trans_vec(@block_ctxt cx, vec[@ast.expr] args,
     auto bcx = cx;
     auto unit_sz = size_of(bcx, unit_ty);
     bcx = unit_sz.bcx;
-    auto data_sz = bcx.build.Mul(C_int(_vec.len[@ast.expr](args) as int),
+    auto data_sz = bcx.build.Mul(C_int(Vec.len[@ast.expr](args) as int),
                                  unit_sz.val);
 
     // FIXME: pass tydesc properly.
@@ -5015,8 +5015,8 @@ fn trans_vec(@block_ctxt cx, vec[@ast.expr] args,
 
     auto pseudo_tup_ty =
         ty.mk_imm_tup(cx.fcx.lcx.ccx.tcx,
-                      _vec.init_elt[ty.t](unit_ty,
-                                           _vec.len[@ast.expr](args)));
+                      Vec.init_elt[ty.t](unit_ty,
+                                           Vec.len[@ast.expr](args)));
     let int i = 0;
 
     for (@ast.expr e in args) {
@@ -5056,7 +5056,7 @@ fn trans_vec(@block_ctxt cx, vec[@ast.expr] args,
 }
 
 fn trans_rec(@block_ctxt cx, vec[ast.field] fields,
-             option.t[@ast.expr] base, &ast.ann ann) -> result {
+             Option.t[@ast.expr] base, &ast.ann ann) -> result {
 
     auto bcx = cx;
     auto t = node_ann_type(bcx.fcx.lcx.ccx, ann);
@@ -5093,7 +5093,7 @@ fn trans_rec(@block_ctxt cx, vec[ast.field] fields,
         auto src_res = res(bcx, C_nil());
 
         for (ast.field f in fields) {
-            if (_str.eq(f.ident, tf.ident)) {
+            if (Str.eq(f.ident, tf.ident)) {
                 expr_provided = true;
                 src_res = trans_expr(bcx, f.expr);
             }
@@ -5326,13 +5326,13 @@ fn load_if_immediate(@block_ctxt cx, ValueRef v, ty.t t) -> ValueRef {
 
 fn trans_log(int lvl, @block_ctxt cx, @ast.expr e) -> result {
     auto lcx = cx.fcx.lcx;
-    auto modname = _str.connect(lcx.module_path, ".");
+    auto modname = Str.connect(lcx.module_path, ".");
     auto global;
     if (lcx.ccx.module_data.contains_key(modname)) {
         global = lcx.ccx.module_data.get(modname);
     } else {
         global = llvm.LLVMAddGlobal(lcx.ccx.llmod, T_int(),
-                                    _str.buf("_rust_mod_log_" + modname));
+                                    Str.buf("_rust_mod_log_" + modname));
         llvm.LLVMSetGlobalConstant(global, False);
         llvm.LLVMSetInitializer(global, C_null(T_int()));
         llvm.LLVMSetLinkage(global, lib.llvm.LLVMInternalLinkage
@@ -5418,7 +5418,7 @@ fn trans_check_expr(@block_ctxt cx, @ast.expr e) -> result {
     ret res(next_cx, C_nil());
 }
 
-fn trans_fail(@block_ctxt cx, option.t[common.span] sp_opt, str fail_str)
+fn trans_fail(@block_ctxt cx, Option.t[common.span] sp_opt, str fail_str)
         -> result {
     auto V_fail_str = p2i(C_cstr(cx.fcx.lcx.ccx, fail_str));
 
@@ -5442,7 +5442,7 @@ fn trans_fail(@block_ctxt cx, option.t[common.span] sp_opt, str fail_str)
     ret res(sub.bcx, C_nil());
 }
 
-fn trans_put(@block_ctxt cx, &option.t[@ast.expr] e) -> result {
+fn trans_put(@block_ctxt cx, &Option.t[@ast.expr] e) -> result {
     auto llcallee = C_nil();
     auto llenv = C_nil();
 
@@ -5490,7 +5490,7 @@ fn trans_break_cont(@block_ctxt cx, bool to_end) -> result {
                     bcx.build.Br(_break.llbb);
                 } else {
                     alt (_cont) {
-                        case (option.some[@block_ctxt](?_cont)) {
+                        case (Option.some[@block_ctxt](?_cont)) {
                             bcx.build.Br(_cont.llbb);
                         }
                         case (_) {
@@ -5519,7 +5519,7 @@ fn trans_cont(@block_ctxt cx) -> result {
 }
 
 
-fn trans_ret(@block_ctxt cx, &option.t[@ast.expr] e) -> result {
+fn trans_ret(@block_ctxt cx, &Option.t[@ast.expr] e) -> result {
     auto bcx = cx;
     auto val = C_nil();
 
@@ -5765,7 +5765,7 @@ fn new_block_ctxt(@fn_ctxt cx, block_parent parent,
     let vec[cleanup] cleanups = vec();
     let BasicBlockRef llbb =
         llvm.LLVMAppendBasicBlock(cx.llfn,
-                                  _str.buf(cx.lcx.ccx.names.next(name)));
+                                  Str.buf(cx.lcx.ccx.names.next(name)));
 
     ret @rec(llbb=llbb,
              build=new_builder(llbb),
@@ -5786,7 +5786,7 @@ fn new_scope_block_ctxt(@block_ctxt bcx, str n) -> @block_ctxt {
     ret new_block_ctxt(bcx.fcx, parent_some(bcx), SCOPE_BLOCK, n);
 }
 
-fn new_loop_scope_block_ctxt(@block_ctxt bcx, option.t[@block_ctxt] _cont,
+fn new_loop_scope_block_ctxt(@block_ctxt bcx, Option.t[@block_ctxt] _cont,
                              @block_ctxt _break, str n) -> @block_ctxt {
     ret new_block_ctxt(bcx.fcx, parent_some(bcx),
                        LOOP_SCOPE_BLOCK(_cont, _break), n);
@@ -5803,10 +5803,10 @@ fn trans_block_cleanups(@block_ctxt cx,
     auto bcx = cx;
 
     if (cleanup_cx.kind == NON_SCOPE_BLOCK) {
-        assert (_vec.len[cleanup](cleanup_cx.cleanups) == 0u);
+        assert (Vec.len[cleanup](cleanup_cx.cleanups) == 0u);
     }
 
-    auto i = _vec.len[cleanup](cleanup_cx.cleanups);
+    auto i = Vec.len[cleanup](cleanup_cx.cleanups);
     while (i > 0u) {
         i -= 1u;
         auto c = cleanup_cx.cleanups.(i);
@@ -5983,7 +5983,7 @@ fn new_fn_ctxt(@local_ctxt cx,
     let hashmap[ast.def_id, ValueRef] llupvars = new_def_hash[ValueRef]();
 
     let BasicBlockRef llallocas =
-        llvm.LLVMAppendBasicBlock(llfndecl, _str.buf("allocas"));
+        llvm.LLVMAppendBasicBlock(llfndecl, Str.buf("allocas"));
 
     ret @rec(llfn=llfndecl,
              lltaskptr=lltaskptr,
@@ -5996,7 +5996,7 @@ fn new_fn_ctxt(@local_ctxt cx,
              llobjfields=llobjfields,
              lllocals=lllocals,
              llupvars=llupvars,
-             mutable lltydescs=_vec.empty[ValueRef](),
+             mutable lltydescs=Vec.empty[ValueRef](),
              lcx=cx);
 }
 
@@ -6009,7 +6009,7 @@ fn new_fn_ctxt(@local_ctxt cx,
 
 fn create_llargs_for_fn_args(&@fn_ctxt cx,
                              ast.proto proto,
-                             option.t[tup(TypeRef, ty.t)] ty_self,
+                             Option.t[tup(TypeRef, ty.t)] ty_self,
                              ty.t ret_ty,
                              &vec[ast.arg] args,
                              &vec[ast.ty_param] ty_params) {
@@ -6052,7 +6052,7 @@ fn create_llargs_for_fn_args(&@fn_ctxt cx,
 // were passed and whatnot. Apparently mem2reg will mop up.
 
 fn copy_any_self_to_alloca(@fn_ctxt fcx,
-                           option.t[tup(TypeRef, ty.t)] ty_self) {
+                           Option.t[tup(TypeRef, ty.t)] ty_self) {
 
     auto bcx = llallocas_block_ctxt(fcx);
 
@@ -6152,7 +6152,7 @@ fn populate_fn_ctxt_from_llself(@fn_ctxt fcx, self_vt llself) {
     // its magic.
     auto fields_tup_ty = ty.mk_imm_tup(fcx.lcx.ccx.tcx, field_tys);
 
-    auto n_typarams = _vec.len[ast.ty_param](bcx.fcx.lcx.obj_typarams);
+    auto n_typarams = Vec.len[ast.ty_param](bcx.fcx.lcx.obj_typarams);
     let TypeRef llobj_box_ty = T_obj_ptr(bcx.fcx.lcx.ccx.tn, n_typarams);
 
     auto box_cell =
@@ -6209,7 +6209,7 @@ fn populate_fn_ctxt_from_llself(@fn_ctxt fcx, self_vt llself) {
 }
 
 fn trans_fn(@local_ctxt cx, &ast._fn f, ast.def_id fid,
-            option.t[tup(TypeRef, ty.t)] ty_self,
+            Option.t[tup(TypeRef, ty.t)] ty_self,
             &vec[ast.ty_param] ty_params, &ast.ann ann) {
     auto llfndecl = cx.ccx.item_ids.get(fid);
 
@@ -6264,10 +6264,10 @@ fn trans_vtbl(@local_ctxt cx,
     let vec[ValueRef] methods = vec(dtor);
 
     fn meth_lteq(&@ast.method a, &@ast.method b) -> bool {
-        ret _str.lteq(a.node.ident, b.node.ident);
+        ret Str.lteq(a.node.ident, b.node.ident);
     }
 
-    auto meths = std.sort.merge_sort[@ast.method](bind meth_lteq(_,_),
+    auto meths = std.Sort.merge_sort[@ast.method](bind meth_lteq(_,_),
                                                   ob.methods);
 
     for (@ast.method m in meths) {
@@ -6278,7 +6278,7 @@ fn trans_vtbl(@local_ctxt cx,
                 llfnty = type_of_fn_full(cx.ccx, proto,
                                          some[TypeRef](llself_ty),
                                          inputs, output,
-                                         _vec.len[ast.ty_param](ty_params));
+                                         Vec.len[ast.ty_param](ty_params));
             }
         }
 
@@ -6297,7 +6297,7 @@ fn trans_vtbl(@local_ctxt cx,
     auto vtbl = C_struct(methods);
     auto vtbl_name = mangle_name_by_seq(cx.ccx, cx.path, "vtbl");
     auto gvar = llvm.LLVMAddGlobal(cx.ccx.llmod, val_ty(vtbl),
-                                   _str.buf(vtbl_name));
+                                   Str.buf(vtbl_name));
     llvm.LLVMSetInitializer(gvar, vtbl);
     llvm.LLVMSetGlobalConstant(gvar, True);
     llvm.LLVMSetLinkage(gvar, lib.llvm.LLVMInternalLinkage
@@ -6368,22 +6368,22 @@ fn trans_obj(@local_ctxt cx, &ast._obj ob, ast.def_id oid,
 
     // FIXME we should probably also allocate a box for empty objs that have a
     // dtor, since otherwise they are never dropped, and the dtor never runs
-    if (_vec.len[ast.ty_param](ty_params) == 0u &&
-        _vec.len[ty.arg](arg_tys) == 0u) {
+    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.
         let vec[ty.t] obj_fields = vec();
         for (ty.arg a in arg_tys) {
-            _vec.push[ty.t](obj_fields, a.ty);
+            Vec.push[ty.t](obj_fields, a.ty);
         }
 
         // Synthesize an obj body type.
         auto tydesc_ty = ty.mk_type(ccx.tcx);
         let vec[ty.t] tps = vec();
         for (ast.ty_param tp in ty_params) {
-            _vec.push[ty.t](tps, tydesc_ty);
+            Vec.push[ty.t](tps, tydesc_ty);
         }
 
         let ty.t typarams_ty = ty.mk_imm_tup(ccx.tcx, tps);
@@ -6467,7 +6467,7 @@ fn trans_obj(@local_ctxt cx, &ast._obj ob, ast.def_id oid,
 fn trans_tag_variant(@local_ctxt cx, ast.def_id tag_id,
                      &ast.variant variant, int index,
                      &vec[ast.ty_param] ty_params) {
-    if (_vec.len[ast.variant_arg](variant.node.args) == 0u) {
+    if (Vec.len[ast.variant_arg](variant.node.args) == 0u) {
         ret;    // nullary constructors are just constants
     }
 
@@ -6477,7 +6477,7 @@ fn trans_tag_variant(@local_ctxt cx, ast.def_id tag_id,
     for (ast.variant_arg varg in variant.node.args) {
         fn_args += vec(rec(mode=ast.alias,
                            ty=varg.ty,
-                           ident="arg" + _uint.to_str(i, 10u),
+                           ident="arg" + UInt.to_str(i, 10u),
                            id=varg.id));
     }
 
@@ -6617,7 +6617,7 @@ fn get_pair_fn_ty(TypeRef llpairty) -> TypeRef {
     // Bit of a kludge: pick the fn typeref out of the pair.
     let vec[TypeRef] pair_tys = vec(T_nil(), T_nil());
     llvm.LLVMGetStructElementTypes(llpairty,
-                                   _vec.buf[TypeRef](pair_tys));
+                                   Vec.buf[TypeRef](pair_tys));
     ret llvm.LLVMGetElementType(pair_tys.(0));
 }
 
@@ -6633,7 +6633,7 @@ fn decl_fn_and_pair(@crate_ctxt ccx,
     alt (ty.struct(ccx.tcx, node_ann_type(ccx, ann))) {
         case (ty.ty_fn(?proto, ?inputs, ?output)) {
             llfty = type_of_fn(ccx, proto, inputs, output,
-                               _vec.len[ast.ty_param](ty_params));
+                               Vec.len[ast.ty_param](ty_params));
             llpairty = T_fn_pair(ccx.tn, llfty);
         }
         case (_) {
@@ -6655,7 +6655,7 @@ fn decl_fn_and_pair(@crate_ctxt ccx,
 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));
+                                           Str.buf(ps));
     auto pair = C_struct(vec(llfn,
                              C_null(T_opaque_closure_ptr(cx.tn))));
 
@@ -6681,7 +6681,7 @@ fn native_fn_ty_param_count(@crate_ctxt cx, &ast.def_id id) -> uint {
             fail;
         }
         case (ast.native_item_fn(_, _, _, ?tps, _, _)) {
-            count = _vec.len[ast.ty_param](tps);
+            count = Vec.len[ast.ty_param](tps);
         }
     }
     ret count;
@@ -6768,7 +6768,7 @@ fn decl_native_fn_and_pair(@crate_ctxt ccx,
     if (pass_task) { call_args += vec(lltaskptr); }
 
     auto arg_n = 3u;
-    for each (uint i in _uint.range(0u, num_ty_param)) {
+    for each (uint i in UInt.range(0u, num_ty_param)) {
         auto llarg = llvm.LLVMGetParam(fcx.llfn, arg_n);
         fcx.lltydescs += vec(llarg);
         assert (llarg as int != 0);
@@ -6900,13 +6900,13 @@ fn new_walk_ctxt() -> @walk_ctxt {
 fn enter_item(@walk_ctxt cx, @ast.item item) {
     alt (item.node) {
         case (ast.item_fn(?name, _, _, _, _)) {
-            _vec.push[str](cx.path, name);
+            Vec.push[str](cx.path, name);
         }
         case (ast.item_obj(?name, _, _, _, _)) {
-            _vec.push[str](cx.path, name);
+            Vec.push[str](cx.path, name);
         }
         case (ast.item_mod(?name, _, _)) {
-            _vec.push[str](cx.path, name);
+            Vec.push[str](cx.path, name);
         }
         case (_) { }
     }
@@ -6915,13 +6915,13 @@ fn enter_item(@walk_ctxt cx, @ast.item item) {
 fn leave_item(@walk_ctxt cx, @ast.item item) {
     alt (item.node) {
         case (ast.item_fn(_, _, _, _, _)) {
-            _vec.pop[str](cx.path);
+            Vec.pop[str](cx.path);
         }
         case (ast.item_obj(_, _, _, _, _)) {
-            _vec.pop[str](cx.path);
+            Vec.pop[str](cx.path);
         }
         case (ast.item_mod(_, _, _)) {
-            _vec.pop[str](cx.path);
+            Vec.pop[str](cx.path);
         }
         case (_) { }
     }
@@ -6948,7 +6948,7 @@ fn collect_item_1(@crate_ctxt ccx, @walk_ctxt wcx, @ast.item i) {
         case (ast.item_const(?name, _, _, ?cid, ?ann)) {
             auto typ = node_ann_type(ccx, ann);
             auto g = llvm.LLVMAddGlobal(ccx.llmod, type_of(ccx, typ),
-                                        _str.buf(ccx.names.next(name)));
+                                        Str.buf(ccx.names.next(name)));
             llvm.LLVMSetLinkage(g, lib.llvm.LLVMInternalLinkage
                                 as llvm.Linkage);
             ccx.items.insert(cid, i);
@@ -7009,7 +7009,7 @@ fn collect_tag_ctor(@crate_ctxt ccx, @walk_ctxt wcx, @ast.item i) {
     alt (i.node) {
         case (ast.item_tag(_, ?variants, ?tps, _, _)) {
             for (ast.variant variant in variants) {
-                if (_vec.len[ast.variant_arg](variant.node.args) != 0u) {
+                if (Vec.len[ast.variant_arg](variant.node.args) != 0u) {
                     decl_fn_and_pair(ccx, wcx.path + vec(variant.node.name),
                                      "tag", tps, variant.node.ann,
                                      variant.node.id);
@@ -7037,7 +7037,7 @@ fn trans_constant(@crate_ctxt ccx, @walk_ctxt wcx, @ast.item it) {
     alt (it.node) {
         case (ast.item_tag(?ident, ?variants, _, ?tag_id, _)) {
             auto i = 0u;
-            auto n_variants = _vec.len[ast.variant](variants);
+            auto n_variants = Vec.len[ast.variant](variants);
             while (i < n_variants) {
                 auto variant = variants.(i);
 
@@ -7047,7 +7047,7 @@ fn trans_constant(@crate_ctxt ccx, @walk_ctxt wcx, @ast.item it) {
                                             #fmt("_rust_tag_discrim_%s_%u",
                                                  ident, i));
                 auto discrim_gvar = llvm.LLVMAddGlobal(ccx.llmod, T_int(),
-                                                       _str.buf(s));
+                                                       Str.buf(s));
 
                 llvm.LLVMSetInitializer(discrim_gvar, discrim_val);
                 llvm.LLVMSetGlobalConstant(discrim_gvar, True);
@@ -7107,7 +7107,7 @@ fn trans_exit_task_glue(@glue_fns glues,
 
     auto llfn = glues.exit_task_glue;
 
-    auto entrybb = llvm.LLVMAppendBasicBlock(llfn, _str.buf("entry"));
+    auto entrybb = llvm.LLVMAppendBasicBlock(llfn, Str.buf("entry"));
     auto build = new_builder(entrybb);
 
     let ValueRef arg1 = llvm.LLVMGetParam(llfn, 0u);
@@ -7129,9 +7129,9 @@ fn trans_exit_task_glue(@glue_fns glues,
 }
 
 fn create_typedefs(@crate_ctxt cx) {
-    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));
+    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(ValueRef crate_ptr, @glue_fns glues) {
@@ -7173,7 +7173,7 @@ fn find_main_fn(@crate_ctxt cx) -> ValueRef {
     let ValueRef v = C_nil();
     let uint n = 0u;
     for each (@tup(ast.def_id, str) i in cx.item_symbols.items()) {
-        if (_str.ends_with(i._1, e)) {
+        if (Str.ends_with(i._1, e)) {
             n += 1u;
             v = cx.item_ids.get(i._0);
         }
@@ -7197,7 +7197,7 @@ fn trans_main_fn(@local_ctxt cx, ValueRef llcrate, ValueRef crate_map) {
     auto T_rust_start_args = vec(T_int(), T_int(), T_int(), T_int(), T_int());
 
     auto main_name;
-    if (_str.eq(std.os.target_os(), "win32")) {
+    if (Str.eq(std.OS.target_os(), "win32")) {
         main_name = "WinMain@16";
     } else {
         main_name = "main";
@@ -7222,7 +7222,7 @@ fn trans_main_fn(@local_ctxt cx, ValueRef llcrate, ValueRef crate_map) {
     //
 
     let BasicBlockRef llbb =
-        llvm.LLVMAppendBasicBlock(llmain, _str.buf(""));
+        llvm.LLVMAppendBasicBlock(llmain, Str.buf(""));
     auto b = new_builder(llbb);
 
     auto start_args = vec(p2i(llrust_main), p2i(llcrate), llargc, llargv,
@@ -7267,7 +7267,7 @@ fn decl_no_op_type_glue(ModuleRef llmod, type_names tn) -> ValueRef {
 }
 
 fn make_no_op_type_glue(ValueRef fun) {
-    auto bb_name = _str.buf("_rust_no_op_type_glue_bb");
+    auto bb_name = Str.buf("_rust_no_op_type_glue_bb");
     auto llbb = llvm.LLVMAppendBasicBlock(fun, bb_name);
     new_builder(llbb).RetVoid();
 }
@@ -7283,10 +7283,10 @@ fn make_memcpy_glue(ValueRef fun) {
     // We're not using the LLVM memcpy intrinsic. It appears to call through
     // to the platform memcpy in some cases, which is not terribly safe to run
     // on a rust stack.
-    auto initbb = llvm.LLVMAppendBasicBlock(fun, _str.buf("init"));
-    auto hdrbb = llvm.LLVMAppendBasicBlock(fun, _str.buf("hdr"));
-    auto loopbb = llvm.LLVMAppendBasicBlock(fun, _str.buf("loop"));
-    auto endbb = llvm.LLVMAppendBasicBlock(fun, _str.buf("end"));
+    auto initbb = llvm.LLVMAppendBasicBlock(fun, Str.buf("init"));
+    auto hdrbb = llvm.LLVMAppendBasicBlock(fun, Str.buf("hdr"));
+    auto loopbb = llvm.LLVMAppendBasicBlock(fun, Str.buf("loop"));
+    auto endbb = llvm.LLVMAppendBasicBlock(fun, Str.buf("end"));
 
     auto dst = llvm.LLVMGetParam(fun, 0u);
     auto src = llvm.LLVMGetParam(fun, 1u);
@@ -7325,10 +7325,10 @@ fn decl_bzero_glue(ModuleRef llmod) -> ValueRef {
 
 fn make_bzero_glue(ValueRef fun) -> ValueRef {
     // We're not using the LLVM memset intrinsic. Same as with memcpy.
-    auto initbb = llvm.LLVMAppendBasicBlock(fun, _str.buf("init"));
-    auto hdrbb = llvm.LLVMAppendBasicBlock(fun, _str.buf("hdr"));
-    auto loopbb = llvm.LLVMAppendBasicBlock(fun, _str.buf("loop"));
-    auto endbb = llvm.LLVMAppendBasicBlock(fun, _str.buf("end"));
+    auto initbb = llvm.LLVMAppendBasicBlock(fun, Str.buf("init"));
+    auto hdrbb = llvm.LLVMAppendBasicBlock(fun, Str.buf("hdr"));
+    auto loopbb = llvm.LLVMAppendBasicBlock(fun, Str.buf("loop"));
+    auto endbb = llvm.LLVMAppendBasicBlock(fun, Str.buf("end"));
 
     auto dst = llvm.LLVMGetParam(fun, 0u);
     auto count = llvm.LLVMGetParam(fun, 1u);
@@ -7440,7 +7440,7 @@ fn trans_vec_append_glue(@local_ctxt cx) {
     let ValueRef llskipnull = llvm.LLVMGetParam(llfn, 5u);
 
     let BasicBlockRef llallocas =
-        llvm.LLVMAppendBasicBlock(llfn, _str.buf("allocas"));
+        llvm.LLVMAppendBasicBlock(llfn, Str.buf("allocas"));
 
     auto fcx = @rec(llfn=llfn,
                     lltaskptr=lltaskptr,
@@ -7453,7 +7453,7 @@ fn trans_vec_append_glue(@local_ctxt cx) {
                     llobjfields=new_def_hash[ValueRef](),
                     lllocals=new_def_hash[ValueRef](),
                     llupvars=new_def_hash[ValueRef](),
-                    mutable lltydescs=_vec.empty[ValueRef](),
+                    mutable lltydescs=Vec.empty[ValueRef](),
                     lcx=cx);
 
     auto bcx = new_top_block_ctxt(fcx);
@@ -7476,14 +7476,14 @@ fn trans_vec_append_glue(@local_ctxt cx) {
     bcx = llnew_vec_res.bcx;
     auto llnew_vec = vi2p(bcx, llnew_vec_res.val,
                           T_opaque_vec_ptr());
-    llvm.LLVMSetValueName(llnew_vec, _str.buf("llnew_vec"));
+    llvm.LLVMSetValueName(llnew_vec, Str.buf("llnew_vec"));
 
     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 = alloca(bcx, T_ptr(T_i8()));
     bcx.build.Store(vec_p1_adjusted(bcx, llnew_vec, llskipnull), pp0);
-    llvm.LLVMSetValueName(pp0, _str.buf("pp0"));
+    llvm.LLVMSetValueName(pp0, Str.buf("pp0"));
 
     bcx.build.CondBr(bcx.build.TruncOrBitCast
                      (bcx.build.Load(llcopy_dst_ptr),
@@ -7499,13 +7499,13 @@ fn trans_vec_append_glue(@local_ctxt cx) {
                  ValueRef n_bytes) -> result {
 
         auto src_lim = cx.build.GEP(src, vec(n_bytes));
-        llvm.LLVMSetValueName(src_lim, _str.buf("src_lim"));
+        llvm.LLVMSetValueName(src_lim, Str.buf("src_lim"));
 
         auto elt_llsz =
             cx.build.Load(cx.build.GEP(elt_tydesc,
                                        vec(C_int(0),
                                            C_int(abi.tydesc_field_size))));
-        llvm.LLVMSetValueName(elt_llsz, _str.buf("elt_llsz"));
+        llvm.LLVMSetValueName(elt_llsz, Str.buf("elt_llsz"));
 
         fn take_one(ValueRef elt_tydesc,
                     @block_ctxt cx,
@@ -7526,7 +7526,7 @@ fn trans_vec_append_glue(@local_ctxt cx) {
     // Copy any dst elements in, omitting null if doing str.
 
     auto n_bytes = vec_fill_adjusted(copy_dst_cx, lldst_vec, llskipnull);
-    llvm.LLVMSetValueName(n_bytes, _str.buf("n_bytes"));
+    llvm.LLVMSetValueName(n_bytes, Str.buf("n_bytes"));
 
     copy_dst_cx = copy_elts(copy_dst_cx,
                             llelt_tydesc,
@@ -7576,13 +7576,13 @@ fn make_glues(ModuleRef llmod, type_names tn) -> @glue_fns {
                                                  T_void())),
 
              native_glues_rust =
-                 _vec.init_fn[ValueRef](bind decl_native_glue(llmod, tn,
+                 Vec.init_fn[ValueRef](bind decl_native_glue(llmod, tn,
                     abi.ngt_rust, _), abi.n_native_glues + 1 as uint),
              native_glues_pure_rust =
-                 _vec.init_fn[ValueRef](bind decl_native_glue(llmod, tn,
+                 Vec.init_fn[ValueRef](bind decl_native_glue(llmod, tn,
                     abi.ngt_pure_rust, _), abi.n_native_glues + 1 as uint),
              native_glues_cdecl =
-                 _vec.init_fn[ValueRef](bind decl_native_glue(llmod, tn,
+                 Vec.init_fn[ValueRef](bind decl_native_glue(llmod, tn,
                     abi.ngt_cdecl, _), abi.n_native_glues + 1 as uint),
              no_op_type_glue = decl_no_op_type_glue(llmod, tn),
              memcpy_glue = decl_memcpy_glue(llmod),
@@ -7595,19 +7595,19 @@ fn make_common_glue(session.session sess, str output) {
     // to autogen it, but things like the memcpy implementation are not
     // and it might be better to just check in a .ll file.
     auto llmod =
-        llvm.LLVMModuleCreateWithNameInContext(_str.buf("rust_out"),
+        llvm.LLVMModuleCreateWithNameInContext(Str.buf("rust_out"),
                                                llvm.LLVMGetGlobalContext());
 
-    llvm.LLVMSetDataLayout(llmod, _str.buf(x86.get_data_layout()));
-    llvm.LLVMSetTarget(llmod, _str.buf(x86.get_target_triple()));
+    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(tn), _str.buf("rust_crate"));
+        llvm.LLVMAddGlobal(llmod, T_crate(tn), Str.buf("rust_crate"));
 
     auto intrinsics = declare_intrinsics(llmod);
 
-    llvm.LLVMSetModuleInlineAsm(llmod, _str.buf(x86.get_module_asm()));
+    llvm.LLVMSetModuleInlineAsm(llmod, Str.buf(x86.get_module_asm()));
 
     auto glues = make_glues(llmod, tn);
     create_crate_constant(crate_ptr, glues);
@@ -7624,22 +7624,22 @@ fn create_module_map(@crate_ctxt ccx) -> ValueRef {
     auto elttype = T_struct(vec(T_int(), T_int()));
     auto maptype = T_array(elttype, ccx.module_data.size() + 1u);
     auto map = llvm.LLVMAddGlobal(ccx.llmod, maptype,
-                                  _str.buf("_rust_mod_map"));
+                                  Str.buf("_rust_mod_map"));
     llvm.LLVMSetLinkage(map, lib.llvm.LLVMInternalLinkage as llvm.Linkage);
     let vec[ValueRef] elts = vec();
     for each (@tup(str, ValueRef) item in ccx.module_data.items()) {
         auto elt = C_struct(vec(p2i(C_cstr(ccx, item._0)), p2i(item._1)));
-        _vec.push[ValueRef](elts, elt);
+        Vec.push[ValueRef](elts, elt);
     }
     auto term = C_struct(vec(C_int(0), C_int(0)));
-    _vec.push[ValueRef](elts, term);
+    Vec.push[ValueRef](elts, term);
     llvm.LLVMSetInitializer(map, C_array(elttype, elts));
     ret map;
 }
 
 fn crate_name(@crate_ctxt ccx, str deflt) -> str {
     for (@ast.meta_item item in ccx.sess.get_metadata()) {
-        if (_str.eq(item.node.name, "name")) {
+        if (Str.eq(item.node.name, "name")) {
             ret item.node.value;
         }
     }
@@ -7653,15 +7653,15 @@ fn create_crate_map(@crate_ctxt ccx) -> ValueRef {
     while (ccx.sess.has_external_crate(i)) {
         auto name = ccx.sess.get_external_crate(i).name;
         auto cr = llvm.LLVMAddGlobal(ccx.llmod, T_int(),
-                                     _str.buf("_rust_crate_map_" + name));
-        _vec.push[ValueRef](subcrates, p2i(cr));
+                                     Str.buf("_rust_crate_map_" + name));
+        Vec.push[ValueRef](subcrates, p2i(cr));
         i += 1;
     }
-    _vec.push[ValueRef](subcrates, C_int(0));
+    Vec.push[ValueRef](subcrates, C_int(0));
     auto sym_name = "_rust_crate_map_" + crate_name(ccx, "__none__");
-    auto arrtype = T_array(T_int(), _vec.len[ValueRef](subcrates));
+    auto arrtype = T_array(T_int(), Vec.len[ValueRef](subcrates));
     auto maptype = T_struct(vec(T_int(), arrtype));
-    auto map = llvm.LLVMAddGlobal(ccx.llmod, maptype, _str.buf(sym_name));
+    auto map = llvm.LLVMAddGlobal(ccx.llmod, maptype, Str.buf(sym_name));
     llvm.LLVMSetLinkage(map, lib.llvm.LLVMExternalLinkage as llvm.Linkage);
     llvm.LLVMSetInitializer(map, C_struct(vec(p2i(create_module_map(ccx)),
                                               C_array(T_int(), subcrates))));
@@ -7672,26 +7672,26 @@ fn trans_crate(session.session sess, @ast.crate crate, ty.ctxt tcx,
                ty.type_cache type_cache, str output)
         -> ModuleRef {
     auto llmod =
-        llvm.LLVMModuleCreateWithNameInContext(_str.buf("rust_out"),
+        llvm.LLVMModuleCreateWithNameInContext(Str.buf("rust_out"),
                                                llvm.LLVMGetGlobalContext());
 
-    llvm.LLVMSetDataLayout(llmod, _str.buf(x86.get_data_layout()));
-    llvm.LLVMSetTarget(llmod, _str.buf(x86.get_target_triple()));
+    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(tn), _str.buf("rust_crate"));
+        llvm.LLVMAddGlobal(llmod, T_crate(tn), Str.buf("rust_crate"));
 
     auto intrinsics = declare_intrinsics(llmod);
 
     auto glues = make_glues(llmod, tn);
     auto hasher = ty.hash_ty;
     auto eqer = ty.eq_ty;
-    auto tag_sizes = map.mk_hashmap[ty.t,uint](hasher, eqer);
-    auto tydescs = map.mk_hashmap[ty.t,@tydesc_info](hasher, eqer);
-    auto lltypes = map.mk_hashmap[ty.t,TypeRef](hasher, eqer);
-    auto sha1s = map.mk_hashmap[ty.t,str](hasher, eqer);
-    auto abbrevs = map.mk_hashmap[ty.t,metadata.ty_abbrev](hasher, eqer);
+    auto tag_sizes = Map.mk_hashmap[ty.t,uint](hasher, eqer);
+    auto tydescs = Map.mk_hashmap[ty.t,@tydesc_info](hasher, eqer);
+    auto lltypes = Map.mk_hashmap[ty.t,TypeRef](hasher, eqer);
+    auto sha1s = Map.mk_hashmap[ty.t,str](hasher, eqer);
+    auto abbrevs = Map.mk_hashmap[ty.t,metadata.ty_abbrev](hasher, eqer);
 
     auto ccx = @rec(sess = sess,
                     llmod = llmod,
@@ -7716,7 +7716,7 @@ fn trans_crate(session.session sess, @ast.crate crate, ty.ctxt tcx,
                     lltypes = lltypes,
                     glues = glues,
                     names = namegen(0),
-                    sha = std.sha1.mk_sha1(),
+                    sha = std.SHA1.mk_sha1(),
                     type_sha1s = sha1s,
                     type_abbrevs = abbrevs,
                     tcx = tcx);
diff --git a/src/comp/middle/ty.rs b/src/comp/middle/ty.rs
index 5baa6b7afe0..44fc5486047 100644
--- a/src/comp/middle/ty.rs
+++ b/src/comp/middle/ty.rs
@@ -1,13 +1,13 @@
-import std._str;
-import std._uint;
-import std._vec;
+import std.Str;
+import std.UInt;
+import std.Vec;
 import std.Box;
 import std.UFind;
-import std.map;
-import std.map.hashmap;
-import std.option;
-import std.option.none;
-import std.option.some;
+import std.Map;
+import std.Map.hashmap;
+import std.Option;
+import std.Option.none;
+import std.Option.some;
 
 import driver.session;
 import front.ast;
@@ -65,7 +65,7 @@ fn method_ty_to_fn_ty(ctxt cx, method m) -> t {
 // TODO: It'd be really nice to be able to hide this definition from the
 // outside world, to enforce the above invariants.
 type raw_t = rec(sty struct,
-                 option.t[str] cname,
+                 Option.t[str] cname,
                  uint magic,
                  uint hash,
                  bool has_params,
@@ -108,7 +108,7 @@ tag sty {
 // Data structures used in type unification
 
 type unify_handler = obj {
-    fn resolve_local(ast.def_id id) -> option.t[t];
+    fn resolve_local(ast.def_id id) -> Option.t[t];
     fn record_local(ast.def_id id, t ty);  // TODO: -> Unify.result
     fn record_param(uint index, t binding) -> Unify.result;
 };
@@ -168,8 +168,8 @@ fn mk_type_store() -> @type_store {
     auto hasher = hash_ty;
     auto eqer = eq_ty_full;
 
-    ret @rec(empty_vec_ty = _vec.empty[ty.t](),
-             empty_vec_mutable_ty = _vec.empty_mut[ty.t](),
+    ret @rec(empty_vec_ty = Vec.empty[ty.t](),
+             empty_vec_mutable_ty = Vec.empty_mut[ty.t](),
              t_nil = mk_ty_full(ty_nil, none[str]),
              t_bool = mk_ty_full(ty_bool, none[str]),
              t_int = mk_ty_full(ty_int, none[str]),
@@ -196,11 +196,11 @@ fn mk_type_store() -> @type_store {
              t_native = mk_ty_full(ty_native, none[str]),
              t_type = mk_ty_full(ty_type, none[str]),
 
-             mutable t_params = _vec.empty[ty.t](),
-             mutable t_bound_params = _vec.empty[ty.t](),
-             mutable t_vars = _vec.empty[ty.t](),
+             mutable t_params = Vec.empty[ty.t](),
+             mutable t_bound_params = Vec.empty[ty.t](),
+             mutable t_vars = Vec.empty[ty.t](),
 
-             others=map.mk_hashmap[t,t](hasher, eqer));
+             others=Map.mk_hashmap[t,t](hasher, eqer));
 }
 
 fn mk_rcache() -> creader_cache {
@@ -215,7 +215,7 @@ fn mk_rcache() -> creader_cache {
     }
     auto h = hash_cache_entry;
     auto e = eq_cache_entries;
-    ret map.mk_hashmap[tup(int,uint,uint),t](h, e);
+    ret Map.mk_hashmap[tup(int,uint,uint),t](h, e);
 }
 
 fn mk_ctxt(session.session s) -> ctxt {
@@ -225,7 +225,7 @@ fn mk_ctxt(session.session s) -> ctxt {
 }
 // Type constructors
 
-fn mk_ty_full(&sty st, option.t[str] cname) -> t {
+fn mk_ty_full(&sty st, Option.t[str] cname) -> t {
     auto h = hash_type_info(st, cname);
     auto magic = mk_magic(st);
 
@@ -350,7 +350,7 @@ fn mk_ty_full(&sty st, option.t[str] cname) -> t {
              has_locals = has_locals);
 }
 
-fn gen_ty_full(ctxt cx, &sty st, option.t[str] cname) -> t {
+fn gen_ty_full(ctxt cx, &sty st, Option.t[str] cname) -> t {
     auto new_type = mk_ty_full(st, cname);
 
