Remove effect system from src.

16 files changed, 285 insertions, 348 deletions

diff --git a/src/comp/driver/rustc.rs b/src/comp/driver/rustc.rs
index 085a1f5888b..5acbea86cf9 100644
--- a/src/comp/driver/rustc.rs
+++ b/src/comp/driver/rustc.rs
@@ -44,7 +44,7 @@ fn default_environment(session.session sess,
             );
 }
 
-impure fn parse_input(session.session sess,
+fn parse_input(session.session sess,
                       parser.parser p,
                       str input) -> @front.ast.crate {
     if (_str.ends_with(input, ".rc")) {
@@ -56,7 +56,7 @@ impure fn parse_input(session.session sess,
     fail;
 }
 
-impure fn compile_input(session.session sess,
+fn compile_input(session.session sess,
                         eval.env env,
                         str input, str output,
                         bool shared,
@@ -79,7 +79,7 @@ impure fn compile_input(session.session sess,
                       ot);
 }
 
-impure fn pretty_print_input(session.session sess,
+fn pretty_print_input(session.session sess,
                              eval.env env,
                              str input) {
     auto def = tup(0, 0);
@@ -116,7 +116,7 @@ fn get_os() -> session.os {
     if (_str.eq(s, "linux")) { ret session.os_linux; }
 }
 
-impure fn main(vec[str] args) {
+fn main(vec[str] args) {
 
     // FIXME: don't hard-wire this.
     auto target_cfg = rec(os = get_os(),
diff --git a/src/comp/front/ast.rs b/src/comp/front/ast.rs
index 2ecd49922bc..7ec5e20a4e8 100644
--- a/src/comp/front/ast.rs
+++ b/src/comp/front/ast.rs
@@ -83,7 +83,7 @@ tag crate_directive_ {
     cdir_view_item(@view_item);
     cdir_meta(vec[@meta_item]);
     cdir_syntax(path);
-    cdir_auth(path, effect);
+    cdir_auth(path, _auth);
 }
 type crate_directive = spanned[crate_directive_];
 
@@ -130,10 +130,8 @@ tag layer {
     layer_gc;
 }
 
-tag effect {
-    eff_pure;
-    eff_impure;
-    eff_unsafe;
+tag _auth {
+    auth_unsafe;
 }
 
 tag proto {
@@ -314,7 +312,7 @@ tag lit_ {
 type mt = rec(@ty ty, mutability mut);
 type ty_field = rec(ident ident, mt mt);
 type ty_arg = rec(mode mode, @ty ty);
-type ty_method = rec(effect effect, proto proto, ident ident,
+type ty_method = rec(proto proto, ident ident,
                      vec[ty_arg] inputs, @ty output);
 type ty = spanned[ty_];
 tag ty_ {
@@ -332,7 +330,7 @@ tag ty_ {
     ty_chan(@ty);
     ty_tup(vec[mt]);
     ty_rec(vec[ty_field]);
-    ty_fn(effect, proto, vec[ty_arg], @ty);
+    ty_fn(proto, vec[ty_arg], @ty);
     ty_obj(vec[ty_method]);
     ty_path(path, option.t[def]);
     ty_type;
@@ -348,8 +346,7 @@ type constr_ = rec(path path, vec[@constr_arg] args);
 type constr = spanned[constr_];
 
 type arg = rec(mode mode, @ty ty, ident ident, def_id id);
-type fn_decl = rec(effect effect,
-                   vec[arg] inputs,
+type fn_decl = rec(vec[arg] inputs,
                    @ty output);
 type _fn = rec(fn_decl decl,
                proto proto,
diff --git a/src/comp/front/creader.rs b/src/comp/front/creader.rs
index ec9c6883ab5..1c910b65c89 100644
--- a/src/comp/front/creader.rs
+++ b/src/comp/front/creader.rs
@@ -55,7 +55,7 @@ fn peek(@pstate st) -> u8 {
     if (st.pos < st.len) {ret st.rep.(st.pos) as u8;}
     else {ret ' ' as u8;}
 }
-impure fn next(@pstate st) -> u8 { // ?? somehow not recognized as impure
+fn next(@pstate st) -> u8 { // ?? somehow not recognized as impure
     if (st.pos >= st.len) {fail;}
     auto ch = st.rep.(st.pos);
     st.pos = st.pos + 1u;
@@ -74,12 +74,12 @@ fn parse_ty_str(str rep, str_def sd) -> @ty.t {
     ret result;
 }
 
-impure fn parse_ty(@pstate st, str_def sd) -> @ty.t {
+fn parse_ty(@pstate st, str_def sd) -> @ty.t {
     ret @rec(struct=parse_sty(st, sd),
              cname=option.none[str]);
 }
 
-impure fn parse_mt(@pstate st, str_def sd) -> ty.mt {
+fn parse_mt(@pstate st, str_def sd) -> ty.mt {
     auto mut;
     alt (peek(st) as char) {
         case ('m') {next(st); mut = ast.mut;}
@@ -89,7 +89,7 @@ impure fn parse_mt(@pstate st, str_def sd) -> ty.mt {
     ret rec(ty=parse_ty(st, sd), mut=mut);
 }
 
-impure fn parse_def(@pstate st, str_def sd) -> ast.def_id {
+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));
@@ -98,7 +98,7 @@ impure fn parse_def(@pstate st, str_def sd) -> ast.def_id {
     ret sd(def);
 }
 
-impure fn parse_sty(@pstate st, str_def sd) -> ty.sty {
+fn parse_sty(@pstate st, str_def sd) -> ty.sty {
     alt (next(st) as char) {
         case ('n') {ret ty.ty_nil;}
         case ('b') {ret ty.ty_bool;}
@@ -205,7 +205,7 @@ impure fn parse_sty(@pstate st, str_def sd) -> ty.sty {
     }
 }
 
-impure fn parse_int(@pstate st) -> int {
+fn parse_int(@pstate st) -> int {
     auto n = 0;
     while (true) {
         auto cur = peek(st) as char;
@@ -217,7 +217,7 @@ impure fn parse_int(@pstate st) -> int {
     ret n;
 }
 