     // Do not intern anything with locals or vars; it'll be nearly
@@ -457,7 +457,7 @@ fn mk_local(ctxt cx, ast.def_id did) -> t {
 }
 
 fn mk_param(ctxt cx, uint n) -> t {
-    let uint i = _vec.len[t](cx.ts.t_params);
+    let uint i = Vec.len[t](cx.ts.t_params);
     while (i <= n) {
         cx.ts.t_params += vec(mk_ty_full(ty_param(i), none[str]));
         i += 1u;
@@ -466,7 +466,7 @@ fn mk_param(ctxt cx, uint n) -> t {
 }
 
 fn mk_bound_param(ctxt cx, uint n) -> t {
-    let uint i = _vec.len[t](cx.ts.t_bound_params);
+    let uint i = Vec.len[t](cx.ts.t_bound_params);
     while (i <= n) {
         cx.ts.t_bound_params += vec(mk_ty_full(ty_bound_param(i), none[str]));
         i += 1u;
@@ -482,17 +482,17 @@ fn mk_native(ctxt cx) -> t  { ret cx.ts.t_native; }
 fn struct(ctxt cx, t typ) -> sty { ret typ.struct; }
 
 // Returns the canonical name of the given type.
-fn cname(ctxt cx, t typ) -> option.t[str] { ret typ.cname; }
+fn cname(ctxt cx, t typ) -> Option.t[str] { ret typ.cname; }
 
 
 // Stringification
 
 fn path_to_str(&ast.path pth) -> str {
-    auto result = _str.connect(pth.node.idents,  ".");
-    if (_vec.len[@ast.ty](pth.node.types) > 0u) {
+    auto result = Str.connect(pth.node.idents,  ".");
+    if (Vec.len[@ast.ty](pth.node.types) > 0u) {
         auto f = pretty.pprust.ty_to_str;
         result += "[";
-        result += _str.connect(_vec.map[@ast.ty,str](f, pth.node.types), ",");
+        result += Str.connect(Vec.map[@ast.ty,str](f, pth.node.types), ",");
         result += "]";
     }
     ret result;
@@ -513,7 +513,7 @@ fn ty_to_str(ctxt cx, &t typ) -> str {
 
     fn fn_to_str(ctxt cx,
                  ast.proto proto,
-                 option.t[ast.ident] ident,
+                 Option.t[ast.ident] ident,
                  vec[arg] inputs, t output) -> str {
             auto f = bind fn_input_to_str(cx, _);
 
@@ -536,7 +536,7 @@ fn ty_to_str(ctxt cx, &t typ) -> str {
             }
 
             s += "(";
-            s += _str.connect(_vec.map[arg,str](f, inputs), ", ");
+            s += Str.connect(Vec.map[arg,str](f, inputs), ", ");
             s += ")";
 
             if (struct(cx, output) != ty_nil) {
@@ -592,24 +592,24 @@ fn ty_to_str(ctxt cx, &t typ) -> str {
 
         case (ty_tup(?elems)) {
             auto f = bind mt_to_str(cx, _);
-            auto strs = _vec.map[mt,str](f, elems);
-            s += "tup(" + _str.connect(strs, ",") + ")";
+            auto strs = Vec.map[mt,str](f, elems);
+            s += "tup(" + Str.connect(strs, ",") + ")";
         }
 
         case (ty_rec(?elems)) {
             auto f = bind field_to_str(cx, _);
-            auto strs = _vec.map[field,str](f, elems);
-            s += "rec(" + _str.connect(strs, ",") + ")";
+            auto strs = Vec.map[field,str](f, elems);
+            s += "rec(" + Str.connect(strs, ",") + ")";
         }
 
         case (ty_tag(?id, ?tps)) {
             // The user should never see this if the cname is set properly!
             s += "<tag#" + util.common.istr(id._0) + ":" +
                 util.common.istr(id._1) + ">";
-            if (_vec.len[t](tps) > 0u) {
+            if (Vec.len[t](tps) > 0u) {
                 auto f = bind ty_to_str(cx, _);
-                auto strs = _vec.map[t,str](f, tps);
-                s += "[" + _str.connect(strs, ",") + "]";
+                auto strs = Vec.map[t,str](f, tps);
+                s += "[" + Str.connect(strs, ",") + "]";
             }
         }
 
@@ -623,8 +623,8 @@ fn ty_to_str(ctxt cx, &t typ) -> str {
 
         case (ty_obj(?meths)) {
             auto f = bind method_to_str(cx, _);
-            auto m = _vec.map[method,str](f, meths);
-            s += "obj {\n\t" + _str.connect(m, "\n\t") + "\n}";
+            auto m = Vec.map[method,str](f, meths);
+            s += "obj {\n\t" + Str.connect(m, "\n\t") + "\n}";
         }
 
         case (ty_var(?v)) {
@@ -637,11 +637,11 @@ fn ty_to_str(ctxt cx, &t typ) -> str {
         }
 
         case (ty_param(?id)) {
-            s += "'" + _str.unsafe_from_bytes(vec(('a' as u8) + (id as u8)));
+            s += "'" + Str.unsafe_from_bytes(vec(('a' as u8) + (id as u8)));
         }
 
         case (ty_bound_param(?id)) {
-            s += "''" + _str.unsafe_from_bytes(vec(('a' as u8) + (id as u8)));
+            s += "''" + Str.unsafe_from_bytes(vec(('a' as u8) + (id as u8)));
         }
     }
 
@@ -652,7 +652,7 @@ fn ty_to_short_str(ctxt cx, t typ) -> str {
     auto f = def_to_str;
     auto ecx = @rec(ds=f, tcx=cx, abbrevs=metadata.ac_no_abbrevs);
     auto s = metadata.Encode.ty_str(ecx, typ);
-    if (_str.byte_len(s) >= 64u) { s = _str.substr(s, 0u, 64u); }
+    if (Str.byte_len(s) >= 64u) { s = Str.substr(s, 0u, 64u); }
     ret s;
 }
 
@@ -956,14 +956,14 @@ fn type_has_dynamic_size(ctxt cx, t ty) -> bool {
     alt (struct(cx, ty)) {
         case (ty_tup(?mts)) {
             auto i = 0u;
-            while (i < _vec.len[mt](mts)) {
+            while (i < Vec.len[mt](mts)) {
                 if (type_has_dynamic_size(cx, mts.(i).ty)) { ret true; }
                 i += 1u;
             }
         }
         case (ty_rec(?fields)) {
             auto i = 0u;
-            while (i < _vec.len[field](fields)) {
+            while (i < Vec.len[field](fields)) {
                 if (type_has_dynamic_size(cx, fields.(i).mt.ty)) {
                     ret true;
                 }
@@ -972,7 +972,7 @@ fn type_has_dynamic_size(ctxt cx, t ty) -> bool {
         }
         case (ty_tag(_, ?subtys)) {
             auto i = 0u;
-            while (i < _vec.len[t](subtys)) {
+            while (i < Vec.len[t](subtys)) {
                 if (type_has_dynamic_size(cx, subtys.(i))) { ret true; }
                 i += 1u;
             }
@@ -1041,7 +1041,7 @@ fn type_is_signed(ctxt cx, t ty) -> bool {
     fail;
 }
 
-fn type_param(ctxt cx, t ty) -> option.t[uint] {
+fn type_param(ctxt cx, t ty) -> Option.t[uint] {
     alt (struct(cx, ty)) {
         case (ty_param(?id)) { ret some[uint](id); }
         case (_)             { /* fall through */  }
@@ -1174,7 +1174,7 @@ fn hash_type_structure(&sty st) -> uint {
         case (ty_obj(?methods)) {
             auto h = 27u;
             for (method m in methods) {
-                h += h << 5u + _str.hash(m.ident);
+                h += h << 5u + Str.hash(m.ident);
             }
             ret h;
         }
@@ -1187,11 +1187,11 @@ fn hash_type_structure(&sty st) -> uint {
     }
 }
 
-fn hash_type_info(&sty st, option.t[str] cname_opt) -> uint {
+fn hash_type_info(&sty st, Option.t[str] cname_opt) -> uint {
     auto h = hash_type_structure(st);
     alt (cname_opt) {
         case (none[str]) { /* no-op */ }
-        case (some[str](?s)) { h += h << 5u + _str.hash(s); }
+        case (some[str](?s)) { h += h << 5u + Str.hash(s); }
     }
     ret h;
 }
@@ -1297,8 +1297,8 @@ fn equal_type_structures(&sty a, &sty b) -> bool {
                 vec[arg] args_b, t rty_b) -> bool {
         if (!eq_ty(rty_a, rty_b)) { ret false; }
 
-        auto len = _vec.len[arg](args_a);
-        if (len != _vec.len[arg](args_b)) { ret false; }
+        auto len = Vec.len[arg](args_a);
+        if (len != Vec.len[arg](args_b)) { ret false; }
 
         auto i = 0u;
         while (i < len) {
@@ -1370,8 +1370,8 @@ fn equal_type_structures(&sty a, &sty b) -> bool {
                 case (ty_tag(?id_b, ?tys_b)) {
                     if (!equal_def(id_a, id_b)) { ret false; }
 
-                    auto len = _vec.len[t](tys_a);
-                    if (len != _vec.len[t](tys_b)) { ret false; }
+                    auto len = Vec.len[t](tys_a);
+                    if (len != Vec.len[t](tys_b)) { ret false; }
                     auto i = 0u;
                     while (i < len) {
                         if (!eq_ty(tys_a.(i), tys_b.(i))) { ret false; }
@@ -1415,8 +1415,8 @@ fn equal_type_structures(&sty a, &sty b) -> bool {
         case (ty_tup(?mts_a)) {
             alt (b) {
                 case (ty_tup(?mts_b)) {
-                    auto len = _vec.len[mt](mts_a);
-                    if (len != _vec.len[mt](mts_b)) { ret false; }
+                    auto len = Vec.len[mt](mts_a);
+                    if (len != Vec.len[mt](mts_b)) { ret false; }
                     auto i = 0u;
                     while (i < len) {
                         if (!equal_mt(mts_a.(i), mts_b.(i))) { ret false; }
@@ -1430,12 +1430,12 @@ fn equal_type_structures(&sty a, &sty b) -> bool {
         case (ty_rec(?flds_a)) {
             alt (b) {
                 case (ty_rec(?flds_b)) {
-                    auto len = _vec.len[field](flds_a);
-                    if (len != _vec.len[field](flds_b)) { ret false; }
+                    auto len = Vec.len[field](flds_a);
+                    if (len != Vec.len[field](flds_b)) { ret false; }
                     auto i = 0u;
                     while (i < len) {
                         auto fld_a = flds_a.(i); auto fld_b = flds_b.(i);
-                        if (!_str.eq(fld_a.ident, fld_b.ident) ||
+                        if (!Str.eq(fld_a.ident, fld_b.ident) ||
                                 !equal_mt(fld_a.mt, fld_b.mt)) {
                             ret false;
                         }
@@ -1467,13 +1467,13 @@ fn equal_type_structures(&sty a, &sty b) -> bool {
         case (ty_obj(?methods_a)) {
             alt (b) {
                 case (ty_obj(?methods_b)) {
-                    auto len = _vec.len[method](methods_a);
-                    if (len != _vec.len[method](methods_b)) { ret false; }
+                    auto len = Vec.len[method](methods_a);
+                    if (len != Vec.len[method](methods_b)) { ret false; }
                     auto i = 0u;
                     while (i < len) {
                         auto m_a = methods_a.(i); auto m_b = methods_b.(i);
                         if (!equal_proto(m_a.proto, m_b.proto) ||
-                                !_str.eq(m_a.ident, m_b.ident) ||
+                                !Str.eq(m_a.ident, m_b.ident) ||
                                 !equal_fn(m_a.inputs, m_a.output,
                                           m_b.inputs, m_b.output)) {
                             ret false;
@@ -1546,7 +1546,7 @@ fn eq_ty_full(&t a, &t b) -> bool {
         case (some[str](?s_a)) {
             alt (b.cname) {
                 case (some[str](?s_b)) {
-                    if (!_str.eq(s_a, s_b)) { ret false; }
+                    if (!Str.eq(s_a, s_b)) { ret false; }
                 }
                 case (_) { ret false; }
             }
@@ -1651,7 +1651,7 @@ fn count_ty_params(ctxt cx, t ty) -> uint {
     let @mutable vec[uint] param_indices = @mutable v;
     auto f = bind counter(cx, param_indices, _);
     walk_ty(cx, f, ty);
-    ret _vec.len[uint](*param_indices);
+    ret Vec.len[uint](*param_indices);
 }
 
 fn type_contains_vars(ctxt cx, t typ) -> bool {
@@ -1721,7 +1721,7 @@ fn native_item_ty(@ast.native_item it) -> ty_param_count_and_ty {
     auto result_ty;
     alt (it.node) {
         case (ast.native_item_fn(_, _, _, ?tps, _, ?ann)) {
-            ty_param_count = _vec.len[ast.ty_param](tps);
+            ty_param_count = Vec.len[ast.ty_param](tps);
             result_ty = ann_to_type(ann);
         }
     }
@@ -1737,22 +1737,22 @@ fn item_ty(@ast.item it) -> ty_param_count_and_ty {
             result_ty = ann_to_type(ann);
         }
         case (ast.item_fn(_, _, ?tps, _, ?ann)) {
-            ty_param_count = _vec.len[ast.ty_param](tps);
+            ty_param_count = Vec.len[ast.ty_param](tps);
             result_ty = ann_to_type(ann);
         }
         case (ast.item_mod(_, _, _)) {
             fail;   // modules are typeless
         }
         case (ast.item_ty(_, _, ?tps, _, ?ann)) {
-            ty_param_count = _vec.len[ast.ty_param](tps);
+            ty_param_count = Vec.len[ast.ty_param](tps);
             result_ty = ann_to_type(ann);
         }
         case (ast.item_tag(_, _, ?tps, ?did, ?ann)) {
-            ty_param_count = _vec.len[ast.ty_param](tps);
+            ty_param_count = Vec.len[ast.ty_param](tps);
             result_ty = ann_to_type(ann);
         }
         case (ast.item_obj(_, _, ?tps, _, ?ann)) {
-            ty_param_count = _vec.len[ast.ty_param](tps);
+            ty_param_count = Vec.len[ast.ty_param](tps);
             result_ty = ann_to_type(ann);
         }
     }
@@ -1924,7 +1924,7 @@ fn expr_has_ty_params(@ast.expr expr) -> bool {
     alt (expr_ann(expr)) {
         case (ast.ann_none) { fail; }
         case (ast.ann_type(_, ?tps_opt, _)) {
-            ret !option.is_none[vec[t]](tps_opt);
+            ret !Option.is_none[vec[t]](tps_opt);
         }
     }
 }
@@ -1987,7 +1987,7 @@ fn field_num(session.session sess, &span sp, &ast.ident id) -> uint {
                 accum += (c as uint) - ('0' as uint);
             } else {
                 auto s = "";
-                s += _str.unsafe_from_byte(c);
+                s += Str.unsafe_from_byte(c);
                 sess.span_err(sp,
                               "bad numeric field on tuple: "
                               + " non-digit character: "
@@ -2003,7 +2003,7 @@ fn field_idx(session.session sess, &span sp,
              &ast.ident id, vec[field] fields) -> uint {
     let uint i = 0u;
     for (field f in fields) {
-        if (_str.eq(f.ident, id)) {
+        if (Str.eq(f.ident, id)) {
             ret i;
         }
         i += 1u;
@@ -2016,7 +2016,7 @@ fn method_idx(session.session sess, &span sp,
               &ast.ident id, vec[method] meths) -> uint {
     let uint i = 0u;
     for (method m in meths) {
-        if (_str.eq(m.ident, id)) {
+        if (Str.eq(m.ident, id)) {
             ret i;
         }
         i += 1u;
@@ -2027,10 +2027,10 @@ fn method_idx(session.session sess, &span sp,
 
 fn sort_methods(vec[method] meths) -> vec[method] {
     fn method_lteq(&method a, &method b) -> bool {
-        ret _str.lteq(a.ident, b.ident);
+        ret Str.lteq(a.ident, b.ident);
     }
 
-    ret std.sort.merge_sort[method](bind method_lteq(_,_), meths);
+    ret std.Sort.merge_sort[method](bind method_lteq(_,_), meths);
 }
 
 fn is_lval(@ast.expr expr) -> bool {
@@ -2078,7 +2078,7 @@ mod Unify {
 
     // Unifies two mutability flags.
     fn unify_mut(ast.mutability expected, ast.mutability actual)
-            -> option.t[ast.mutability] {
+            -> Option.t[ast.mutability] {
         if (expected == actual) {
             ret some[ast.mutability](expected);
         }
@@ -2102,8 +2102,8 @@ mod Unify {
                        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);
+        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));
@@ -2213,8 +2213,8 @@ mod Unify {
                  vec[method] actual_meths) -> result {
       let vec[method] result_meths = vec();
       let uint i = 0u;
-      let uint expected_len = _vec.len[method](expected_meths);
-      let uint actual_len = _vec.len[method](actual_meths);
+      let uint expected_len = Vec.len[method](expected_meths);
+      let uint actual_len = Vec.len[method](actual_meths);
 
       if (expected_len != actual_len) {
         ret ures_err(terr_meth_count, expected, actual);
@@ -2223,7 +2223,7 @@ mod Unify {
       while (i < expected_len) {
         auto e_meth = expected_meths.(i);
         auto a_meth = actual_meths.(i);
-        if (! _str.eq(e_meth.ident, a_meth.ident)) {
+        if (! Str.eq(e_meth.ident, a_meth.ident)) {
           ret ures_err(terr_obj_meths(e_meth.ident, a_meth.ident),
                        expected, actual);
         }
@@ -2287,7 +2287,7 @@ mod Unify {
 
                     case (_) {
                         // Just bind the type variable to the expected type.
-                        auto vlen = _vec.len[vec[t]](cx.types);
+                        auto vlen = Vec.len[vec[t]](cx.types);
                         if (actual_n < vlen) {
                             cx.types.(actual_n) += vec(expected);
                         } else {
@@ -2354,7 +2354,7 @@ mod Unify {
                         // ty.ty_tup case
                         let vec[t] result_tps = vec();
                         auto i = 0u;
-                        auto expected_len = _vec.len[t](expected_tps);
+                        auto expected_len = Vec.len[t](expected_tps);
                         while (i < expected_len) {
                             auto expected_tp = expected_tps.(i);
                             auto actual_tp = actual_tps.(i);
@@ -2365,7 +2365,7 @@ mod Unify {
 
                             alt (result) {
                                 case (ures_ok(?rty)) {
-                                    _vec.push[t](result_tps, rty);
+                                    Vec.push[t](result_tps, rty);
                                 }
                                 case (_) {
                                     ret result;
@@ -2494,8 +2494,8 @@ mod Unify {
             case (ty.ty_tup(?expected_elems)) {
                 alt (struct(cx.tcx, actual)) {
                     case (ty.ty_tup(?actual_elems)) {
-                        auto expected_len = _vec.len[ty.mt](expected_elems);
-                        auto actual_len = _vec.len[ty.mt](actual_elems);
+                        auto expected_len = Vec.len[ty.mt](expected_elems);
+                        auto actual_len = Vec.len[ty.mt](actual_elems);
                         if (expected_len != actual_len) {
                             auto err = terr_tuple_size(expected_len,
                                                        actual_len);
@@ -2548,8 +2548,8 @@ mod Unify {
             case (ty.ty_rec(?expected_fields)) {
                 alt (struct(cx.tcx, actual)) {
                     case (ty.ty_rec(?actual_fields)) {
-                        auto expected_len = _vec.len[field](expected_fields);
-                        auto actual_len = _vec.len[field](actual_fields);
+                        auto expected_len = Vec.len[field](expected_fields);
+                        auto actual_len = Vec.len[field](actual_fields);
                         if (expected_len != actual_len) {
                             auto err = terr_record_size(expected_len,
                                                         actual_len);
@@ -2574,7 +2574,7 @@ mod Unify {
                                 case (some[ast.mutability](?m)) { mut = m; }
                             }
 
-                            if (!_str.eq(expected_field.ident,
+                            if (!Str.eq(expected_field.ident,
                                          actual_field.ident)) {
                                 auto err =
                                     terr_record_fields(expected_field.ident,
@@ -2588,7 +2588,7 @@ mod Unify {
                             alt (result) {
                                 case (ures_ok(?rty)) {
                                     auto mt = rec(ty=rty, mut=mut);
-                                    _vec.push[field]
+                                    Vec.push[field]
                                         (result_fields,
                                          rec(mt=mt with expected_field));
                                 }
@@ -2655,7 +2655,7 @@ mod Unify {
             case (ty.ty_var(?expected_id)) {
                 // Add a binding.
                 auto expected_n = get_or_create_set(cx, expected_id);
-                auto vlen = _vec.len[vec[t]](cx.types);
+                auto vlen = Vec.len[vec[t]](cx.types);
                 if (expected_n < vlen) {
                     cx.types.(expected_n) += vec(actual);
                 } else {
@@ -2719,7 +2719,7 @@ mod Unify {
     fn unify_sets(@ctxt cx) -> vec[t] {
         let vec[t] throwaway = vec();
         let vec[mutable vec[t]] set_types = vec(mutable throwaway);
-        _vec.pop[vec[t]](set_types);   // FIXME: botch
+        Vec.pop[vec[t]](set_types);   // FIXME: botch
 
         for (UFind.node node in cx.sets.nodes) {
             let vec[t] v = vec();
@@ -2727,7 +2727,7 @@ mod Unify {
         }
 
         auto i = 0u;
-        while (i < _vec.len[vec[t]](set_types)) {
+        while (i < Vec.len[vec[t]](set_types)) {
             auto root = UFind.find(cx.sets, i);
             set_types.(root) += cx.types.(i);
             i += 1u;
@@ -2735,7 +2735,7 @@ mod Unify {
 
         let vec[t] result = vec();
         for (vec[t] types in set_types) {
-            if (_vec.len[t](types) > 1u) {
+            if (Vec.len[t](types) > 1u) {
                 log_err "unification of > 1 types in a type set is " +
                     "unimplemented";
                 fail;
@@ -2752,7 +2752,7 @@ mod Unify {
              ty_ctxt tcx) -> result {
         let vec[t] throwaway = vec();
         let vec[mutable vec[t]] types = vec(mutable throwaway);
-        _vec.pop[vec[t]](types);   // FIXME: botch
+        Vec.pop[vec[t]](types);   // FIXME: botch
 
         auto cx = @rec(sets=UFind.make(),
                        var_ids=common.new_int_hash[uint](),
@@ -2765,7 +2765,7 @@ mod Unify {
         case (ures_ok(?typ)) {
             // Fast path: if there are no local variables, don't perform
             // substitutions.
-            if (_vec.len(cx.sets.nodes) == 0u) {
+            if (Vec.len(cx.sets.nodes) == 0u) {
                 ret ures_ok(typ);
             }
 
@@ -2791,16 +2791,16 @@ fn type_err_to_str(&ty.type_err err) -> str {
             ret "vectors differ in mutability";
         }
         case (terr_tuple_size(?e_sz, ?a_sz)) {
-            ret "expected a tuple with " + _uint.to_str(e_sz, 10u) +
-                " elements but found one with " + _uint.to_str(a_sz, 10u) +
+            ret "expected a tuple with " + UInt.to_str(e_sz, 10u) +
+                " elements but found one with " + UInt.to_str(a_sz, 10u) +
                 " elements";
         }
         case (terr_tuple_mutability) {
             ret "tuple elements differ in mutability";
         }
         case (terr_record_size(?e_sz, ?a_sz)) {
-            ret "expected a record with " + _uint.to_str(e_sz, 10u) +
-                " fields but found one with " + _uint.to_str(a_sz, 10u) +
+            ret "expected a record with " + UInt.to_str(e_sz, 10u) +
+                " fields but found one with " + UInt.to_str(a_sz, 10u) +
                 " fields";
         }
         case (terr_record_mutability) {
diff --git a/src/comp/middle/typeck.rs b/src/comp/middle/typeck.rs
index 65e443dfffc..091616fcda7 100644
--- a/src/comp/middle/typeck.rs
+++ b/src/comp/middle/typeck.rs
@@ -32,15 +32,15 @@ import middle.ty.ty_nil;
 import middle.ty.Unify.ures_ok;
 import middle.ty.Unify.ures_err;
 
-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;
-import std.option.from_maybe;
+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;
+import std.Option.from_maybe;
 
 import util.typestate_ann.ts_ann;
 
@@ -61,7 +61,7 @@ type crate_ctxt = rec(session.session sess,
                       ty.type_cache type_cache,
                       @ty_item_table item_items,
                       vec[ast.obj_field] obj_fields,
-                      option.t[ast.def_id] this_obj,
+                      Option.t[ast.def_id] this_obj,
                       @fn_purity_table fn_purity_table,
                       mutable int next_var_id,
                       unify_cache unify_cache,
@@ -91,12 +91,12 @@ fn substitute_ty_params(&@crate_ctxt ccx,
         }
     }
 
-    auto supplied_len = _vec.len[ty.t](supplied);
+    auto supplied_len = Vec.len[ty.t](supplied);
     if (ty_param_count != supplied_len) {
         ccx.sess.span_err(sp, "expected " +
-                          _uint.to_str(ty_param_count, 10u) +
+                          UInt.to_str(ty_param_count, 10u) +
                           " type parameter(s) but found " +
-                          _uint.to_str(supplied_len, 10u) + " parameter(s)");
+                          UInt.to_str(supplied_len, 10u) + " parameter(s)");
         fail;
     }
 
@@ -181,7 +181,7 @@ fn instantiate_path(@fn_ctxt fcx, &ast.path pth, &ty_param_count_and_ty tpt,
     auto t = bind_params_in_type(fcx.ccx.tcx, tpt._1);
 
     auto ty_substs_opt;
-    auto ty_substs_len = _vec.len[@ast.ty](pth.node.types);
+    auto ty_substs_len = Vec.len[@ast.ty](pth.node.types);
     if (ty_substs_len > 0u) {
         let vec[ty.t] ty_substs = vec();
         auto i = 0u;
@@ -281,7 +281,7 @@ fn ast_ty_to_ty(ty.ctxt tcx, ty_getter getter, &@ast.ty ast_ty) -> ty.t {
         case (ast.ty_tup(?fields)) {
             let vec[ty.mt] flds = vec();
             for (ast.mt field in fields) {
-                _vec.push[ty.mt](flds, ast_mt_to_mt(tcx, getter, field));
+                Vec.push[ty.mt](flds, ast_mt_to_mt(tcx, getter, field));
             }
             typ = ty.mk_tup(tcx, flds);
         }
@@ -289,21 +289,21 @@ fn ast_ty_to_ty(ty.ctxt tcx, ty_getter getter, &@ast.ty ast_ty) -> ty.t {
             let vec[field] flds = vec();
             for (ast.ty_field f in fields) {
                 auto tm = ast_mt_to_mt(tcx, getter, f.mt);
-                _vec.push[field](flds, rec(ident=f.ident, mt=tm));
+                Vec.push[field](flds, rec(ident=f.ident, mt=tm));
             }
             typ = ty.mk_rec(tcx, flds);
         }
 
         case (ast.ty_fn(?proto, ?inputs, ?output)) {
             auto f = bind ast_arg_to_arg(tcx, getter, _);
-            auto i = _vec.map[ast.ty_arg, arg](f, inputs);
+            auto i = Vec.map[ast.ty_arg, arg](f, inputs);
             auto out_ty = ast_ty_to_ty(tcx, getter, output);
             typ = ty.mk_fn(tcx, proto, i, out_ty);
         }
 
         case (ast.ty_path(?path, ?def)) {
             assert (def != none[ast.def]);
-            alt (option.get[ast.def](def)) {
+            alt (Option.get[ast.def](def)) {
                 case (ast.def_ty(?id)) {
                     typ = instantiate(tcx, getter, id, path.node.types);
                 }
@@ -325,9 +325,9 @@ fn ast_ty_to_ty(ty.ctxt tcx, ty_getter getter, &@ast.ty ast_ty) -> ty.t {
             let vec[ty.method] tmeths = vec();
             auto f = bind ast_arg_to_arg(tcx, getter, _);
             for (ast.ty_method m in meths) {
-                auto ins = _vec.map[ast.ty_arg, arg](f, m.inputs);
+                auto ins = Vec.map[ast.ty_arg, arg](f, m.inputs);
                 auto out = ast_ty_to_ty(tcx, getter, m.output);
-                _vec.push[ty.method](tmeths,
+                Vec.push[ty.method](tmeths,
                                   rec(proto=m.proto,
                                       ident=m.ident,
                                       inputs=ins,
@@ -383,10 +383,10 @@ mod Collect {
                      ast.proto proto,
                      vec[ast.ty_param] ty_params,
                      ast.def_id def_id) -> ty.ty_param_count_and_ty {
-        auto input_tys = _vec.map[ast.arg,arg](ty_of_arg, decl.inputs);
+        auto input_tys = Vec.map[ast.arg,arg](ty_of_arg, decl.inputs);
         auto output_ty = convert(decl.output);
         auto t_fn = ty.mk_fn(cx.tcx, proto, input_tys, output_ty);
-        auto ty_param_count = _vec.len[ast.ty_param](ty_params);
+        auto ty_param_count = Vec.len[ast.ty_param](ty_params);
         auto tpt = tup(ty_param_count, t_fn);
         cx.type_cache.insert(def_id, tpt);
         ret tpt;
@@ -399,10 +399,10 @@ mod Collect {
                             ast.native_abi abi,
                             vec[ast.ty_param] ty_params,
                             ast.def_id def_id) -> ty.ty_param_count_and_ty {
-        auto input_tys = _vec.map[ast.arg,arg](ty_of_arg, decl.inputs);
+        auto input_tys = Vec.map[ast.arg,arg](ty_of_arg, decl.inputs);
         auto output_ty = convert(decl.output);
         auto t_fn = ty.mk_native_fn(cx.tcx, abi, input_tys, output_ty);
-        auto ty_param_count = _vec.len[ast.ty_param](ty_params);
+        auto ty_param_count = Vec.len[ast.ty_param](ty_params);
         auto tpt = tup(ty_param_count, t_fn);
         cx.type_cache.insert(def_id, tpt);
         ret tpt;
@@ -438,7 +438,7 @@ mod Collect {
         auto get = bind getter(cx, _);
         auto convert = bind ast_ty_to_ty(cx.tcx, get, _);
         auto f = bind ty_of_arg(cx, _);
-        auto inputs = _vec.map[ast.arg,arg](f, m.node.meth.decl.inputs);
+        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);
@@ -449,11 +449,11 @@ mod Collect {
                  &ast._obj obj_info,
                  vec[ast.ty_param] ty_params) -> ty.ty_param_count_and_ty {
         auto f = bind ty_of_method(cx, _);
-        auto methods = _vec.map[@ast.method,method](f, obj_info.methods);
+        auto methods = Vec.map[@ast.method,method](f, obj_info.methods);
 
         auto t_obj = ty.mk_obj(cx.tcx, ty.sort_methods(methods));
         t_obj = ty.rename(cx.tcx, t_obj, id);
-        auto ty_param_count = _vec.len[ast.ty_param](ty_params);
+        auto ty_param_count = Vec.len[ast.ty_param](ty_params);
         ret tup(ty_param_count, t_obj);
     }
 
@@ -468,7 +468,7 @@ mod Collect {
         for (ast.obj_field f in obj_info.fields) {
             auto g = bind getter(cx, _);
             auto t_field = ast_ty_to_ty(cx.tcx, g, f.ty);
-            _vec.push[arg](t_inputs, rec(mode=ast.alias, ty=t_field));
+            Vec.push[arg](t_inputs, rec(mode=ast.alias, ty=t_field));
         }
 
         cx.type_cache.insert(obj_ty_id, t_obj);
@@ -515,7 +515,7 @@ mod Collect {
                 // Tell ast_ty_to_ty() that we want to perform a recursive
                 // call to resolve any named types.
                 auto typ = convert(t);
-                auto ty_param_count = _vec.len[ast.ty_param](tps);
+                auto ty_param_count = Vec.len[ast.ty_param](tps);
                 auto tpt = tup(ty_param_count, typ);
                 cx.type_cache.insert(def_id, tpt);
                 ret tpt;
@@ -533,7 +533,7 @@ mod Collect {
 
                 auto t = ty.mk_tag(cx.tcx, def_id, subtys);
 
-                auto ty_param_count = _vec.len[ast.ty_param](tps);
+                auto ty_param_count = Vec.len[ast.ty_param](tps);
                 auto tpt = tup(ty_param_count, t);
                 cx.type_cache.insert(def_id, tpt);
                 ret tpt;
@@ -585,13 +585,13 @@ mod Collect {
             i += 1u;
         }
 
-        auto ty_param_count = _vec.len[ast.ty_param](ty_params);
+        auto ty_param_count = Vec.len[ast.ty_param](ty_params);
 
         for (ast.variant variant in variants) {
             // 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.node.args) == 0u) {
+            if (Vec.len[ast.variant_arg](variant.node.args) == 0u) {
                 result_ty = ty.mk_tag(cx.tcx, tag_id, ty_param_tys);
             } else {
                 // As above, tell ast_ty_to_ty() that trans_ty_item_to_ty()
@@ -691,7 +691,7 @@ mod Collect {
         ret @fold.respan[ast.item_](sp, item);
     }
 
-    fn fold_native_item_fn(&@env e, &span sp, ast.ident i, option.t[str] ln,
+    fn fold_native_item_fn(&@env e, &span sp, ast.ident i, Option.t[str] ln,
                            &ast.fn_decl d, vec[ast.ty_param] ty_params,
                            ast.def_id id, ast.ann a) -> @ast.native_item {
         // assert (e.cx.type_cache.contains_key(id));
@@ -746,7 +746,7 @@ mod Collect {
                 with meth.node
             );
             m = @rec(node=m_ with *meth);
-            _vec.push[@ast.method](methods, m);
+            Vec.push[@ast.method](methods, m);
         }
         auto g = bind getter(e.cx, _);
         for (ast.obj_field fld in ob.fields) {
@@ -754,7 +754,7 @@ mod Collect {
             let ast.obj_field f = rec(ann=triv_ann(fty)
                 with fld
             );
-            _vec.push[ast.obj_field](fields, f);
+            Vec.push[ast.obj_field](fields, f);
         }
 
         auto dtor = none[@ast.method];
@@ -847,7 +847,7 @@ mod Unify {
         // FIXME: horrid botch
         let vec[mutable ty.t] param_substs =
             vec(mutable ty.mk_nil(fcx.ccx.tcx));
-        _vec.pop(param_substs);
+        Vec.pop(param_substs);
         ret with_params(fcx, expected, actual, param_substs);
     }
 
@@ -865,7 +865,7 @@ mod Unify {
         }
 
         obj unify_handler(@fn_ctxt fcx, vec[mutable ty.t] param_substs) {
-            fn resolve_local(ast.def_id id) -> option.t[ty.t] {
+            fn resolve_local(ast.def_id id) -> Option.t[ty.t] {
                 alt (fcx.locals.find(id)) {
                     case (none[ty.t]) { ret none[ty.t]; }
                     case (some[ty.t](?existing_type)) {
@@ -905,7 +905,7 @@ mod Unify {
             }
             fn record_param(uint index, ty.t binding) -> ty.Unify.result {
                 // Unify with the appropriate type in the parameter
-                // substitution list.
+                // substitution List.
                 auto old_subst = param_substs.(index);
 
                 auto result = with_params(fcx, old_subst, binding,
@@ -1004,7 +1004,7 @@ mod Demand {
 
         let vec[mutable ty.t] ty_param_substs =
             vec(mutable ty.mk_nil(fcx.ccx.tcx));
-        _vec.pop(ty_param_substs);   // FIXME: horrid botch
+        Vec.pop(ty_param_substs);   // FIXME: horrid botch
         for (ty.t ty_param_subst in ty_param_substs_0) {
             ty_param_substs += vec(mutable ty_param_subst);
         }
@@ -1047,7 +1047,7 @@ fn are_compatible(&@fn_ctxt fcx, ty.t expected, ty.t actual) -> bool {
 // Returns the types of the arguments to a tag variant.
 fn variant_arg_types(@crate_ctxt ccx, &span sp, ast.def_id vid,
                      vec[ty.t] tag_ty_params) -> vec[ty.t] {
-    auto ty_param_count = _vec.len[ty.t](tag_ty_params);
+    auto ty_param_count = Vec.len[ty.t](tag_ty_params);
 
     let vec[ty.t] result = vec();
 
@@ -1130,7 +1130,7 @@ mod Pushdown {
                 }
 
                 // Get the types of the arguments of the variant.
-                auto vdef = option.get[ast.variant_def](vdef_opt);
+                auto vdef = Option.get[ast.variant_def](vdef_opt);
                 auto arg_tys = variant_arg_types(fcx.ccx, pat.span, vdef._1,
                                                  tag_tps);
 
@@ -1218,7 +1218,7 @@ mod Pushdown {
                             case (none[@ast.expr]) {
                                 auto i = 0u;
                                 for (ast.field field_0 in fields_0) {
-                                    assert (_str.eq(field_0.ident,
+                                    assert (Str.eq(field_0.ident,
                                                    field_mts.(i).ident));
                                     auto e_1 =
                                         pushdown_expr(fcx,
@@ -1240,7 +1240,7 @@ mod Pushdown {
                                 for (ast.field field_0 in fields_0) {
 
                                     for (ty.field ft in field_mts) {
-                                        if (_str.eq(field_0.ident,
+                                        if (Str.eq(field_0.ident,
                                                     ft.ident)) {
                                             auto e_1 =
                                                 pushdown_expr(fcx, ft.mt.ty,
@@ -1508,9 +1508,9 @@ mod Pushdown {
 // Local variable resolution: the phase that finds all the types in the AST
 // and replaces opaque "ty_local" types with the resolved local types.
 