-impure fn parse_ty_fn(@pstate st, str_def sd) -> tup(vec[ty.arg], @ty.t) {
+fn parse_ty_fn(@pstate st, str_def sd) -> tup(vec[ty.arg], @ty.t) {
     check(next(st) as char == '[');
     let vec[ty.arg] inputs = vec();
     while (peek(st) as char != ']') {
@@ -565,7 +565,7 @@ fn get_tag_variants(session.session sess, ast.def_id def)
     ret infos;
 }
 
-impure 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)) {
             list_crate_metadata(bytes, out);
@@ -584,7 +584,7 @@ fn read_path(&ebml.doc d) -> tup(str, uint) {
     ret tup(path, pos);
 }
 
-impure fn list_crate_metadata(vec[u8] bytes, io.writer out) {
+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);
diff --git a/src/comp/front/eval.rs b/src/comp/front/eval.rs
index 8306bcf01e0..06fa9cea0f5 100644
--- a/src/comp/front/eval.rs
+++ b/src/comp/front/eval.rs
@@ -224,7 +224,7 @@ fn val_eq(session.session sess, span sp, val av, val bv) -> bool {
     fail;
 }
 
-impure fn eval_crate_directives(ctx cx,
+fn eval_crate_directives(ctx cx,
                                 env e,
                                 vec[@ast.crate_directive] cdirs,
                                 str prefix,
@@ -240,7 +240,7 @@ impure fn eval_crate_directives(ctx cx,
 }
 
 
-impure fn eval_crate_directives_to_mod(ctx cx, env e,
+fn eval_crate_directives_to_mod(ctx cx, env e,
                                        vec[@ast.crate_directive] cdirs,
                                        str prefix) -> ast._mod {
     let vec[@ast.view_item] view_items = vec();
@@ -254,7 +254,7 @@ impure fn eval_crate_directives_to_mod(ctx cx, env e,
 }
 
 
-impure fn eval_crate_directive_block(ctx cx,
+fn eval_crate_directive_block(ctx cx,
                                      env e,
                                      &ast.block blk,
                                      str prefix,
@@ -277,7 +277,7 @@ impure fn eval_crate_directive_block(ctx cx,
     }
 }
 
-impure fn eval_crate_directive_expr(ctx cx,
+fn eval_crate_directive_expr(ctx cx,
                                     env e,
                                     @ast.expr x,
                                     str prefix,
@@ -349,7 +349,7 @@ impure fn eval_crate_directive_expr(ctx cx,
     }
 }
 
-impure fn eval_crate_directive(ctx cx,
+fn eval_crate_directive(ctx cx,
                                env e,
                                @ast.crate_directive cdir,
                                str prefix,
diff --git a/src/comp/front/lexer.rs b/src/comp/front/lexer.rs
index e34ddd4f782..3a9eb1ed99d 100644
--- a/src/comp/front/lexer.rs
+++ b/src/comp/front/lexer.rs
@@ -14,8 +14,8 @@ state type reader = state obj {
     fn is_eof() -> bool;
     fn curr() -> char;
     fn next() -> char;
-    impure fn init();
-    impure fn bump();
+    fn init();
+    fn bump();
     fn mark();
     fn get_mark_chpos() -> uint;
     fn get_chpos() -> uint;
@@ -24,7 +24,7 @@ state type reader = state obj {
     fn get_filemap() -> codemap.filemap;
 };
 
-impure 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,
@@ -53,7 +53,7 @@ impure fn new_reader(io.reader rdr, str filename, codemap.filemap filemap)
             else {ret -1 as char;}
         }
 
-        impure fn init() {
+        fn init() {
             if (pos < len) {
                 auto next = _str.char_range_at(file, pos);
                 pos = next._1;
@@ -61,7 +61,7 @@ impure fn new_reader(io.reader rdr, str filename, codemap.filemap filemap)
             }
         }
 
-        impure fn bump() {
+        fn bump() {
             if (pos < len) {
                 chpos += 1u;
                 if (ch == '\n') {
@@ -135,7 +135,6 @@ fn keyword_table() -> std.map.hashmap[str, token.token] {
     keywords.insert("state", token.STATE);
     keywords.insert("gc", token.GC);
 
-    keywords.insert("impure", token.IMPURE);
     keywords.insert("unsafe", token.UNSAFE);
 
     keywords.insert("native", token.NATIVE);
@@ -274,14 +273,14 @@ fn is_whitespace(char c) -> bool {
     ret c == ' ' || c == '\t' || c == '\r' || c == '\n';
 }
 
-impure fn consume_any_whitespace(reader rdr) {
+fn consume_any_whitespace(reader rdr) {
     while (is_whitespace(rdr.curr())) {
         rdr.bump();
     }
     be consume_any_line_comment(rdr);
 }
 
-impure fn consume_any_line_comment(reader rdr) {
+fn consume_any_line_comment(reader rdr) {
     if (rdr.curr() == '/') {
         alt (rdr.next()) {
             case ('/') {
@@ -304,7 +303,7 @@ impure fn consume_any_line_comment(reader rdr) {
 }
 
 
-impure fn consume_block_comment(reader rdr) {
+fn consume_block_comment(reader rdr) {
     let int level = 1;
     while (level > 0) {
         if (rdr.curr() == '/' && rdr.next() == '*') {
@@ -342,7 +341,7 @@ fn digits_to_string(str s) -> int {
     ret accum_int;
 }
 
-impure fn scan_exponent(reader rdr) -> option.t[str] {
+fn scan_exponent(reader rdr) -> option.t[str] {
     auto c = rdr.curr();
     auto res = "";
 
@@ -368,7 +367,7 @@ impure fn scan_exponent(reader rdr) -> option.t[str] {
     }
 }
 
-impure fn scan_dec_digits(reader rdr) -> str {
+fn scan_dec_digits(reader rdr) -> str {
 
     auto c = rdr.curr();
     let str res = "";
@@ -384,7 +383,7 @@ impure fn scan_dec_digits(reader rdr) -> str {
     ret res;
 }
 
-impure fn scan_number(mutable char c, reader rdr) -> token.token {
+fn scan_number(mutable char c, reader rdr) -> token.token {
     auto accum_int = 0;
     let str dec_str = "";
     let bool is_dec_integer = false;
@@ -527,7 +526,7 @@ impure fn scan_number(mutable char c, reader rdr) -> token.token {
     }
 }
 
-impure fn scan_numeric_escape(reader rdr) -> char {
+fn scan_numeric_escape(reader rdr) -> char {
 
     auto n_hex_digits = 0;
 
@@ -563,7 +562,7 @@ impure fn scan_numeric_escape(reader rdr) -> char {
 }
 
 
-impure fn next_token(reader rdr) -> token.token {
+fn next_token(reader rdr) -> token.token {
     auto accum_str = "";
 
     consume_any_whitespace(rdr);
@@ -602,7 +601,7 @@ impure fn next_token(reader rdr) -> token.token {
         ret scan_number(c, rdr);
     }
 
-    impure fn binop(reader rdr, token.binop op) -> token.token {
+    fn binop(reader rdr, token.binop op) -> token.token {
         rdr.bump();
         if (rdr.curr() == '=') {
             rdr.bump();
@@ -856,7 +855,7 @@ tag cmnt_ {
 
 type cmnt = rec(cmnt_ val, uint pos, bool space_after);
 
-impure fn consume_whitespace(reader rdr) -> uint {
+fn consume_whitespace(reader rdr) -> uint {
     auto lines = 0u;
     while (is_whitespace(rdr.curr())) {
         if (rdr.curr() == '\n') {lines += 1u;}
@@ -865,7 +864,7 @@ impure fn consume_whitespace(reader rdr) -> uint {
     ret lines;
 }
 
-impure fn read_line_comment(reader rdr) -> cmnt {
+fn read_line_comment(reader rdr) -> cmnt {
     auto p = rdr.get_chpos();
     rdr.bump(); rdr.bump();
     while (rdr.curr() == ' ') {rdr.bump();}
@@ -879,7 +878,7 @@ impure fn read_line_comment(reader rdr) -> cmnt {
             space_after=consume_whitespace(rdr) > 1u);
 }
 
-impure fn read_block_comment(reader rdr) -> cmnt {
+fn read_block_comment(reader rdr) -> cmnt {
     auto p = rdr.get_chpos();
     rdr.bump(); rdr.bump();
     while (rdr.curr() == ' ') {rdr.bump();}
@@ -912,7 +911,7 @@ impure fn read_block_comment(reader rdr) -> cmnt {
             space_after=consume_whitespace(rdr) > 1u);
 }
 
-impure fn gather_comments(str path) -> vec[cmnt] {
+fn gather_comments(str path) -> vec[cmnt] {
     auto srdr = io.file_reader(path);
     auto rdr = new_reader(srdr, path, codemap.new_filemap(path, 0u));
     let vec[cmnt] comments = vec();
diff --git a/src/comp/front/parser.rs b/src/comp/front/parser.rs
index 2c21c957f75..3ed74abc582 100644
--- a/src/comp/front/parser.rs
+++ b/src/comp/front/parser.rs
@@ -26,9 +26,9 @@ tag file_type {
 state type parser =
     state obj {
           fn peek() -> token.token;
-          impure fn bump();
-          impure fn err(str s);
-          impure fn restrict(restriction r);
+          fn bump();
+          fn err(str s);
+          fn restrict(restriction r);
           fn get_restriction() -> restriction;
           fn get_file_type() -> file_type;
           fn get_env() -> eval.env;
@@ -43,7 +43,7 @@ state type parser =
           fn get_chpos() -> uint;
     };
 
-impure fn new_parser(session.session sess,
+fn new_parser(session.session sess,
                      eval.env env,
                      ast.def_id initial_def,
                      str path, uint pos) -> parser {
@@ -63,7 +63,7 @@ impure fn new_parser(session.session sess,
                 ret tok;
             }
 
-            impure fn bump() {
+            fn bump() {
                 // log rdr.get_filename()
                 //   + ":" + common.istr(lo.line as int);
                 tok = lexer.next_token(rdr);
@@ -71,11 +71,11 @@ impure fn new_parser(session.session sess,
                 hi = rdr.get_chpos();
             }
 
-            impure fn err(str m) {
+            fn err(str m) {
                 sess.span_err(rec(lo=lo, hi=hi), m);
             }
 
-            impure fn restrict(restriction r) {
+            fn restrict(restriction r) {
                 res = r;
             }
 
@@ -134,13 +134,13 @@ impure fn new_parser(session.session sess,
                      rdr, prec_table());
 }
 
-impure fn unexpected(parser p, token.token t) {
+fn unexpected(parser p, token.token t) {
     let str s = "unexpected token: ";
     s += token.to_str(t);
     p.err(s);
 }
 
-impure fn expect(parser p, token.token t) {
+fn expect(parser p, token.token t) {
     if (p.peek() == t) {
         p.bump();
     } else {
@@ -156,7 +156,7 @@ fn spanned[T](uint lo, uint hi, &T node) -> ast.spanned[T] {
     ret rec(node=node, span=rec(lo=lo, hi=hi));
 }
 
-impure fn parse_ident(parser p) -> ast.ident {
+fn parse_ident(parser p) -> ast.ident {
     alt (p.peek()) {
         case (token.IDENT(?i)) { p.bump(); ret i; }
         case (_) {
@@ -172,7 +172,7 @@ impure fn parse_ident(parser p) -> ast.ident {
  * lexical sytnax-extension or something similar. For now we just imitate
  * rustboot.
  */
-impure fn parse_str_lit_or_env_ident(parser p) -> ast.ident {
+fn parse_str_lit_or_env_ident(parser p) -> ast.ident {
     alt (p.peek()) {
         case (token.LIT_STR(?s)) { p.bump(); ret s; }
         case (token.IDENT(?i)) {
@@ -192,9 +192,9 @@ impure fn parse_str_lit_or_env_ident(parser p) -> ast.ident {
 }
 