-fn writeback_local(&option.t[@fn_ctxt] env, &span sp, @ast.local local)
+fn writeback_local(&Option.t[@fn_ctxt] env, &span sp, @ast.local local)
         -> @ast.decl {
-    auto fcx = option.get[@fn_ctxt](env);
+    auto fcx = Option.get[@fn_ctxt](env);
 
     auto local_ty;
     alt (fcx.locals.find(local.id)) {
@@ -1530,7 +1530,7 @@ fn writeback_local(&option.t[@fn_ctxt] env, &span sp, @ast.local local)
     ret @fold.respan[ast.decl_](sp, ast.decl_local(local_wb));
 }
 
-fn resolve_local_types_in_annotation(&option.t[@fn_ctxt] env, ast.ann ann)
+fn resolve_local_types_in_annotation(&Option.t[@fn_ctxt] env, ast.ann ann)
         -> ast.ann {
     fn resolver(@fn_ctxt fcx, ty.t typ) -> ty.t {
         alt (struct(fcx.ccx.tcx, typ)) {
@@ -1539,7 +1539,7 @@ fn resolve_local_types_in_annotation(&option.t[@fn_ctxt] env, ast.ann ann)
         }
     }
 
-    auto fcx = option.get[@fn_ctxt](env);
+    auto fcx = Option.get[@fn_ctxt](env);
     alt (ann) {
         case (ast.ann_none) {
             log "warning: no type for expression";
@@ -1559,16 +1559,16 @@ fn resolve_local_types_in_annotation(&option.t[@fn_ctxt] env, ast.ann ann)
 
 fn resolve_local_types_in_block(&@fn_ctxt fcx, &ast.block block)
         -> ast.block {
-    fn update_env_for_item(&option.t[@fn_ctxt] env, @ast.item i)
-            -> option.t[@fn_ctxt] {
+    fn update_env_for_item(&Option.t[@fn_ctxt] env, @ast.item i)
+            -> Option.t[@fn_ctxt] {
         ret none[@fn_ctxt];
     }
-    fn keep_going(&option.t[@fn_ctxt] env) -> bool {
-        ret !option.is_none[@fn_ctxt](env);
+    fn keep_going(&Option.t[@fn_ctxt] env) -> bool {
+        ret !Option.is_none[@fn_ctxt](env);
     }
 
     // FIXME: rustboot bug prevents us from using these functions directly
-    auto fld = fold.new_identity_fold[option.t[@fn_ctxt]]();
+    auto fld = fold.new_identity_fold[Option.t[@fn_ctxt]]();
     auto wbl = writeback_local;
     auto rltia = bind resolve_local_types_in_annotation(_,_);
     auto uefi = update_env_for_item;
@@ -1580,7 +1580,7 @@ fn resolve_local_types_in_block(&@fn_ctxt fcx, &ast.block block)
         keep_going = kg
         with *fld
     );
-    ret fold.fold_block[option.t[@fn_ctxt]](some[@fn_ctxt](fcx), fld, block);
+    ret fold.fold_block[Option.t[@fn_ctxt]](some[@fn_ctxt](fcx), fld, block);
 }
 
 // AST fragment checking
@@ -1616,10 +1616,10 @@ fn check_pat(&@fn_ctxt fcx, @ast.pat pat) -> @ast.pat {
             new_pat = ast.pat_bind(id, def_id, ann);
         }
         case (ast.pat_tag(?p, ?subpats, ?vdef_opt, _)) {
-            auto vdef = option.get[ast.variant_def](vdef_opt);
+            auto vdef = Option.get[ast.variant_def](vdef_opt);
             auto t = ty.lookup_item_type(fcx.ccx.sess, fcx.ccx.tcx,
                                          fcx.ccx.type_cache, vdef._1)._1;
-            auto len = _vec.len[ast.ident](p.node.idents);
+            auto len = Vec.len[ast.ident](p.node.idents);
             auto last_id = p.node.idents.(len - 1u);
 
             auto tpt = ty.lookup_item_type(fcx.ccx.sess, fcx.ccx.tcx,
@@ -1629,14 +1629,14 @@ fn check_pat(&@fn_ctxt fcx, @ast.pat pat) -> @ast.pat {
             alt (struct(fcx.ccx.tcx, t)) {
                 // N-ary variants have function types.
                 case (ty.ty_fn(_, ?args, ?tag_ty)) {
-                    auto arg_len = _vec.len[arg](args);
-                    auto subpats_len = _vec.len[@ast.pat](subpats);
+                    auto arg_len = Vec.len[arg](args);
+                    auto subpats_len = Vec.len[@ast.pat](subpats);
                     if (arg_len != subpats_len) {
                         // TODO: pluralize properly
                         auto err_msg = "tag type " + last_id + " has " +
-                                       _uint.to_str(subpats_len, 10u) +
+                                       UInt.to_str(subpats_len, 10u) +
                                        " field(s), but this pattern has " +
-                                       _uint.to_str(arg_len, 10u) +
+                                       UInt.to_str(arg_len, 10u) +
                                        " field(s)";
 
                         fcx.ccx.sess.span_err(pat.span, err_msg);
@@ -1653,13 +1653,13 @@ fn check_pat(&@fn_ctxt fcx, @ast.pat pat) -> @ast.pat {
 
                 // Nullary variants have tag types.
                 case (ty.ty_tag(?tid, _)) {
-                    auto subpats_len = _vec.len[@ast.pat](subpats);
+                    auto subpats_len = Vec.len[@ast.pat](subpats);
                     if (subpats_len > 0u) {
                         // TODO: pluralize properly
                         auto err_msg = "tag type " + last_id +
                                        " has no field(s)," +
                                        " but this pattern has " +
-                                       _uint.to_str(subpats_len, 10u) +
+                                       UInt.to_str(subpats_len, 10u) +
                                        " field(s)";
 
                         fcx.ccx.sess.span_err(pat.span, err_msg);
@@ -1689,7 +1689,7 @@ fn require_impure(&session.session sess,
 }
 
 fn get_function_purity(@crate_ctxt ccx, &ast.def_id d_id) -> ast.purity {
-    let option.t[ast.purity] o = ccx.fn_purity_table.find(d_id);
+    let Option.t[ast.purity] o = ccx.fn_purity_table.find(d_id);
     ret from_maybe[ast.purity](ast.impure_fn, o);
 }
 
@@ -1738,16 +1738,16 @@ 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]]) {
+                          &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[Option.t[@ast.expr]] args_0 = vec();
         let vec[arg] arg_tys_0 = vec();
-        for (option.t[@ast.expr] a_opt in args) {
+        for (Option.t[@ast.expr] a_opt in args) {
             alt (a_opt) {
                 case (some[@ast.expr](?a)) {
                     auto a_0 = check_expr(fcx, a);
@@ -1756,14 +1756,14 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                     // FIXME: this breaks aliases. We need a ty_fn_arg.
                     auto arg_ty = rec(mode=ast.val,
                                       ty=expr_ty(fcx.ccx.tcx, a_0));
-                    _vec.push[arg](arg_tys_0, arg_ty);
+                    Vec.push[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);
-                    _vec.push[arg](arg_tys_0, rec(mode=ast.val, ty=typ));
+                    Vec.push[arg](arg_tys_0, rec(mode=ast.val, ty=typ));
                 }
             }
         }
@@ -1812,7 +1812,7 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
     fn check_call(&@fn_ctxt fcx, @ast.expr f, vec[@ast.expr] args)
         -> tup(@ast.expr, vec[@ast.expr]) {
 
-        let vec[option.t[@ast.expr]] args_opt_0 = vec();
+        let vec[Option.t[@ast.expr]] args_opt_0 = vec();
         for (@ast.expr arg in args) {
             args_opt_0 += vec(some[@ast.expr](arg));
         }
@@ -1822,8 +1822,8 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
 
         // Pull out the arguments.
         let vec[@ast.expr] args_1 = vec();
-        for (option.t[@ast.expr] arg in result._1) {
-            args_1 += vec(option.get[@ast.expr](arg));
+        for (Option.t[@ast.expr] arg in result._1) {
+            args_1 += vec(Option.get[@ast.expr](arg));
         }
 
         ret tup(result._0, args_1);
@@ -1901,7 +1901,7 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
         case (ast.expr_path(?pth, ?defopt, _)) {
             auto t = ty.mk_nil(fcx.ccx.tcx);
             assert (defopt != none[ast.def]);
-            auto defn = option.get[ast.def](defopt);
+            auto defn = Option.get[ast.def](defopt);
 
             auto tpt = ty_param_count_and_ty_for_def(fcx, expr.span, defn);
 
@@ -1913,7 +1913,7 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
 
             // The definition doesn't take type parameters. If the programmer
             // supplied some, that's an error.
-            if (_vec.len[@ast.ty](pth.node.types) > 0u) {
+            if (Vec.len[@ast.ty](pth.node.types) > 0u) {
                 fcx.ccx.sess.span_err(expr.span, "this kind of value does " +
                                       "not take type parameters");
                 fail;
@@ -2295,7 +2295,7 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                     // 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)) {
+                    while (i < Vec.len[Option.t[@ast.expr]](args)) {
                         alt (args.(i)) {
                             case (some[@ast.expr](_)) { /* no-op */ }
                             case (none[@ast.expr]) {
@@ -2434,7 +2434,7 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
             let vec[@ast.expr] args_1 = vec();
 
             let ty.t t;
-            if (_vec.len[@ast.expr](args) == 0u) {
+            if (Vec.len[@ast.expr](args) == 0u) {
                 t = next_ty_var(fcx.ccx);
             } else {
                 auto expr_1 = check_expr(fcx, args.(0));
@@ -2445,7 +2445,7 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                 auto expr_1 = check_expr(fcx, e);
                 auto expr_t = expr_ty(fcx.ccx.tcx, expr_1);
                 Demand.simple(fcx, expr.span, t, expr_t);
-                _vec.push[@ast.expr](args_1,expr_1);
+                Vec.push[@ast.expr](args_1,expr_1);
             }
 
             auto ann = triv_ann(ty.mk_vec(fcx.ccx.tcx,
@@ -2461,7 +2461,7 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
             for (ast.elt e in elts) {
                 auto expr_1 = check_expr(fcx, e.expr);
                 auto expr_t = expr_ty(fcx.ccx.tcx, expr_1);
-                _vec.push[ast.elt](elts_1, rec(expr=expr_1 with e));
+                Vec.push[ast.elt](elts_1, rec(expr=expr_1 with e));
                 elts_mt += vec(rec(ty=expr_t, mut=e.mut));
             }
 
@@ -2486,10 +2486,10 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
             for (ast.field f in fields) {
                 auto expr_1 = check_expr(fcx, f.expr);
                 auto expr_t = expr_ty(fcx.ccx.tcx, expr_1);
-                _vec.push[ast.field](fields_1, rec(expr=expr_1 with f));
+                Vec.push[ast.field](fields_1, rec(expr=expr_1 with f));
 
                 auto expr_mt = rec(ty=expr_t, mut=f.mut);
-                _vec.push[field](fields_t, rec(ident=f.ident, mt=expr_mt));
+                Vec.push[field](fields_t, rec(ident=f.ident, mt=expr_mt));
             }
 
             auto ann = ast.ann_none;
@@ -2521,7 +2521,7 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                     for (ty.field f in fields_t) {
                         auto found = false;
                         for (ty.field bf in base_fields) {
-                            if (_str.eq(f.ident, bf.ident)) {
+                            if (Str.eq(f.ident, bf.ident)) {
                                 Demand.simple(fcx, expr.span, f.mt.ty,
                                               bf.mt.ty);
                                 found = true;
@@ -2549,7 +2549,7 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                 case (ty.ty_tup(?args)) {
                     let uint ix = ty.field_num(fcx.ccx.sess,
                                                expr.span, field);
-                    if (ix >= _vec.len[ty.mt](args)) {
+                    if (ix >= Vec.len[ty.mt](args)) {
                         fcx.ccx.sess.span_err(expr.span,
                                               "bad index on tuple");
                     }
@@ -2563,7 +2563,7 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                 case (ty.ty_rec(?fields)) {
                     let uint ix = ty.field_idx(fcx.ccx.sess,
                                                expr.span, field, fields);
-                    if (ix >= _vec.len[typeck.field](fields)) {
+                    if (ix >= Vec.len[typeck.field](fields)) {
                         fcx.ccx.sess.span_err(expr.span,
                                               "bad index on record");
                     }
@@ -2577,7 +2577,7 @@ fn check_expr(&@fn_ctxt fcx, @ast.expr expr) -> @ast.expr {
                 case (ty.ty_obj(?methods)) {
                     let uint ix = ty.method_idx(fcx.ccx.sess,
                                                 expr.span, field, methods);
-                    if (ix >= _vec.len[typeck.method](methods)) {
+                    if (ix >= Vec.len[typeck.method](methods)) {
                         fcx.ccx.sess.span_err(expr.span,
                                               "bad index on obj");
                     }
@@ -2775,7 +2775,7 @@ fn check_stmt(&@fn_ctxt fcx, &@ast.stmt stmt) -> @ast.stmt {
 fn check_block(&@fn_ctxt fcx, &ast.block block) -> ast.block {
     let vec[@ast.stmt] stmts = vec();
     for (@ast.stmt s in block.node.stmts) {
-        _vec.push[@ast.stmt](stmts, check_stmt(fcx, s));
+        Vec.push[@ast.stmt](stmts, check_stmt(fcx, s));
     }
 
     auto expr = none[@ast.expr];
@@ -2900,7 +2900,7 @@ fn hash_unify_cache_entry(&unify_cache_entry uce) -> uint {
     h += h << 5u + ty.hash_ty(uce._1);
 
     auto i = 0u;
-    auto tys_len = _vec.len(uce._2);
+    auto tys_len = Vec.len(uce._2);
     while (i < tys_len) {
         h += h << 5u + ty.hash_ty(uce._2.(i));
         i += 1u;
@@ -2913,8 +2913,8 @@ fn eq_unify_cache_entry(&unify_cache_entry a, &unify_cache_entry b) -> bool {
     if (!ty.eq_ty(a._0, b._0) || !ty.eq_ty(a._1, b._1)) { ret false; }
 
     auto i = 0u;
-    auto tys_len = _vec.len(a._2);
-    if (_vec.len(b._2) != tys_len) { ret false; }
+    auto tys_len = Vec.len(a._2);
+    if (Vec.len(b._2) != tys_len) { ret false; }
 
     while (i < tys_len) {
         if (!ty.eq_ty(a._2.(i), b._2.(i))) { ret false; }
@@ -2957,7 +2957,7 @@ fn check_crate(ty.ctxt tcx, @ast.crate crate)
     auto hasher = hash_unify_cache_entry;
     auto eqer = eq_unify_cache_entry;
     auto unify_cache =
-        map.mk_hashmap[unify_cache_entry,ty.Unify.result](hasher, eqer);
+        Map.mk_hashmap[unify_cache_entry,ty.Unify.result](hasher, eqer);
     auto fpt =
         mk_fn_purity_table(crate); // use a variation on Collect
 
diff --git a/src/comp/middle/typestate_check.rs b/src/comp/middle/typestate_check.rs
index e15c720a3d9..e571fa21ee5 100644
--- a/src/comp/middle/typestate_check.rs
+++ b/src/comp/middle/typestate_check.rs
@@ -155,37 +155,37 @@ import pretty.pprust.print_block;
 import pretty.pprust.print_expr;
 import pretty.pprust.print_decl;
 import pretty.pp.mkstate;
-import std.io.stdout;
-import std.io.str_writer;
-import std.io.string_writer;
-import std._vec.map;
-import std._vec;
-import std._vec.len;
-import std._vec.pop;
-import std._vec.push;
-import std._vec.slice;
-import std._vec.unzip;
-import std._vec.plus_option;
-import std._vec.cat_options;
-import std.option;
-import std.option.t;
-import std.option.some;
-import std.option.none;
-import std.option.from_maybe;
-import std.option.maybe;
-import std.option.is_none;
-import std.option.get;
-import std.map.hashmap;
-import std.list;
-import std.list.list;
-import std.list.cons;
-import std.list.nil;
-import std.list.foldl;
-import std.list.find;
-import std._uint;
-import std.bitv;
-import std.util.fst;
-import std.util.snd;
+import std.IO.stdout;
+import std.IO.str_writer;
+import std.IO.string_writer;
+import std.Vec.map;
+import std.Vec;
+import std.Vec.len;
+import std.Vec.pop;
+import std.Vec.push;
+import std.Vec.slice;
+import std.Vec.unzip;
+import std.Vec.plus_option;
+import std.Vec.cat_options;
+import std.Option;
+import std.Option.t;
+import std.Option.some;
+import std.Option.none;
+import std.Option.from_maybe;
+import std.Option.maybe;
+import std.Option.is_none;
+import std.Option.get;
+import std.Map.hashmap;
+import std.List;
+import std.List.list;
+import std.List.cons;
+import std.List.nil;
+import std.List.foldl;
+import std.List.find;
+import std.UInt;
+import std.BitV;
+import std.Util.fst;
+import std.Util.snd;
 
 import util.typestate_ann;
 import util.typestate_ann.difference;
@@ -195,22 +195,22 @@ import util.typestate_ann.require_and_preserve;
 
 /**** debugging junk  ****/
 
-fn bitv_to_str(fn_info enclosing, bitv.t v) -> str {
+fn bitv_to_str(fn_info enclosing, BitV.t v) -> str {
   auto s = "";
 
   for each (@tup(def_id, tup(uint, ident)) p in enclosing.items()) {
-    if (bitv.get(v, p._1._0)) {
+    if (BitV.get(v, p._1._0)) {
       s += " " + p._1._1 + " ";
     }
   }
   ret s;
 }
 
-fn log_bitv(fn_info enclosing, bitv.t v) {
+fn log_bitv(fn_info enclosing, BitV.t v) {
     log(bitv_to_str(enclosing, v));
 }
 
-fn log_bitv_err(fn_info enclosing, bitv.t v) {
+fn log_bitv_err(fn_info enclosing, BitV.t v) {
     log_err(bitv_to_str(enclosing, v));
 }
 
@@ -235,8 +235,8 @@ fn log_cond_err(vec[uint] v) -> () {
 }
 
 fn log_pp(&pre_and_post pp) -> () {
-  auto p1 = bitv.to_vec(pp.precondition);
-  auto p2 = bitv.to_vec(pp.postcondition);
+  auto p1 = BitV.to_vec(pp.precondition);
+  auto p2 = BitV.to_vec(pp.postcondition);
   log("pre:");
   log_cond(p1);
   log("post:");
@@ -244,8 +244,8 @@ fn log_pp(&pre_and_post pp) -> () {
 }
 
 fn log_pp_err(&pre_and_post pp) -> () {
-  auto p1 = bitv.to_vec(pp.precondition);
-  auto p2 = bitv.to_vec(pp.postcondition);
+  auto p1 = BitV.to_vec(pp.precondition);
+  auto p2 = BitV.to_vec(pp.postcondition);
   log_err("pre:");
   log_cond_err(p1);
   log_err("post:");
@@ -253,8 +253,8 @@ fn log_pp_err(&pre_and_post pp) -> () {
 }
 
 fn log_states(&pre_and_post_state pp) -> () {
-  auto p1 = bitv.to_vec(pp.prestate);
-  auto p2 = bitv.to_vec(pp.poststate);
+  auto p1 = BitV.to_vec(pp.prestate);
+  auto p2 = BitV.to_vec(pp.poststate);
   log("prestate:");
   log_cond(p1);
   log("poststate:");
@@ -262,8 +262,8 @@ fn log_states(&pre_and_post_state pp) -> () {
 }
 
 fn log_states_err(&pre_and_post_state pp) -> () {
-  auto p1 = bitv.to_vec(pp.prestate);
-  auto p2 = bitv.to_vec(pp.poststate);
+  auto p1 = BitV.to_vec(pp.prestate);
+  auto p2 = BitV.to_vec(pp.poststate);
   log_err("prestate:");
   log_cond_err(p1);
   log_err("poststate:");
@@ -288,9 +288,9 @@ fn print_idents(vec[ident] idents) -> () {
    variable in a given function) to bit number 
    (also remembers the ident for error-logging purposes) */
 type var_info     = tup(uint, ident);
-type fn_info      = std.map.hashmap[def_id, var_info];
+type fn_info      = std.Map.hashmap[def_id, var_info];
 /* mapping from function name to fn_info map */
-type fn_info_map = std.map.hashmap[def_id, fn_info];
+type fn_info_map = std.Map.hashmap[def_id, fn_info];
  
 fn bit_num(def_id v, fn_info m) -> uint {
   assert (m.contains_key(v));
@@ -312,12 +312,12 @@ fn num_locals(fn_info m) -> uint {
 fn collect_local(&@vec[tup(ident, def_id)] vars, &span sp, @ast.local loc) 
     -> @decl {
     log("collect_local: pushing " + loc.ident);
-    _vec.push[tup(ident, def_id)](*vars, tup(loc.ident, loc.id));
+    Vec.push[tup(ident, def_id)](*vars, tup(loc.ident, loc.id));
     ret @respan(sp, decl_local(loc));
 }
 
 fn find_locals(_fn f) -> @vec[tup(ident,def_id)] {
-  auto res = @_vec.alloc[tup(ident,def_id)](0u);
+  auto res = @Vec.alloc[tup(ident,def_id)](0u);
 
   auto fld = fold.new_identity_fold[@vec[tup(ident, def_id)]]();
   fld = @rec(fold_decl_local = bind collect_local(_,_,_) with *fld);
@@ -343,7 +343,7 @@ fn mk_fn_info(_fn f) -> fn_info {
      just collect locally declared vars */
 
   let @vec[tup(ident,def_id)] locals = find_locals(f);
-  log(uistr(_vec.len[tup(ident, def_id)](*locals)) + " locals");
+  log(uistr(Vec.len[tup(ident, def_id)](*locals)) + " locals");
   for (tup(ident,def_id) p in *locals) {
     next = add_var(p._1, p._0, next, res);
   }
@@ -364,7 +364,7 @@ fn mk_fn_info_item_fn(&fn_info_map fi, &span sp, ident i, &ast._fn f,
    function IDs to fn_info maps */
 fn mk_fn_info_item_obj(&fn_info_map fi, &span sp, ident i, &ast._obj o,
      vec[ast.ty_param] ty_params, ast.obj_def_ids odid, ann a) -> @item {
-    auto all_methods = _vec.clone[@method](o.methods);
+    auto all_methods = Vec.clone[@method](o.methods);
     plus_option[@method](all_methods, o.dtor);
     for (@method m in all_methods) {
         fi.insert(m.node.id, mk_fn_info(m.node.meth));
@@ -403,7 +403,7 @@ fn ann_to_ts_ann(ann a, uint nv) -> ts_ann {
   }
 }
 
-fn ann_to_ts_ann_fail(ann a) -> option.t[@ts_ann] {
+fn ann_to_ts_ann_fail(ann a) -> Option.t[@ts_ann] {
   alt (a) {
       case (ann_none) { 
           log("ann_to_ts_ann_fail: didn't expect ann_none here");
@@ -432,7 +432,7 @@ fn ann_to_poststate(ann a) -> poststate {
     ret (ann_to_ts_ann_fail_more(a)).states.poststate;
 }
 
-fn stmt_to_ann(&stmt s) -> option.t[@ts_ann] {
+fn stmt_to_ann(&stmt s) -> Option.t[@ts_ann] {
   alt (s.node) {
     case (stmt_decl(_,?a)) {
         ret ann_to_ts_ann_fail(a);
@@ -652,7 +652,7 @@ fn seq_preconds(fn_info enclosing, vec[pre_and_post] pps) -> precond {
 /* works on either postconds or preconds
  should probably rethink the whole type synonym situation */
 fn union_postconds_go(&postcond first, &vec[postcond] rest) -> postcond {
-  auto sz = _vec.len[postcond](rest);
+  auto sz = Vec.len[postcond](rest);
 
   if (sz > 0u) {
     auto other = rest.(0);
@@ -665,7 +665,7 @@ fn union_postconds_go(&postcond first, &vec[postcond] rest) -> postcond {
 
 fn union_postconds(uint nv, &vec[postcond] pcs) -> postcond {
   if (len[postcond](pcs) > 0u) {
-      ret union_postconds_go(bitv.clone(pcs.(0)), pcs);
+      ret union_postconds_go(BitV.clone(pcs.(0)), pcs);
   }
   else {
       ret empty_prestate(nv);
@@ -674,7 +674,7 @@ fn union_postconds(uint nv, &vec[postcond] pcs) -> postcond {
 
 /* Gee, maybe we could use foldl or something */
 fn intersect_postconds_go(&postcond first, &vec[postcond] rest) -> postcond {
-  auto sz = _vec.len[postcond](rest);
+  auto sz = Vec.len[postcond](rest);
 
   if (sz > 0u) {
     auto other = rest.(0);
@@ -689,7 +689,7 @@ fn intersect_postconds_go(&postcond first, &vec[postcond] rest) -> postcond {
 fn intersect_postconds(&vec[postcond] pcs) -> postcond {
   assert (len[postcond](pcs) > 0u);
 
-  ret intersect_postconds_go(bitv.clone(pcs.(0)), pcs);
+  ret intersect_postconds_go(BitV.clone(pcs.(0)), pcs);
 }
 
 /******* AST-traversing code ********/
@@ -720,8 +720,8 @@ fn find_pre_post_obj(&fn_info_map fm, _obj o) -> () {
         find_pre_post_fn(fm, fm.get(m.node.id), m.node.meth);
     }
     auto f = bind do_a_method(fm,_);
-    _vec.map[@method, ()](f, o.methods);
-    option.map[@method, ()](f, o.dtor);
+    Vec.map[@method, ()](f, o.methods);
+    Option.map[@method, ()](f, o.dtor);
 }
 
 fn find_pre_post_state_obj(fn_info_map fm, _obj o) -> bool {
@@ -730,8 +730,8 @@ fn find_pre_post_state_obj(fn_info_map fm, _obj o) -> bool {
         ret find_pre_post_state_fn(fm, fm.get(m.node.id), m.node.meth);
     }
     auto f = bind do_a_method(fm,_);
-    auto flags = _vec.map[@method, bool](f, o.methods);
-    auto changed = _vec.or(flags);
+    auto flags = Vec.map[@method, bool](f, o.methods);
+    auto changed = Vec.or(flags);
     changed = changed || maybe[@method, bool](false, f, o.dtor);
     ret changed;
 }
@@ -777,19 +777,19 @@ fn find_pre_post_exprs(&fn_info_map fm, &fn_info enclosing,
     }
     auto f = bind do_one(fm, enclosing, _);
 
-    _vec.map[@expr, ()](f, args);
+    Vec.map[@expr, ()](f, args);
 
     fn get_pp(&@expr e) -> pre_and_post {
         ret expr_pp(e);
     }
     auto g = get_pp;
-    auto pps = _vec.map[@expr, pre_and_post](g, args);
+    auto pps = Vec.map[@expr, pre_and_post](g, args);
     auto h = get_post;
 
     set_pre_and_post(a,
        rec(precondition=seq_preconds(enclosing, pps),
            postcondition=union_postconds
-           (nv, (_vec.map[pre_and_post, postcond](h, pps)))));
+           (nv, (Vec.map[pre_and_post, postcond](h, pps)))));
 }
 
 fn find_pre_post_loop(&fn_info_map fm, &fn_info enclosing, &@decl d,
@@ -822,13 +822,13 @@ fn find_pre_post_expr(&fn_info_map fm, &fn_info enclosing, @expr e) -> () {
     
     alt (e.node) {
         case (expr_call(?operator, ?operands, ?a)) {
-            auto args = _vec.clone[@expr](operands);
-            _vec.push[@expr](args, operator);
+            auto args = Vec.clone[@expr](operands);
+            Vec.push[@expr](args, operator);
             find_pre_post_exprs(fm, enclosing, args, a);
         }
         case (expr_spawn(_, _, ?operator, ?operands, ?a)) {
-            auto args = _vec.clone[@expr](operands);
-            _vec.push[@expr](args, operator);
+            auto args = Vec.clone[@expr](operands);
+            Vec.push[@expr](args, operator);
             find_pre_post_exprs(fm, enclosing, args, a);
         }
         case (expr_vec(?args, _, ?a)) {
@@ -888,7 +888,7 @@ fn find_pre_post_expr(&fn_info_map fm, &fn_info enclosing, @expr e) -> () {
         }
         case (expr_rec(?fields,?maybe_base,?a)) {
             auto es = field_exprs(fields);
-            _vec.plus_option[@expr](es, maybe_base);
+            Vec.plus_option[@expr](es, maybe_base);
             find_pre_post_exprs(fm, enclosing, es, a);
         }
         case (expr_assign(?lhs, ?rhs, ?a)) {
@@ -1051,7 +1051,7 @@ fn find_pre_post_expr(&fn_info_map fm, &fn_info enclosing, @expr e) -> () {
                 ret block_pp(an_alt.block);
             }
             auto f = bind do_an_alt(fm, enclosing, _);
-            auto alt_pps = _vec.map[arm, pre_and_post](f, alts);
+            auto alt_pps = Vec.map[arm, pre_and_post](f, alts);
             fn combine_pp(pre_and_post antec, 
                           fn_info enclosing, &pre_and_post pp,
                           &pre_and_post next) -> pre_and_post {
@@ -1065,7 +1065,7 @@ fn find_pre_post_expr(&fn_info_map fm, &fn_info enclosing, @expr e) -> () {
                              postcondition=false_postcond(num_local_vars));
             auto g = bind combine_pp(antec_pp, enclosing, _, _);
 
-            auto alts_overall_pp = _vec.foldl[pre_and_post, pre_and_post]
+            auto alts_overall_pp = Vec.foldl[pre_and_post, pre_and_post]
                                     (g, e_pp, alt_pps);
 
             set_pre_and_post(a, alts_overall_pp);
@@ -1091,8 +1091,8 @@ fn find_pre_post_expr(&fn_info_map fm, &fn_info enclosing, @expr e) -> () {
             set_pre_and_post(a, expr_pp(p));
         }
         case(expr_bind(?operator, ?maybe_args, ?a)) {
-            auto args = _vec.cat_options[@expr](maybe_args);
-            _vec.push[@expr](args, operator); /* ??? order of eval? */
+            auto args = Vec.cat_options[@expr](maybe_args);
+            Vec.push[@expr](args, operator); /* ??? order of eval? */
             find_pre_post_exprs(fm, enclosing, args, a);
         }
         case (expr_break(?a)) {
@@ -1210,12 +1210,12 @@ fn find_pre_post_block(&fn_info_map fm, &fn_info enclosing, block b)
     }
     auto do_one = bind do_one_(fm, enclosing, _);
     
-    _vec.map[@stmt, ()](do_one, b.node.stmts);
+    Vec.map[@stmt, ()](do_one, b.node.stmts);
     fn do_inner_(fn_info_map fm, fn_info i, &@expr e) -> () {
         find_pre_post_expr(fm, i, e);
     }
     auto do_inner = bind do_inner_(fm, enclosing, _);
-    option.map[@expr, ()](do_inner, b.node.expr);
+    Option.map[@expr, ()](do_inner, b.node.expr);
 
     let vec[pre_and_post] pps = vec();
 
@@ -1223,20 +1223,20 @@ fn find_pre_post_block(&fn_info_map fm, &fn_info enclosing, block b)
         ret stmt_pp(*s);
     }
     auto f = get_pp_stmt;
-    pps += _vec.map[@stmt, pre_and_post](f, b.node.stmts);
+    pps += Vec.map[@stmt, pre_and_post](f, b.node.stmts);
     fn get_pp_expr(&@expr e) -> pre_and_post {
         ret expr_pp(e);
     }
     auto g = get_pp_expr;
     plus_option[pre_and_post](pps,
-       option.map[@expr, pre_and_post](g, b.node.expr));
+       Option.map[@expr, pre_and_post](g, b.node.expr));
 
     auto block_precond  = seq_preconds(enclosing, pps);
     auto h = get_post;
-    auto postconds =  _vec.map[pre_and_post, postcond](h, pps);
+    auto postconds =  Vec.map[pre_and_post, postcond](h, pps);
     /* A block may be empty, so this next line ensures that the postconds
        vector is non-empty. */
-    _vec.push[postcond](postconds, block_precond);
+    Vec.push[postcond](postconds, block_precond);
     auto block_postcond = empty_poststate(nv);
     /* conservative approximation */
     if (! has_nonlocal_exits(b)) {
@@ -1696,7 +1696,7 @@ fn find_pre_post_state_expr(&fn_info_map fm, &fn_info enclosing,
         changed = find_pre_post_state_expr(fm, enclosing, pres, e) || changed;
         auto e_post = expr_poststate(e);
         auto a_post;
-        if (_vec.len[arm](alts) > 0u) {
+        if (Vec.len[arm](alts) > 0u) {
             a_post = false_postcond(num_local_vars);
             for (arm an_alt in alts) {
                 changed = find_pre_post_state_block(fm, enclosing, e_post,
@@ -1775,9 +1775,9 @@ fn find_pre_post_state_stmt(&fn_info_map fm, &fn_info enclosing,
               log("*At beginning: stmt = ");
               log_stmt(*s);
               log("*prestate = ");
-              log(bitv.to_str(stmt_ann.states.prestate));
+              log(BitV.to_str(stmt_ann.states.prestate));
               log("*poststate =");
-              log(bitv.to_str(stmt_ann.states.poststate));
+              log(BitV.to_str(stmt_ann.states.poststate));
               log("*changed =");
               log(changed);
   
@@ -1798,7 +1798,7 @@ fn find_pre_post_state_stmt(&fn_info_map fm, &fn_info enclosing,
               log("Summary: stmt = ");
               log_stmt(*s);
               log("prestate = ");
-              log(bitv.to_str(stmt_ann.states.prestate));
+              log(BitV.to_str(stmt_ann.states.prestate));
               log_bitv(enclosing, stmt_ann.states.prestate);
               log("poststate =");
               log_bitv(enclosing, stmt_ann.states.poststate);
@@ -1835,10 +1835,10 @@ fn find_pre_post_state_stmt(&fn_info_map fm, &fn_info enclosing,
                     log("Summary: stmt = ");
               log_stmt(*s);
               log("prestate = ");
-              log(bitv.to_str(stmt_ann.states.prestate));
+              log(BitV.to_str(stmt_ann.states.prestate));
               log_bitv(enclosing, stmt_ann.states.prestate);
               log("poststate =");
-              log(bitv.to_str(stmt_ann.states.poststate));
+              log(BitV.to_str(stmt_ann.states.poststate));
               log_bitv(enclosing, stmt_ann.states.poststate);
               log("changed =");
               log(changed);
@@ -1986,12 +1986,12 @@ fn check_states_against_conditions(fn_info enclosing, &ast._fn f) -> () {
   }
   auto do_one = bind do_one_(enclosing, _);
  
-  _vec.map[@stmt, ()](do_one, f.body.node.stmts);
+  Vec.map[@stmt, ()](do_one, f.body.node.stmts);
   fn do_inner_(fn_info i, &@expr e) -> () {
     check_states_expr(i, e);
   }
   auto do_inner = bind do_inner_(enclosing, _);
-  option.map[@expr, ()](do_inner, f.body.node.expr);
+  Option.map[@expr, ()](do_inner, f.body.node.expr);
   
 }
 
@@ -2027,13 +2027,13 @@ fn check_method_states(&fn_info_map f_info_map, @method m) -> () {
 }
 
 fn check_obj_state(&fn_info_map f_info_map, vec[obj_field] fields,
-                  vec[@method] methods, option.t[@method] dtor) -> ast._obj {
+                  vec[@method] methods, Option.t[@method] dtor) -> ast._obj {
     fn one(fn_info_map fm, &@method m) -> () {
         ret check_method_states(fm, m);
     }
     auto f = bind one(f_info_map,_);
-    _vec.map[@method, ()](f, methods);
-    option.map[@method, ()](f, dtor);
+    Vec.map[@method, ()](f, methods);
+    Option.map[@method, ()](f, dtor);
     ret rec(fields=fields, methods=methods, dtor=dtor);
 }
 
@@ -2122,7 +2122,7 @@ fn annotate_exprs(&fn_info_map fm, &vec[@expr] es) -> vec[@expr] {
         ret annotate_expr(fm, e);
     }
     auto f = bind one(fm,_);
-    ret _vec.map[@expr, @expr](f, es);
+    ret Vec.map[@expr, @expr](f, es);
 }
 fn annotate_elts(&fn_info_map fm, &vec[elt] es) -> vec[elt] {
     fn one(fn_info_map fm, &elt e) -> elt {
@@ -2130,7 +2130,7 @@ fn annotate_elts(&fn_info_map fm, &vec[elt] es) -> vec[elt] {
                 expr=annotate_expr(fm, e.expr));
     }
     auto f = bind one(fm,_);
-    ret _vec.map[elt, elt](f, es);
+    ret Vec.map[elt, elt](f, es);
 }
 fn annotate_fields(&fn_info_map fm, &vec[field] fs) -> vec[field] {
     fn one(fn_info_map fm, &field f) -> field {
@@ -2139,23 +2139,23 @@ fn annotate_fields(&fn_info_map fm, &vec[field] fs) -> vec[field] {
                  expr=annotate_expr(fm, f.expr));
     }
     auto f = bind one(fm,_);
-    ret _vec.map[field, field](f, fs);
+    ret Vec.map[field, field](f, fs);
 }
-fn annotate_option_exp(&fn_info_map fm, &option.t[@expr] o)
-  -> option.t[@expr] {
+fn annotate_option_exp(&fn_info_map fm, &Option.t[@expr] o)
+  -> Option.t[@expr] {
     fn one(fn_info_map fm, &@expr e) -> @expr {
         ret annotate_expr(fm, e);
     }
     auto f = bind one(fm,_);
-    ret option.map[@expr, @expr](f, o);
+    ret Option.map[@expr, @expr](f, o);
 }
-fn annotate_option_exprs(&fn_info_map fm, &vec[option.t[@expr]] es)
-  -> vec[option.t[@expr]] {
-    fn one(fn_info_map fm, &option.t[@expr] o) -> option.t[@expr] {
+fn annotate_option_exprs(&fn_info_map fm, &vec[Option.t[@expr]] es)
+  -> vec[Option.t[@expr]] {
+    fn one(fn_info_map fm, &Option.t[@expr] o) -> Option.t[@expr] {
         ret annotate_option_exp(fm, o);
     }
     auto f = bind one(fm,_);
-    ret _vec.map[option.t[@expr], option.t[@expr]](f, es);
+    ret Vec.map[Option.t[@expr], Option.t[@expr]](f, es);
 }
 fn annotate_decl(&fn_info_map fm, &@decl d) -> @decl {
     auto d1 = d.node;
@@ -2163,7 +2163,7 @@ fn annotate_decl(&fn_info_map fm, &@decl d) -> @decl {
         case (decl_local(?l)) {
             alt(l.init) {
                 case (some[initializer](?init)) {
-                    let option.t[initializer] an_i =
+                    let Option.t[initializer] an_i =
                         some[initializer]
                           (rec(expr=annotate_expr(fm, init.expr)
                                  with init));
@@ -2186,7 +2186,7 @@ fn annotate_alts(&fn_info_map fm, &vec[arm] alts) -> vec[arm] {
                  index=a.index);
     }
     auto f = bind one(fm,_);
-    ret _vec.map[arm, arm](f, alts);
+    ret Vec.map[arm, arm](f, alts);
 
 }
 fn annotate_expr(&fn_info_map fm, &@expr e) -> @expr {
@@ -2338,7 +2338,7 @@ fn annotate_block(&fn_info_map fm, &block b) -> block {
 
     for (@stmt s in b.node.stmts) {
         auto new_s = annotate_stmt(fm, s);
-        _vec.push[@stmt](new_stmts, new_s);
+        Vec.push[@stmt](new_stmts, new_s);
         ast.index_stmt(new_index, new_s);
     }
     fn ann_e(fn_info_map fm, &@expr e) -> @expr {
@@ -2346,7 +2346,7 @@ fn annotate_block(&fn_info_map fm, &block b) -> block {
     }
     auto f = bind ann_e(fm,_);
 