 
-impure fn parse_ty_fn(ast.effect eff, ast.proto proto, parser p, uint lo)
+fn parse_ty_fn(ast.proto proto, parser p, uint lo)
     -> ast.ty_ {
-    impure fn parse_fn_input_ty(parser p) -> rec(ast.mode mode, @ast.ty ty) {
+    fn parse_fn_input_ty(parser p) -> rec(ast.mode mode, @ast.ty ty) {
         auto mode;
         if (p.peek() == token.BINOP(token.AND)) {
             p.bump();
@@ -236,10 +236,10 @@ impure fn parse_ty_fn(ast.effect eff, ast.proto proto, parser p, uint lo)
         output = @spanned(lo, inputs.span.hi, ast.ty_nil);
     }
 
-    ret ast.ty_fn(eff, proto, inputs.node, output);
+    ret ast.ty_fn(proto, inputs.node, output);
 }
 
-impure fn parse_proto(parser p) -> ast.proto {
+fn parse_proto(parser p) -> ast.proto {
     alt (p.peek()) {
         case (token.ITER) { p.bump(); ret ast.proto_iter; }
         case (token.FN) { p.bump(); ret ast.proto_fn; }
@@ -248,19 +248,18 @@ impure fn parse_proto(parser p) -> ast.proto {
     fail;
 }
 
-impure fn parse_ty_obj(parser p, &mutable uint hi) -> ast.ty_ {
+fn parse_ty_obj(parser p, &mutable uint hi) -> ast.ty_ {
     expect(p, token.OBJ);
-    impure fn parse_method_sig(parser p) -> ast.ty_method {
+    fn parse_method_sig(parser p) -> ast.ty_method {
         auto flo = p.get_lo_pos();
 
-        let ast.effect eff = parse_effect(p);
         let ast.proto proto = parse_proto(p);
         auto ident = parse_ident(p);
-        auto f = parse_ty_fn(eff, proto, p, flo);
+        auto f = parse_ty_fn(proto, p, flo);
         expect(p, token.SEMI);
         alt (f) {
-            case (ast.ty_fn(?eff, ?proto, ?inputs, ?output)) {
-                ret rec(effect=eff, proto=proto, ident=ident,
+            case (ast.ty_fn(?proto, ?inputs, ?output)) {
+                ret rec(proto=proto, ident=ident,
                         inputs=inputs, output=output);
             }
         }
@@ -276,19 +275,19 @@ impure fn parse_ty_obj(parser p, &mutable uint hi) -> ast.ty_ {
     ret ast.ty_obj(meths.node);
 }
 
-impure fn parse_mt(parser p) -> ast.mt {
+fn parse_mt(parser p) -> ast.mt {
     auto mut = parse_mutability(p);
     auto t = parse_ty(p);
     ret rec(ty=t, mut=mut);
 }
 
-impure fn parse_ty_field(parser p) -> ast.ty_field {
+fn parse_ty_field(parser p) -> ast.ty_field {
     auto mt = parse_mt(p);
     auto id = parse_ident(p);
     ret rec(ident=id, mt=mt);
 }
 
-impure fn parse_constr_arg(parser p) -> @ast.constr_arg {
+fn parse_constr_arg(parser p) -> @ast.constr_arg {
     auto sp = p.get_span();
     auto carg = ast.carg_base;
     if (p.peek() == token.BINOP(token.STAR)) {
@@ -299,7 +298,7 @@ impure fn parse_constr_arg(parser p) -> @ast.constr_arg {
     ret @rec(node=carg, span=sp);
 }
 
-impure fn parse_ty_constr(parser p) -> @ast.constr {
+fn parse_ty_constr(parser p) -> @ast.constr {
     auto lo = p.get_lo_pos();
     auto path = parse_path(p, GREEDY);
     auto pf = parse_constr_arg;
@@ -309,7 +308,7 @@ impure fn parse_ty_constr(parser p) -> @ast.constr {
     ret @spanned(lo, args.span.hi, rec(path=path, args=args.node));
 }
 
-impure fn parse_constrs(parser p) -> common.spanned[vec[@ast.constr]] {
+fn parse_constrs(parser p) -> common.spanned[vec[@ast.constr]] {
     auto lo = p.get_lo_pos();
     auto hi = p.get_hi_pos();
     let vec[@ast.constr] constrs = vec();
@@ -334,7 +333,7 @@ impure fn parse_constrs(parser p) -> common.spanned[vec[@ast.constr]] {
    ret spanned(lo, hi, constrs);
 }
 
-impure fn parse_ty_constrs(@ast.ty t, parser p) -> @ast.ty {
+fn parse_ty_constrs(@ast.ty t, parser p) -> @ast.ty {
    if (p.peek() == token.COLON) {
        auto constrs = parse_constrs(p);
        ret @spanned(t.span.lo, constrs.span.hi,
@@ -343,13 +342,11 @@ impure fn parse_ty_constrs(@ast.ty t, parser p) -> @ast.ty {
    ret t;
 }
 
-impure fn parse_ty(parser p) -> @ast.ty {
+fn parse_ty(parser p) -> @ast.ty {
     auto lo = p.get_lo_pos();
     auto hi = lo;
     let ast.ty_ t;
 
-    // FIXME: make sure these are only used when valid
-    let ast.effect eff = parse_effect(p);
     // FIXME: do something with this
     let ast.layer lyr = parse_layer(p);
 
@@ -418,9 +415,9 @@ impure fn parse_ty(parser p) -> @ast.ty {
         case (token.FN) {
             auto flo = p.get_lo_pos();
             p.bump();
-            t = parse_ty_fn(eff, ast.proto_fn, p, flo);
+            t = parse_ty_fn(ast.proto_fn, p, flo);
             alt (t) {
-                case (ast.ty_fn(_, _, _, ?out)) {
+                case (ast.ty_fn(_, _, ?out)) {
                     hi = out.span.hi;
                 }
             }
@@ -429,9 +426,9 @@ impure fn parse_ty(parser p) -> @ast.ty {
         case (token.ITER) {
             auto flo = p.get_lo_pos();
             p.bump();
-            t = parse_ty_fn(eff, ast.proto_iter, p, flo);
+            t = parse_ty_fn(ast.proto_iter, p, flo);
             alt (t) {
-                case (ast.ty_fn(_, _, _, ?out)) {
+                case (ast.ty_fn(_, _, ?out)) {
                     hi = out.span.hi;
                 }
             }
@@ -482,7 +479,7 @@ impure fn parse_ty(parser p) -> @ast.ty {
     ret parse_ty_constrs(@spanned(lo, hi, t), p);
 }
 
-impure fn parse_arg(parser p) -> ast.arg {
+fn parse_arg(parser p) -> ast.arg {
     let ast.mode m = ast.val;
     if (p.peek() == token.BINOP(token.AND)) {
         m = ast.alias;
@@ -498,9 +495,9 @@ impure fn parse_arg(parser p) -> ast.arg {
     ret rec(mode=m, ty=t, ident=i, id=p.next_def_id());
 }
 
-impure fn parse_seq_to_end[T](token.token ket,
+fn parse_seq_to_end[T](token.token ket,
                               option.t[token.token] sep,
-                              (impure fn(parser) -> T) f,
+                              (fn(parser) -> T) f,
                               mutable uint hi,
                               parser p) -> vec[T] {
     let bool first = true;
@@ -526,10 +523,10 @@ impure fn parse_seq_to_end[T](token.token ket,
     ret v;
 }
 
-impure fn parse_seq[T](token.token bra,
+fn parse_seq[T](token.token bra,
                        token.token ket,
                        option.t[token.token] sep,
-                       (impure fn(parser) -> T) f,
+                       (fn(parser) -> T) f,
                        parser p) -> util.common.spanned[vec[T]] {
     auto lo = p.get_lo_pos();
     auto hi = p.get_hi_pos();
@@ -538,7 +535,7 @@ impure fn parse_seq[T](token.token bra,
     ret spanned(lo, hi, result);
 }
 
-impure fn parse_lit(parser p) -> ast.lit {
+fn parse_lit(parser p) -> ast.lit {
     auto sp = p.get_span();
     let ast.lit_ lit = ast.lit_nil;
     alt (p.peek()) {
@@ -594,7 +591,7 @@ tag greed {
     MINIMAL;
 }
 
-impure fn parse_ty_args(parser p, uint hi) ->
+fn parse_ty_args(parser p, uint hi) ->
     util.common.spanned[vec[@ast.ty]] {
 
     if (p.peek() == token.LBRACKET) {
@@ -609,7 +606,7 @@ impure fn parse_ty_args(parser p, uint hi) ->
     ret spanned(hi, hi, v);
 }
 
-impure fn parse_path(parser p, greed g) -> ast.path {
+fn parse_path(parser p, greed g) -> ast.path {
 
     auto lo = p.get_lo_pos();
     auto hi = lo;
@@ -643,7 +640,7 @@ impure fn parse_path(parser p, greed g) -> ast.path {
     ret spanned(lo, tys.span.hi, rec(idents=ids, types=tys.node));
 }
 
-impure fn parse_mutability(parser p) -> ast.mutability {
+fn parse_mutability(parser p) -> ast.mutability {
     if (p.peek() == token.MUTABLE) {
         p.bump();
         if (p.peek() == token.QUES) {
@@ -655,7 +652,7 @@ impure fn parse_mutability(parser p) -> ast.mutability {
     ret ast.imm;
 }
 
-impure fn parse_field(parser p) -> ast.field {
+fn parse_field(parser p) -> ast.field {
     auto m = parse_mutability(p);
     auto i = parse_ident(p);
     expect(p, token.EQ);
@@ -663,7 +660,7 @@ impure fn parse_field(parser p) -> ast.field {
     ret rec(mut=m, ident=i, expr=e);
 }
 
-impure fn parse_bottom_expr(parser p) -> @ast.expr {
+fn parse_bottom_expr(parser p) -> @ast.expr {
 
     auto lo = p.get_lo_pos();
     auto hi = p.get_hi_pos();
@@ -701,7 +698,7 @@ impure fn parse_bottom_expr(parser p) -> @ast.expr {
 
         case (token.TUP) {
             p.bump();
-            impure fn parse_elt(parser p) -> ast.elt {
+            fn parse_elt(parser p) -> ast.elt {
                 auto m = parse_mutability(p);
                 auto e = parse_expr(p);
                 ret rec(mut=m, expr=e);
@@ -767,7 +764,7 @@ impure fn parse_bottom_expr(parser p) -> @ast.expr {
         case (token.BIND) {
             p.bump();
             auto e = parse_expr_res(p, RESTRICT_NO_CALL_EXPRS);
-            impure 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();
@@ -937,7 +934,7 @@ impure fn parse_bottom_expr(parser p) -> @ast.expr {
  * rust crates. At the moment we have neither.
  */
 
-impure fn expand_syntax_ext(parser p, ast.span sp,
+fn expand_syntax_ext(parser p, ast.span sp,
                      &ast.path path, vec[@ast.expr] args,
                      option.t[@ast.expr] body) -> ast.expr_ {
 
@@ -956,7 +953,7 @@ impure fn expand_syntax_ext(parser p, ast.span sp,
     }
 }
 
-impure fn extend_expr_by_ident(parser p, uint lo, uint hi,
+fn extend_expr_by_ident(parser p, uint lo, uint hi,
                                @ast.expr e, ast.ident i) -> @ast.expr {
     auto e_ = e.node;
     alt (e.node) {
@@ -981,14 +978,14 @@ impure fn extend_expr_by_ident(parser p, uint lo, uint hi,
     ret @spanned(lo, hi, e_);
 }
 
-impure fn parse_self_method(parser p) -> @ast.expr {
+fn parse_self_method(parser p) -> @ast.expr {
     auto sp = p.get_span();
     let ast.ident f_name = parse_ident(p);
     auto hi = p.get_span();
     ret @rec(node=ast.expr_self_method(f_name, ast.ann_none), span=sp);
 }
 
-impure fn parse_dot_or_call_expr(parser p) -> @ast.expr {
+fn parse_dot_or_call_expr(parser p) -> @ast.expr {
     auto lo = p.get_lo_pos();
     auto e = parse_bottom_expr(p);
     auto hi = e.span.hi;
@@ -1043,7 +1040,7 @@ impure fn parse_dot_or_call_expr(parser p) -> @ast.expr {
     ret e;
 }
 