-    auto new_e = option.map[@expr, @expr](f, b.node.expr);
+    auto new_e = Option.map[@expr, @expr](f, b.node.expr);
 
     ret respan(b.span,
           rec(stmts=new_stmts, expr=new_e, index=new_index with b.node));
@@ -2362,7 +2362,7 @@ fn annotate_mod(&fn_info_map fm, &ast._mod m) -> ast._mod {
 
     for (@item i in m.items) {
         auto new_i = annotate_item(fm, i);
-        _vec.push[@item](new_items, new_i);
+        Vec.push[@item](new_items, new_i);
         ast.index_item(new_index, new_i);
     }
     ret rec(items=new_items, index=new_index with m);
@@ -2383,8 +2383,8 @@ fn annotate_obj(&fn_info_map fm, &ast._obj o) -> ast._obj {
         ret annotate_method(fm, m);
     }
     auto f = bind one(fm,_);
-    auto new_methods = _vec.map[@method, @method](f, o.methods);
-    auto new_dtor    = option.map[@method, @method](f, o.dtor);
+    auto new_methods = Vec.map[@method, @method](f, o.methods);
+    auto new_dtor    = Option.map[@method, @method](f, o.dtor);
     ret rec(methods=new_methods, dtor=new_dtor with o);
 }
 
@@ -2476,7 +2476,7 @@ fn annotate_module(&fn_info_map fm, &ast._mod module) -> ast._mod {
 
     for (@item i in module.items) {
         auto new_item = annotate_item(fm, i);
-        _vec.push[@item](new_items, new_item);
+        Vec.push[@item](new_items, new_item);
         ast.index_item(new_index, new_item);
     }
 
diff --git a/src/comp/middle/walk.rs b/src/comp/middle/walk.rs
index 8a5d40dc563..2df69261f38 100644
--- a/src/comp/middle/walk.rs
+++ b/src/comp/middle/walk.rs
@@ -1,8 +1,8 @@
 import front.ast;
 
-import std.option;
-import std.option.some;
-import std.option.none;
+import std.Option;
+import std.Option.some;
+import std.Option.none;
 
 type ast_visitor =
     rec(fn () -> bool                 keep_going,
@@ -257,7 +257,7 @@ fn walk_decl(&ast_visitor v, @ast.decl d) {
     v.visit_decl_post(d);
 }
 
-fn walk_expr_opt(&ast_visitor v, option.t[@ast.expr] eo) {
+fn walk_expr_opt(&ast_visitor v, Option.t[@ast.expr] eo) {
     alt (eo) {
         case (none[@ast.expr]) {}
         case (some[@ast.expr](?e)) {
@@ -297,7 +297,7 @@ fn walk_expr(&ast_visitor v, @ast.expr e) {
         case (ast.expr_self_method(_, _)) { }
         case (ast.expr_bind(?callee, ?args, _)) {
             walk_expr(v, callee);
-            for (option.t[@ast.expr] eo in args) {
+            for (Option.t[@ast.expr] eo in args) {
                 walk_expr_opt(v, eo);
             }
         }
diff --git a/src/comp/pretty/pp.rs b/src/comp/pretty/pp.rs
index 85651c78c3c..f966704253c 100644
--- a/src/comp/pretty/pp.rs
+++ b/src/comp/pretty/pp.rs
@@ -1,6 +1,6 @@
-import std.io;
-import std._vec;
-import std._str;
+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;}
@@ -19,7 +19,7 @@ type context = rec(contexttype tp, uint indent);
 
 type ps = @rec(mutable vec[context] context,
                uint width,
-               io.writer out,
+               IO.writer out,
                mutable uint col,
                mutable uint spaces,
                mutable vec[token] buffered,
@@ -30,7 +30,7 @@ type ps = @rec(mutable vec[context] context,
                mutable bool start_of_box,
                mutable bool potential_brk);
 
-fn mkstate(io.writer out, uint width) -> ps {
+fn mkstate(IO.writer out, uint width) -> ps {
   let vec[context] stack = vec(rec(tp=cx_v, indent=0u));
   let vec[token] buff = vec();
   let vec[boxtype] sd = vec();
@@ -57,12 +57,12 @@ fn write_spaces(ps p, uint i) {
 
 fn push_context(ps p, contexttype tp, uint indent) {
   before_print(p, false);
-  _vec.push[context](p.context, rec(tp=tp, indent=indent));
+  Vec.push[context](p.context, rec(tp=tp, indent=indent));
   p.start_of_box = true;
 }
 
 fn pop_context(ps p) {
-  _vec.pop[context](p.context);
+  Vec.pop[context](p.context);
 }
 
 fn add_token(ps p, token tok) {
@@ -89,7 +89,7 @@ fn buffer_token(ps p, token tok) {
   } else {
     alt (tok) {
       case (open(?tp,_)) {
-        _vec.push[boxtype](p.scandepth, tp);
+        Vec.push[boxtype](p.scandepth, tp);
         if (p.scanning == scan_h) {
           if (tp == box_h) {
             check_potential_brk(p);
@@ -97,14 +97,14 @@ fn buffer_token(ps p, token tok) {
         }
       }
       case (close) {
-        _vec.pop[boxtype](p.scandepth);
-        if (_vec.len[boxtype](p.scandepth) == 0u) {
+        Vec.pop[boxtype](p.scandepth);
+        if (Vec.len[boxtype](p.scandepth) == 0u) {
           finish_scan(p, true);
         }
       }
       case (brk(_)) {
         if (p.scanning == scan_h) {
-          if (p.scandepth.(_vec.len[boxtype](p.scandepth)-1u) == box_v) {
+          if (p.scandepth.(Vec.len[boxtype](p.scandepth)-1u) == box_v) {
             finish_scan(p, true);
           }
         }
@@ -123,7 +123,7 @@ fn check_potential_brk(ps p) {
 
 fn finish_scan(ps p, bool fits) {
   auto buf = p.buffered;
-  auto front = _vec.shift[token](buf);
+  auto front = Vec.shift[token](buf);
   auto chosen_tp = cx_h;
   if (!fits) {chosen_tp = cx_v;}
   alt (front) {
@@ -154,10 +154,10 @@ fn start_scan(ps p, token tok, scantype tp) {
 }
 
 fn cur_context(ps p) -> context {
-  ret p.context.(_vec.len[context](p.context)-1u);
+  ret p.context.(Vec.len[context](p.context)-1u);
 }
 fn base_indent(ps p) -> uint {
-  auto i = _vec.len[context](p.context);
+  auto i = Vec.len[context](p.context);
   while (i > 0u) {
     i -= 1u;
     auto cx = p.context.(i);
@@ -190,7 +190,7 @@ fn do_token(ps p, token tok) {
       line_break(p);
     }
     case (word(?w)) {
-      auto len = _str.char_len(w);
+      auto len = Str.char_len(w);
       if (len + p.col + p.spaces > p.width && !start_of_box &&
           !p.start_of_line) {
         line_break(p);
@@ -202,7 +202,7 @@ fn do_token(ps p, token tok) {
     case (cword(?w)) {
       before_print(p, true);
       p.out.write_str(w);
-      p.col += _str.char_len(w);
+      p.col += Str.char_len(w);
     }
     case (open(?tp, ?indent)) {
       if (tp == box_v) {
@@ -247,8 +247,8 @@ fn token_size(token tok) -> uint {
   alt (tok) {
     case (brk(?sz)) {ret sz;}
     case (hardbrk) {ret 0xFFFFFFu;}
-    case (word(?w)) {ret _str.char_len(w);}
-    case (cword(?w)) {ret _str.char_len(w);}
+    case (word(?w)) {ret Str.char_len(w);}
+    case (cword(?w)) {ret Str.char_len(w);}
     case (open(_, _)) {ret 0u;}
     case (close) {ret 0u;}
   }
diff --git a/src/comp/pretty/pprust.rs b/src/comp/pretty/pprust.rs
index 3111b0127a0..17547bb65ac 100644
--- a/src/comp/pretty/pprust.rs
+++ b/src/comp/pretty/pprust.rs
@@ -1,7 +1,7 @@
-import std._vec;
-import std._str;
-import std.io;
-import std.option;
+import std.Vec;
+import std.Str;
+import std.IO;
+import std.Option;
 import front.ast;
 import front.lexer;
 import util.common;
@@ -12,39 +12,39 @@ const int as_prec = 5;
 const uint default_columns = 78u;
 
 type ps = @rec(pp.ps s,
-               option.t[vec[lexer.cmnt]] comments,
+               Option.t[vec[lexer.cmnt]] comments,
                mutable uint cur_cmnt);
 
-fn print_file(ast._mod _mod, str filename, io.writer out) {
+fn print_file(ast._mod _mod, str filename, IO.writer out) {
     auto cmnts = lexer.gather_comments(filename);
     auto s = @rec(s=pp.mkstate(out, default_columns),
-                  comments=option.some[vec[lexer.cmnt]](cmnts),
+                  comments=Option.some[vec[lexer.cmnt]](cmnts),
                   mutable cur_cmnt=0u);
     print_mod(s, _mod);
 }
 
 fn ty_to_str(&@ast.ty ty) -> str {
-    auto writer = io.string_writer();
+    auto writer = IO.string_writer();
     auto s = @rec(s=pp.mkstate(writer.get_writer(), 0u),
-                  comments=option.none[vec[lexer.cmnt]],
+                  comments=Option.none[vec[lexer.cmnt]],
                   mutable cur_cmnt=0u);
     print_type(s, ty);
     ret writer.get_str();
 }
 
 fn block_to_str(&ast.block blk) -> str {
-    auto writer = io.string_writer();
+    auto writer = IO.string_writer();
     auto s = @rec(s=pp.mkstate(writer.get_writer(), 78u),
-                  comments=option.none[vec[lexer.cmnt]],
+                  comments=Option.none[vec[lexer.cmnt]],
                   mutable cur_cmnt=0u);
     print_block(s, blk);
     ret writer.get_str();
 }
 
 fn pat_to_str(&@ast.pat p) -> str {
-    auto writer = io.string_writer();
+    auto writer = IO.string_writer();
     auto s = @rec(s=pp.mkstate(writer.get_writer(), 78u),
-                  comments=option.none[vec[lexer.cmnt]],
+                  comments=Option.none[vec[lexer.cmnt]],
                   mutable cur_cmnt=0u);
     print_pat(s, p);
     ret writer.get_str();
@@ -92,7 +92,7 @@ fn commasep[IN](ps s, vec[IN] elts, fn(ps, &IN) op) {
 }
 fn commasep_cmnt[IN](ps s, vec[IN] elts, fn(ps, &IN) op,
                             fn(&IN) -> common.span get_span) {
-    auto len = _vec.len[IN](elts);
+    auto len = Vec.len[IN](elts);
     auto i = 0u;
     for (IN elt in elts) {
         op(s, elt);
@@ -160,7 +160,7 @@ fn print_type(ps s, &@ast.ty ty) {
             fn get_span(&ast.ty_field f) -> common.span {
               // Try to reconstruct the span for this field
               auto sp = f.mt.ty.span;
-              auto hi = sp.hi + _str.char_len(f.ident) + 1u;
+              auto hi = sp.hi + Str.char_len(f.ident) + 1u;
               ret rec(hi=hi with sp);
             }
             auto f = print_field;
@@ -173,7 +173,7 @@ fn print_type(ps s, &@ast.ty ty) {
             bopen(s);
             for (ast.ty_method m in methods) {
                 hbox(s);
-                print_ty_fn(s, m.proto, option.some[str](m.ident),
+                print_ty_fn(s, m.proto, Option.some[str](m.ident),
                             m.inputs, m.output);
                 wrd(s.s, ";");
                 end(s.s);
@@ -182,7 +182,7 @@ fn print_type(ps s, &@ast.ty ty) {
             bclose_c(s, ty.span);
         }
         case (ast.ty_fn(?proto,?inputs,?output)) {
-            print_ty_fn(s, proto, option.none[str], inputs, output);
+            print_ty_fn(s, proto, Option.none[str], inputs, output);
         }
         case (ast.ty_path(?path,_)) {
             print_path(s, path);
@@ -240,8 +240,8 @@ fn print_item(ps s, @ast.item item) {
                                              ?typarams,_,_)) {
                         print_fn(s, decl, id, typarams);
                         alt (lname) {
-                            case (option.none[str]) {}
-                            case (option.some[str](?ss)) {
+                            case (Option.none[str]) {}
+                            case (Option.some[str](?ss)) {
                                 print_string(s, ss);
                             }
                         }
@@ -270,7 +270,7 @@ fn print_item(ps s, @ast.item item) {
             for (ast.variant v in variants) {
                 maybe_print_comment(s, v.span.lo);
                 wrd(s.s, v.node.name);
-                if (_vec.len[ast.variant_arg](v.node.args) > 0u) {
+                if (Vec.len[ast.variant_arg](v.node.args) > 0u) {
                     popen(s);
                     fn print_variant_arg(ps s, &ast.variant_arg arg) {
                         print_type(s, arg.ty);
@@ -314,7 +314,7 @@ fn print_item(ps s, @ast.item item) {
                 line(s.s);
             }
             alt (_obj.dtor) {
-                case (option.some[@ast.method](?dtor)) {
+                case (Option.some[@ast.method](?dtor)) {
                     hbox(s);
                     wrd1(s, "close");
                     print_block(s, dtor.node.meth.body);
@@ -344,7 +344,7 @@ fn print_block(ps s, ast.block blk) {
         if (!maybe_print_line_comment(s, st.span)) {line(s.s);}
     }
     alt (blk.node.expr) {
-        case (option.some[@ast.expr](?expr)) {
+        case (Option.some[@ast.expr](?expr)) {
             print_expr(s, expr);
             if (!maybe_print_line_comment(s, expr.span)) {line(s.s);}
         }
@@ -358,7 +358,7 @@ 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.s, "'" + escape_str(_str.from_bytes(vec(ch as u8)), '\'')
+            wrd(s.s, "'" + escape_str(Str.from_bytes(vec(ch as u8)), '\'')
                 + "'");
         }
         case (ast.lit_int(?val)) {
@@ -432,8 +432,8 @@ fn print_expr(ps s, &@ast.expr expr) {
             auto gs = get_span;
             commasep_cmnt[ast.field](s, fields, f, gs);
             alt (wth) {
-                case (option.some[@ast.expr](?expr)) {
-                    if (_vec.len[ast.field](fields) > 0u) {space(s.s);}
+                case (Option.some[@ast.expr](?expr)) {
+                    if (Vec.len[ast.field](fields) > 0u) {space(s.s);}
                     hbox(s);
                     wrd1(s, "with");
                     print_expr(s, expr);
@@ -454,9 +454,9 @@ fn print_expr(ps s, &@ast.expr expr) {
             print_ident(s, ident);
         }
         case (ast.expr_bind(?func,?args,_)) {
-            fn print_opt(ps s, &option.t[@ast.expr] expr) {
+            fn print_opt(ps s, &Option.t[@ast.expr] expr) {
                 alt (expr) {
-                    case (option.some[@ast.expr](?expr)) {
+                    case (Option.some[@ast.expr](?expr)) {
                         print_expr(s, expr);
                     }
                     case (_) {wrd(s.s, "_");}
@@ -466,7 +466,7 @@ fn print_expr(ps s, &@ast.expr expr) {
             print_expr(s, func);
             popen(s);
             auto f = print_opt;
-            commasep[option.t[@ast.expr]](s, args, f);
+            commasep[Option.t[@ast.expr]](s, args, f);
             pclose(s);
         }
     case (ast.expr_spawn(_,_,?e,?es,_)) {
@@ -504,7 +504,7 @@ fn print_expr(ps s, &@ast.expr expr) {
             space(s.s);
             print_block(s, block);
             alt (elseopt) {
-                case (option.some[@ast.expr](?_else)) {
+                case (Option.some[@ast.expr](?_else)) {
                     space(s.s);
                     wrd1(s, "else");
                     print_expr(s, _else);
@@ -627,7 +627,7 @@ fn print_expr(ps s, &@ast.expr expr) {
         case (ast.expr_ret(?result,_)) {
             wrd(s.s, "ret");
             alt (result) {
-                case (option.some[@ast.expr](?expr)) {
+                case (Option.some[@ast.expr](?expr)) {
                     space(s.s);
                     print_expr(s, expr);
                 }
@@ -637,7 +637,7 @@ fn print_expr(ps s, &@ast.expr expr) {
         case (ast.expr_put(?result,_)) {
             wrd(s.s, "put");
             alt (result) {
-                case (option.some[@ast.expr](?expr)) {
+                case (Option.some[@ast.expr](?expr)) {
                     space(s.s);
                     print_expr(s, expr);
                 }
@@ -670,7 +670,7 @@ fn print_expr(ps s, &@ast.expr expr) {
         case (ast.expr_ext(?path, ?args, ?body, _, _)) {
             wrd(s.s, "#");
             print_path(s, path);
-            if (_vec.len[@ast.expr](args) > 0u) {
+            if (Vec.len[@ast.expr](args) > 0u) {
                 popen(s);
                 commasep_exprs(s, args);
                 pclose(s);
@@ -698,7 +698,7 @@ fn print_decl(ps s, @ast.decl decl) {
     alt (decl.node) {
         case (ast.decl_local(?loc)) {
             alt (loc.ty) {
-                case (option.some[@ast.ty](?ty)) {
+                case (Option.some[@ast.ty](?ty)) {
                     wrd1(s, "let");
                     print_type(s, ty);
                     space(s.s);
@@ -709,7 +709,7 @@ fn print_decl(ps s, @ast.decl decl) {
             }
             wrd(s.s, loc.ident);
             alt (loc.init) {
-                case (option.some[ast.initializer](?init)) {
+                case (Option.some[ast.initializer](?init)) {
                     space(s.s);
                     alt (init.op) {
                         case (ast.init_assign) {
@@ -738,7 +738,7 @@ fn print_ident(ps s, ast.ident ident) {
 fn print_for_decl(ps s, @ast.decl decl) {
     alt (decl.node) {
         case (ast.decl_local(?loc)) {
-            print_type(s, option.get[@ast.ty](loc.ty));
+            print_type(s, Option.get[@ast.ty](loc.ty));
             space(s.s);
             wrd(s.s, loc.ident);
         }
@@ -753,7 +753,7 @@ fn print_path(ps s, ast.path path) {
         else {wrd(s.s, ".");}
         wrd(s.s, id);
     }
-    if (_vec.len[@ast.ty](path.node.types) > 0u) {
+    if (Vec.len[@ast.ty](path.node.types) > 0u) {
         wrd(s.s, "[");
         auto f = print_type;
         commasep[@ast.ty](s, path.node.types, f);
@@ -769,7 +769,7 @@ fn print_pat(ps s, &@ast.pat pat) {
         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) {
+            if (Vec.len[@ast.pat](args) > 0u) {
                 popen_h(s);
                 auto f = print_pat;
                 commasep[@ast.pat](s, args, f);
@@ -814,7 +814,7 @@ fn print_fn(ps s, ast.fn_decl decl, str name,
 }
 
 fn print_type_params(ps s, vec[ast.ty_param] params) {
-    if (_vec.len[ast.ty_param](params) > 0u) {
+    if (Vec.len[ast.ty_param](params) > 0u) {
         wrd(s.s, "[");
         fn printParam(ps s, &ast.ty_param param) {
             wrd(s.s, param);
@@ -832,7 +832,7 @@ fn print_view_item(ps s, @ast.view_item item) {
         case (ast.view_item_use(?id,?mta,_,_)) {
             wrd1(s, "use");
             wrd(s.s, id);
-            if (_vec.len[@ast.meta_item](mta) > 0u) {
+            if (Vec.len[@ast.meta_item](mta) > 0u) {
                 popen(s);
                 fn print_meta(ps s, &@ast.meta_item item) {
                     hbox(s);
@@ -848,7 +848,7 @@ fn print_view_item(ps s, @ast.view_item item) {
         }
         case (ast.view_item_import(?id,?ids,_,_)) {
             wrd1(s, "import");
-            if (!_str.eq(id, ids.(_vec.len[str](ids)-1u))) {
+            if (!Str.eq(id, ids.(Vec.len[str](ids)-1u))) {
                 wrd1(s, id);
                 wrd1(s, "=");
             }
@@ -898,7 +898,7 @@ fn print_maybe_parens(ps s, @ast.expr expr, int outer_prec) {
 
 fn escape_str(str st, char to_escape) -> str {
     let str out = "";
-    auto len = _str.byte_len(st);
+    auto len = Str.byte_len(st);
     auto i = 0u;
     while (i < len) {
         alt (st.(i) as char) {
@@ -908,7 +908,7 @@ fn escape_str(str st, char to_escape) -> str {
             case ('\\') {out += "\\\\";}
             case (?cur) {
                 if (cur == to_escape) {out += "\\";}
-                _str.push_byte(out, cur as u8);
+                Str.push_byte(out, cur as u8);
             }
         }
         i += 1u;
@@ -929,12 +929,12 @@ fn print_string(ps s, str st) {
     wrd(s.s, "\""); wrd(s.s, escape_str(st, '"')); wrd(s.s, "\"");
 }
 
-fn print_ty_fn(ps s, ast.proto proto, option.t[str] id,
+fn print_ty_fn(ps s, ast.proto proto, Option.t[str] id,
                vec[ast.ty_arg] inputs, @ast.ty output) {
     if (proto == ast.proto_fn) {wrd(s.s, "fn");}
     else {wrd(s.s, "iter");}
     alt (id) {
-        case (option.some[str](?id)) {space(s.s); wrd(s.s, id);}
+        case (Option.some[str](?id)) {space(s.s); wrd(s.s, id);}
         case (_) {}
     }
     popen_h(s);
@@ -955,21 +955,21 @@ fn print_ty_fn(ps s, ast.proto proto, option.t[str] id,
     }
 }
 
-fn next_comment(ps s) -> option.t[lexer.cmnt] {
+fn next_comment(ps s) -> Option.t[lexer.cmnt] {
     alt (s.comments) {
-        case (option.some[vec[lexer.cmnt]](?cmnts)) {
-            if (s.cur_cmnt < _vec.len[lexer.cmnt](cmnts)) {
-                ret option.some[lexer.cmnt](cmnts.(s.cur_cmnt));
-            } else {ret option.none[lexer.cmnt];}
+        case (Option.some[vec[lexer.cmnt]](?cmnts)) {
+            if (s.cur_cmnt < Vec.len[lexer.cmnt](cmnts)) {
+                ret Option.some[lexer.cmnt](cmnts.(s.cur_cmnt));
+            } else {ret Option.none[lexer.cmnt];}
         }
-        case (_) {ret option.none[lexer.cmnt];}
+        case (_) {ret Option.none[lexer.cmnt];}
     }
 }
 
 fn maybe_print_comment(ps s, uint pos) {
     while (true) {
         alt (next_comment(s)) {
-            case (option.some[lexer.cmnt](?cmnt)) {
+            case (Option.some[lexer.cmnt](?cmnt)) {
                 if (cmnt.pos < pos) {
                     print_comment(s, cmnt.val);
                     if (cmnt.space_after) {line(s.s);}
@@ -983,7 +983,7 @@ fn maybe_print_comment(ps s, uint pos) {
 
 fn maybe_print_line_comment(ps s, common.span span) -> bool {
     alt (next_comment(s)) {
-        case (option.some[lexer.cmnt](?cmnt)) {
+        case (Option.some[lexer.cmnt](?cmnt)) {
             if (span.hi + 4u >= cmnt.pos) {
                 wrd(s.s, " ");
                 print_comment(s, cmnt.val);
@@ -999,7 +999,7 @@ fn maybe_print_line_comment(ps s, common.span span) -> bool {
 fn print_remaining_comments(ps s) {
     while (true) {
         alt (next_comment(s)) {
-            case (option.some[lexer.cmnt](?cmnt)) {
+            case (Option.some[lexer.cmnt](?cmnt)) {
                 print_comment(s, cmnt.val);
                 if (cmnt.space_after) {line(s.s);}
                 s.cur_cmnt += 1u;
diff --git a/src/comp/util/common.rs b/src/comp/util/common.rs
index b736b048278..b1a39893986 100644
--- a/src/comp/util/common.rs
+++ b/src/comp/util/common.rs
@@ -1,18 +1,18 @@
-import std.map;
-import std.map.hashmap;
-import std._uint;
-import std._int;
-import std._vec;
-import std.option.none;
+import std.Map;
+import std.Map.hashmap;
+import std.UInt;
+import std.Int;
+import std.Vec;
+import std.Option.none;
 import front.ast;
 import util.typestate_ann.ts_ann;
 
 import middle.fold;
 import middle.fold.respan;
 
-import std.io.stdout;
-import std.io.str_writer;
-import std.io.string_writer;
+import std.IO.stdout;
+import std.IO.str_writer;
+import std.IO.string_writer;
 import pretty.pprust.print_block;
 import pretty.pprust.print_expr;
 import pretty.pprust.print_decl;
@@ -56,10 +56,10 @@ fn ty_mach_to_str(ty_mach tm) -> str {
     }
 }
 
-fn new_str_hash[V]() -> std.map.hashmap[str,V] {
-    let std.map.hashfn[str] hasher = std._str.hash;
-    let std.map.eqfn[str] eqer = std._str.eq;
-    ret std.map.mk_hashmap[str,V](hasher, eqer);
+fn new_str_hash[V]() -> std.Map.hashmap[str,V] {
+    let std.Map.hashfn[str] hasher = std.Str.hash;
+    let std.Map.eqfn[str] eqer = std.Str.eq;
+    ret std.Map.mk_hashmap[str,V](hasher, eqer);
 }
 
 fn def_eq(&ast.def_id a, &ast.def_id b) -> bool {
@@ -73,48 +73,48 @@ fn hash_def(&ast.def_id d) -> uint {
     ret h;
 }
 
-fn new_def_hash[V]() -> std.map.hashmap[ast.def_id,V] {
-    let std.map.hashfn[ast.def_id] hasher = hash_def;
-    let std.map.eqfn[ast.def_id] eqer = def_eq;
-    ret std.map.mk_hashmap[ast.def_id,V](hasher, eqer);
+fn new_def_hash[V]() -> std.Map.hashmap[ast.def_id,V] {
+    let std.Map.hashfn[ast.def_id] hasher = hash_def;
+    let std.Map.eqfn[ast.def_id] eqer = def_eq;
+    ret std.Map.mk_hashmap[ast.def_id,V](hasher, eqer);
 }
 
-fn new_int_hash[V]() -> std.map.hashmap[int,V] {
+fn new_int_hash[V]() -> std.Map.hashmap[int,V] {
     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;
-    ret std.map.mk_hashmap[int,V](hasher, eqer);
+    ret std.Map.mk_hashmap[int,V](hasher, eqer);
 }
 
-fn new_uint_hash[V]() -> std.map.hashmap[uint,V] {
+fn new_uint_hash[V]() -> std.Map.hashmap[uint,V] {
     fn hash_uint(&uint x) -> uint { ret x; }
     fn eq_uint(&uint a, &uint b) -> bool { ret a == b; }
     auto hasher = hash_uint;
     auto eqer = eq_uint;
-    ret std.map.mk_hashmap[uint,V](hasher, eqer);
+    ret std.Map.mk_hashmap[uint,V](hasher, eqer);
 }
 
 fn istr(int i) -> str {
-    ret _int.to_str(i, 10u);
+    ret Int.to_str(i, 10u);
 }
 
 fn uistr(uint i) -> str {
-    ret _uint.to_str(i, 10u);
+    ret UInt.to_str(i, 10u);
 }
 
 fn elt_expr(&ast.elt e) -> @ast.expr { ret e.expr; }
 
 fn elt_exprs(&vec[ast.elt] elts) -> vec[@ast.expr] {
     auto f = elt_expr;
-    ret _vec.map[ast.elt, @ast.expr](f, elts);
+    ret Vec.map[ast.elt, @ast.expr](f, elts);
 }
 
 fn field_expr(&ast.field f) -> @ast.expr { ret f.expr; }
 
 fn field_exprs(vec[ast.field] fields) -> vec [@ast.expr] {
     auto f = field_expr;
-    ret _vec.map[ast.field, @ast.expr](f, fields);
+    ret Vec.map[ast.field, @ast.expr](f, fields);
 }
 
 fn plain_ann(middle.ty.ctxt tcx) -> ast.ann {
diff --git a/src/comp/util/typestate_ann.rs b/src/comp/util/typestate_ann.rs
index 9e815b46484..949eaeb2f54 100644
--- a/src/comp/util/typestate_ann.rs
+++ b/src/comp/util/typestate_ann.rs
@@ -1,21 +1,21 @@
 import front.ast.ident;
-import std._vec;
-import std.bitv;
+import std.Vec;
+import std.BitV;
 
 /* 
    This says: this expression requires the idents in <pre> to be initialized,
    and given the precondition, it guarantees that the idents in <post> are
    initialized.
  */
-type precond  = bitv.t; /* 1 means "this variable must be initialized"
+type precond  = BitV.t; /* 1 means "this variable must be initialized"
                            0 means "don't care about this variable" */
-type postcond = bitv.t; /* 1 means "this variable is initialized"
+type postcond = BitV.t; /* 1 means "this variable is initialized"
                            0 means "don't know about this variable */
 
-type prestate = bitv.t; /* 1 means "this variable is definitely initialized"
+type prestate = BitV.t; /* 1 means "this variable is definitely initialized"
                            0 means "don't know whether this variable is
                            initialized" */
-type poststate = bitv.t; /* 1 means "this variable is definitely initialized"
+type poststate = BitV.t; /* 1 means "this variable is definitely initialized"
                             0 means "don't know whether this variable is
                             initialized" */
 
@@ -29,7 +29,7 @@ type pre_and_post_state = rec(prestate prestate, poststate poststate);
 type ts_ann = rec(pre_and_post conditions, pre_and_post_state states);
 
 fn true_precond(uint num_vars) -> precond {
-  be bitv.create(num_vars, false);
+  be BitV.create(num_vars, false);
 }
 
 fn true_postcond(uint num_vars) -> postcond {
@@ -45,7 +45,7 @@ fn empty_poststate(uint num_vars) -> poststate {
 }
 
 fn false_postcond(uint num_vars) -> postcond {
-    be bitv.create(num_vars, true);
+    be BitV.create(num_vars, true);
 }
 
 fn empty_pre_post(uint num_vars) -> pre_and_post {
@@ -72,15 +72,15 @@ fn get_post(&pre_and_post p) -> postcond {
 }
 
 fn difference(&precond p1, &precond p2) -> bool {
-  be bitv.difference(p1, p2);
+  be BitV.difference(p1, p2);
 }
 
 fn union(&precond p1, &precond p2) -> bool {
-  be bitv.union(p1, p2);
+  be BitV.union(p1, p2);
 }
 
 fn intersect(&precond p1, &precond p2) -> bool {
-  be bitv.intersect(p1, p2);
+  be BitV.intersect(p1, p2);
 }
 
 fn pps_len(&pre_and_post p) -> uint {
@@ -91,62 +91,62 @@ fn pps_len(&pre_and_post p) -> uint {
 
 fn require_and_preserve(uint i, &pre_and_post p) -> () {
   // sets the ith bit in p's pre and post
-  bitv.set(p.precondition, i, true);
-  bitv.set(p.postcondition, i, true);
+  BitV.set(p.precondition, i, true);
+  BitV.set(p.postcondition, i, true);
 }
 
 fn set_in_postcond(uint i, &pre_and_post p) -> bool {
   // sets the ith bit in p's post
-  auto was_set = bitv.get(p.postcondition, i);
-  bitv.set(p.postcondition, i, true);
+  auto was_set = BitV.get(p.postcondition, i);
+  BitV.set(p.postcondition, i, true);
   ret !was_set;
 }
 
 fn set_in_poststate(uint i, &pre_and_post_state s) -> bool {
   // sets the ith bit in p's post
-  auto was_set = bitv.get(s.poststate, i);
-  bitv.set(s.poststate, i, true);
+  auto was_set = BitV.get(s.poststate, i);
+  BitV.set(s.poststate, i, true);
   ret !was_set;
 }
 
 // Sets all the bits in a's precondition to equal the
 // corresponding bit in p's precondition.
 fn set_precondition(&ts_ann a, &precond p) -> () {
-  bitv.copy(a.conditions.precondition, p);
+  BitV.copy(a.conditions.precondition, p);
 }
 
 // Sets all the bits in a's postcondition to equal the
 // corresponding bit in p's postcondition.
 fn set_postcondition(&ts_ann a, &postcond p) -> () {
-  bitv.copy(a.conditions.postcondition, p);
+  BitV.copy(a.conditions.postcondition, p);
 }
 
 // Sets all the bits in a's prestate to equal the
 // corresponding bit in p's prestate.
 fn set_prestate(@ts_ann a, &prestate p) -> bool {
-  ret bitv.copy(a.states.prestate, p);
+  ret BitV.copy(a.states.prestate, p);
 }
 
 // Sets all the bits in a's postcondition to equal the
 // corresponding bit in p's postcondition.
 fn set_poststate(@ts_ann a, &poststate p) -> bool {
-  ret bitv.copy(a.states.poststate, p);
+  ret BitV.copy(a.states.poststate, p);
 }
 
 // Set all the bits in p that are set in new
 fn extend_prestate(&prestate p, &poststate new) -> bool {
-  ret bitv.union(p, new);
+  ret BitV.union(p, new);
 }
 
 // Set all the bits in p that are set in new
 fn extend_poststate(&poststate p, &poststate new) -> bool {
-  ret bitv.union(p, new);
+  ret BitV.union(p, new);
 }
 
 // Clears the given bit in p
 fn relax_prestate(uint i, &prestate p) -> bool {
-    auto was_set = bitv.get(p, i);
-    bitv.set(p, i, false);
+    auto was_set = BitV.get(p, i);
+    BitV.set(p, i, false);
     ret was_set;
 }
 
@@ -164,16 +164,16 @@ fn pp_clone(&pre_and_post p) -> pre_and_post {
 }
 
 fn clone(prestate p) -> prestate {
-    ret bitv.clone(p);
+    ret BitV.clone(p);
 }
 
 // returns true if a implies b
 // that is, returns true except if for some bits c and d,
 // c = 1 and d = 0
-fn implies(bitv.t a, bitv.t b) -> bool {
-  auto tmp = bitv.clone(b);
-  bitv.difference(tmp, a);
-  ret bitv.is_false(tmp);
+fn implies(BitV.t a, BitV.t b) -> bool {
+  auto tmp = BitV.clone(b);
+  BitV.difference(tmp, a);
+  ret BitV.is_false(tmp);
 }
 
 //
diff --git a/src/lib/bitv.rs b/src/lib/BitV.rs
index 1002abc83a6..b0a4c9ea7f7 100644
--- a/src/lib/bitv.rs
+++ b/src/lib/BitV.rs
@@ -21,19 +21,19 @@ fn create(uint nbits, bool init) -> t {
         elt = 0u;
     }
 
-    auto storage = _vec.init_elt_mut[uint](elt, nbits / uint_bits() + 1u);
+    auto storage = Vec.init_elt_mut[uint](elt, nbits / uint_bits() + 1u);
     ret rec(storage = storage, nbits = nbits);
 }
 
 fn process(&fn(uint, uint) -> uint op, &t v0, &t v1) -> bool {
-    auto len = _vec.len(v1.storage);
+    auto len = Vec.len(v1.storage);
 
-    assert (_vec.len(v0.storage) == len);
+    assert (Vec.len(v0.storage) == len);
     assert (v0.nbits == v1.nbits);
 
     auto changed = false;
 
-    for each (uint i in _uint.range(0u, len)) {
+    for each (uint i in UInt.range(0u, len)) {
         auto w0 = v0.storage.(i);
         auto w1 = v1.storage.(i);
 
@@ -75,9 +75,9 @@ fn copy(&t v0, t v1) -> bool {
 }
 
 fn clone(t v) -> t {
-    auto storage = _vec.init_elt_mut[uint](0u, v.nbits / uint_bits() + 1u);
-    auto len = _vec.len(v.storage);
-    for each (uint i in _uint.range(0u, len)) {
+    auto storage = Vec.init_elt_mut[uint](0u, v.nbits / uint_bits() + 1u);
+    auto len = Vec.len(v.storage);
+    for each (uint i in UInt.range(0u, len)) {
         storage.(i) = v.storage.(i);
     }
     ret rec(storage = storage, nbits = v.nbits);
@@ -97,7 +97,7 @@ fn get(&t v, uint i) -> bool {
 fn equal(&t v0, &t v1) -> bool {
     // FIXME: when we can break or return from inside an iterator loop,
     //        we can eliminate this painful while-loop
-    auto len = _vec.len(v1.storage);
+    auto len = Vec.len(v1.storage);
     auto i = 0u;
     while (i < len) {
         if (v0.storage.(i) != v1.storage.(i)) {
@@ -109,13 +109,13 @@ fn equal(&t v0, &t v1) -> bool {
 }
 
 fn clear(&t v) {
-    for each (uint i in _uint.range(0u, _vec.len(v.storage))) {
+    for each (uint i in UInt.range(0u, Vec.len(v.storage))) {
         v.storage.(i) = 0u;
     }
 }
 
 fn invert(&t v) {
-    for each (uint i in _uint.range(0u, _vec.len(v.storage))) {
+    for each (uint i in UInt.range(0u, Vec.len(v.storage))) {
         v.storage.(i) = ~v.storage.(i);
     }
 }
@@ -176,13 +176,13 @@ fn init_to_vec(t v, uint i) -> uint {
 
 fn to_vec(&t v) -> vec[uint] {
     auto sub = bind init_to_vec(v, _);
-    ret _vec.init_fn[uint](sub, v.nbits);
+    ret Vec.init_fn[uint](sub, v.nbits);
 }
 
 fn to_str(&t v) -> str {
     auto res = "";
 
-    for (uint i in bitv.to_vec(v)) {
+    for (uint i in BitV.to_vec(v)) {
         if (i == 1u) {
             res += "1";
         }
@@ -196,7 +196,7 @@ fn to_str(&t v) -> str {
 