-impure fn parse_prefix_expr(parser p) -> @ast.expr {
+fn parse_prefix_expr(parser p) -> @ast.expr {
 
     if (p.peek() == token.MUTABLE) {
         p.bump();
@@ -1140,11 +1137,11 @@ fn prec_table() -> vec[op_spec] {
             rec(tok=token.OROR, op=ast.or, prec=1));
 }
 
-impure fn parse_binops(parser p) -> @ast.expr {
+fn parse_binops(parser p) -> @ast.expr {
     ret parse_more_binops(p, parse_prefix_expr(p), 0);
 }
 
-impure fn parse_more_binops(parser p, @ast.expr lhs, int min_prec)
+fn parse_more_binops(parser p, @ast.expr lhs, int min_prec)
     -> @ast.expr {
     // Magic nonsense to work around rustboot bug
     fn op_eq(token.token a, token.token b) -> bool {
@@ -1176,7 +1173,7 @@ impure fn parse_more_binops(parser p, @ast.expr lhs, int min_prec)
     ret lhs;
 }
 
-impure fn parse_assign_expr(parser p) -> @ast.expr {
+fn parse_assign_expr(parser p) -> @ast.expr {
     auto lo = p.get_lo_pos();
     auto lhs = parse_binops(p);
     alt (p.peek()) {
@@ -1223,7 +1220,7 @@ impure fn parse_assign_expr(parser p) -> @ast.expr {
     ret lhs;
 }
 
-impure fn parse_if_expr(parser p) -> @ast.expr {
+fn parse_if_expr(parser p) -> @ast.expr {
     auto lo = p.get_lo_pos();
 
     expect(p, token.IF);
@@ -1245,7 +1242,7 @@ impure fn parse_if_expr(parser p) -> @ast.expr {
     ret @spanned(lo, hi, ast.expr_if(cond, thn, els, ast.ann_none));
 }
 
-impure fn parse_else_expr(parser p) -> @ast.expr {
+fn parse_else_expr(parser p) -> @ast.expr {
     expect(p, token.ELSE);
     alt (p.peek()) {
         case (token.IF) {
@@ -1259,7 +1256,7 @@ impure fn parse_else_expr(parser p) -> @ast.expr {
     }
 }
 
-impure fn parse_head_local(parser p) -> @ast.decl {
+fn parse_head_local(parser p) -> @ast.decl {
     auto lo = p.get_lo_pos();
     let @ast.local local;
     if (p.peek() == token.AUTO) {
@@ -1272,7 +1269,7 @@ impure fn parse_head_local(parser p) -> @ast.decl {
 
 
 
-impure fn parse_for_expr(parser p) -> @ast.expr {
+fn parse_for_expr(parser p) -> @ast.expr {
     auto lo = p.get_lo_pos();
     auto is_each = false;
 
@@ -1301,7 +1298,7 @@ impure fn parse_for_expr(parser p) -> @ast.expr {
 }
 
 
-impure fn parse_while_expr(parser p) -> @ast.expr {
+fn parse_while_expr(parser p) -> @ast.expr {
     auto lo = p.get_lo_pos();
 
     expect(p, token.WHILE);
@@ -1313,7 +1310,7 @@ impure fn parse_while_expr(parser p) -> @ast.expr {
     ret @spanned(lo, hi, ast.expr_while(cond, body, ast.ann_none));
 }
 
-impure fn parse_do_while_expr(parser p) -> @ast.expr {
+fn parse_do_while_expr(parser p) -> @ast.expr {
     auto lo = p.get_lo_pos();
 
     expect(p, token.DO);
@@ -1326,7 +1323,7 @@ impure fn parse_do_while_expr(parser p) -> @ast.expr {
     ret @spanned(lo, hi, ast.expr_do_while(body, cond, ast.ann_none));
 }
 
-impure fn parse_alt_expr(parser p) -> @ast.expr {
+fn parse_alt_expr(parser p) -> @ast.expr {
     auto lo = p.get_lo_pos();
     expect(p, token.ALT);
     expect(p, token.LPAREN);
@@ -1377,7 +1374,7 @@ impure fn parse_alt_expr(parser p) -> @ast.expr {
     ret @spanned(lo, hi, expr);
 }
 
-impure fn parse_spawn_expr(parser p) -> @ast.expr {
+fn parse_spawn_expr(parser p) -> @ast.expr {
     auto lo = p.get_lo_pos();
     expect(p, token.SPAWN);
 
@@ -1398,11 +1395,11 @@ impure fn parse_spawn_expr(parser p) -> @ast.expr {
     ret @spanned(lo, hi, spawn_expr);
 }
 
-impure fn parse_expr(parser p) -> @ast.expr {
+fn parse_expr(parser p) -> @ast.expr {
     ret parse_expr_res(p, UNRESTRICTED);
 }
 
-impure fn parse_expr_res(parser p, restriction r) -> @ast.expr {
+fn parse_expr_res(parser p, restriction r) -> @ast.expr {
     auto old = p.get_restriction();
     p.restrict(r);
     auto e = parse_expr_inner(p);
@@ -1410,7 +1407,7 @@ impure fn parse_expr_res(parser p, restriction r) -> @ast.expr {
     ret e;
 }
 
-impure fn parse_expr_inner(parser p) -> @ast.expr {
+fn parse_expr_inner(parser p) -> @ast.expr {
     alt (p.peek()) {
         case (token.LBRACE) {
             auto blk = parse_block(p);
@@ -1442,7 +1439,7 @@ impure fn parse_expr_inner(parser p) -> @ast.expr {
     }
 }
 
-impure 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();
@@ -1460,7 +1457,7 @@ impure fn parse_initializer(parser p) -> option.t[ast.initializer] {
     }
 }
 
-impure fn parse_pat(parser p) -> @ast.pat {
+fn parse_pat(parser p) -> @ast.pat {
     auto lo = p.get_lo_pos();
     auto hi = p.get_hi_pos();
     auto pat;
@@ -1514,7 +1511,7 @@ impure fn parse_pat(parser p) -> @ast.pat {
     ret @spanned(lo, hi, pat);
 }
 
-impure 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);
@@ -1526,30 +1523,30 @@ impure fn parse_local_full(&option.t[@ast.ty] tyopt,
              ann = ast.ann_none);
 }
 
-impure fn parse_typed_local(parser p) -> @ast.local {
+fn parse_typed_local(parser p) -> @ast.local {
     auto ty = parse_ty(p);
     ret parse_local_full(some(ty), p);
 }
 
-impure fn parse_auto_local(parser p) -> @ast.local {
+fn parse_auto_local(parser p) -> @ast.local {
     ret parse_local_full(none[@ast.ty], p);
 }
 
-impure fn parse_let(parser p) -> @ast.decl {
+fn parse_let(parser p) -> @ast.decl {
     auto lo = p.get_lo_pos();
     expect(p, token.LET);
     auto local = parse_typed_local(p);
     ret @spanned(lo, p.get_hi_pos(), ast.decl_local(local));
 }
 
-impure fn parse_auto(parser p) -> @ast.decl {
+fn parse_auto(parser p) -> @ast.decl {
     auto lo = p.get_lo_pos();
     expect(p, token.AUTO);
     auto local = parse_auto_local(p);
     ret @spanned(lo, p.get_hi_pos(), ast.decl_local(local));
 }
 
-impure fn parse_stmt(parser p) -> @ast.stmt {
+fn parse_stmt(parser p) -> @ast.stmt {
     if (p.get_file_type() == SOURCE_FILE) {
         ret parse_source_stmt(p);
     } else {
@@ -1557,13 +1554,13 @@ impure fn parse_stmt(parser p) -> @ast.stmt {
     }
 }
 
-impure fn parse_crate_stmt(parser p) -> @ast.stmt {
+fn parse_crate_stmt(parser p) -> @ast.stmt {
     auto cdir = parse_crate_directive(p);
     ret @spanned(cdir.span.lo, cdir.span.hi,
                  ast.stmt_crate_directive(@cdir));
 }
 
-impure fn parse_source_stmt(parser p) -> @ast.stmt {
+fn parse_source_stmt(parser p) -> @ast.stmt {
     auto lo = p.get_lo_pos();
     alt (p.peek()) {
 
@@ -1685,7 +1682,7 @@ fn stmt_ends_with_semi(@ast.stmt stmt) -> bool {
     }
 }
 
-impure fn parse_block(parser p) -> ast.block {
+fn parse_block(parser p) -> ast.block {
     auto lo = p.get_lo_pos();
 
     let vec[@ast.stmt] stmts = vec();
@@ -1746,11 +1743,11 @@ impure fn parse_block(parser p) -> ast.block {
     ret spanned[ast.block_](lo, hi, bloc);
 }
 
-impure fn parse_ty_param(parser p) -> ast.ty_param {
+fn parse_ty_param(parser p) -> ast.ty_param {
     ret parse_ident(p);
 }
 
-impure fn parse_ty_params(parser p) -> vec[ast.ty_param] {
+fn parse_ty_params(parser p) -> vec[ast.ty_param] {
     let vec[ast.ty_param] ty_params = vec();
     if (p.peek() == token.LBRACKET) {
         auto f = parse_ty_param;   // FIXME: pass as lval directly
@@ -1760,7 +1757,7 @@ impure fn parse_ty_params(parser p) -> vec[ast.ty_param] {
     ret ty_params;
 }
 
-impure fn parse_fn_decl(parser p, ast.effect eff) -> ast.fn_decl {
+fn parse_fn_decl(parser p) -> ast.fn_decl {
     auto pf = parse_arg;
     let util.common.spanned[vec[ast.arg]] inputs =
         // FIXME: passing parse_arg as an lval doesn't work at the
@@ -1783,61 +1780,59 @@ impure fn parse_fn_decl(parser p, ast.effect eff) -> ast.fn_decl {
     } else {
         output = @spanned(inputs.span.lo, inputs.span.hi, ast.ty_nil);
     }
-    ret rec(effect=eff, inputs=inputs.node, output=output);
+    ret rec(inputs=inputs.node, output=output);
 }
 
-impure fn parse_fn(parser p, ast.effect eff, ast.proto proto) -> ast._fn {
-    auto decl = parse_fn_decl(p, eff);
+fn parse_fn(parser p, ast.proto proto) -> ast._fn {
+    auto decl = parse_fn_decl(p);
     auto body = parse_block(p);
     ret rec(decl = decl,
             proto = proto,
             body = body);
 }
 
-impure fn parse_fn_header(parser p)
+fn parse_fn_header(parser p)
     -> tup(ast.ident, vec[ast.ty_param]) {
     auto id = parse_ident(p);
     auto ty_params = parse_ty_params(p);
     ret tup(id, ty_params);
 }
 
-impure fn parse_item_fn_or_iter(parser p, ast.effect eff) -> @ast.item {
+fn parse_item_fn_or_iter(parser p) -> @ast.item {
     auto lo = p.get_lo_pos();
     auto proto = parse_proto(p);
     auto t = parse_fn_header(p);
-    auto f = parse_fn(p, eff, proto);
+    auto f = parse_fn(p, proto);
     auto item = ast.item_fn(t._0, f, t._1,
                             p.next_def_id(), ast.ann_none);
     ret @spanned(lo, f.body.span.hi, item);
 }
 
 
-impure fn parse_obj_field(parser p) -> ast.obj_field {
+fn parse_obj_field(parser p) -> ast.obj_field {
     auto mut = parse_mutability(p); // TODO: store this, use it in typeck
     auto ty = parse_ty(p);
     auto ident = parse_ident(p);
     ret rec(ty=ty, ident=ident, id=p.next_def_id(), ann=ast.ann_none);
 }
 
-impure fn parse_method(parser p) -> @ast.method {
+fn parse_method(parser p) -> @ast.method {
     auto lo = p.get_lo_pos();
-    auto eff = parse_effect(p);
     auto proto = parse_proto(p);
     auto ident = parse_ident(p);
-    auto f = parse_fn(p, eff, proto);
+    auto f = parse_fn(p, proto);
     auto meth = rec(ident=ident, meth=f,
                     id=p.next_def_id(), ann=ast.ann_none);
     ret @spanned(lo, f.body.span.hi, meth);
 }
 