 // FIXME: can we just use structural equality on to_vec?
 fn eq_vec(&t v0, &vec[uint] v1) -> bool {
-    assert (v0.nbits == _vec.len[uint](v1));
+    assert (v0.nbits == Vec.len[uint](v1));
     auto len = v0.nbits;
     auto i = 0u;
     while (i < len) {
diff --git a/src/lib/dbg.rs b/src/lib/Dbg.rs
index b63f363e702..f155d1198f8 100644
--- a/src/lib/dbg.rs
+++ b/src/lib/Dbg.rs
@@ -20,7 +20,7 @@ native "rust" mod rustrt {
 }
 
 fn debug_vec[T](vec[T] v) {
-    _vec.print_debug_info[T](v);
+    Vec.print_debug_info[T](v);
 }
 
 fn debug_tydesc[T]() {
diff --git a/src/lib/deque.rs b/src/lib/Deque.rs
index b8404a7d885..a38e4fec446 100644
--- a/src/lib/deque.rs
+++ b/src/lib/Deque.rs
@@ -19,7 +19,7 @@ type t[T] = obj {
 
 fn create[T]() -> t[T] {
 
-    type cell[T] = option.t[T];
+    type cell[T] = Option.t[T];
 
     let uint initial_capacity = 32u; // 2^5
 
@@ -28,25 +28,25 @@ fn create[T]() -> t[T] {
      * elsewhere.
      */
     fn grow[T](uint nelts, uint lo, vec[cell[T]] elts) -> vec[cell[T]] {
-        assert (nelts == _vec.len[cell[T]](elts));
+        assert (nelts == Vec.len[cell[T]](elts));
 
         fn fill[T](uint i, uint nelts, uint lo,
                    vec[cell[T]] old) -> cell[T] {
             if (i < nelts) {
                 ret old.((lo + i) % nelts);
             } else {
-                ret option.none[T];
+                ret Option.none[T];
             }
         }
 
-        let uint nalloc = _uint.next_power_of_two(nelts + 1u);
-        let _vec.init_op[cell[T]] copy_op = bind fill[T](_, nelts, lo, elts);
-        ret _vec.init_fn[cell[T]](copy_op, nalloc);
+        let uint nalloc = UInt.next_power_of_two(nelts + 1u);
+        let Vec.init_op[cell[T]] copy_op = bind fill[T](_, nelts, lo, elts);
+        ret Vec.init_fn[cell[T]](copy_op, nalloc);
     }
 
     fn get[T](vec[cell[T]] elts, uint i) -> T {
         alt (elts.(i)) {
-            case (option.some[T](?t)) { ret t; }
+            case (Option.some[T](?t)) { ret t; }
             case (_) { fail; }
         }
         fail;   // FIXME: remove me when exhaustiveness checking works
@@ -63,18 +63,18 @@ fn create[T]() -> t[T] {
                 let uint oldlo = lo;
 
                 if (lo == 0u) {
-                    lo = _vec.len[cell[T]](elts) - 1u;
+                    lo = Vec.len[cell[T]](elts) - 1u;
                 } else {
                     lo -= 1u;
                 }
 
                 if (lo == hi) {
                     elts = grow[T](nelts, oldlo, elts);
-                    lo = _vec.len[cell[T]](elts) - 1u;
+                    lo = Vec.len[cell[T]](elts) - 1u;
                     hi = nelts;
                 }
 
-                elts.(lo) = option.some[T](t);
+                elts.(lo) = Option.some[T](t);
                 nelts += 1u;
             }
 
@@ -85,8 +85,8 @@ fn create[T]() -> t[T] {
                     hi = nelts;
                 }
 
-                elts.(hi) = option.some[T](t);
-                hi = (hi + 1u) % _vec.len[cell[T]](elts);
+                elts.(hi) = Option.some[T](t);
+                hi = (hi + 1u) % Vec.len[cell[T]](elts);
                 nelts += 1u;
             }
 
@@ -96,21 +96,21 @@ fn create[T]() -> t[T] {
              */
             fn pop_front() -> T {
                 let T t = get[T](elts, lo);
-                elts.(lo) = option.none[T];
-                lo = (lo + 1u) % _vec.len[cell[T]](elts);
+                elts.(lo) = Option.none[T];
+                lo = (lo + 1u) % Vec.len[cell[T]](elts);
                 nelts -= 1u;
                 ret t;
             }
 
             fn pop_back() -> T {
                 if (hi == 0u) {
-                    hi = _vec.len[cell[T]](elts) - 1u;
+                    hi = Vec.len[cell[T]](elts) - 1u;
                 } else {
                     hi -= 1u;
                 }
 
                 let T t = get[T](elts, hi);
-                elts.(hi) = option.none[T];
+                elts.(hi) = Option.none[T];
                 nelts -= 1u;
                 ret t;
             }
@@ -124,12 +124,12 @@ fn create[T]() -> t[T] {
             }
 
             fn get(int i) -> T {
-                let uint idx = (lo + (i as uint)) % _vec.len[cell[T]](elts);
+                let uint idx = (lo + (i as uint)) % Vec.len[cell[T]](elts);
                 ret get[T](elts, idx);
             }
 
         }
-    let vec[cell[T]] v = _vec.init_elt[cell[T]](option.none[T],
+    let vec[cell[T]] v = Vec.init_elt[cell[T]](Option.none[T],
                                                 initial_capacity);
 
     ret deque[T](0u, 0u, 0u, v);
diff --git a/src/lib/ebml.rs b/src/lib/EBML.rs
index 9bad0f3311d..9b17bf06a68 100644
--- a/src/lib/ebml.rs
+++ b/src/lib/EBML.rs
@@ -2,8 +2,8 @@
 // cursor model. See the specification here:
 //     http://www.matroska.org/technical/specs/rfc/index.html
 
-import option.none;
-import option.some;
+import Option.none;
+import Option.some;
 
 type ebml_tag = rec(uint id, uint size);
 type ebml_state = rec(ebml_tag ebml_tag, uint tag_pos, uint data_pos);
@@ -38,7 +38,7 @@ fn vint_at(vec[u8] data, uint start) -> tup(uint, uint) {
 }
 
 fn new_doc(vec[u8] data) -> doc {
-    ret rec(data=data, start=0u, end=_vec.len[u8](data));
+    ret rec(data=data, start=0u, end=Vec.len[u8](data));
 }
 
 fn doc_at(vec[u8] data, uint start) -> doc {
@@ -48,7 +48,7 @@ fn doc_at(vec[u8] data, uint start) -> doc {
     ret rec(data=data, start=elt_size._1, end=end);
 }
 
-fn maybe_get_doc(doc d, uint tg) -> option.t[doc] {
+fn maybe_get_doc(doc d, uint tg) -> Option.t[doc] {
     auto pos = d.start;
     while (pos < d.end) {
         auto elt_tag = vint_at(d.data, pos);
@@ -65,7 +65,7 @@ fn get_doc(doc d, uint tg) -> doc {
     alt (maybe_get_doc(d, tg)) {
         case (some[doc](?d)) {ret d;}
         case (none[doc]) {
-            log_err "failed to find block with tag " + _uint.to_str(tg, 10u);
+            log_err "failed to find block with tag " + UInt.to_str(tg, 10u);
             fail;
         }
     }
@@ -94,7 +94,7 @@ iter tagged_docs(doc d, uint tg) -> doc {
 }
 
 fn doc_data(doc d) -> vec[u8] {
-    ret _vec.slice[u8](d.data, d.start, d.end);
+    ret Vec.slice[u8](d.data, d.start, d.end);
 }
 
 fn be_uint_from_bytes(vec[u8] data, uint start, uint size) -> uint {
@@ -116,9 +116,9 @@ fn doc_as_uint(doc d) -> uint {
 
 // EBML writing
 
-type writer = rec(io.buf_writer writer, mutable vec[uint] size_positions);
+type writer = rec(IO.buf_writer writer, mutable vec[uint] size_positions);
 
-fn write_sized_vint(&io.buf_writer w, uint n, uint size) {
+fn write_sized_vint(&IO.buf_writer w, uint n, uint size) {
     let vec[u8] buf;
     alt (size) {
         case (1u) {
@@ -148,7 +148,7 @@ fn write_sized_vint(&io.buf_writer w, uint n, uint size) {
     w.write(buf);
 }
 
-fn write_vint(&io.buf_writer w, uint n) {
+fn write_vint(&IO.buf_writer w, uint n) {
     if (n < 0x7fu)          { write_sized_vint(w, n, 1u); ret; }
     if (n < 0x4000u)        { write_sized_vint(w, n, 2u); ret; }
     if (n < 0x200000u)      { write_sized_vint(w, n, 3u); ret; }
@@ -157,7 +157,7 @@ fn write_vint(&io.buf_writer w, uint n) {
     fail;
 }
 
-fn create_writer(&io.buf_writer w) -> writer {
+fn create_writer(&IO.buf_writer w) -> writer {
     let vec[uint] size_positions = vec();
     ret rec(writer=w, mutable size_positions=size_positions);
 }
@@ -175,11 +175,11 @@ fn start_tag(&writer w, uint tag_id) {
 }
 
 fn end_tag(&writer w) {
-    auto last_size_pos = _vec.pop[uint](w.size_positions);
+    auto last_size_pos = Vec.pop[uint](w.size_positions);
     auto cur_pos = w.writer.tell();
-    w.writer.seek(last_size_pos as int, io.seek_set);
+    w.writer.seek(last_size_pos as int, IO.seek_set);
     write_sized_vint(w.writer, cur_pos - last_size_pos - 4u, 4u);
-    w.writer.seek(cur_pos as int, io.seek_set);
+    w.writer.seek(cur_pos as int, IO.seek_set);
 }
 
 // TODO: optionally perform "relaxations" on end_tag to more efficiently
diff --git a/src/lib/ExtFmt.rs b/src/lib/ExtFmt.rs
index c71e49a39b2..0510a2a87ec 100644
--- a/src/lib/ExtFmt.rs
+++ b/src/lib/ExtFmt.rs
@@ -13,8 +13,8 @@
  * combinations at the moment.
  */
 
-import option.none;
-import option.some;
+import Option.none;
+import Option.some;
 
 /*
  * We have a CT (compile-time) module that parses format strings into a
@@ -66,7 +66,7 @@ mod CT {
     }
 
     // A formatted conversion from an expression to a string
-    type conv = rec(option.t[int] param,
+    type conv = rec(Option.t[int] param,
                     vec[flag] flags,
                     count width,
                     count precision,
@@ -80,11 +80,11 @@ mod CT {
 
     fn parse_fmt_string(str s) -> vec[piece] {
         let vec[piece] pieces = vec();
-        auto lim = _str.byte_len(s);
+        auto lim = Str.byte_len(s);
         auto buf = "";
 
         fn flush_buf(str buf, &vec[piece] pieces) -> str {
-            if (_str.byte_len(buf) > 0u) {
+            if (Str.byte_len(buf) > 0u) {
                 auto piece = piece_string(buf);
                 pieces += vec(piece);
             }
@@ -93,15 +93,15 @@ mod CT {
 
         auto i = 0u;
         while (i < lim) {
-            auto curr = _str.substr(s, i, 1u);
-            if (_str.eq(curr, "%")) {
+            auto curr = Str.substr(s, i, 1u);
+            if (Str.eq(curr, "%")) {
                 i += 1u;
                 if (i >= lim) {
                     log_err "unterminated conversion at end of string";
                     fail;
                 }
-                auto curr2 = _str.substr(s, i, 1u);
-                if (_str.eq(curr2, "%")) {
+                auto curr2 = Str.substr(s, i, 1u);
+                if (Str.eq(curr2, "%")) {
                     i += 1u;
                 } else {
                     buf = flush_buf(buf, pieces);
@@ -118,14 +118,14 @@ mod CT {
         ret pieces;
     }
 
-    fn peek_num(str s, uint i, uint lim) -> option.t[tup(uint, uint)] {
+    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)];
+            ret Option.none[tup(uint, uint)];
         }
 
         auto n = (c - ('0' as u8)) as uint;
@@ -156,7 +156,7 @@ mod CT {
                 ty._1);
     }
 
-    fn parse_parameter(str s, uint i, uint lim) -> tup(option.t[int], uint) {
+    fn parse_parameter(str s, uint i, uint lim) -> tup(Option.t[int], uint) {
         if (i >= lim) {
             ret tup(none[int], i);
         }
@@ -270,27 +270,27 @@ mod CT {
         }
 
         auto t;
-        auto tstr = _str.substr(s, i, 1u);
-        if (_str.eq(tstr, "b")) {
+        auto tstr = Str.substr(s, i, 1u);
+        if (Str.eq(tstr, "b")) {
             t = ty_bool;
-        } else if (_str.eq(tstr, "s")) {
+        } else if (Str.eq(tstr, "s")) {
             t = ty_str;
-        } else if (_str.eq(tstr, "c")) {
+        } else if (Str.eq(tstr, "c")) {
             t = ty_char;
-        } else if (_str.eq(tstr, "d")
-                   || _str.eq(tstr, "i")) {
+        } 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")) {
+        } else if (Str.eq(tstr, "u")) {
             t = ty_int(unsigned);
-        } else if (_str.eq(tstr, "x")) {
+        } else if (Str.eq(tstr, "x")) {
             t = ty_hex(case_lower);
-        } else if (_str.eq(tstr, "X")) {
+        } else if (Str.eq(tstr, "X")) {
             t = ty_hex(case_upper);
-        } else if (_str.eq(tstr, "t")) {
+        } else if (Str.eq(tstr, "t")) {
             t = ty_bits;
-        } else if (_str.eq(tstr, "o")) {
+        } else if (Str.eq(tstr, "o")) {
             t = ty_octal;
         } else {
             log_err "unknown type in conversion";
@@ -364,7 +364,7 @@ mod RT {
                 res = uint_to_str_prec(u, 16u, prec);
             }
             case (ty_hex_upper) {
-                res = _str.to_upper(uint_to_str_prec(u, 16u, prec));
+                res = Str.to_upper(uint_to_str_prec(u, 16u, prec));
             }
             case (ty_bits) {
                 res = uint_to_str_prec(u, 2u, prec);
@@ -389,7 +389,7 @@ mod RT {
     }
 
     fn conv_char(&conv cv, char c) -> str {
-        ret pad(cv, _str.from_char(c), pad_nozero);
+        ret pad(cv, Str.from_char(c), pad_nozero);
     }
 
     fn conv_str(&conv cv, str s) -> str {
@@ -399,9 +399,9 @@ mod RT {
             }
             case (count_is(?max)) {
                 // For strings, precision is the maximum characters displayed
-                if (max as uint < _str.char_len(s)) {
+                if (max as uint < Str.char_len(s)) {
                     // FIXME: substr works on bytes, not chars!
-                    unpadded = _str.substr(s, 0u, max as uint);
+                    unpadded = Str.substr(s, 0u, max as uint);
                 }
             }
         }
@@ -420,15 +420,15 @@ mod RT {
 
     // Convert a uint to string with a minimum number of digits.  If precision
     // is 0 and num is 0 then the result is the empty string. Could move this
-    // to _uint, but it doesn't seem all that useful.
+    // to UInt. but it doesn't seem all that useful.
     fn uint_to_str_prec(uint num, uint radix, uint prec) -> str {
         auto s;
 
         if (prec == 0u && num == 0u) {
             s = "";
         } else {
-            s = _uint.to_str(num, radix);
-            auto len = _str.char_len(s);
+            s = UInt.to_str(num, radix);
+            auto len = Str.char_len(s);
             if (len < prec) {
                 auto diff = prec - len;
                 auto pad = str_init_elt('0', diff);
@@ -450,12 +450,12 @@ mod RT {
         }
     }
 
-    // FIXME: This might be useful in _str, but needs to be utf8 safe first
+    // FIXME: This might be useful in Str. but needs to be utf8 safe first
     fn str_init_elt(char c, uint n_elts) -> str {
-        auto svec = _vec.init_elt[u8](c as u8, n_elts);
+        auto svec = Vec.init_elt[u8](c as u8, n_elts);
         // FIXME: Using unsafe_from_bytes because rustboot
         // can't figure out the is_utf8 predicate on from_bytes?
-        ret _str.unsafe_from_bytes(svec);
+        ret Str.unsafe_from_bytes(svec);
     }
 
     tag pad_mode {
@@ -476,7 +476,7 @@ mod RT {
             }
         }
 
-        auto strlen = _str.char_len(s);
+        auto strlen = Str.char_len(s);
         if (uwidth <= strlen) {
             ret s;
         }
@@ -532,16 +532,16 @@ mod RT {
         // instead.
         if (signed
             && zero_padding
-            && _str.byte_len(s) > 0u) {
+            && Str.byte_len(s) > 0u) {
 
             auto head = s.(0);
             if (head == '+' as u8
                 || head == '-' as u8
                 || head == ' ' as u8) {
 
-                auto headstr = _str.unsafe_from_bytes(vec(head));
-                auto bytelen = _str.byte_len(s);
-                auto numpart = _str.substr(s, 1u, bytelen - 1u);
+                auto headstr = Str.unsafe_from_bytes(vec(head));
+                auto bytelen = Str.byte_len(s);
+                auto numpart = Str.substr(s, 1u, bytelen - 1u);
                 ret headstr + padstr + numpart;
             }
         }
diff --git a/src/lib/fs.rs b/src/lib/FS.rs
index 0a951e5a6d6..69edf247a3e 100644
--- a/src/lib/fs.rs
+++ b/src/lib/FS.rs
@@ -3,25 +3,25 @@ native "rust" mod rustrt {
 }
 
 fn path_sep() -> str {
-    ret _str.from_char(os_fs.path_sep);
+    ret Str.from_char(OS_FS.path_sep);
 }
 
 type path = str;
 
 fn dirname(path p) -> path {
-    let int i = _str.rindex(p, os_fs.path_sep as u8);
+    let int i = Str.rindex(p, OS_FS.path_sep as u8);
     if (i == -1) {
-        i = _str.rindex(p, os_fs.alt_path_sep as u8);
+        i = Str.rindex(p, OS_FS.alt_path_sep as u8);
         if (i == -1) {
             ret p;
         }
     }
-    ret _str.substr(p, 0u, i as uint);
+    ret Str.substr(p, 0u, i as uint);
 }
 
 fn connect(path pre, path post) -> path {
-    auto len = _str.byte_len(pre);
-    if (pre.(len - 1u) == (os_fs.path_sep as u8)) { // Trailing '/'?
+    auto len = Str.byte_len(pre);
+    if (pre.(len - 1u) == (OS_FS.path_sep as u8)) { // Trailing '/'?
         ret pre + post;
     }
     ret pre + path_sep() + post;
@@ -32,14 +32,14 @@ fn file_is_dir(path p) -> bool {
 }
 
 fn list_dir(path p) -> vec[str] {
-  auto pl = _str.byte_len(p);
-  if (pl == 0u || p.(pl - 1u) as char != os_fs.path_sep) {
+  auto pl = Str.byte_len(p);
+  if (pl == 0u || p.(pl - 1u) as char != OS_FS.path_sep) {
     p += path_sep();
   }
   let vec[str] full_paths = vec();
-  for (str filename in os_fs.list_dir(p)) {
-    if (!_str.eq(filename, ".")) {if (!_str.eq(filename, "..")) {
-      _vec.push[str](full_paths, p + filename);
+  for (str filename in OS_FS.list_dir(p)) {
+    if (!Str.eq(filename, ".")) {if (!Str.eq(filename, "..")) {
+      Vec.push[str](full_paths, p + filename);
     }}
   }
   ret full_paths;
diff --git a/src/lib/GenericOS.rs b/src/lib/GenericOS.rs
index 2d375652140..c60fa2b8ed1 100644
--- a/src/lib/GenericOS.rs
+++ b/src/lib/GenericOS.rs
@@ -1,4 +1,4 @@
 fn getenv(str n) -> str {
-    ret _str.str_from_cstr(os.libc.getenv(_str.buf(n)));
+    ret Str.str_from_cstr(OS.libc.getenv(Str.buf(n)));
 }
 
diff --git a/src/lib/GetOpts.rs b/src/lib/GetOpts.rs
index f85ce85c136..0cacf3ffc65 100644
--- a/src/lib/GetOpts.rs
+++ b/src/lib/GetOpts.rs
@@ -7,8 +7,8 @@
  * argument values out of the match object.
  */ 
 
-import option.some;
-import option.none;
+import Option.some;
+import Option.none;
 
 tag name { long(str); short(char); }
 tag hasarg { yes; no; maybe; }
@@ -17,7 +17,7 @@ tag occur { req; optional; multi; }
 type opt = rec(name name, hasarg hasarg, occur occur);
 
 fn mkname(str nm) -> name {
-    if (_str.char_len(nm) == 1u) { ret short(_str.char_at(nm, 0u)); }
+    if (Str.char_len(nm) == 1u) { ret short(Str.char_at(nm, 0u)); }
     else { ret long(nm); }
 }
 fn reqopt(str name) -> opt {
@@ -41,11 +41,11 @@ tag optval {
 type match = rec(vec[opt] opts, vec[mutable vec[optval]] vals, vec[str] free);
 
 fn is_arg(str arg) -> bool {
-    ret _str.byte_len(arg) > 1u && arg.(0) == '-' as u8;
+    ret Str.byte_len(arg) > 1u && arg.(0) == '-' as u8;
 }
 fn name_str(name nm) -> str {
     alt (nm) {
-        case (short(?ch)) {ret _str.from_char(ch);}
+        case (short(?ch)) {ret Str.from_char(ch);}
         case (long(?s)) {ret s;}
     }
 }
@@ -55,16 +55,16 @@ fn name_eq(name a, name b) -> bool {
     alt (a) {
         case (long(?a)) {
             alt (b) {
-                case (long(?b)) { ret _str.eq(a, b); }
+                case (long(?b)) { ret Str.eq(a, b); }
                 case (_) { ret false; }
             }
         }
         case (_) { if (a == b) { ret true; } else {ret false; } }
     }
 }
-fn find_opt(vec[opt] opts, name nm) -> option.t[uint] {
+fn find_opt(vec[opt] opts, name nm) -> Option.t[uint] {
     auto i = 0u;
-    auto l = _vec.len[opt](opts);
+    auto l = Vec.len[opt](opts);
     while (i < l) {
         if (name_eq(opts.(i).name, nm)) { ret some[uint](i); }
         i += 1u;
@@ -102,41 +102,41 @@ tag result {
 }
 
 fn getopts(vec[str] args, vec[opt] opts) -> result {
-    auto n_opts = _vec.len[opt](opts);
-    fn empty_(uint x) -> vec[optval]{ret _vec.empty[optval]();}
+    auto n_opts = Vec.len[opt](opts);
+    fn empty_(uint x) -> vec[optval]{ret Vec.empty[optval]();}
     auto f = empty_;
-    auto vals = _vec.init_fn_mut[vec[optval]](f, n_opts);
+    auto vals = Vec.init_fn_mut[vec[optval]](f, n_opts);
     let vec[str] free = vec();
 
-    auto l = _vec.len[str](args);
+    auto l = Vec.len[str](args);
     auto i = 0u;
     while (i < l) {
         auto cur = args.(i);
-        auto curlen = _str.byte_len(cur);
+        auto curlen = Str.byte_len(cur);
         if (!is_arg(cur)) {
-            _vec.push[str](free, cur);
-        } else if (_str.eq(cur, "--")) {
-            free += _vec.slice[str](args, i + 1u, l);
+            Vec.push[str](free, cur);
+        } else if (Str.eq(cur, "--")) {
+            free += Vec.slice[str](args, i + 1u, l);
             break;
         } else {
             auto names;
-            auto i_arg = option.none[str];
+            auto i_arg = Option.none[str];
             if (cur.(1) == '-' as u8) {
-                auto tail = _str.slice(cur, 2u, curlen);
-                auto eq = _str.index(tail, '=' as u8);
+                auto tail = Str.slice(cur, 2u, curlen);
+                auto eq = Str.index(tail, '=' as u8);
                 if (eq == -1) {
                     names = vec(long(tail));
                 } else {
-                    names = vec(long(_str.slice(tail, 0u, eq as uint)));
-                    i_arg = option.some[str]
-                        (_str.slice(tail, (eq as uint) + 1u, curlen - 2u));
+                    names = vec(long(Str.slice(tail, 0u, eq as uint)));
+                    i_arg = Option.some[str]
+                        (Str.slice(tail, (eq as uint) + 1u, curlen - 2u));
                 }
             } else {
                 auto j = 1u;
                 names = vec();
                 while (j < curlen) {
-                    auto range = _str.char_range_at(cur, j);
-                    _vec.push[name](names, short(range._0));
+                    auto range = Str.char_range_at(cur, j);
+                    Vec.push[name](names, short(range._0));
                     j = range._1;
                 }
             }
@@ -152,29 +152,29 @@ fn getopts(vec[str] args, vec[opt] opts) -> result {
                 }
                 alt (opts.(optid).hasarg) {
                     case (no) {
-                        _vec.push[optval](vals.(optid), given);
+                        Vec.push[optval](vals.(optid), given);
                     }
                     case (maybe) {
-                        if (!option.is_none[str](i_arg)) {
-                            _vec.push[optval](vals.(optid),
-                                              val(option.get[str](i_arg)));
-                        } else if (name_pos < _vec.len[name](names) ||
+                        if (!Option.is_none[str](i_arg)) {
+                            Vec.push[optval](vals.(optid),
+                                              val(Option.get[str](i_arg)));
+                        } else if (name_pos < Vec.len[name](names) ||
                                    i + 1u == l || is_arg(args.(i + 1u))) {
-                            _vec.push[optval](vals.(optid), given);
+                            Vec.push[optval](vals.(optid), given);
                         } else {
                             i += 1u;
-                            _vec.push[optval](vals.(optid), val(args.(i)));
+                            Vec.push[optval](vals.(optid), val(args.(i)));
                         }
                     }
                     case (yes) {
-                        if (!option.is_none[str](i_arg)) {
-                            _vec.push[optval](vals.(optid),
-                                              val(option.get[str](i_arg)));
+                        if (!Option.is_none[str](i_arg)) {
+                            Vec.push[optval](vals.(optid),
+                                              val(Option.get[str](i_arg)));
                         } else if (i + 1u == l) {
                             ret failure(argument_missing(name_str(nm)));
                         } else {
                             i += 1u;
-                            _vec.push[optval](vals.(optid), val(args.(i)));
+                            Vec.push[optval](vals.(optid), val(args.(i)));
                         }
                     }
                 }
@@ -185,7 +185,7 @@ fn getopts(vec[str] args, vec[opt] opts) -> result {
 
     i = 0u;
     while (i < n_opts) {
-        auto n = _vec.len[optval](vals.(i));
+        auto n = Vec.len[optval](vals.(i));
         auto occ = opts.(i).occur;
         if (occ == req) {if (n == 0u) {
             ret failure(option_missing(name_str(opts.(i).name)));
@@ -212,7 +212,7 @@ fn opt_val(match m, str nm) -> optval {
     ret opt_vals(m, nm).(0);
 }
 fn opt_present(match m, str nm) -> bool {
-    ret _vec.len[optval](opt_vals(m, nm)) > 0u;
+    ret Vec.len[optval](opt_vals(m, nm)) > 0u;
 }
 fn opt_str(match m, str nm) -> str {
     alt (opt_val(m, nm)) {
@@ -224,15 +224,15 @@ fn opt_strs(match m, str nm) -> vec[str] {
     let vec[str] acc = vec();
     for (optval v in opt_vals(m, nm)) {
         alt (v) {
-            case (val(?s)) { _vec.push[str](acc, s); }
+            case (val(?s)) { Vec.push[str](acc, s); }
             case (_) {}
         }
     }
     ret acc;
 }
-fn opt_maybe_str(match m, str nm) -> option.t[str] {
+fn opt_maybe_str(match m, str nm) -> Option.t[str] {
     auto vals = opt_vals(m, nm);
-    if (_vec.len[optval](vals) == 0u) { ret none[str]; }
+    if (Vec.len[optval](vals) == 0u) { ret none[str]; }
     alt (vals.(0)) {
         case (val(?s)) { ret some[str](s); }
         case (_) { ret none[str]; }
diff --git a/src/lib/io.rs b/src/lib/IO.rs
index 364810ba3d3..60416ab1e77 100644
--- a/src/lib/io.rs
+++ b/src/lib/IO.rs
@@ -1,8 +1,8 @@
-import os.libc;
+import OS.libc;
 
 native "rust" mod rustrt {
-  fn rust_get_stdin() -> os.libc.FILE;
-  fn rust_get_stdout() -> os.libc.FILE;
+  fn rust_get_stdin() -> OS.libc.FILE;
+  fn rust_get_stdout() -> OS.libc.FILE;
 }
 
 // Reading
@@ -55,30 +55,30 @@ fn convert_whence(seek_style whence) -> int {
     }
 }
 
-state obj FILE_buf_reader(os.libc.FILE f, bool must_close) {
+state obj FILE_buf_reader(OS.libc.FILE f, bool must_close) {
     fn read(uint len) -> vec[u8] {
-        auto buf = _vec.alloc[u8](len);
-        auto read = os.libc.fread(_vec.buf[u8](buf), 1u, len, f);
-        _vec.len_set[u8](buf, read);
+        auto buf = Vec.alloc[u8](len);
+        auto read = OS.libc.fread(Vec.buf[u8](buf), 1u, len, f);
+        Vec.len_set[u8](buf, read);
         ret buf;
     }
     fn read_byte() -> int {
-        ret os.libc.fgetc(f);
+        ret OS.libc.fgetc(f);
     }
     fn unread_byte(int byte) {
-        os.libc.ungetc(byte, f);
+        OS.libc.ungetc(byte, f);
     }
     fn eof() -> bool {
-        ret os.libc.feof(f) != 0;
+        ret OS.libc.feof(f) != 0;
     }
     fn seek(int offset, seek_style whence) {
-        assert (os.libc.fseek(f, offset, convert_whence(whence)) == 0);
+        assert (OS.libc.fseek(f, offset, convert_whence(whence)) == 0);
     }
     fn tell() -> uint {
-        ret os.libc.ftell(f) as uint;
+        ret OS.libc.ftell(f) as uint;
     }
     drop {
-        if (must_close) { os.libc.fclose(f); }
+        if (must_close) { OS.libc.fclose(f); }
     }
 }
 
@@ -100,7 +100,7 @@ state obj new_reader(buf_reader rdr) {
         auto c0 = rdr.read_byte();
         if (c0 == -1) {ret -1 as char;} // FIXME will this stay valid?
         auto b0 = c0 as u8;
-        auto w = _str.utf8_char_width(b0);
+        auto w = Str.utf8_char_width(b0);
         assert (w > 0u);
         if (w == 1u) {ret b0 as char;}
         auto val = 0u;
@@ -112,7 +112,7 @@ state obj new_reader(buf_reader rdr) {
             val <<= 6u;
             val += (next & 0x3f) as uint;
         }
-        // See _str.char_at
+        // See Str.char_at
         val += ((b0 << ((w + 1u) as u8)) as uint) << ((w - 1u) * 6u - w - 1u);
         ret val as char;
     }
@@ -126,9 +126,9 @@ state obj new_reader(buf_reader rdr) {
         while (go_on) {
             auto ch = rdr.read_byte();
             if (ch == -1 || ch == 10) {go_on = false;}
-            else {_vec.push[u8](buf, ch as u8);}
+            else {Vec.push[u8](buf, ch as u8);}
         }
-        ret _str.unsafe_from_bytes(buf);
+        ret Str.unsafe_from_bytes(buf);
     }
     fn read_c_str() -> str {
         let vec[u8] buf = vec();
@@ -136,9 +136,9 @@ state obj new_reader(buf_reader rdr) {
         while (go_on) {
             auto ch = rdr.read_byte();
             if (ch < 1) {go_on = false;}
-            else {_vec.push[u8](buf, ch as u8);}
+            else {Vec.push[u8](buf, ch as u8);}
         }
-        ret _str.unsafe_from_bytes(buf);
+        ret Str.unsafe_from_bytes(buf);
     }
     // FIXME deal with eof?
     fn read_le_uint(uint size) -> uint {
@@ -191,7 +191,7 @@ fn stdin() -> reader {
 }
 
 fn file_reader(str path) -> reader {
-    auto f = os.libc.fopen(_str.buf(path), _str.buf("r"));
+    auto f = OS.libc.fopen(Str.buf(path), Str.buf("r"));
     if (f as uint == 0u) {
         log_err "error opening " + path;
         fail;
@@ -212,17 +212,17 @@ type byte_buf = @rec(vec[u8] buf, mutable uint pos);
 
 state obj byte_buf_reader(byte_buf bbuf) {
     fn read(uint len) -> vec[u8] {
-        auto rest = _vec.len[u8](bbuf.buf) - bbuf.pos;
+        auto rest = Vec.len[u8](bbuf.buf) - bbuf.pos;
         auto to_read = len;
         if (rest < to_read) {
             to_read = rest;
         }
-        auto range = _vec.slice[u8](bbuf.buf, bbuf.pos, bbuf.pos + to_read);
+        auto range = Vec.slice[u8](bbuf.buf, bbuf.pos, bbuf.pos + to_read);
         bbuf.pos += to_read;
         ret range;
     }
     fn read_byte() -> int {
-        if (bbuf.pos == _vec.len[u8](bbuf.buf)) {ret -1;}
+        if (bbuf.pos == Vec.len[u8](bbuf.buf)) {ret -1;}
         auto b = bbuf.buf.(bbuf.pos);
         bbuf.pos += 1u;
         ret b as int;
@@ -234,12 +234,12 @@ state obj byte_buf_reader(byte_buf bbuf) {
     }
 
     fn eof() -> bool {
-        ret bbuf.pos == _vec.len[u8](bbuf.buf);
+        ret bbuf.pos == Vec.len[u8](bbuf.buf);
     }
 
     fn seek(int offset, seek_style whence) {
         auto pos = bbuf.pos;
-        auto len = _vec.len[u8](bbuf.buf);
+        auto len = Vec.len[u8](bbuf.buf);
         bbuf.pos = seek_in_buf(offset, pos, len, whence);
     }
 
@@ -268,40 +268,40 @@ type buf_writer = state obj {
   fn tell() -> uint; // FIXME: eventually u64
 };
 
-state obj FILE_writer(os.libc.FILE f, bool must_close) {
+state obj FILE_writer(OS.libc.FILE f, bool must_close) {
     fn write(vec[u8] v) {
-        auto len = _vec.len[u8](v);
-        auto vbuf = _vec.buf[u8](v);
-        auto nout = os.libc.fwrite(vbuf, len, 1u, f);
+        auto len = Vec.len[u8](v);
+        auto vbuf = Vec.buf[u8](v);
+        auto nout = OS.libc.fwrite(vbuf, len, 1u, f);
         if (nout < 1u) {
             log_err "error dumping buffer";
         }
     }
 
     fn seek(int offset, seek_style whence) {
-        assert (os.libc.fseek(f, offset, convert_whence(whence)) == 0);
+        assert (OS.libc.fseek(f, offset, convert_whence(whence)) == 0);
     }
 
     fn tell() -> uint {
-        ret os.libc.ftell(f) as uint;
+        ret OS.libc.ftell(f) as uint;
     }
 
     drop {
-        if (must_close) {os.libc.fclose(f);}
+        if (must_close) {OS.libc.fclose(f);}
     }
 }
 
 state obj fd_buf_writer(int fd, bool must_close) {
     fn write(vec[u8] v) {
-        auto len = _vec.len[u8](v);
+        auto len = Vec.len[u8](v);
         auto count = 0u;
         auto vbuf;
         while (count < len) {
-            vbuf = _vec.buf_off[u8](v, count);
-            auto nout = os.libc.write(fd, vbuf, len);
+            vbuf = Vec.buf_off[u8](v, count);
+            auto nout = OS.libc.write(fd, vbuf, len);
             if (nout < 0) {
                 log_err "error dumping buffer";
-                log_err sys.rustrt.last_os_error();
+                log_err Sys.rustrt.last_os_error();
                 fail;
             }
             count += nout as uint;
@@ -319,32 +319,32 @@ state obj fd_buf_writer(int fd, bool must_close) {
     }
 
     drop {
-        if (must_close) {os.libc.close(fd);}
+        if (must_close) {OS.libc.close(fd);}
     }
 }
 
 fn file_buf_writer(str path, vec[fileflag] flags) -> buf_writer {
     let int fflags =
-        os.libc_constants.O_WRONLY() |
-        os.libc_constants.O_BINARY();
+        OS.libc_constants.O_WRONLY() |
+        OS.libc_constants.O_BINARY();
 
     for (fileflag f in flags) {
         alt (f) {
-            case (append)   { fflags |= os.libc_constants.O_APPEND(); }
-            case (create)   { fflags |= os.libc_constants.O_CREAT(); }
-            case (truncate) { fflags |= os.libc_constants.O_TRUNC(); }
+            case (append)   { fflags |= OS.libc_constants.O_APPEND(); }
+            case (create)   { fflags |= OS.libc_constants.O_CREAT(); }
+            case (truncate) { fflags |= OS.libc_constants.O_TRUNC(); }
             case (none) {}
         }
     }
 
-    auto fd = os.libc.open(_str.buf(path),
+    auto fd = OS.libc.open(Str.buf(path),
                            fflags,
-                           os.libc_constants.S_IRUSR() |
-                           os.libc_constants.S_IWUSR());
+                           OS.libc_constants.S_IRUSR() |
+                           OS.libc_constants.S_IWUSR());
 
     if (fd < 0) {
         log_err "error opening file for writing";
-        log_err sys.rustrt.last_os_error();
+        log_err Sys.rustrt.last_os_error();
         fail;
     }
     ret fd_buf_writer(fd, true);
@@ -390,17 +390,17 @@ state obj new_writer(buf_writer out) {
         ret out;
     }
     fn write_str(str s) {
-        out.write(_str.bytes(s));
+        out.write(Str.bytes(s));
     }
     fn write_char(char ch) {
         // FIXME needlessly consy
-        out.write(_str.bytes(_str.from_char(ch)));
+        out.write(Str.bytes(Str.from_char(ch)));
     }
     fn write_int(int n) {
-        out.write(_str.bytes(_int.to_str(n, 10u)));
+        out.write(Str.bytes(Int.to_str(n, 10u)));
     }
     fn write_uint(uint n) {
-        out.write(_str.bytes(_uint.to_str(n, 10u)));
+        out.write(Str.bytes(UInt.to_str(n, 10u)));
     }
     fn write_bytes(vec[u8] bytes) {
         out.write(bytes);
@@ -427,7 +427,7 @@ fn file_writer(str path, vec[fileflag] flags) -> writer {
 
 // FIXME: fileflags
 fn buffered_file_buf_writer(str path) -> buf_writer {
-    auto f = os.libc.fopen(_str.buf(path), _str.buf("w"));
+    auto f = OS.libc.fopen(Str.buf(path), Str.buf("w"));
     if (f as uint == 0u) {
         log_err "error opening " + path;
         fail;
@@ -451,21 +451,21 @@ type mutable_byte_buf = @rec(mutable vec[mutable u8] buf, mutable uint pos);
 state obj byte_buf_writer(mutable_byte_buf buf) {
     fn write(vec[u8] v) {
         // Fast path.
-        if (buf.pos == _vec.len(buf.buf)) {
+        if (buf.pos == Vec.len(buf.buf)) {
             // FIXME: Fix our type system. There's no reason you shouldn't be
             // able to add a mutable vector to an immutable one.
-            auto mv = _vec.rustrt.unsafe_vec_to_mut[u8](v);
+            auto mv = Vec.rustrt.unsafe_vec_to_mut[u8](v);
             buf.buf += mv;
-            buf.pos += _vec.len[u8](v);
+            buf.pos += Vec.len[u8](v);
             ret;
         }
 
         // FIXME: Optimize. These should be unique pointers.
-        auto vlen = _vec.len[u8](v);
+        auto vlen = Vec.len[u8](v);
         auto vpos = 0u;
         while (vpos < vlen) {
             auto b = v.(vpos);
-            if (buf.pos == _vec.len(buf.buf)) {
+            if (buf.pos == Vec.len(buf.buf)) {
                 buf.buf += vec(mutable b);
             } else {
                 buf.buf.(buf.pos) = b;
@@ -477,7 +477,7 @@ state obj byte_buf_writer(mutable_byte_buf buf) {
 
     fn seek(int offset, seek_style whence) {
         auto pos = buf.pos;
-        auto len = _vec.len(buf.buf);
+        auto len = Vec.len(buf.buf);
         buf.pos = seek_in_buf(offset, pos, len, whence);
     }
 
@@ -487,12 +487,12 @@ state obj byte_buf_writer(mutable_byte_buf buf) {
 fn string_writer() -> str_writer {
     // FIXME: yikes, this is bad. Needs fixing of mutable syntax.
     let vec[mutable u8] b = vec(mutable 0u8);
-    _vec.pop(b);
+    Vec.pop(b);
 
     let mutable_byte_buf buf = @rec(mutable buf = b, mutable pos = 0u);
     state obj str_writer_wrap(writer wr, mutable_byte_buf buf) {
         fn get_writer() -> writer {ret wr;}
-        fn get_str() -> str {ret _str.unsafe_from_mutable_bytes(buf.buf);}
+        fn get_str() -> str {ret Str.unsafe_from_mutable_bytes(buf.buf);}
     }
     ret str_writer_wrap(new_writer(byte_buf_writer(buf)), buf);
 }
diff --git a/src/lib/_int.rs b/src/lib/Int.rs
index 1824d142dab..59fb507f7fb 100644
--- a/src/lib/_int.rs
+++ b/src/lib/Int.rs
@@ -29,9 +29,9 @@ fn to_str(int n, uint radix) -> str
 {
     assert (0u < radix && radix <= 16u);
     if (n < 0) {
-        ret "-" + _uint.to_str((-n) as uint, radix);
+        ret "-" + UInt.to_str((-n) as uint, radix);
     } else {
-        ret _uint.to_str(n as uint, radix);
+        ret UInt.to_str(n as uint, radix);
     }
 }
 
diff --git a/src/lib/list.rs b/src/lib/List.rs
index 33f7c06003f..58ea29f2964 100644
--- a/src/lib/list.rs
+++ b/src/lib/List.rs
@@ -1,5 +1,5 @@
-import option.some;
-import option.none;
+import Option.some;
+import Option.none;
 
 // FIXME: It would probably be more appealing to define this as
 // type list[T] = rec(T hd, option[@list[T]] tl), but at the moment
@@ -27,7 +27,7 @@ fn foldl[T,U](&list[T] ls, &U u, fn(&T t, &U u) -> U f) -> U {
 }
 
 fn find[T,U](&list[T] ls,
-             (fn(&T) -> option.t[U]) f) -> option.t[U] {
+             (fn(&T) -> Option.t[U]) f) -> Option.t[U] {
   alt(ls) {
     case (cons[T](?hd, ?tl)) {
         alt (f(hd)) {
diff --git a/src/lib/map.rs b/src/lib/Map.rs
index 4ab2f076b9c..6f1ad6d7029 100644
--- a/src/lib/map.rs
+++ b/src/lib/Map.rs
@@ -11,8 +11,8 @@ state type hashmap[K, V] = state obj {
                                  fn insert(&K key, &V val) -> bool;
                                  fn contains_key(&K key) -> bool;
                                  fn get(&K key) -> V;
-                                 fn find(&K key) -> option.t[V];
-                                 fn remove(&K key) -> option.t[V];
+                                 fn find(&K key) -> Option.t[V];
+                                 fn remove(&K key) -> Option.t[V];
                                  fn rehash();
                                  iter items() -> @tup(K,V);
 };
@@ -20,7 +20,7 @@ state type hashmap[K, V] = state obj {
 fn mk_hashmap[K, V](&hashfn[K] hasher, &eqfn[K] eqer) -> hashmap[K, V] {
 
     let uint initial_capacity = 32u; // 2^5
-    let util.rational load_factor = rec(num=3, den=4);
+    let Util.rational load_factor = rec(num=3, den=4);
 
     tag bucket[K, V] {
         nil;
@@ -29,7 +29,7 @@ fn mk_hashmap[K, V](&hashfn[K] hasher, &eqfn[K] eqer) -> hashmap[K, V] {
     }
 
     fn make_buckets[K, V](uint nbkts) -> vec[mutable bucket[K, V]] {
-        ret _vec.init_elt_mut[bucket[K, V]](nil[K, V], nbkts);
+        ret Vec.init_elt_mut[bucket[K, V]](nil[K, V], nbkts);
     }
 
     // Derive two hash functions from the one given by taking the upper
@@ -96,7 +96,7 @@ fn mk_hashmap[K, V](&hashfn[K] hasher, &eqfn[K] eqer) -> hashmap[K, V] {
                          vec[mutable bucket[K, V]] bkts,
                          uint nbkts,
                          &K key)
-        -> option.t[V]
+        -> Option.t[V]
         {
             let uint i = 0u;
             let uint h = hasher(key);
@@ -105,17 +105,17 @@ fn mk_hashmap[K, V](&hashfn[K] hasher, &eqfn[K] eqer) -> hashmap[K, V] {
                 alt (bkts.(j)) {
                     case (some[K, V](?k, ?v)) {
                         if (eqer(key, k)) {
-                            ret option.some[V](v);
+                            ret Option.some[V](v);
                         }
                     }
                     case (nil[K, V]) {
-                        ret option.none[V];
+                        ret Option.none[V];
                     }
                     case (deleted[K, V]) { }
                 }
                 i += 1u;
             }
-            ret option.none[V];
+            ret Option.none[V];
         }
 
 
@@ -140,15 +140,15 @@ fn mk_hashmap[K, V](&hashfn[K] hasher, &eqfn[K] eqer) -> hashmap[K, V] {
                             mutable vec[mutable bucket[K, V]] bkts,
                             mutable uint nbkts,
                             mutable uint nelts,
-                            util.rational lf)
+                            Util.rational lf)
         {
             fn size() -> uint { ret nelts; }
 
             fn insert(&K key, &V val) -> bool {
-                let util.rational load = rec(num=(nelts + 1u) as int,
+                let Util.rational load = rec(num=(nelts + 1u) as int,
                                              den=nbkts as int);
-                if (!util.rational_leq(load, lf)) {
-                    let uint nnewbkts = _uint.next_power_of_two(nbkts + 1u);
+                if (!Util.rational_leq(load, lf)) {
+                    let uint nnewbkts = UInt.next_power_of_two(nbkts + 1u);
                     let vec[mutable bucket[K, V]] newbkts =
                         make_buckets[K, V](nnewbkts);
                     rehash[K, V](hasher, eqer, bkts, nbkts,
@@ -167,7 +167,7 @@ fn mk_hashmap[K, V](&hashfn[K] hasher, &eqfn[K] eqer) -> hashmap[K, V] {
 
             fn contains_key(&K key) -> bool {
                 alt (find_common[K, V](hasher, eqer, bkts, nbkts, key)) {
-                    case (option.some[V](_)) { ret true; }
+                    case (Option.some[V](_)) { ret true; }
                     case (_) { ret false; }
                 }
                 fail;   // FIXME: remove me when exhaustiveness checking works
@@ -175,19 +175,19 @@ fn mk_hashmap[K, V](&hashfn[K] hasher, &eqfn[K] eqer) -> hashmap[K, V] {
 
             fn get(&K key) -> V {
                 alt (find_common[K, V](hasher, eqer, bkts, nbkts, key)) {
-                    case (option.some[V](?val)) { ret val; }
+                    case (Option.some[V](?val)) { ret val; }
                     case (_) { fail; }
                 }
                 fail;   // FIXME: remove me when exhaustiveness checking works
             }
 
-            fn find(&K key) -> option.t[V] {
+            fn find(&K key) -> Option.t[V] {
                 // FIXME: should be 'be' but parametric tail-calls don't
                 // work at the moment.
                 ret find_common[K, V](hasher, eqer, bkts, nbkts, key);
             }
 
-            fn remove(&K key) -> option.t[V] {
+            fn remove(&K key) -> Option.t[V] {
                 let uint i = 0u;
                 let uint h = hasher(key);
                 while (i < nbkts) {
@@ -197,17 +197,17 @@ fn mk_hashmap[K, V](&hashfn[K] hasher, &eqfn[K] eqer) -> hashmap[K, V] {
                             if (eqer(key, k)) {
                                 bkts.(j) = deleted[K, V];
                                 nelts -= 1u;
-                                ret option.some[V](v);
+                                ret Option.some[V](v);
                             }
                         }
                         case (deleted[K, V]) { }
                         case (nil[K, V]) {
-                            ret option.none[V];
+                            ret Option.none[V];
                         }
                     }
                     i += 1u;
                 }
-                ret option.none[V];
+                ret Option.none[V];
             }
 
             fn rehash() {
diff --git a/src/lib/option.rs b/src/lib/Option.rs
index e214c77487f..3fb9aa3b613 100644
--- a/src/lib/option.rs
+++ b/src/lib/Option.rs
@@ -1,4 +1,4 @@
-// lib/option.rs
+// lib/Option.rs
 
 tag t[T] {
     none;
@@ -39,7 +39,7 @@ fn is_none[T](&t[T] opt) -> bool {
 }
 
 fn from_maybe[T](&T def, &t[T] opt) -> T {
-    auto f = bind util.id[T](_);
+    auto f = bind Util.id[T](_);
     ret maybe[T, T](def, f, opt);
 }
 
diff --git a/src/lib/rand.rs b/src/lib/Rand.rs
index 06eb2f06fd7..06eb2f06fd7 100644
--- a/src/lib/rand.rs
+++ b/src/lib/Rand.rs
diff --git a/src/lib/run_program.rs b/src/lib/Run_Program.rs
index 31758984f9e..30c0ee9c9a2 100644
--- a/src/lib/run_program.rs
+++ b/src/lib/Run_Program.rs
@@ -1,74 +1,74 @@
-import _str.sbuf;
-import _vec.vbuf;
+import Str.sbuf;
+import Vec.vbuf;
 
 native "rust" mod rustrt {
     fn rust_run_program(vbuf argv, int in_fd, int out_fd, int err_fd) -> int;
 }
 
 fn argvec(str prog, vec[str] args) -> vec[sbuf] {
-    auto argptrs = vec(_str.buf(prog));
+    auto argptrs = vec(Str.buf(prog));
     for (str arg in args) {
-        _vec.push[sbuf](argptrs, _str.buf(arg));
+        Vec.push[sbuf](argptrs, Str.buf(arg));
     }
-    _vec.push[sbuf](argptrs, 0 as sbuf);
+    Vec.push[sbuf](argptrs, 0 as sbuf);
     ret argptrs;
 }
 
 fn run_program(str prog, vec[str] args) -> int {
-    auto pid = rustrt.rust_run_program(_vec.buf[sbuf](argvec(prog, args)),
+    auto pid = rustrt.rust_run_program(Vec.buf[sbuf](argvec(prog, args)),
                                        0, 0, 0);
-    ret os.waitpid(pid);
+    ret OS.waitpid(pid);
 }
 
 type program =
     state obj {
         fn get_id() -> int;
-        fn input() -> io.writer;
-        fn output() -> io.reader;
+        fn input() -> IO.writer;
+        fn output() -> IO.reader;
         fn close_input();
         fn finish() -> int;
     };
 
 fn start_program(str prog, vec[str] args) -> @program {
-    auto pipe_input = os.pipe();
-    auto pipe_output = os.pipe();
+    auto pipe_input = OS.pipe();
+    auto pipe_output = OS.pipe();
     auto pid = rustrt.rust_run_program
-        (_vec.buf[sbuf](argvec(prog, args)),
+        (Vec.buf[sbuf](argvec(prog, args)),
          pipe_input._0, pipe_output._1, 0);
     if (pid == -1) {fail;}
-    os.libc.close(pipe_input._0);
-    os.libc.close(pipe_output._1);
+    OS.libc.close(pipe_input._0);
+    OS.libc.close(pipe_output._1);
 
     state obj new_program(int pid,
                           int in_fd,
-                          os.libc.FILE out_file,
+                          OS.libc.FILE out_file,
                           mutable bool finished) {
         fn get_id() -> int {ret pid;}
-        fn input() -> io.writer {
-            ret io.new_writer(io.fd_buf_writer(in_fd, false));
+        fn input() -> IO.writer {
+            ret IO.new_writer(IO.fd_buf_writer(in_fd, false));
         }
-        fn output() -> io.reader {
-            ret io.new_reader(io.FILE_buf_reader(out_file, false));
+        fn output() -> IO.reader {
+            ret IO.new_reader(IO.FILE_buf_reader(out_file, false));
         }
         fn close_input() {
-            os.libc.close(in_fd);
+            OS.libc.close(in_fd);
         }
         fn finish() -> int {
             if (finished) {ret 0;}
             finished = true;
-            os.libc.close(in_fd);
-            ret os.waitpid(pid);
+            OS.libc.close(in_fd);
+            ret OS.waitpid(pid);
         }
         drop {
             if (!finished) {
-                os.libc.close(in_fd);
-                os.waitpid(pid);
+                OS.libc.close(in_fd);
+                OS.waitpid(pid);
             }
-            os.libc.fclose(out_file);
+            OS.libc.fclose(out_file);
         }
     }
     ret @new_program(pid, pipe_input._1,
-                     os.fd_FILE(pipe_output._0),
+                     OS.fd_FILE(pipe_output._0),
                      false);
 }
 
@@ -80,7 +80,7 @@ fn program_output(str prog, vec[str] args)
     auto buf = "";
     while (!out.eof()) {
         auto bytes = out.read_bytes(4096u);
-        buf += _str.unsafe_from_bytes(bytes);
+        buf += Str.unsafe_from_bytes(bytes);
     }
     ret rec(status=pr.finish(), out=buf);
 }
diff --git a/src/lib/sha1.rs b/src/lib/SHA1.rs
index e84787a23d7..b6ac0521f14 100644
--- a/src/lib/sha1.rs
+++ b/src/lib/SHA1.rs
@@ -67,7 +67,7 @@ fn mk_sha1() -> sha1 {
     fn process_msg_block(&sha1state st) {
 
         // FIXME: Make precondition
-        assert (_vec.len(st.h) == digest_buf_len);
+        assert (Vec.len(st.h) == digest_buf_len);
 
         // Constants
         auto k = vec(0x5A827999u32,
@@ -76,7 +76,7 @@ fn mk_sha1() -> sha1 {
                      0xCA62C1D6u32);
 
         let int t; // Loop counter
-        let vec[mutable u32] w = _vec.init_elt_mut[u32](0u32, 80u);
+        let vec[mutable u32] w = Vec.init_elt_mut[u32](0u32, 80u);
 
         // Initialize the first 16 words of the vector w
         t = 0;
@@ -192,7 +192,7 @@ fn mk_sha1() -> sha1 {
      */
     fn pad_msg(&sha1state st) {
         // FIXME: Should be a precondition
-        assert (_vec.len(st.msg_block) == msg_block_len);
+        assert (Vec.len(st.msg_block) == msg_block_len);
 
         /*
          * Check to see if the current message block is too small to hold
@@ -236,7 +236,7 @@ fn mk_sha1() -> sha1 {
 
         fn reset() {
             // FIXME: Should be typestate precondition
-            assert (_vec.len(st.h) == digest_buf_len);
+            assert (Vec.len(st.h) == digest_buf_len);
 
             st.len_low = 0u32;
             st.len_high = 0u32;
@@ -256,7 +256,7 @@ fn mk_sha1() -> sha1 {
         }
 
         fn input_str(&str msg) {
-            add_input(st, _str.bytes(msg));
+            add_input(st, Str.bytes(msg));
         }
 
         fn result() -> vec[u8] {
@@ -267,16 +267,16 @@ fn mk_sha1() -> sha1 {
             auto r = mk_result(st);
             auto s = "";
             for (u8 b in r) {
-                s += _uint.to_str(b as uint, 16u);
+                s += UInt.to_str(b as uint, 16u);
             }
             ret s;
         }
     }
 
-    auto st = rec(h = _vec.init_elt_mut[u32](0u32, digest_buf_len),
+    auto st = rec(h = Vec.init_elt_mut[u32](0u32, digest_buf_len),
                   mutable len_low = 0u32,
                   mutable len_high = 0u32,
-                  msg_block = _vec.init_elt_mut[u8](0u8, msg_block_len),
+                  msg_block = Vec.init_elt_mut[u8](0u8, msg_block_len),
                   mutable msg_block_idx = 0u,
                   mutable computed = false);
     auto sh = sha1(st);
diff --git a/src/lib/sort.rs b/src/lib/Sort.rs
index f712d22e621..7ecaaaba0cf 100644
--- a/src/lib/sort.rs
+++ b/src/lib/Sort.rs
@@ -1,5 +1,5 @@
-import _vec.len;
-import _vec.slice;
+import Vec.len;
+import Vec.slice;
 
 type lteq[T] = fn(&T a, &T b) -> bool;
 
diff --git a/src/lib/_str.rs b/src/lib/Str.rs
index 5239afb1fea..3886ee19164 100644
--- a/src/lib/_str.rs
+++ b/src/lib/Str.rs
@@ -1,6 +1,6 @@
 import rustrt.sbuf;
 
-import _vec.rustrt.vbuf;
+import Vec.rustrt.vbuf;
 
 native "rust" mod rustrt {
     type sbuf;
@@ -83,7 +83,7 @@ const uint tag_six_b = 0xfc_u;
 
 fn is_utf8(vec[u8] v) -> bool {
     auto i = 0u;
-    auto total = _vec.len[u8](v);
+    auto total = Vec.len[u8](v);
     while (i < total) {
         auto chsize = utf8_char_width(v.(i));
         if (chsize == 0u) {ret false;}
@@ -261,7 +261,7 @@ fn to_chars(str s) -> vec[char] {
     auto len = byte_len(s);
     while (i < len) {
         auto cur = char_range_at(s, i);
-        _vec.push[char](buf, cur._0);
+        Vec.push[char](buf, cur._0);
         i = cur._1;
     }
     ret buf;
@@ -296,7 +296,7 @@ fn unshift_char(&mutable str s, char ch) {
 
 fn refcount(str s) -> uint {
     auto r = rustrt.refcount[u8](s);
-    if (r == dbg.const_refcount) {
+    if (r == Dbg.const_refcount) {
         ret r;
     } else {
         // -1 because calling this function incremented the refcount.
@@ -319,7 +319,7 @@ fn index(str s, u8 c) -> int {
 }
 
 fn rindex(str s, u8 c) -> int {
-    let int n = _str.byte_len(s) as int;
+    let int n = Str.byte_len(s) as int;
     while (n >= 0) {
         if (s.(n) == c) {
             ret n;
@@ -443,7 +443,7 @@ fn split(str s, u8 sep) -> vec[str] {
             ends_with_sep = false;
         }
     }
-    if (_str.byte_len(accum) != 0u ||
+    if (Str.byte_len(accum) != 0u ||
         ends_with_sep) {
         v += vec(accum);
     }
diff --git a/src/lib/sys.rs b/src/lib/Sys.rs
index 77eab003573..77eab003573 100644
--- a/src/lib/sys.rs
+++ b/src/lib/Sys.rs
diff --git a/src/lib/_task.rs b/src/lib/Task.rs
index 8eece16b508..8eece16b508 100644
--- a/src/lib/_task.rs
+++ b/src/lib/Task.rs
diff --git a/src/lib/Term.rs b/src/lib/Term.rs
index 368fe21710e..fca04bffb56 100644
--- a/src/lib/Term.rs
+++ b/src/lib/Term.rs
@@ -21,20 +21,20 @@ const u8 color_bright_magenta = 13u8;
 const u8 color_bright_cyan = 14u8;
 const u8 color_bright_white = 15u8;
 
-fn esc(io.buf_writer writer) {
+fn esc(IO.buf_writer writer) {
     writer.write(vec(0x1bu8, '[' as u8));
 }
 
-fn reset(io.buf_writer writer) {
+fn reset(IO.buf_writer writer) {
     esc(writer);
     writer.write(vec('0' as u8, 'm' as u8));
 }
 
 fn color_supported() -> bool {
-    ret _str.eq(GenericOS.getenv("TERM"), "xterm-color");
+    ret Str.eq(GenericOS.getenv("TERM"), "xterm-color");
 }
 
-fn set_color(io.buf_writer writer, u8 first_char, u8 color) {
+fn set_color(IO.buf_writer writer, u8 first_char, u8 color) {
     assert (color < 16u8);
 
     esc(writer);
@@ -45,11 +45,11 @@ fn set_color(io.buf_writer writer, u8 first_char, u8 color) {
     writer.write(vec(first_char, ('0' as u8) + color, 'm' as u8));
 }
 
-fn fg(io.buf_writer writer, u8 color) {
+fn fg(IO.buf_writer writer, u8 color) {
     ret set_color(writer, '3' as u8, color);
 }
 
-fn bg(io.buf_writer writer, u8 color) {
+fn bg(IO.buf_writer writer, u8 color) {
     ret set_color(writer, '4' as u8, color);
 }
 
diff --git a/src/lib/_u8.rs b/src/lib/U8.rs
index e094e5812bd..e094e5812bd 100644
--- a/src/lib/_u8.rs
+++ b/src/lib/U8.rs
diff --git a/src/lib/UFind.rs b/src/lib/UFind.rs
index 9593e787e0d..0bb06d7cfb8 100644
--- a/src/lib/UFind.rs
+++ b/src/lib/UFind.rs
@@ -1,19 +1,19 @@
-import option.none;
-import option.some;
+import Option.none;
+import Option.some;
 
 // A very naive implementation of union-find with unsigned integer nodes.
 
-type node = option.t[uint];
+type node = Option.t[uint];
 type ufind = rec(mutable vec[mutable node] nodes);
 
 fn make() -> ufind {
     let vec[mutable node] v = vec(mutable none[uint]);
-    _vec.pop(v);  // FIXME: botch
+    Vec.pop(v);  // FIXME: botch
     ret rec(mutable nodes=v);
 }
 
 fn make_set(&ufind ufnd) -> uint {
-    auto idx = _vec.len(ufnd.nodes);
+    auto idx = Vec.len(ufnd.nodes);
     ufnd.nodes += vec(mutable none[uint]);
     ret idx;
 }
diff --git a/src/lib/_uint.rs b/src/lib/UInt.rs
index 2d373cdd2ba..eea52325694 100644
--- a/src/lib/_uint.rs
+++ b/src/lib/UInt.rs
@@ -23,7 +23,7 @@ iter range(uint lo, uint hi) -> uint {
 fn next_power_of_two(uint n) -> uint {
     // FIXME change |* uint(4)| below to |* uint(8) / uint(2)| and watch the
     // world explode.
-    let uint halfbits = sys.rustrt.size_of[uint]() * 4u;
+    let uint halfbits = Sys.rustrt.size_of[uint]() * 4u;
     let uint tmp = n - 1u;
     let uint shift = 1u;
     while (shift <= halfbits) {
@@ -34,12 +34,12 @@ fn next_power_of_two(uint n) -> uint {
 }
 
 fn parse_buf(vec[u8] buf, uint radix) -> uint {
-    if (_vec.len[u8](buf) == 0u) {
+    if (Vec.len[u8](buf) == 0u) {
         log_err "parse_buf(): buf is empty";
         fail;
     }
 
-    auto i = _vec.len[u8](buf) - 1u;
+    auto i = Vec.len[u8](buf) - 1u;
     auto power = 1u;
     auto n = 0u;
     while (true) {
@@ -83,15 +83,15 @@ fn to_str(uint num, uint radix) -> str
 
     let str s = "";
     while (n != 0u) {
-        s += _str.unsafe_from_byte(digit(n % radix) as u8);
+        s += Str.unsafe_from_byte(digit(n % radix) as u8);
         n /= radix;
     }
 
     let str s1 = "";
-    let uint len = _str.byte_len(s);
+    let uint len = Str.byte_len(s);
     while (len != 0u) {
         len -= 1u;
-        s1 += _str.unsafe_from_byte(s.(len));
+        s1 += Str.unsafe_from_byte(s.(len));
     }
     ret s1;
 
diff --git a/src/lib/util.rs b/src/lib/Util.rs
index 2f797f69216..a385aafda64 100644
--- a/src/lib/util.rs
+++ b/src/lib/Util.rs
@@ -4,7 +4,7 @@ fn id[T](&T x) -> T {
 
 /* FIXME (issue #141):  See test/run-pass/constrained-type.rs.  Uncomment
  * the constraint once fixed. */
-type rational = rec(int num, int den); // : _int.positive(*.den);
+type rational = rec(int num, int den); // : Int.positive(*.den);
 
 fn rational_leq(&rational x, &rational y) -> bool {
     // NB: Uses the fact that rationals have positive denominators WLOG.
diff --git a/src/lib/_vec.rs b/src/lib/Vec.rs
index 3a197ac24bf..28b5d018d54 100644
--- a/src/lib/_vec.rs
+++ b/src/lib/Vec.rs
@@ -1,6 +1,6 @@
-import option.none;
-import option.some;
-import util.orb;
+import Option.none;
+import Option.some;
+import Util.orb;
 
 type vbuf = rustrt.vbuf;
 
@@ -47,7 +47,7 @@ fn alloc_mut[T](uint n_elts) -> vec[mutable T] {
 
 fn refcount[T](array[T] v) -> uint {
     auto r = rustrt.refcount[T](v);
-    if (r == dbg.const_refcount) {
+    if (r == Dbg.const_refcount) {
         ret r;
     } else {
         // -1 because calling this function incremented the refcount.
@@ -140,7 +140,7 @@ fn print_debug_info[T](array[T] v) {
 }
 
 // Returns the last element of v.
-fn last[T](array[T] v) -> option.t[T] {
+fn last[T](array[T] v) -> Option.t[T] {
     auto l = len[T](v);
     if (l == 0u) {
         ret none[T];
@@ -199,14 +199,14 @@ fn grow[T](&array[T] v, uint n, &T initval) {
 }
 
 fn grow_set[T](&vec[mutable T] v, uint index, &T initval, &T val) {
-    auto length = _vec.len(v);
+    auto length = Vec.len(v);
     if (index >= length) {
         grow(v, index - length + 1u, initval);
     }
     v.(index) = val;
 }
 
-fn map[T, U](&option.operator[T,U] f, &array[T] v) -> vec[U] {
+fn map[T, U](&Option.operator[T,U] f, &array[T] v) -> vec[U] {
     let vec[U] u = alloc[U](len[T](v));
     for (T ve in v) {
         u += vec(f(ve));
@@ -230,7 +230,7 @@ fn map2[T,U,V](&operator2[T,U,V] f, &array[T] v0, &array[U] v1) -> vec[V] {
     ret u;
 }
 
-fn find[T](fn (&T) -> bool f, &array[T] v) -> option.t[T] {
+fn find[T](fn (&T) -> bool f, &array[T] v) -> Option.t[T] {
     for (T elt in v) {
         if (f(elt)) {
             ret some[T](elt);
@@ -270,24 +270,24 @@ fn unzip[T, U](&vec[tup(T, U)] v) -> tup(vec[T], vec[U]) {
 
 fn or(&vec[bool] v) -> bool {
     auto f = orb;
-    ret _vec.foldl[bool, bool](f, false, v);
+    ret Vec.foldl[bool, bool](f, false, v);
 }
 
 fn clone[T](&vec[T] v) -> vec[T] {
     ret slice[T](v, 0u, len[T](v));
 }
 
-fn plus_option[T](&vec[T] v, &option.t[T] o) -> () {
+fn plus_option[T](&vec[T] v, &Option.t[T] o) -> () {
     alt (o) {
         case (none[T]) {}
         case (some[T](?x)) { v += vec(x); }
     }
 }
 
-fn cat_options[T](&vec[option.t[T]] v) -> vec[T] {
+fn cat_options[T](&vec[Option.t[T]] v) -> vec[T] {
     let vec[T] res = vec();
 
-    for (option.t[T] o in v) {
+    for (Option.t[T] o in v) {
         alt (o) {
             case (none[T]) { }
             case (some[T](?t)) {
diff --git a/src/lib/linux_os.rs b/src/lib/linux_OS.rs
index a37db418109..02c9183bded 100644
--- a/src/lib/linux_os.rs
+++ b/src/lib/linux_OS.rs
@@ -1,5 +1,5 @@
-import _str.sbuf;
-import _vec.vbuf;
+import Str.sbuf;
+import Vec.vbuf;
 
 // FIXME Somehow merge stuff duplicated here and macosx_os.rs. Made difficult
 // by https://github.com/graydon/rust/issues#issue/268
@@ -66,17 +66,17 @@ fn dylib_filename(str base) -> str {
 
 fn pipe() -> tup(int, int) {
     let vec[mutable int] fds = vec(mutable 0, 0);
-    assert (os.libc.pipe(_vec.buf(fds)) == 0);
+    assert (OS.libc.pipe(Vec.buf(fds)) == 0);
     ret tup(fds.(0), fds.(1));
 }
 
 fn fd_FILE(int fd) -> libc.FILE {
-    ret libc.fdopen(fd, _str.buf("r"));
+    ret libc.fdopen(fd, Str.buf("r"));
 }
 
 fn waitpid(int pid) -> int {
     let vec[mutable int] status = vec(mutable 0);
-    assert (os.libc.waitpid(pid, _vec.buf(status), 0) != -1);
+    assert (OS.libc.waitpid(pid, Vec.buf(status), 0) != -1);
     ret status.(0);
 }
 
diff --git a/src/lib/macos_os.rs b/src/lib/macos_OS.rs
index a52b02c5658..700ac17c7b6 100644
--- a/src/lib/macos_os.rs
+++ b/src/lib/macos_OS.rs
@@ -1,5 +1,5 @@
-import _str.sbuf;
-import _vec.vbuf;
+import Str.sbuf;
+import Vec.vbuf;
 
 native mod libc = "libc.dylib" {
 
@@ -63,17 +63,17 @@ fn dylib_filename(str base) -> str {
 
 fn pipe() -> tup(int, int) {
     let vec[mutable int] fds = vec(mutable 0, 0);
-    assert (os.libc.pipe(_vec.buf[mutable int](fds)) == 0);
+    assert (OS.libc.pipe(Vec.buf[mutable int](fds)) == 0);
     ret tup(fds.(0), fds.(1));
 }
 
 fn fd_FILE(int fd) -> libc.FILE {
-    ret libc.fdopen(fd, _str.buf("r"));
+    ret libc.fdopen(fd, Str.buf("r"));
 }
 
 fn waitpid(int pid) -> int {
     let vec[mutable int] status = vec(mutable 0);
-    assert (os.libc.waitpid(pid, _vec.buf[mutable int](status), 0) != -1);
+    assert (OS.libc.waitpid(pid, Vec.buf[mutable int](status), 0) != -1);
     ret status.(0);
 }
 
diff --git a/src/lib/posix_fs.rs b/src/lib/posix_FS.rs
index 99f411e7343..b1f01a66414 100644
--- a/src/lib/posix_fs.rs
+++ b/src/lib/posix_FS.rs
@@ -1,21 +1,21 @@
 native "rust" mod rustrt {
-  fn rust_dirent_filename(os.libc.dirent ent) -> str;
+  fn rust_dirent_filename(OS.libc.dirent ent) -> str;
 }
 
 fn list_dir(str path) -> vec[str] {
   // TODO ensure this is always closed
-  auto dir = os.libc.opendir(_str.buf(path));
+  auto dir = OS.libc.opendir(Str.buf(path));
   assert (dir as uint != 0u);
   let vec[str] result = vec();
   while (true) {
-    auto ent = os.libc.readdir(dir);
+    auto ent = OS.libc.readdir(dir);
     if (ent as int == 0) {
-        os.libc.closedir(dir);
+        OS.libc.closedir(dir);
         ret result;
     }
-    _vec.push[str](result, rustrt.rust_dirent_filename(ent));
+    Vec.push[str](result, rustrt.rust_dirent_filename(ent));
   }
-  os.libc.closedir(dir);
+  OS.libc.closedir(dir);
   ret result;
 }
 
diff --git a/src/lib/std.rc b/src/lib/std.rc
index 44a0689c09f..a317b1148f7 100644
--- a/src/lib/std.rc
+++ b/src/lib/std.rc
@@ -6,39 +6,38 @@ meta (name = "std",
 
 // Built-in types support modules.
 
-mod _int;
-mod _uint;
-mod _u8;
-mod _vec;
-mod _str;
+mod Int;
+mod UInt;
+mod U8;
+mod Vec;
+mod Str;
 
 // General IO and system-services modules.
 
-mod io;
-mod sys;
-mod _task;
+mod IO;
+mod Sys;
+mod Task;
 
 // Utility modules.
 
-mod option;
-mod util;
+mod Option;
+mod Util;
 
 // Authorize various rule-bendings.
 
-auth io = unsafe;
-auth fs = unsafe;
-auth os = unsafe;
-auth os_fs = unsafe;
-auth run = unsafe;
-auth _str = unsafe;
-auth _vec = unsafe;
-auth _task = unsafe;
+auth IO = unsafe;
+auth FS = unsafe;
+auth OS_FS = unsafe;
+auth Run = unsafe;
+auth Str = unsafe;
+auth Vec = unsafe;
+auth Task = unsafe;
 
-auth dbg = unsafe;
+auth Dbg = unsafe;
 
-auth _uint.next_power_of_two = unsafe;
-auth map.mk_hashmap = unsafe;
-auth rand.mk_rng = unsafe;
+auth UInt.next_power_of_two = unsafe;
+auth Map.mk_hashmap = unsafe;
+auth Rand.mk_rng = unsafe;
 
 // Target-OS module.
 
@@ -47,30 +46,30 @@ mod GenericOS;
 
 alt (target_os) {
     case ("win32") {
-        mod os = "win32_os.rs";
-        mod os_fs = "win32_fs.rs";
+        mod OS = "win32_OS.rs";
+        mod OS_FS = "win32_FS.rs";
     } case ("macos") {
-        mod os = "macos_os.rs";
-        mod os_fs = "posix_fs.rs";
+        mod OS = "macos_OS.rs";
+        mod OS_FS = "posix_FS.rs";
     } else {
-        mod os = "linux_os.rs";
-        mod os_fs = "posix_fs.rs";
+        mod OS = "linux_OS.rs";
+        mod OS_FS = "posix_FS.rs";
     }
 }
 
-mod run = "run_program.rs";
-mod fs;
+mod Run = "Run_Program.rs";
+mod FS;
 
 // FIXME: parametric
-mod map;
-mod deque;
-mod list;
-mod rand;
-mod dbg;
-mod bitv;
-mod sort;
-mod sha1;
-mod ebml;
+mod Map;
+mod Deque;
+mod List;
+mod Rand;
+mod Dbg;
+mod BitV;
+mod Sort;
+mod SHA1;
+mod EBML;
 mod UFind;
 mod ExtFmt;
 mod Box;
diff --git a/src/lib/win32_fs.rs b/src/lib/win32_FS.rs
index 94599e3c3df..94599e3c3df 100644
--- a/src/lib/win32_fs.rs
+++ b/src/lib/win32_FS.rs
diff --git a/src/lib/win32_os.rs b/src/lib/win32_OS.rs
index 1c6521e31f6..b799287c950 100644
--- a/src/lib/win32_os.rs
+++ b/src/lib/win32_OS.rs
@@ -1,5 +1,5 @@
-import _str.sbuf;
-import _vec.vbuf;
+import Str.sbuf;
+import Vec.vbuf;
 
 native mod libc = "msvcrt.dll" {
     fn open(sbuf s, int flags, uint mode) -> int = "_open";
@@ -53,13 +53,13 @@ fn dylib_filename(str base) -> str {
 
 fn pipe() -> tup(int, int) {
     let vec[mutable int] fds = vec(mutable 0, 0);
-    assert (os.libc._pipe(_vec.buf[mutable int](fds), 1024u,
+    assert (OS.libc._pipe(Vec.buf[mutable int](fds), 1024u,
                         libc_constants.O_BINARY()) == 0);
     ret tup(fds.(0), fds.(1));
 }
 
 fn fd_FILE(int fd) -> libc.FILE {
-    ret libc._fdopen(fd, _str.buf("r"));
+    ret libc._fdopen(fd, Str.buf("r"));
 }
 
 native "rust" mod rustrt {
diff --git a/src/test/bench/99-bottles/99bob-iter.rs b/src/test/bench/99-bottles/99bob-iter.rs
index 096389416a8..e8cc4b4bb91 100644
--- a/src/test/bench/99-bottles/99bob-iter.rs
+++ b/src/test/bench/99-bottles/99bob-iter.rs
@@ -3,8 +3,8 @@
  * http://99-bottles-of-beer.net/
  */
 use std;
-import std._int;
-import std._str;
+import std.Int;
+import std.Str;
 
 fn b1() -> str {
   ret "# of beer on the wall, # of beer.";
@@ -32,15 +32,15 @@ case (1) {
     ns = "1 bottle";
   }
  case (_) {
-    ns = _int.to_str(n, 10u) + " bottles";
+    ns = Int.to_str(n, 10u) + " bottles";
   }
   }
-  while (i < _str.byte_len(t)) {
+  while (i < Str.byte_len(t)) {
     if (t.(i) == ('#' as u8)) {
       b += ns;
     }
     else {
-      _str.push_byte(b, t.(i));
+      Str.push_byte(b, t.(i));
     }
     i += 1u;
   }
diff --git a/src/test/bench/99-bottles/99bob-pattern.rs b/src/test/bench/99-bottles/99bob-pattern.rs
index 58d2d2c3e54..fc9ddddb35d 100644
--- a/src/test/bench/99-bottles/99bob-pattern.rs
+++ b/src/test/bench/99-bottles/99bob-pattern.rs
@@ -3,8 +3,8 @@
  * http://99-bottles-of-beer.net/
  */
 use std;
-import std._int;
-import std._str;
+import std.Int;
+import std.Str;
 
 tag bottle { none; dual; single; multiple(int);}
 
@@ -25,8 +25,8 @@ fn show(bottle b) {
       log "Take one down and pass it around, 1 bottle of beer on the wall.";
     }
     case (multiple(?n)) {
-      let str nb =  _int.to_str(n, 10u);
-      let str mb = _int.to_str(n - 1, 10u);
+      let str nb =  Int.to_str(n, 10u);
+      let str mb = Int.to_str(n - 1, 10u);
       log nb + " bottles of beer on the wall, " + nb + " bottles of beer,";
       log "Take one down and pass it around, " 
         + mb + " bottles of beer on the wall.";
diff --git a/src/test/bench/99-bottles/99bob-simple.rs b/src/test/bench/99-bottles/99bob-simple.rs
index 3c426f51036..5c0f0824059 100644
--- a/src/test/bench/99-bottles/99bob-simple.rs
+++ b/src/test/bench/99-bottles/99bob-simple.rs
@@ -3,8 +3,8 @@
  * http://99-bottles-of-beer.net/
  */
 use std;
-import std._int;
-import std._str;
+import std.Int;
+import std.Str;
 
 fn b1() -> str {
   ret "# of beer on the wall, # of beer.";
@@ -31,15 +31,15 @@ case (1) {
     ns = "1 bottle";
   }
  case (_) {
-    ns = _int.to_str(n, 10u) + " bottles";
+    ns = Int.to_str(n, 10u) + " bottles";
   }
   }
-  while (i < _str.byte_len(t)) {
+  while (i < Str.byte_len(t)) {
     if (t.(i) == ('#' as u8)) {
       b += ns;
     }
     else {
-      _str.push_byte(b, t.(i));
+      Str.push_byte(b, t.(i));
     }
     i += 1u;
   }
diff --git a/src/test/bench/99-bottles/99bob-tail.rs b/src/test/bench/99-bottles/99bob-tail.rs
index 16e66d333d3..985d9b4b709 100644
--- a/src/test/bench/99-bottles/99bob-tail.rs
+++ b/src/test/bench/99-bottles/99bob-tail.rs
@@ -3,13 +3,13 @@
  * http://99-bottles-of-beer.net/
  */
 use std;
-import std._int;
-import std._str;
+import std.Int;
+import std.Str;
 
 fn main() {
   fn multiple(int n) {
-    let str nb =  _int.to_str(n, 10u);
-    let str mb =  _int.to_str(n - 1, 10u);
+    let str nb =  Int.to_str(n, 10u);
+    let str mb =  Int.to_str(n - 1, 10u);
     log nb + " bottles of beer on the wall, " + nb + " bottles of beer,";
     log "Take one down and pass it around, " 
       + mb + " bottles of beer on the wall.";
diff --git a/src/test/bench/shootout/binarytrees.rs b/src/test/bench/shootout/binarytrees.rs
index 92bedb8b9e6..aa81aaac31d 100644
--- a/src/test/bench/shootout/binarytrees.rs
+++ b/src/test/bench/shootout/binarytrees.rs
@@ -1,6 +1,6 @@
 use std;
 
-import std._int;
+import std.Int;
 
 tag tree {
   nil;
@@ -49,7 +49,7 @@ fn main() {
 
   auto depth = min_depth;
   while (depth <= max_depth) {
-    auto iterations = _int.pow(2, (max_depth - depth + min_depth) as uint);
+    auto iterations = Int.pow(2, (max_depth - depth + min_depth) as uint);
     auto chk = 0;
 
     auto i = 1;
diff --git a/src/test/bench/shootout/fannkuchredux.rs b/src/test/bench/shootout/fannkuchredux.rs
index 7853a89210b..ad3d7dd253d 100644
--- a/src/test/bench/shootout/fannkuchredux.rs
+++ b/src/test/bench/shootout/fannkuchredux.rs
@@ -2,8 +2,8 @@
 
 use std;
 
-import std._int;
-import std._vec;
+import std.Int;
+import std.Vec;
 
 fn fannkuch(int n) -> int {
 
@@ -12,9 +12,9 @@ fn fannkuch(int n) -> int {
   }
   auto perm1init_ = perm1init; // Rustboot workaround
 
-  auto perm = _vec.init_elt[mutable int](0, n as uint);
-  auto perm1 = _vec.init_fn[mutable int](perm1init_, n as uint);
-  auto count = _vec.init_elt[mutable int](0, n as uint);
+  auto perm = Vec.init_elt[mutable int](0, n as uint);
+  auto perm1 = Vec.init_fn[mutable int](perm1init_, n as uint);
+  auto count = Vec.init_elt[mutable int](0, n as uint);
 
   auto f = 0;
   auto i = 0;
diff --git a/src/test/bench/shootout/fasta.rs b/src/test/bench/shootout/fasta.rs
index 7afa1a7a8d6..3543c298754 100644
--- a/src/test/bench/shootout/fasta.rs
+++ b/src/test/bench/shootout/fasta.rs
@@ -7,10 +7,10 @@
  * http://shootout.alioth.debian.org/
  */
 use std;
-import std._vec;
-import std._str;
-import std._uint;
-import std._int;
+import std.Vec;
+import std.Str;
+import std.UInt;
+import std.Int;
 
 fn LINE_LENGTH() -> uint {
   ret 60u;
@@ -54,21 +54,21 @@ fn select_random(u32 r, vec[aminoacids] genelist) -> char {
       ret v.(hi)._0;
     }
   }
-  ret bisect(genelist, 0u, _vec.len[aminoacids](genelist) - 1u, r);
+  ret bisect(genelist, 0u, Vec.len[aminoacids](genelist) - 1u, r);
 }
 
 fn make_random_fasta(str id, str desc, vec[aminoacids] genelist, int n) {
   log(">" + id + " " + desc);
-  auto rng = myrandom(std.rand.mk_rng().next());
+  auto rng = myrandom(std.Rand.mk_rng().next());
   let str op = "";
-  for each (uint i in _uint.range(0u, n as uint)) {
-    _str.push_byte(op, select_random(rng.next(100u32), genelist) as u8);
-    if (_str.byte_len(op) >= LINE_LENGTH()) {
+  for each (uint i in UInt.range(0u, n as uint)) {
+    Str.push_byte(op, select_random(rng.next(100u32), genelist) as u8);
+    if (Str.byte_len(op) >= LINE_LENGTH()) {
       log(op);
       op = "";
     }
   }
-  if (_str.byte_len(op) > 0u) {
+  if (Str.byte_len(op) > 0u) {
     log(op);
   }
 }
@@ -76,16 +76,16 @@ fn make_random_fasta(str id, str desc, vec[aminoacids] genelist, int n) {
 fn make_repeat_fasta(str id, str desc, str s, int n) {
   log(">" + id + " " + desc);
   let str op = "";
-  let uint sl = _str.byte_len(s);
-  for each (uint i in _uint.range(0u, n as uint)) {
+  let uint sl = Str.byte_len(s);
+  for each (uint i in UInt.range(0u, n as uint)) {
 
-    _str.push_byte(op, s.(i % sl));
-    if (_str.byte_len(op) >= LINE_LENGTH()) {
+    Str.push_byte(op, s.(i % sl));
+    if (Str.byte_len(op) >= LINE_LENGTH()) {
       log(op);
       op = "";
     }
   }
-  if (_str.byte_len(op) > 0u) {
+  if (Str.byte_len(op) > 0u) {
     log(op);
   }
 }
diff --git a/src/test/run-pass/alt-join.rs b/src/test/run-pass/alt-join.rs
index 152fac5d7bc..8f45e6ff5ac 100644
--- a/src/test/run-pass/alt-join.rs
+++ b/src/test/run-pass/alt-join.rs
@@ -1,10 +1,10 @@
 use std;
-import std.option;
-import std.option.t;
-import std.option.none;
-import std.option.some;
+import std.Option;
+import std.Option.t;
+import std.Option.none;
+import std.Option.some;
 
-fn foo[T](&option.t[T] y) {
+fn foo[T](&Option.t[T] y) {
   let int x;
   
   let vec[int] res = vec();
diff --git a/src/test/run-pass/alt-pattern-drop.rs b/src/test/run-pass/alt-pattern-drop.rs
index b92ffd7481b..76e7c3aa18d 100644
--- a/src/test/run-pass/alt-pattern-drop.rs
+++ b/src/test/run-pass/alt-pattern-drop.rs
@@ -1,9 +1,9 @@
 // -*- rust -*-
 
 use std;
-import std._str;
+import std.Str;
 
-// FIXME: import std.dbg.const_refcount. Currently
+// FIXME: import std.Dbg.const_refcount. Currently
 // cross-crate const references don't work.
 const uint const_refcount = 0x7bad_face_u;
 
@@ -20,13 +20,13 @@ fn foo(str s) {
     case (_) { log "?"; fail; }
   }
 
-  log _str.refcount(s);
-  assert (_str.refcount(s) == const_refcount);
+  log Str.refcount(s);
+  assert (Str.refcount(s) == const_refcount);
 }
 
 fn main() {
   let str s = "hi";     // ref up
   foo(s);               // ref up then down
-  log _str.refcount(s);
-  assert (_str.refcount(s) == const_refcount);
+  log Str.refcount(s);
+  assert (Str.refcount(s) == const_refcount);
 }
diff --git a/src/test/run-pass/lib-bitv.rs b/src/test/run-pass/lib-bitv.rs
index 8f2d939005c..b047f47a5cb 100644
--- a/src/test/run-pass/lib-bitv.rs
+++ b/src/test/run-pass/lib-bitv.rs
@@ -1,132 +1,132 @@
 use std;
-import std._vec;
-import std.bitv;
+import std.Vec;
+import std.BitV;
 
 fn test_0_elements() {
   auto act;
   auto exp;
 
-  act = bitv.create(0u, false);
-  exp = _vec.init_elt[uint](0u, 0u);
+  act = BitV.create(0u, false);
+  exp = Vec.init_elt[uint](0u, 0u);
   // FIXME: why can't I write vec[uint]()?
-  assert (bitv.eq_vec(act, exp));
+  assert (BitV.eq_vec(act, exp));
 }
 
 fn test_1_element() {
   auto act;
 
-  act = bitv.create(1u, false);
-  assert (bitv.eq_vec(act, vec(0u)));
+  act = BitV.create(1u, false);
+  assert (BitV.eq_vec(act, vec(0u)));
 
-  act = bitv.create(1u, true);
-  assert (bitv.eq_vec(act, vec(1u)));
+  act = BitV.create(1u, true);
+  assert (BitV.eq_vec(act, vec(1u)));
 }
 
 fn test_10_elements() {
   auto act;
 
   // all 0
-  act = bitv.create(10u, false);
-  assert (bitv.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u)));
+  act = BitV.create(10u, false);
+  assert (BitV.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u)));
 
   // all 1
-  act = bitv.create(10u, true);
-  assert (bitv.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u)));
+  act = BitV.create(10u, true);
+  assert (BitV.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u)));
 
   // mixed
-  act = bitv.create(10u, false);
-  bitv.set(act, 0u, true);
-  bitv.set(act, 1u, true);
-  bitv.set(act, 2u, true);
-  bitv.set(act, 3u, true);
-  bitv.set(act, 4u, true);
-  assert (bitv.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 0u, 0u, 0u, 0u, 0u)));
+  act = BitV.create(10u, false);
+  BitV.set(act, 0u, true);
+  BitV.set(act, 1u, true);
+  BitV.set(act, 2u, true);
+  BitV.set(act, 3u, true);
+  BitV.set(act, 4u, true);
+  assert (BitV.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 0u, 0u, 0u, 0u, 0u)));
 
   // mixed
-  act = bitv.create(10u, false);
-  bitv.set(act, 5u, true);
-  bitv.set(act, 6u, true);
-  bitv.set(act, 7u, true);
-  bitv.set(act, 8u, true);
-  bitv.set(act, 9u, true);
-  assert (bitv.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 1u, 1u, 1u, 1u, 1u)));
+  act = BitV.create(10u, false);
+  BitV.set(act, 5u, true);
+  BitV.set(act, 6u, true);
+  BitV.set(act, 7u, true);
+  BitV.set(act, 8u, true);
+  BitV.set(act, 9u, true);
+  assert (BitV.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 1u, 1u, 1u, 1u, 1u)));
 
   // mixed
-  act = bitv.create(10u, false);
-  bitv.set(act, 0u, true);
-  bitv.set(act, 3u, true);
-  bitv.set(act, 6u, true);
-  bitv.set(act, 9u, true);
-  assert (bitv.eq_vec(act, vec(1u, 0u, 0u, 1u, 0u, 0u, 1u, 0u, 0u, 1u)));
+  act = BitV.create(10u, false);
+  BitV.set(act, 0u, true);
+  BitV.set(act, 3u, true);
+  BitV.set(act, 6u, true);
+  BitV.set(act, 9u, true);
+  assert (BitV.eq_vec(act, vec(1u, 0u, 0u, 1u, 0u, 0u, 1u, 0u, 0u, 1u)));
 }
 
 fn test_31_elements() {
   auto act;
 
   // all 0
-  act = bitv.create(31u, false);
-  assert (bitv.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
+  act = BitV.create(31u, false);
+  assert (BitV.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u)));
 
   // all 1
-  act = bitv.create(31u, true);
-  assert (bitv.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
+  act = BitV.create(31u, true);
+  assert (BitV.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               1u, 1u, 1u, 1u, 1u, 1u, 1u)));
 
   // mixed
-  act = bitv.create(31u, false);
-  bitv.set(act, 0u, true);
-  bitv.set(act, 1u, true);
-  bitv.set(act, 2u, true);
-  bitv.set(act, 3u, true);
-  bitv.set(act, 4u, true);
-  bitv.set(act, 5u, true);
-  bitv.set(act, 6u, true);
-  bitv.set(act, 7u, true);
-  assert (bitv.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
+  act = BitV.create(31u, false);
+  BitV.set(act, 0u, true);
+  BitV.set(act, 1u, true);
+  BitV.set(act, 2u, true);
+  BitV.set(act, 3u, true);
+  BitV.set(act, 4u, true);
+  BitV.set(act, 5u, true);
+  BitV.set(act, 6u, true);
+  BitV.set(act, 7u, true);
+  assert (BitV.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u)));
 
   // mixed
-  act = bitv.create(31u, false);
-  bitv.set(act, 16u, true);
-  bitv.set(act, 17u, true);
-  bitv.set(act, 18u, true);
-  bitv.set(act, 19u, true);
-  bitv.set(act, 20u, true);
-  bitv.set(act, 21u, true);
-  bitv.set(act, 22u, true);
-  bitv.set(act, 23u, true);
-  assert (bitv.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
+  act = BitV.create(31u, false);
+  BitV.set(act, 16u, true);
+  BitV.set(act, 17u, true);
+  BitV.set(act, 18u, true);
+  BitV.set(act, 19u, true);
+  BitV.set(act, 20u, true);
+  BitV.set(act, 21u, true);
+  BitV.set(act, 22u, true);
+  BitV.set(act, 23u, true);
+  assert (BitV.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u)));
 
   // mixed
-  act = bitv.create(31u, false);
-  bitv.set(act, 24u, true);
-  bitv.set(act, 25u, true);
-  bitv.set(act, 26u, true);
-  bitv.set(act, 27u, true);
-  bitv.set(act, 28u, true);
-  bitv.set(act, 29u, true);
-  bitv.set(act, 30u, true);
-  assert (bitv.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
+  act = BitV.create(31u, false);
+  BitV.set(act, 24u, true);
+  BitV.set(act, 25u, true);
+  BitV.set(act, 26u, true);
+  BitV.set(act, 27u, true);
+  BitV.set(act, 28u, true);
+  BitV.set(act, 29u, true);
+  BitV.set(act, 30u, true);
+  assert (BitV.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               1u, 1u, 1u, 1u, 1u, 1u, 1u)));
 
   // mixed
-  act = bitv.create(31u, false);
-  bitv.set(act, 3u, true);
-  bitv.set(act, 17u, true);
-  bitv.set(act, 30u, true);
-  assert (bitv.eq_vec(act, vec(0u, 0u, 0u, 1u, 0u, 0u, 0u, 0u,
+  act = BitV.create(31u, false);
+  BitV.set(act, 3u, true);
+  BitV.set(act, 17u, true);
+  BitV.set(act, 30u, true);
+  assert (BitV.eq_vec(act, vec(0u, 0u, 0u, 1u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 1u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 1u)));
@@ -136,71 +136,71 @@ fn test_32_elements() {
   auto act;
 
   // all 0
-  act = bitv.create(32u, false);
-  assert (bitv.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
+  act = BitV.create(32u, false);
+  assert (BitV.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u)));
 
   // all 1
-  act = bitv.create(32u, true);
-  assert (bitv.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
+  act = BitV.create(32u, true);
+  assert (BitV.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u)));
 
   // mixed
-  act = bitv.create(32u, false);
-  bitv.set(act, 0u, true);
-  bitv.set(act, 1u, true);
-  bitv.set(act, 2u, true);
-  bitv.set(act, 3u, true);
-  bitv.set(act, 4u, true);
-  bitv.set(act, 5u, true);
-  bitv.set(act, 6u, true);
-  bitv.set(act, 7u, true);
-  assert (bitv.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
+  act = BitV.create(32u, false);
+  BitV.set(act, 0u, true);
+  BitV.set(act, 1u, true);
+  BitV.set(act, 2u, true);
+  BitV.set(act, 3u, true);
+  BitV.set(act, 4u, true);
+  BitV.set(act, 5u, true);
+  BitV.set(act, 6u, true);
+  BitV.set(act, 7u, true);
+  assert (BitV.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u)));
 
   // mixed
-  act = bitv.create(32u, false);
-  bitv.set(act, 16u, true);
-  bitv.set(act, 17u, true);
-  bitv.set(act, 18u, true);
-  bitv.set(act, 19u, true);
-  bitv.set(act, 20u, true);
-  bitv.set(act, 21u, true);
-  bitv.set(act, 22u, true);
-  bitv.set(act, 23u, true);
-  assert (bitv.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
+  act = BitV.create(32u, false);
+  BitV.set(act, 16u, true);
+  BitV.set(act, 17u, true);
+  BitV.set(act, 18u, true);
+  BitV.set(act, 19u, true);
+  BitV.set(act, 20u, true);
+  BitV.set(act, 21u, true);
+  BitV.set(act, 22u, true);
+  BitV.set(act, 23u, true);
+  assert (BitV.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u)));
 
   // mixed
-  act = bitv.create(32u, false);
-  bitv.set(act, 24u, true);
-  bitv.set(act, 25u, true);
-  bitv.set(act, 26u, true);
-  bitv.set(act, 27u, true);
-  bitv.set(act, 28u, true);
-  bitv.set(act, 29u, true);
-  bitv.set(act, 30u, true);
-  bitv.set(act, 31u, true);
-  assert (bitv.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
+  act = BitV.create(32u, false);
+  BitV.set(act, 24u, true);
+  BitV.set(act, 25u, true);
+  BitV.set(act, 26u, true);
+  BitV.set(act, 27u, true);
+  BitV.set(act, 28u, true);
+  BitV.set(act, 29u, true);
+  BitV.set(act, 30u, true);
+  BitV.set(act, 31u, true);
+  assert (BitV.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u)));
 
   // mixed
-  act = bitv.create(32u, false);
-  bitv.set(act, 3u, true);
-  bitv.set(act, 17u, true);
-  bitv.set(act, 30u, true);
-  bitv.set(act, 31u, true);
-  assert (bitv.eq_vec(act, vec(0u, 0u, 0u, 1u, 0u, 0u, 0u, 0u,
+  act = BitV.create(32u, false);
+  BitV.set(act, 3u, true);
+  BitV.set(act, 17u, true);
+  BitV.set(act, 30u, true);
+  BitV.set(act, 31u, true);
+  assert (BitV.eq_vec(act, vec(0u, 0u, 0u, 1u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 1u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 1u, 1u)));
@@ -210,77 +210,77 @@ fn test_33_elements() {
   auto act;
 
   // all 0
-  act = bitv.create(33u, false);
-  assert (bitv.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
+  act = BitV.create(33u, false);
+  assert (BitV.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u)));
 
   // all 1
-  act = bitv.create(33u, true);
-  assert (bitv.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
+  act = BitV.create(33u, true);
+  assert (BitV.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               1u)));
 
   // mixed
-  act = bitv.create(33u, false);
-  bitv.set(act, 0u, true);
-  bitv.set(act, 1u, true);
-  bitv.set(act, 2u, true);
-  bitv.set(act, 3u, true);
-  bitv.set(act, 4u, true);
-  bitv.set(act, 5u, true);
-  bitv.set(act, 6u, true);
-  bitv.set(act, 7u, true);
-  assert (bitv.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
+  act = BitV.create(33u, false);
+  BitV.set(act, 0u, true);
+  BitV.set(act, 1u, true);
+  BitV.set(act, 2u, true);
+  BitV.set(act, 3u, true);
+  BitV.set(act, 4u, true);
+  BitV.set(act, 5u, true);
+  BitV.set(act, 6u, true);
+  BitV.set(act, 7u, true);
+  assert (BitV.eq_vec(act, vec(1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u)));
 
   // mixed
-  act = bitv.create(33u, false);
-  bitv.set(act, 16u, true);
-  bitv.set(act, 17u, true);
-  bitv.set(act, 18u, true);
-  bitv.set(act, 19u, true);
-  bitv.set(act, 20u, true);
-  bitv.set(act, 21u, true);
-  bitv.set(act, 22u, true);
-  bitv.set(act, 23u, true);
-  assert (bitv.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
+  act = BitV.create(33u, false);
+  BitV.set(act, 16u, true);
+  BitV.set(act, 17u, true);
+  BitV.set(act, 18u, true);
+  BitV.set(act, 19u, true);
+  BitV.set(act, 20u, true);
+  BitV.set(act, 21u, true);
+  BitV.set(act, 22u, true);
+  BitV.set(act, 23u, true);
+  assert (BitV.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u)));
 
   // mixed
-  act = bitv.create(33u, false);
-  bitv.set(act, 24u, true);
-  bitv.set(act, 25u, true);
-  bitv.set(act, 26u, true);
-  bitv.set(act, 27u, true);
-  bitv.set(act, 28u, true);
-  bitv.set(act, 29u, true);
-  bitv.set(act, 30u, true);
-  bitv.set(act, 31u, true);
-  assert (bitv.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
+  act = BitV.create(33u, false);
+  BitV.set(act, 24u, true);
+  BitV.set(act, 25u, true);
+  BitV.set(act, 26u, true);
+  BitV.set(act, 27u, true);
+  BitV.set(act, 28u, true);
+  BitV.set(act, 29u, true);
+  BitV.set(act, 30u, true);
+  BitV.set(act, 31u, true);
+  assert (BitV.eq_vec(act, vec(0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               1u, 1u, 1u, 1u, 1u, 1u, 1u, 1u,
                               0u)));
 
   // mixed
-  act = bitv.create(33u, false);
-  bitv.set(act, 3u, true);
-  bitv.set(act, 17u, true);
-  bitv.set(act, 30u, true);
-  bitv.set(act, 31u, true);
-  bitv.set(act, 32u, true);
-  assert (bitv.eq_vec(act, vec(0u, 0u, 0u, 1u, 0u, 0u, 0u, 0u,
+  act = BitV.create(33u, false);
+  BitV.set(act, 3u, true);
+  BitV.set(act, 17u, true);
+  BitV.set(act, 30u, true);
+  BitV.set(act, 31u, true);
+  BitV.set(act, 32u, true);
+  assert (BitV.eq_vec(act, vec(0u, 0u, 0u, 1u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 1u, 0u, 0u, 0u, 0u, 0u, 0u,
                               0u, 0u, 0u, 0u, 0u, 0u, 1u, 1u,
diff --git a/src/test/run-pass/lib-deque.rs b/src/test/run-pass/lib-deque.rs
index 405ab72be20..9de238dc8f7 100644
--- a/src/test/run-pass/lib-deque.rs
+++ b/src/test/run-pass/lib-deque.rs
@@ -1,10 +1,10 @@
 // -*- rust -*-
 
 use std;
-import std.deque;
+import std.Deque;
 
 fn test_simple() {
-  let deque.t[int] d = deque.create[int]();
+  let Deque.t[int] d = Deque.create[int]();
   assert (d.size() == 0u);
   d.add_front(17);
   d.add_front(42);
@@ -57,7 +57,7 @@ fn test_simple() {
 }
 
 fn test_boxes(@int a, @int b, @int c, @int d) {
-  let deque.t[@int] deq = deque.create[@int]();
+  let Deque.t[@int] deq = Deque.create[@int]();
   assert (deq.size() == 0u);
   deq.add_front(a);
   deq.add_front(b);
@@ -93,7 +93,7 @@ fn test_boxes(@int a, @int b, @int c, @int d) {
 type eqfn[T] = fn(&T a, &T b) -> bool;
 
 fn test_parameterized[T](eqfn[T] e, &T a, &T b, &T c, &T d) {
-  let deque.t[T] deq = deque.create[T]();
+  let Deque.t[T] deq = Deque.create[T]();
   assert (deq.size() == 0u);
   deq.add_front(a);
   deq.add_front(b);
diff --git a/src/test/run-pass/lib-int.rs b/src/test/run-pass/lib-int.rs
index e4e68351aab..a5a9a2a10ce 100644
--- a/src/test/run-pass/lib-int.rs
+++ b/src/test/run-pass/lib-int.rs
@@ -1,25 +1,25 @@
 use std;
 
-import std._int;
-import std._str.eq;
+import std.Int;
+import std.Str.eq;
 
 fn test_to_str() {
-  assert (eq(_int.to_str(0, 10u), "0"));
-  assert (eq(_int.to_str(1, 10u), "1"));
-  assert (eq(_int.to_str(-1, 10u), "-1"));
-  assert (eq(_int.to_str(255, 16u), "ff"));
-  assert (eq(_int.to_str(100, 10u), "100"));
+  assert (eq(Int.to_str(0, 10u), "0"));
+  assert (eq(Int.to_str(1, 10u), "1"));
+  assert (eq(Int.to_str(-1, 10u), "-1"));
+  assert (eq(Int.to_str(255, 16u), "ff"));
+  assert (eq(Int.to_str(100, 10u), "100"));
 }
 
 fn test_pow() {
-  assert (_int.pow(0, 0u) == 1);
-  assert (_int.pow(0, 1u) == 0);
-  assert (_int.pow(0, 2u) == 0);
-  assert (_int.pow(-1, 0u) == -1);
-  assert (_int.pow(1, 0u) == 1);
-  assert (_int.pow(-3, 2u) == 9);
-  assert (_int.pow(-3, 3u) == -27);
-  assert (_int.pow(4, 9u) == 262144);
+  assert (Int.pow(0, 0u) == 1);
+  assert (Int.pow(0, 1u) == 0);
+  assert (Int.pow(0, 2u) == 0);
+  assert (Int.pow(-1, 0u) == -1);
+  assert (Int.pow(1, 0u) == 1);
+  assert (Int.pow(-3, 2u) == 9);
+  assert (Int.pow(-3, 3u) == -27);
+  assert (Int.pow(4, 9u) == 262144);
 }
 
 fn main() {
diff --git a/src/test/run-pass/lib-io.rs b/src/test/run-pass/lib-io.rs
index 5c97c2f05e8..e124cde3b22 100644
--- a/src/test/run-pass/lib-io.rs
+++ b/src/test/run-pass/lib-io.rs
@@ -5,8 +5,8 @@
 // -*- rust -*-
 
 use std;
-import std.io;
-import std._str;
+import std.IO;
+import std.Str;
 
 fn test_simple(str tmpfilebase) {
   let str tmpfile = tmpfilebase + ".tmp";
@@ -15,14 +15,14 @@ fn test_simple(str tmpfilebase) {
   log frood;
 
   {
-    let io.writer out = io.file_writer(tmpfile, vec(io.create));
+    let IO.writer out = IO.file_writer(tmpfile, vec(IO.create));
     out.write_str(frood);
   }
 
-  let io.reader inp = io.file_reader(tmpfile);
+  let IO.reader inp = IO.file_reader(tmpfile);
   let str frood2 = inp.read_c_str();
   log frood2;
-  assert (_str.eq(frood, frood2));
+  assert (Str.eq(frood, frood2));
 }
 
 fn main(vec[str] argv) {
diff --git a/src/test/run-pass/lib-map.rs b/src/test/run-pass/lib-map.rs
index abd2041e151..1f9560558d9 100644
--- a/src/test/run-pass/lib-map.rs
+++ b/src/test/run-pass/lib-map.rs
@@ -1,31 +1,31 @@
 // -*- rust -*-
 
 use std;
-import std.map;
-import std._str;
-import std._uint;
-import std.util;
+import std.Map;
+import std.Str;
+import std.UInt;
+import std.Util;
 
 fn test_simple() {
   log "*** starting test_simple";
 
   fn eq_uint(&uint x, &uint y) -> bool { ret x == y; }
   fn hash_uint(&uint u) -> uint {
-    // FIXME: can't use std.util.id since we'd be capturing a type param,
+    // FIXME: can't use std.Util.id since we'd be capturing a type param,
     // and presently we can't close items over type params.
     ret u;
   }
 
-  let map.hashfn[uint] hasher_uint = hash_uint;
-  let map.eqfn[uint] eqer_uint = eq_uint;
+  let Map.hashfn[uint] hasher_uint = hash_uint;
+  let Map.eqfn[uint] eqer_uint = eq_uint;
 
-  let map.hashfn[str] hasher_str = _str.hash;
-  let map.eqfn[str] eqer_str = _str.eq;
+  let Map.hashfn[str] hasher_str = Str.hash;
+  let Map.eqfn[str] eqer_str = Str.eq;
 
 
   log "uint -> uint";
 
-  let map.hashmap[uint, uint] hm_uu = map.mk_hashmap[uint, uint](hasher_uint,
+  let Map.hashmap[uint, uint] hm_uu = Map.mk_hashmap[uint, uint](hasher_uint,
                                                                  eqer_uint);
 
   assert (hm_uu.insert(10u, 12u));
@@ -49,7 +49,7 @@ fn test_simple() {
 
   log "str -> uint";
 
-  let map.hashmap[str, uint] hm_su = map.mk_hashmap[str, uint](hasher_str,
+  let Map.hashmap[str, uint] hm_su = Map.mk_hashmap[str, uint](hasher_str,
                                                                eqer_str);
   assert (hm_su.insert("ten", 12u));
   assert (hm_su.insert(eleven, 13u));
@@ -70,42 +70,42 @@ fn test_simple() {
 
   log "uint -> str";
 
-  let map.hashmap[uint, str] hm_us = map.mk_hashmap[uint, str](hasher_uint,
+  let Map.hashmap[uint, str] hm_us = Map.mk_hashmap[uint, str](hasher_uint,
                                                                eqer_uint);
 
   assert (hm_us.insert(10u, "twelve"));
   assert (hm_us.insert(11u, "thirteen"));
   assert (hm_us.insert(12u, "fourteen"));
 
-  assert (_str.eq(hm_us.get(11u), "thirteen"));
-  assert (_str.eq(hm_us.get(12u), "fourteen"));
-  assert (_str.eq(hm_us.get(10u), "twelve"));
+  assert (Str.eq(hm_us.get(11u), "thirteen"));
+  assert (Str.eq(hm_us.get(12u), "fourteen"));
+  assert (Str.eq(hm_us.get(10u), "twelve"));
 
   assert (!hm_us.insert(12u, "fourteen"));
-  assert (_str.eq(hm_us.get(12u), "fourteen"));
+  assert (Str.eq(hm_us.get(12u), "fourteen"));
 
   assert (!hm_us.insert(12u, "twelve"));
-  assert (_str.eq(hm_us.get(12u), "twelve"));
+  assert (Str.eq(hm_us.get(12u), "twelve"));
 
 
   log "str -> str";
 
-  let map.hashmap[str, str] hm_ss = map.mk_hashmap[str, str](hasher_str,
+  let Map.hashmap[str, str] hm_ss = Map.mk_hashmap[str, str](hasher_str,
                                                              eqer_str);
 
   assert (hm_ss.insert(ten, "twelve"));
   assert (hm_ss.insert(eleven, "thirteen"));
   assert (hm_ss.insert(twelve, "fourteen"));
 
-  assert (_str.eq(hm_ss.get("eleven"), "thirteen"));
-  assert (_str.eq(hm_ss.get("twelve"), "fourteen"));
-  assert (_str.eq(hm_ss.get("ten"), "twelve"));
+  assert (Str.eq(hm_ss.get("eleven"), "thirteen"));
+  assert (Str.eq(hm_ss.get("twelve"), "fourteen"));
+  assert (Str.eq(hm_ss.get("ten"), "twelve"));
 
   assert (!hm_ss.insert("twelve", "fourteen"));
-  assert (_str.eq(hm_ss.get("twelve"), "fourteen"));
+  assert (Str.eq(hm_ss.get("twelve"), "fourteen"));
 
   assert (!hm_ss.insert("twelve", "twelve"));
-  assert (_str.eq(hm_ss.get("twelve"), "twelve"));
+  assert (Str.eq(hm_ss.get("twelve"), "twelve"));
 
   log "*** finished test_simple";
 }
@@ -120,7 +120,7 @@ fn test_growth() {
 
   fn eq_uint(&uint x, &uint y) -> bool { ret x == y; }
   fn hash_uint(&uint u) -> uint {
-    // FIXME: can't use std.util.id since we'd be capturing a type param,
+    // FIXME: can't use std.Util.id since we'd be capturing a type param,
     // and presently we can't close items over type params.
     ret u;
   }
@@ -128,16 +128,16 @@ fn test_growth() {
 
   log "uint -> uint";
 
-  let map.hashfn[uint] hasher_uint = hash_uint;
-  let map.eqfn[uint] eqer_uint = eq_uint;
-  let map.hashmap[uint, uint] hm_uu = map.mk_hashmap[uint, uint](hasher_uint,
+  let Map.hashfn[uint] hasher_uint = hash_uint;
+  let Map.eqfn[uint] eqer_uint = eq_uint;
+  let Map.hashmap[uint, uint] hm_uu = Map.mk_hashmap[uint, uint](hasher_uint,
                                                                  eqer_uint);
 
   let uint i = 0u;
   while (i < num_to_insert) {
     assert (hm_uu.insert(i, i * i));
-    log "inserting " + _uint.to_str(i, 10u)
-      + " -> " + _uint.to_str(i * i, 10u);
+    log "inserting " + UInt.to_str(i, 10u)
+      + " -> " + UInt.to_str(i * i, 10u);
     i += 1u;
   }
 
@@ -145,8 +145,8 @@ fn test_growth() {
 
   i = 0u;
   while (i < num_to_insert) {
-    log "get(" + _uint.to_str(i, 10u) + ") = "
-      + _uint.to_str(hm_uu.get(i), 10u);
+    log "get(" + UInt.to_str(i, 10u) + ") = "
+      + UInt.to_str(hm_uu.get(i), 10u);
     assert (hm_uu.get(i) == i * i);
     i += 1u;
   }
@@ -160,8 +160,8 @@ fn test_growth() {
 
   i = 0u;
   while (i < num_to_insert) {
-    log "get(" + _uint.to_str(i, 10u) + ") = "
-      + _uint.to_str(hm_uu.get(i), 10u);
+    log "get(" + UInt.to_str(i, 10u) + ") = "
+      + UInt.to_str(hm_uu.get(i), 10u);
     assert (hm_uu.get(i) == i * i);
     i += 1u;
   }
@@ -169,16 +169,16 @@ fn test_growth() {
 
   log "str -> str";
 
-  let map.hashfn[str] hasher_str = _str.hash;
-  let map.eqfn[str] eqer_str = _str.eq;
-  let map.hashmap[str, str] hm_ss = map.mk_hashmap[str, str](hasher_str,
+  let Map.hashfn[str] hasher_str = Str.hash;
+  let Map.eqfn[str] eqer_str = Str.eq;
+  let Map.hashmap[str, str] hm_ss = Map.mk_hashmap[str, str](hasher_str,
                                                              eqer_str);
 
   i = 0u;
   while (i < num_to_insert) {
-    assert (hm_ss.insert(_uint.to_str(i, 2u), _uint.to_str(i * i, 2u)));
-    log "inserting \"" + _uint.to_str(i, 2u)
-      + "\" -> \"" + _uint.to_str(i * i, 2u) + "\"";
+    assert (hm_ss.insert(UInt.to_str(i, 2u), UInt.to_str(i * i, 2u)));
+    log "inserting \"" + UInt.to_str(i, 2u)
+      + "\" -> \"" + UInt.to_str(i * i, 2u) + "\"";
     i += 1u;
   }
 
@@ -187,20 +187,20 @@ fn test_growth() {
   i = 0u;
   while (i < num_to_insert) {
     log "get(\""
-      + _uint.to_str(i, 2u)
+      + UInt.to_str(i, 2u)
       + "\") = \""
-      + hm_ss.get(_uint.to_str(i, 2u)) + "\"";
+      + hm_ss.get(UInt.to_str(i, 2u)) + "\"";
 
-    assert (_str.eq(hm_ss.get(_uint.to_str(i, 2u)),
-                   _uint.to_str(i * i, 2u)));
+    assert (Str.eq(hm_ss.get(UInt.to_str(i, 2u)),
+                   UInt.to_str(i * i, 2u)));
     i += 1u;
   }
 
-  assert (hm_ss.insert(_uint.to_str(num_to_insert, 2u),
-                      _uint.to_str(17u, 2u)));
+  assert (hm_ss.insert(UInt.to_str(num_to_insert, 2u),
+                      UInt.to_str(17u, 2u)));
 
-  assert (_str.eq(hm_ss.get(_uint.to_str(num_to_insert, 2u)),
-                 _uint.to_str(17u, 2u)));
+  assert (Str.eq(hm_ss.get(UInt.to_str(num_to_insert, 2u)),
+                 UInt.to_str(17u, 2u)));
 
   log "-----";
 
@@ -208,10 +208,10 @@ fn test_growth() {
 
   i = 0u;
   while (i < num_to_insert) {
-    log "get(\"" + _uint.to_str(i, 2u) + "\") = \""
-      + hm_ss.get(_uint.to_str(i, 2u)) + "\"";
-    assert (_str.eq(hm_ss.get(_uint.to_str(i, 2u)),
-                   _uint.to_str(i * i, 2u)));
+    log "get(\"" + UInt.to_str(i, 2u) + "\") = \""
+      + hm_ss.get(UInt.to_str(i, 2u)) + "\"";
+    assert (Str.eq(hm_ss.get(UInt.to_str(i, 2u)),
+                   UInt.to_str(i * i, 2u)));
     i += 1u;
   }
 
@@ -234,15 +234,15 @@ fn test_removal() {
   assert (hash(2u) == hash(3u));
   assert (hash(0u) != hash(2u));
 
-  let map.hashfn[uint] hasher = hash;
-  let map.eqfn[uint] eqer = eq;
-  let map.hashmap[uint, uint] hm = map.mk_hashmap[uint, uint](hasher, eqer);
+  let Map.hashfn[uint] hasher = hash;
+  let Map.eqfn[uint] eqer = eq;
+  let Map.hashmap[uint, uint] hm = Map.mk_hashmap[uint, uint](hasher, eqer);
 
   let uint i = 0u;
   while (i < num_to_insert) {
     assert (hm.insert(i, i * i));
-    log "inserting " + _uint.to_str(i, 10u)
-      + " -> " + _uint.to_str(i * i, 10u);
+    log "inserting " + UInt.to_str(i, 10u)
+      + " -> " + UInt.to_str(i * i, 10u);
     i += 1u;
   }
 
@@ -279,8 +279,8 @@ fn test_removal() {
 
   i = 1u;
   while (i < num_to_insert) {
-    log "get(" + _uint.to_str(i, 10u) + ") = "
-      + _uint.to_str(hm.get(i), 10u);
+    log "get(" + UInt.to_str(i, 10u) + ") = "
+      + UInt.to_str(hm.get(i), 10u);
     assert (hm.get(i) == i * i);
     i += 2u;
   }
@@ -294,8 +294,8 @@ fn test_removal() {
 
   i = 1u;
   while (i < num_to_insert) {
-    log "get(" + _uint.to_str(i, 10u) + ") = "
-      + _uint.to_str(hm.get(i), 10u);
+    log "get(" + UInt.to_str(i, 10u) + ") = "
+      + UInt.to_str(hm.get(i), 10u);
     assert (hm.get(i) == i * i);
     i += 2u;
   }
@@ -305,8 +305,8 @@ fn test_removal() {
   i = 0u;
   while (i < num_to_insert) {
     assert (hm.insert(i, i * i));
-    log "inserting " + _uint.to_str(i, 10u)
-      + " -> " + _uint.to_str(i * i, 10u);
+    log "inserting " + UInt.to_str(i, 10u)
+      + " -> " + UInt.to_str(i * i, 10u);
     i += 2u;
   }
 
@@ -316,8 +316,8 @@ fn test_removal() {
 
   i = 0u;
   while (i < num_to_insert) {
-    log "get(" + _uint.to_str(i, 10u) + ") = "
-      + _uint.to_str(hm.get(i), 10u);
+    log "get(" + UInt.to_str(i, 10u) + ") = "
+      + UInt.to_str(hm.get(i), 10u);
     assert (hm.get(i) == i * i);
     i += 1u;
   }
@@ -333,8 +333,8 @@ fn test_removal() {
 
   i = 0u;
   while (i < num_to_insert) {
-    log "get(" + _uint.to_str(i, 10u) + ") = "
-      + _uint.to_str(hm.get(i), 10u);
+    log "get(" + UInt.to_str(i, 10u) + ") = "
+      + UInt.to_str(hm.get(i), 10u);
     assert (hm.get(i) == i * i);
     i += 1u;
   }
diff --git a/src/test/run-pass/lib-option.rs b/src/test/run-pass/lib-option.rs
index 922072e5759..417ab482764 100644
--- a/src/test/run-pass/lib-option.rs
+++ b/src/test/run-pass/lib-option.rs
@@ -1,5 +1,5 @@
 use std;
 
 fn main() {
-  auto x = std.option.some[int](10);
+  auto x = std.Option.some[int](10);
 }
diff --git a/src/test/run-pass/lib-qsort.rs b/src/test/run-pass/lib-qsort.rs
index f7f0f99782c..aed5009dd24 100644
--- a/src/test/run-pass/lib-qsort.rs
+++ b/src/test/run-pass/lib-qsort.rs
@@ -1,13 +1,13 @@
 use std;
 
 fn check_sort(vec[mutable int] v1, vec[mutable int] v2) {
-  auto len = std._vec.len[int](v1);
+  auto len = std.Vec.len[int](v1);
 
   fn ltequal(&int a, &int b) -> bool {
     ret a <= b;
   }
   auto f = ltequal;
-  std.sort.quick_sort[int](f, v1);
+  std.Sort.quick_sort[int](f, v1);
   auto i = 0u;
   while (i < len) {
     log v2.(i);
diff --git a/src/test/run-pass/lib-rand.rs b/src/test/run-pass/lib-rand.rs
index 3ef949733f7..e423bcba53f 100644
--- a/src/test/run-pass/lib-rand.rs
+++ b/src/test/run-pass/lib-rand.rs
@@ -4,14 +4,14 @@
 // -*- rust -*-
 
 use std;
-import std.rand;
+import std.Rand;
 
 fn main() {
-  let rand.rng r1 = rand.mk_rng();
+  let Rand.rng r1 = Rand.mk_rng();
   log r1.next();
   log r1.next();
   {
-    auto r2 = rand.mk_rng();
+    auto r2 = Rand.mk_rng();
     log r1.next();
     log r2.next();
     log r1.next();
diff --git a/src/test/run-pass/lib-sha1.rs b/src/test/run-pass/lib-sha1.rs
index 7e8efb5eba7..2a7e8646a63 100644
--- a/src/test/run-pass/lib-sha1.rs
+++ b/src/test/run-pass/lib-sha1.rs
@@ -2,9 +2,9 @@
 
 use std;
 
-import std.sha1;
-import std._vec;
-import std._str;
+import std.SHA1;
+import std.Vec;
+import std.Str;
 
 fn main() {
 
@@ -69,8 +69,8 @@ fn main() {
     auto tests = fips_180_1_tests + wikipedia_tests;
 
     fn check_vec_eq(vec[u8] v0, vec[u8] v1) {
-        assert (_vec.len[u8](v0) == _vec.len[u8](v1));
-        auto len = _vec.len[u8](v0);
+        assert (Vec.len[u8](v0) == Vec.len[u8](v1));
+        auto len = Vec.len[u8](v0);
         auto i = 0u;
         while (i < len) {
             auto a = v0.(i);
@@ -81,7 +81,7 @@ fn main() {
     }
 
     // Test that it works when accepting the message all at once
-    auto sh = sha1.mk_sha1();
+    auto sh = SHA1.mk_sha1();
     for (test t in tests) {
         sh.input_str(t.input);
         auto out = sh.result();
@@ -91,11 +91,11 @@ fn main() {
 
     // Test that it works when accepting the message in pieces
     for (test t in tests) {
-        auto len = _str.byte_len(t.input);
+        auto len = Str.byte_len(t.input);
         auto left = len;
         while (left > 0u) {
             auto take = (left + 1u) / 2u;
-            sh.input_str(_str.substr(t.input, len - left, take));
+            sh.input_str(Str.substr(t.input, len - left, take));
             left = left - take;
         }
         auto out = sh.result();
diff --git a/src/test/run-pass/lib-sort.rs b/src/test/run-pass/lib-sort.rs
index a342b24eb56..145d0175ddb 100644
--- a/src/test/run-pass/lib-sort.rs
+++ b/src/test/run-pass/lib-sort.rs
@@ -1,12 +1,12 @@
 use std;
 
 fn check_sort(vec[int] v1, vec[int] v2) {
-  auto len = std._vec.len[int](v1);
+  auto len = std.Vec.len[int](v1);
   fn lteq(&int a, &int b) -> bool {
     ret a <= b;
   }
   auto f = lteq;
-  auto v3 = std.sort.merge_sort[int](f, v1);
+  auto v3 = std.Sort.merge_sort[int](f, v1);
   auto i = 0u;
   while (i < len) {
     log v3.(i);
diff --git a/src/test/run-pass/lib-str-buf.rs b/src/test/run-pass/lib-str-buf.rs
index 1f25373a4a0..cd8ba9e9fd0 100644
--- a/src/test/run-pass/lib-str-buf.rs
+++ b/src/test/run-pass/lib-str-buf.rs
@@ -4,14 +4,14 @@
 // -*- rust -*-
 
 use std;
-import std._str;
+import std.Str;
 
 fn main() {
     auto s = "hello";
-    auto sb = _str.rustrt.str_buf(s);
-    auto s_cstr = _str.rustrt.str_from_cstr(sb);
-    assert (_str.eq(s_cstr, s));
-    auto s_buf = _str.rustrt.str_from_buf(sb, 5u);
-    assert (_str.eq(s_buf, s));
+    auto sb = Str.rustrt.str_buf(s);
+    auto s_cstr = Str.rustrt.str_from_cstr(sb);
+    assert (Str.eq(s_cstr, s));
+    auto s_buf = Str.rustrt.str_from_buf(sb, 5u);
+    assert (Str.eq(s_buf, s));
 }
 
diff --git a/src/test/run-pass/lib-str.rs b/src/test/run-pass/lib-str.rs
index 767177111b2..58779f674e3 100644
--- a/src/test/run-pass/lib-str.rs
+++ b/src/test/run-pass/lib-str.rs
@@ -1,36 +1,36 @@
 use std;
-import std._str;
+import std.Str;
 
 fn test_bytes_len() {
-  assert (_str.byte_len("") == 0u);
-  assert (_str.byte_len("hello world") == 11u);
-  assert (_str.byte_len("\x63") == 1u);
-  assert (_str.byte_len("\xa2") == 2u);
-  assert (_str.byte_len("\u03c0") == 2u);
-  assert (_str.byte_len("\u2620") == 3u);
-  assert (_str.byte_len("\U0001d11e") == 4u);
+  assert (Str.byte_len("") == 0u);
+  assert (Str.byte_len("hello world") == 11u);
+  assert (Str.byte_len("\x63") == 1u);
+  assert (Str.byte_len("\xa2") == 2u);
+  assert (Str.byte_len("\u03c0") == 2u);
+  assert (Str.byte_len("\u2620") == 3u);
+  assert (Str.byte_len("\U0001d11e") == 4u);
 }
 
 fn test_index_and_rindex() {
-  assert (_str.index("hello", 'e' as u8) == 1);
-  assert (_str.index("hello", 'o' as u8) == 4);
-  assert (_str.index("hello", 'z' as u8) == -1);
-  assert (_str.rindex("hello", 'l' as u8) == 3);
-  assert (_str.rindex("hello", 'h' as u8) == 0);
-  assert (_str.rindex("hello", 'z' as u8) == -1);
+  assert (Str.index("hello", 'e' as u8) == 1);
+  assert (Str.index("hello", 'o' as u8) == 4);
+  assert (Str.index("hello", 'z' as u8) == -1);
+  assert (Str.rindex("hello", 'l' as u8) == 3);
+  assert (Str.rindex("hello", 'h' as u8) == 0);
+  assert (Str.rindex("hello", 'z' as u8) == -1);
 }
 
 fn test_split() {
   fn t(&str s, char c, int i, &str k) {
     log "splitting: " + s;
     log i;
-    auto v = _str.split(s, c as u8);
+    auto v = Str.split(s, c as u8);
     log "split to: ";
     for (str z in v) {
       log z;
     }
     log "comparing: " + v.(i) + " vs. " + k;
-    assert (_str.eq(v.(i), k));
+    assert (Str.eq(v.(i), k));
   }
   t("abc.hello.there", '.', 0, "abc");
   t("abc.hello.there", '.', 1, "hello");
@@ -43,7 +43,7 @@ fn test_split() {
 
 fn test_find() {
   fn t(&str haystack, &str needle, int i) {
-    let int j = _str.find(haystack,needle);
+    let int j = Str.find(haystack,needle);
     log "searched for " + needle;
     log j;
     assert (i == j);
@@ -57,8 +57,8 @@ fn test_find() {
 
 fn test_substr() {
   fn t(&str a, &str b, int start) {
-    assert (_str.eq(_str.substr(a, start as uint,
-                              _str.byte_len(b)), b));
+    assert (Str.eq(Str.substr(a, start as uint,
+                              Str.byte_len(b)), b));
   }
 
   t("hello", "llo", 2);
@@ -68,7 +68,7 @@ fn test_substr() {
 
 fn test_concat() {
   fn t(&vec[str] v, &str s) {
-    assert (_str.eq(_str.concat(v), s));
+    assert (Str.eq(Str.concat(v), s));
   }
 
   t(vec("you", "know", "I'm", "no", "good"), "youknowI'mnogood");
@@ -79,7 +79,7 @@ fn test_concat() {
 
 fn test_connect() {
   fn t(&vec[str] v, &str sep, &str s) {
-    assert (_str.eq(_str.connect(v, sep), s));
+    assert (Str.eq(Str.connect(v, sep), s));
   }
 
   t(vec("you", "know", "I'm", "no", "good"), " ", "you know I'm no good");
@@ -94,8 +94,8 @@ fn test_to_upper() {
   auto unicode = "\u65e5\u672c";
   auto input = "abcDEF" + unicode + "xyz:.;";
   auto expected = "ABCDEF" + unicode + "XYZ:.;";
-  auto actual = _str.to_upper(input);
-  assert (_str.eq(expected, actual));
+  auto actual = Str.to_upper(input);
+  assert (Str.eq(expected, actual));
 }
 
 
diff --git a/src/test/run-pass/lib-task.rs b/src/test/run-pass/lib-task.rs
index 18499f4e5d0..8e07962ce9e 100644
--- a/src/test/run-pass/lib-task.rs
+++ b/src/test/run-pass/lib-task.rs
@@ -1,6 +1,6 @@
 use std;
-import std._task;
+import std.Task;
 
 fn main() {
-  _task.sleep(1000000u);
+  Task.sleep(1000000u);
 }
\ No newline at end of file
diff --git a/src/test/run-pass/lib-uint.rs b/src/test/run-pass/lib-uint.rs
index 64d39619f0b..4f787745081 100644
--- a/src/test/run-pass/lib-uint.rs
+++ b/src/test/run-pass/lib-uint.rs
@@ -1,47 +1,47 @@
 // -*- rust -*-
 
 use std;
-import std._uint;
+import std.UInt;
 
 fn main() {
-  assert (_uint.next_power_of_two(0u) == 0u);
-  assert (_uint.next_power_of_two(1u) == 1u);
-  assert (_uint.next_power_of_two(2u) == 2u);
-  assert (_uint.next_power_of_two(3u) == 4u);
-  assert (_uint.next_power_of_two(4u) == 4u);
-  assert (_uint.next_power_of_two(5u) == 8u);
-  assert (_uint.next_power_of_two(6u) == 8u);
-  assert (_uint.next_power_of_two(7u) == 8u);
-  assert (_uint.next_power_of_two(8u) == 8u);
-  assert (_uint.next_power_of_two(9u) == 16u);
-  assert (_uint.next_power_of_two(10u) == 16u);
-  assert (_uint.next_power_of_two(11u) == 16u);
-  assert (_uint.next_power_of_two(12u) == 16u);
-  assert (_uint.next_power_of_two(13u) == 16u);
-  assert (_uint.next_power_of_two(14u) == 16u);
-  assert (_uint.next_power_of_two(15u) == 16u);
-  assert (_uint.next_power_of_two(16u) == 16u);
-  assert (_uint.next_power_of_two(17u) == 32u);
-  assert (_uint.next_power_of_two(18u) == 32u);
-  assert (_uint.next_power_of_two(19u) == 32u);
-  assert (_uint.next_power_of_two(20u) == 32u);
-  assert (_uint.next_power_of_two(21u) == 32u);
-  assert (_uint.next_power_of_two(22u) == 32u);
-  assert (_uint.next_power_of_two(23u) == 32u);
-  assert (_uint.next_power_of_two(24u) == 32u);
-  assert (_uint.next_power_of_two(25u) == 32u);
-  assert (_uint.next_power_of_two(26u) == 32u);
-  assert (_uint.next_power_of_two(27u) == 32u);
-  assert (_uint.next_power_of_two(28u) == 32u);
-  assert (_uint.next_power_of_two(29u) == 32u);
-  assert (_uint.next_power_of_two(30u) == 32u);
-  assert (_uint.next_power_of_two(31u) == 32u);
-  assert (_uint.next_power_of_two(32u) == 32u);
-  assert (_uint.next_power_of_two(33u) == 64u);
-  assert (_uint.next_power_of_two(34u) == 64u);
-  assert (_uint.next_power_of_two(35u) == 64u);
-  assert (_uint.next_power_of_two(36u) == 64u);
-  assert (_uint.next_power_of_two(37u) == 64u);
-  assert (_uint.next_power_of_two(38u) == 64u);
-  assert (_uint.next_power_of_two(39u) == 64u);
+  assert (UInt.next_power_of_two(0u) == 0u);
+  assert (UInt.next_power_of_two(1u) == 1u);
+  assert (UInt.next_power_of_two(2u) == 2u);
+  assert (UInt.next_power_of_two(3u) == 4u);
+  assert (UInt.next_power_of_two(4u) == 4u);
+  assert (UInt.next_power_of_two(5u) == 8u);
+  assert (UInt.next_power_of_two(6u) == 8u);
+  assert (UInt.next_power_of_two(7u) == 8u);
+  assert (UInt.next_power_of_two(8u) == 8u);
+  assert (UInt.next_power_of_two(9u) == 16u);
+  assert (UInt.next_power_of_two(10u) == 16u);
+  assert (UInt.next_power_of_two(11u) == 16u);
+  assert (UInt.next_power_of_two(12u) == 16u);
+  assert (UInt.next_power_of_two(13u) == 16u);
+  assert (UInt.next_power_of_two(14u) == 16u);
+  assert (UInt.next_power_of_two(15u) == 16u);
+  assert (UInt.next_power_of_two(16u) == 16u);
+  assert (UInt.next_power_of_two(17u) == 32u);
+  assert (UInt.next_power_of_two(18u) == 32u);
+  assert (UInt.next_power_of_two(19u) == 32u);
+  assert (UInt.next_power_of_two(20u) == 32u);
+  assert (UInt.next_power_of_two(21u) == 32u);
+  assert (UInt.next_power_of_two(22u) == 32u);
+  assert (UInt.next_power_of_two(23u) == 32u);
+  assert (UInt.next_power_of_two(24u) == 32u);
+  assert (UInt.next_power_of_two(25u) == 32u);
+  assert (UInt.next_power_of_two(26u) == 32u);
+  assert (UInt.next_power_of_two(27u) == 32u);
+  assert (UInt.next_power_of_two(28u) == 32u);
+  assert (UInt.next_power_of_two(29u) == 32u);
+  assert (UInt.next_power_of_two(30u) == 32u);
+  assert (UInt.next_power_of_two(31u) == 32u);
+  assert (UInt.next_power_of_two(32u) == 32u);
+  assert (UInt.next_power_of_two(33u) == 64u);
+  assert (UInt.next_power_of_two(34u) == 64u);
+  assert (UInt.next_power_of_two(35u) == 64u);
+  assert (UInt.next_power_of_two(36u) == 64u);
+  assert (UInt.next_power_of_two(37u) == 64u);
+  assert (UInt.next_power_of_two(38u) == 64u);
+  assert (UInt.next_power_of_two(39u) == 64u);
 }
diff --git a/src/test/run-pass/lib-vec-str-conversions.rs b/src/test/run-pass/lib-vec-str-conversions.rs
index 3724d627b49..cd8b64a889e 100644
--- a/src/test/run-pass/lib-vec-str-conversions.rs
+++ b/src/test/run-pass/lib-vec-str-conversions.rs
@@ -1,8 +1,8 @@
 // -*- rust -*-
 
 use std;
-import std._str;
-import std._vec;
+import std.Str;
+import std.Vec;
 
 fn test_simple() {
   let str s1 = "All mimsy were the borogoves";
@@ -14,12 +14,12 @@ fn test_simple() {
    * working, but we should implement is_utf8 before that happens.
    */
 
-  let vec[u8] v = _str.bytes(s1);
-  let str s2 = _str.from_bytes(v);
+  let vec[u8] v = Str.bytes(s1);
+  let str s2 = Str.from_bytes(v);
 
   let uint i = 0u;
-  let uint n1 = _str.byte_len(s1);
-  let uint n2 = _vec.len[u8](v);
+  let uint n1 = Str.byte_len(s1);
+  let uint n2 = Vec.len[u8](v);
 
   assert (n1 == n2);
 
@@ -33,7 +33,7 @@ fn test_simple() {
   }
 
   log "refcnt is";
-  log _str.refcount(s1);
+  log Str.refcount(s1);
 }
 
 fn main() {
diff --git a/src/test/run-pass/lib-vec.rs b/src/test/run-pass/lib-vec.rs
index 51341039c69..0905652a5d0 100644
--- a/src/test/run-pass/lib-vec.rs
+++ b/src/test/run-pass/lib-vec.rs
@@ -1,8 +1,8 @@
 use std;
 
 fn test_init_elt() {
-  let vec[uint] v = std._vec.init_elt[uint](5u, 3u);
-  assert (std._vec.len[uint](v) == 3u);
+  let vec[uint] v = std.Vec.init_elt[uint](5u, 3u);
+  assert (std.Vec.len[uint](v) == 3u);
   assert (v.(0) == 5u);
   assert (v.(1) == 5u);
   assert (v.(2) == 5u);
@@ -13,8 +13,8 @@ fn id(uint x) -> uint {
 }
 fn test_init_fn() {
   let fn(uint)->uint op = id;
-  let vec[uint] v = std._vec.init_fn[uint](op, 5u);
-  assert (std._vec.len[uint](v) == 5u);
+  let vec[uint] v = std.Vec.init_fn[uint](op, 5u);
+  assert (std.Vec.len[uint](v) == 5u);
   assert (v.(0) == 0u);
   assert (v.(1) == 1u);
   assert (v.(2) == 2u);
@@ -24,17 +24,17 @@ fn test_init_fn() {
 
 fn test_slice() {
   let vec[int] v = vec(1,2,3,4,5);
-  auto v2 = std._vec.slice[int](v, 2u, 4u);
-  assert (std._vec.len[int](v2) == 2u);
+  auto v2 = std.Vec.slice[int](v, 2u, 4u);
+  assert (std.Vec.len[int](v2) == 2u);
   assert (v2.(0) == 3);
   assert (v2.(1) == 4);
 }
 
 fn test_map() {
   fn square(&int x) -> int { ret x * x; }
-  let std.option.operator[int, int] op = square;
+  let std.Option.operator[int, int] op = square;
   let vec[int] v = vec(1, 2, 3, 4, 5);
-  let vec[int] s = std._vec.map[int, int](op, v);
+  let vec[int] s = std.Vec.map[int, int](op, v);
   let int i = 0;
   while (i < 5) {
     assert (v.(i) * v.(i) == s.(i));
@@ -47,7 +47,7 @@ fn test_map2() {
   auto f = times;
   auto v0 = vec(1, 2, 3, 4, 5);
   auto v1 = vec(5, 4, 3, 2, 1);
-  auto u = std._vec.map2[int,int,int](f, v0, v1);
+  auto u = std.Vec.map2[int,int,int](f, v0, v1);
 
   auto i = 0;
   while (i < 5) {
diff --git a/src/test/run-pass/mlist-cycle.rs b/src/test/run-pass/mlist-cycle.rs
index 7c41e4b5676..b5eff76f4dc 100644
--- a/src/test/run-pass/mlist-cycle.rs
+++ b/src/test/run-pass/mlist-cycle.rs
@@ -16,6 +16,6 @@ fn main() {
   let @cell first = @tup(mutable @nil());
   let @cell second = @tup(mutable @link(first));
   first._0 = @link(second);
-  std.sys.rustrt.gc();
+  std.Sys.rustrt.gc();
   let @cell third = @tup(mutable @nil());
 }
diff --git a/src/test/run-pass/mutable-alias-vec.rs b/src/test/run-pass/mutable-alias-vec.rs
index 71d4dfe927d..5919abdc5d4 100644
--- a/src/test/run-pass/mutable-alias-vec.rs
+++ b/src/test/run-pass/mutable-alias-vec.rs
@@ -11,7 +11,7 @@ fn main() {
   grow(v);
   grow(v);
   grow(v);
-  auto len = std._vec.len[int](v);
+  auto len = std.Vec.len[int](v);
   log len;
   assert (len == (3 as uint));
 }
diff --git a/src/test/run-pass/nested-pattern.rs b/src/test/run-pass/nested-pattern.rs
index e59c2dd5a41..cb244cc8b10 100644
--- a/src/test/run-pass/nested-pattern.rs
+++ b/src/test/run-pass/nested-pattern.rs
@@ -1,13 +1,13 @@
 // a bug was causing this to complain about leaked memory on exit
 
 use std;
-import std.option;
-import std.option.some;
-import std.option.none;
+import std.Option;
+import std.Option.some;
+import std.Option.none;
 
 tag t {
   foo(int, uint);
-  bar(int, option.t[int]);
+  bar(int, Option.t[int]);
 }
 
 fn nested(t o) {
diff --git a/src/test/run-pass/rt-circular-buffer.rs b/src/test/run-pass/rt-circular-buffer.rs
index cd808ad733d..b6c545b2782 100644
--- a/src/test/run-pass/rt-circular-buffer.rs
+++ b/src/test/run-pass/rt-circular-buffer.rs
@@ -5,9 +5,9 @@
 
 use std;
 
-import std.option;
-import std._uint;
-import std._vec;
+import std.Option;
+import std.UInt;
+import std.Vec;
 
 // A 12-byte unit to send over the channel
 type record = rec(u32 val1, u32 val2, u32 val3);
@@ -33,7 +33,7 @@ fn test_grow() {
 
     let record val = rec(val1=0u32, val2=0u32, val3=0u32);
 
-    for each (uint i in _uint.range(0u, 100u)) {
+    for each (uint i in UInt.range(0u, 100u)) {
         mychan <| val;
     }
 }
@@ -53,11 +53,11 @@ fn test_shrink2() {
 
     let record val = rec(val1=0u32, val2=0u32, val3=0u32);
 
-    for each (uint i in _uint.range(0u, 100u)) {
+    for each (uint i in UInt.range(0u, 100u)) {
         mychan <| val;
     }
 
-    for each (uint i in _uint.range(0u, 100u)) {
+    for each (uint i in UInt.range(0u, 100u)) {
         auto x <- myport;
     }
 }
@@ -67,7 +67,7 @@ fn test_rotate() {
     let port[record] myport = port();
     auto mychan = chan(myport);
 
-    for each (uint i in _uint.range(0u, 100u)) {
+    for each (uint i in UInt.range(0u, 100u)) {
         auto val = rec(val1=i as u32,
                        val2=i as u32,
                        val3=i as u32);
@@ -86,15 +86,15 @@ fn test_rotate_grow() {
     let port[record] myport = port();
     auto mychan = chan(myport);
 
-    for each (uint j in _uint.range(0u, 10u)) {
-        for each (uint i in _uint.range(0u, 10u)) {
+    for each (uint j in UInt.range(0u, 10u)) {
+        for each (uint i in UInt.range(0u, 10u)) {
             let record val = rec(val1=i as u32,
                                  val2=i as u32,
                                  val3=i as u32);
             mychan <| val;
         }
 
-        for each (uint i in _uint.range(0u, 10u)) {
+        for each (uint i in UInt.range(0u, 10u)) {
             auto x <- myport;
             assert (x.val1 == i as u32);
             assert (x.val2 == i as u32);
diff --git a/src/test/run-pass/str-append.rs b/src/test/run-pass/str-append.rs
index abfbe938e22..afca72a8d1d 100644
--- a/src/test/run-pass/str-append.rs
+++ b/src/test/run-pass/str-append.rs
@@ -1,7 +1,7 @@
 // -*- rust -*-
 
 use std;
-import std._str;
+import std.Str;
 
 fn test1() {
   let str s = "hello";
@@ -20,8 +20,8 @@ fn test2() {
   log a;
   log b;
 
-  assert (_str.eq(a, "abcABCabc"));
-  assert (_str.eq(b, "ABCabcABC"));
+  assert (Str.eq(a, "abcABCabc"));
+  assert (Str.eq(b, "ABCabcABC"));
 }
 
 fn main() {
diff --git a/src/test/run-pass/syntax-extension-fmt.rs b/src/test/run-pass/syntax-extension-fmt.rs
index bb0c851fe13..08a8c499668 100644
--- a/src/test/run-pass/syntax-extension-fmt.rs
+++ b/src/test/run-pass/syntax-extension-fmt.rs
@@ -3,12 +3,12 @@
 // xfail-stage1
 // xfail-stage2
 use std;
-import std._str;
+import std.Str;
 
 fn test(str actual, str expected) {
   log actual;
   log expected;
-  assert (_str.eq(actual, expected));
+  assert (Str.eq(actual, expected));
 }
 
 fn main() {
diff --git a/src/test/run-pass/task-comm-12.rs b/src/test/run-pass/task-comm-12.rs
index 2f8ef985688..d4a135c2a39 100644
--- a/src/test/run-pass/task-comm-12.rs
+++ b/src/test/run-pass/task-comm-12.rs
@@ -3,7 +3,7 @@
 // xfail-stage1
 // xfail-stage2
 use std;
-import std._task;
+import std.Task;
 
 fn main() -> () {
     test00();
@@ -18,7 +18,7 @@ fn test00() {
     let task t = spawn thread "child" start(i);
     
     // Sleep long enough for the task to finish.
-    _task.sleep(10000u);
+    Task.sleep(10000u);
     
     // Try joining tasks that have already finished.
     join t;
diff --git a/src/test/run-pass/task-comm-13-thread.rs b/src/test/run-pass/task-comm-13-thread.rs
index e5e420105a0..fedc516bd59 100644
--- a/src/test/run-pass/task-comm-13-thread.rs
+++ b/src/test/run-pass/task-comm-13-thread.rs
@@ -2,7 +2,7 @@
 // xfail-stage1
 // xfail-stage2
 use std;
-import std._task;
+import std.Task;
 
 fn start(chan[int] c, int start, int number_of_messages) {
     let int i = 0;
diff --git a/src/test/run-pass/task-comm-13.rs b/src/test/run-pass/task-comm-13.rs
index bcae26e54cd..1bf5d1f56f6 100644
--- a/src/test/run-pass/task-comm-13.rs
+++ b/src/test/run-pass/task-comm-13.rs
@@ -2,7 +2,7 @@
 // xfail-stage1
 // xfail-stage2
 use std;
-import std._task;
+import std.Task;
 
 fn start(chan[int] c, int start, int number_of_messages) {
     let int i = 0;
diff --git a/src/test/run-pass/type-sizes.rs b/src/test/run-pass/type-sizes.rs
index e416e9b561a..d39a2064828 100644
--- a/src/test/run-pass/type-sizes.rs
+++ b/src/test/run-pass/type-sizes.rs
@@ -2,7 +2,7 @@
 // xfail-stage1
 // xfail-stage2
 
-import size_of = std.sys.rustrt.size_of;
+import size_of = std.Sys.rustrt.size_of;
 
 use std;
 
diff --git a/src/test/run-pass/use.rs b/src/test/run-pass/use.rs
index 37cfe0747c3..3d1a6947f7c 100644
--- a/src/test/run-pass/use.rs
+++ b/src/test/run-pass/use.rs
@@ -7,8 +7,8 @@ use zed(name = "std");
 use bar(name = "std", ver = "0.0.1");
 
 // FIXME: commented out since resolve doesn't know how to handle crates yet.
-// import std._str;
-// import x = std._str;
+// import std.Str;
+// import x = std.Str;
 
 mod baz {
   use std;
@@ -16,8 +16,8 @@ mod baz {
   use zed(name = "std");
   use bar(name = "std", ver = "0.0.1");
 
-  // import std._str;
-  // import x = std._str;
+  // import std.Str;
+  // import x = std.Str;
 }
 
 fn main() {
diff --git a/src/test/run-pass/user.rs b/src/test/run-pass/user.rs
index 679d3e485e0..877c416bbb3 100644
--- a/src/test/run-pass/user.rs
+++ b/src/test/run-pass/user.rs
@@ -8,10 +8,10 @@ use std (name = "std",
          uuid = _, ver = _);
 
 fn main() {
-  auto s = std._str.alloc(10 as uint);
+  auto s = std.Str.alloc(10 as uint);
   s += "hello ";
   log s;
   s += "there";
   log s;
-  auto z = std._vec.alloc[int](10 as uint);
+  auto z = std.Vec.alloc[int](10 as uint);
 }
diff --git a/src/test/run-pass/utf8_chars.rs b/src/test/run-pass/utf8_chars.rs
index e2df05dc7f0..95cbc64e0ab 100644
--- a/src/test/run-pass/utf8_chars.rs
+++ b/src/test/run-pass/utf8_chars.rs
@@ -2,34 +2,34 @@
 // xfail-stage1
 // xfail-stage2
 use std;
-import std._str;
-import std._vec;
-import std.io;
+import std.Str;
+import std.Vec;
+import std.IO;
 
 fn main() {
   // Chars of 1, 2, 3, and 4 bytes
   let vec[char] chs = vec('e', 'é', '€', 0x10000 as char);
-  let str s = _str.from_chars(chs);
+  let str s = Str.from_chars(chs);
 
-  assert (_str.byte_len(s) == 10u);
-  assert (_str.char_len(s) == 4u);
-  assert (_vec.len[char](_str.to_chars(s)) == 4u);
-  assert (_str.eq(_str.from_chars(_str.to_chars(s)), s));
-  assert (_str.char_at(s, 0u) == 'e');
-  assert (_str.char_at(s, 1u) == 'é');
+  assert (Str.byte_len(s) == 10u);
+  assert (Str.char_len(s) == 4u);
+  assert (Vec.len[char](Str.to_chars(s)) == 4u);
+  assert (Str.eq(Str.from_chars(Str.to_chars(s)), s));
+  assert (Str.char_at(s, 0u) == 'e');
+  assert (Str.char_at(s, 1u) == 'é');
 
-  assert (_str.is_utf8(_str.bytes(s)));
-  assert (!_str.is_utf8(vec(0x80_u8)));
-  assert (!_str.is_utf8(vec(0xc0_u8)));
-  assert (!_str.is_utf8(vec(0xc0_u8, 0x10_u8)));
+  assert (Str.is_utf8(Str.bytes(s)));
+  assert (!Str.is_utf8(vec(0x80_u8)));
+  assert (!Str.is_utf8(vec(0xc0_u8)));
+  assert (!Str.is_utf8(vec(0xc0_u8, 0x10_u8)));
 
   auto stack = "a×c€";
-  assert (_str.pop_char(stack) == '€');
-  assert (_str.pop_char(stack) == 'c');
-  _str.push_char(stack, 'u');
-  assert (_str.eq(stack, "a×u"));
-  assert (_str.shift_char(stack) == 'a');
-  assert (_str.shift_char(stack) == '×');
-  _str.unshift_char(stack, 'ß');
-  assert (_str.eq(stack, "ßu"));
+  assert (Str.pop_char(stack) == '€');
+  assert (Str.pop_char(stack) == 'c');
+  Str.push_char(stack, 'u');
+  assert (Str.eq(stack, "a×u"));
+  assert (Str.shift_char(stack) == 'a');
+  assert (Str.shift_char(stack) == '×');
+  Str.unshift_char(stack, 'ß');
+  assert (Str.eq(stack, "ßu"));
 }
diff --git a/src/test/run-pass/vec-alloc-append.rs b/src/test/run-pass/vec-alloc-append.rs
index 616823ae942..4327e789cd5 100644
--- a/src/test/run-pass/vec-alloc-append.rs
+++ b/src/test/run-pass/vec-alloc-append.rs
@@ -6,7 +6,7 @@
 use std;
 
 fn slice[T](vec[T] e) {
-  let vec[T] result = std._vec.alloc[T](1 as uint);
+  let vec[T] result = std.Vec.alloc[T](1 as uint);
   log "alloced";
   result += e;
   log "appended";
diff --git a/src/test/run-pass/vec-append.rs b/src/test/run-pass/vec-append.rs
index e63b1d09d57..cd87ec230ce 100644
--- a/src/test/run-pass/vec-append.rs
+++ b/src/test/run-pass/vec-append.rs
@@ -4,11 +4,11 @@
 // -*- rust -*-
 
 use std;
-import std._str;
-import std._vec;
+import std.Str;
+import std.Vec;
 
 
-// FIXME: import std.dbg.const_refcount. Currently
+// FIXME: import std.Dbg.const_refcount. Currently
 // cross-crate const references don't work.
 const uint const_refcount = 0x7bad_face_u;
 
@@ -53,30 +53,30 @@ fn slow_growth2_helper(str s) {   // ref up: s
     let vec[str] v = vec(mumble); // ref up: v, mumble
     let acc a = acc(v);           // ref up: a, v
 
-    log _vec.refcount[str](v);
-    assert (_vec.refcount[str](v) == 2u);
+    log Vec.refcount[str](v);
+    assert (Vec.refcount[str](v) == 2u);
 
     a.add(s);                     // ref up: mumble, s.  ref down: v
 
-    log _vec.refcount[str](v);
-    log _str.refcount(s);
-    log _str.refcount(mumble);
+    log Vec.refcount[str](v);
+    log Str.refcount(s);
+    log Str.refcount(mumble);
 
-    assert (_vec.refcount[str](v) == 1u);
-    assert (_str.refcount(s) == const_refcount);
-    assert (_str.refcount(mumble) == const_refcount);
+    assert (Vec.refcount[str](v) == 1u);
+    assert (Str.refcount(s) == const_refcount);
+    assert (Str.refcount(mumble) == const_refcount);
 
     log v.(0);
-    log _vec.len[str](v);
-    assert (_str.eq(v.(0), mumble));
-    assert (_vec.len[str](v) == 1u);
+    log Vec.len[str](v);
+    assert (Str.eq(v.(0), mumble));
+    assert (Vec.len[str](v) == 1u);
   }                               // ref down: a, mumble, s, v
 
-  log _str.refcount(s);
-  log _str.refcount(mumble);
+  log Str.refcount(s);
+  log Str.refcount(mumble);
 
-  assert (_str.refcount(s) == const_refcount);
-  assert (_str.refcount(mumble) == const_refcount);
+  assert (Str.refcount(s) == const_refcount);
+  assert (Str.refcount(mumble) == const_refcount);
 
   log mumble;
   log ss;
@@ -85,8 +85,8 @@ fn slow_growth2_helper(str s) {   // ref up: s
 fn slow_growth2() {
   let str s = "hi";               // ref up: s
   slow_growth2_helper(s);
-  log _str.refcount(s);
-  assert (_str.refcount(s) == const_refcount);
+  log Str.refcount(s);
+  assert (Str.refcount(s) == const_refcount);
 }
 
 fn main() {
diff --git a/src/test/run-pass/vec-ref-count.rs b/src/test/run-pass/vec-ref-count.rs
index 45f28f9bff2..4534a86195a 100644
--- a/src/test/run-pass/vec-ref-count.rs
+++ b/src/test/run-pass/vec-ref-count.rs
@@ -1,12 +1,12 @@
 use std;
-import std._vec;
+import std.Vec;
 
 fn main() {
     auto v = vec(1, 2, 3);
-    log_err _vec.refcount[int](v);
-    log_err _vec.refcount[int](v);
-    log_err _vec.refcount[int](v);
-    assert (_vec.refcount[int](v) == 1u || _vec.refcount[int](v) == 2u);
-    assert (_vec.refcount[int](v) == 1u || _vec.refcount[int](v) == 2u);
+    log_err Vec.refcount[int](v);
+    log_err Vec.refcount[int](v);
+    log_err Vec.refcount[int](v);
+    assert (Vec.refcount[int](v) == 1u || Vec.refcount[int](v) == 2u);
+    assert (Vec.refcount[int](v) == 1u || Vec.refcount[int](v) == 2u);
 }