-impure fn parse_dtor(parser p) -> @ast.method {
+fn parse_dtor(parser p) -> @ast.method {
     auto lo = p.get_lo_pos();
     expect(p, token.DROP);
     let ast.block b = parse_block(p);
     let vec[ast.arg] inputs = vec();
     let @ast.ty output = @spanned(lo, lo, ast.ty_nil);
-    let ast.fn_decl d = rec(effect=ast.eff_pure,
-                            inputs=inputs,
+    let ast.fn_decl d = rec(inputs=inputs,
                             output=output);
     let ast._fn f = rec(decl = d,
                         proto = ast.proto_fn,
@@ -1849,7 +1844,7 @@ impure fn parse_dtor(parser p) -> @ast.method {
     ret @spanned(lo, f.body.span.hi, m);
 }
 
-impure fn parse_item_obj(parser p, ast.layer lyr) -> @ast.item {
+fn parse_item_obj(parser p, ast.layer lyr) -> @ast.item {
     auto lo = p.get_lo_pos();
     expect(p, token.OBJ);
     auto ident = parse_ident(p);
@@ -1890,7 +1885,7 @@ impure fn parse_item_obj(parser p, ast.layer lyr) -> @ast.item {
     ret @spanned(lo, hi, item);
 }
 
-impure fn parse_mod_items(parser p, token.token term) -> ast._mod {
+fn parse_mod_items(parser p, token.token term) -> ast._mod {
     auto index = new_str_hash[ast.mod_index_entry]();
     auto view_items = parse_view(p, index);
     let vec[@ast.item] items = vec();
@@ -1904,7 +1899,7 @@ impure fn parse_mod_items(parser p, token.token term) -> ast._mod {
     ret rec(view_items=view_items, items=items, index=index);
 }
 
-impure fn parse_item_const(parser p) -> @ast.item {
+fn parse_item_const(parser p) -> @ast.item {
     auto lo = p.get_lo_pos();
     expect(p, token.CONST);
     auto ty = parse_ty(p);
@@ -1917,7 +1912,7 @@ impure fn parse_item_const(parser p) -> @ast.item {
     ret @spanned(lo, hi, item);
 }
 
-impure fn parse_item_mod(parser p) -> @ast.item {
+fn parse_item_mod(parser p) -> @ast.item {
     auto lo = p.get_lo_pos();
     expect(p, token.MOD);
     auto id = parse_ident(p);
@@ -1929,7 +1924,7 @@ impure fn parse_item_mod(parser p) -> @ast.item {
     ret @spanned(lo, hi, item);
 }
 
-impure fn parse_item_native_type(parser p) -> @ast.native_item {
+fn parse_item_native_type(parser p) -> @ast.native_item {
     auto t = parse_type_decl(p);
     auto hi = p.get_hi_pos();
     expect(p, token.SEMI);
@@ -1937,11 +1932,11 @@ impure fn parse_item_native_type(parser p) -> @ast.native_item {
     ret @spanned(t._0, hi, item);
 }
 
-impure fn parse_item_native_fn(parser p, ast.effect eff) -> @ast.native_item {
+fn parse_item_native_fn(parser p) -> @ast.native_item {
     auto lo = p.get_lo_pos();
     expect(p, token.FN);
     auto t = parse_fn_header(p);
-    auto decl = parse_fn_decl(p, eff);
+    auto decl = parse_fn_decl(p);
     auto link_name = none[str];
     if (p.peek() == token.EQ) {
         p.bump();
@@ -1955,8 +1950,7 @@ impure fn parse_item_native_fn(parser p, ast.effect eff) -> @ast.native_item {
     ret @spanned(lo, hi, item);
 }
 
-impure fn parse_native_item(parser p) -> @ast.native_item {
-    let ast.effect eff = parse_effect(p);
+fn parse_native_item(parser p) -> @ast.native_item {
     let ast.opacity opa = parse_opacity(p);
     let ast.layer lyr = parse_layer(p);
     alt (p.peek()) {
@@ -1964,7 +1958,7 @@ impure fn parse_native_item(parser p) -> @ast.native_item {
             ret parse_item_native_type(p);
         }
         case (token.FN) {
-            ret parse_item_native_fn(p, eff);
+            ret parse_item_native_fn(p);
         }
         case (?t) {
             unexpected(p, t);
@@ -1973,7 +1967,7 @@ impure fn parse_native_item(parser p) -> @ast.native_item {
     }
 }
 
-impure fn parse_native_mod_items(parser p,
+fn parse_native_mod_items(parser p,
                                  str native_name,
                                  ast.native_abi abi) -> ast.native_mod {
     auto index = new_str_hash[ast.native_mod_index_entry]();
@@ -2008,7 +2002,7 @@ fn default_native_name(session.session sess, str id) -> str {
     }
 }
 
-impure fn parse_item_native_mod(parser p) -> @ast.item {
+fn parse_item_native_mod(parser p) -> @ast.item {
     auto lo = p.get_lo_pos();
     expect(p, token.NATIVE);
     auto abi = ast.native_abi_cdecl;
@@ -2041,14 +2035,14 @@ impure fn parse_item_native_mod(parser p) -> @ast.item {
     ret @spanned(lo, hi, item);
 }
 
-impure fn parse_type_decl(parser p) -> tup(uint, ast.ident) {
+fn parse_type_decl(parser p) -> tup(uint, ast.ident) {
     auto lo = p.get_lo_pos();
     expect(p, token.TYPE);
     auto id = parse_ident(p);
     ret tup(lo, id);
 }
 
-impure fn parse_item_type(parser p) -> @ast.item {
+fn parse_item_type(parser p) -> @ast.item {
     auto t = parse_type_decl(p);
     auto tps = parse_ty_params(p);
 
@@ -2060,7 +2054,7 @@ impure fn parse_item_type(parser p) -> @ast.item {
     ret @spanned(t._0, hi, item);
 }
 
-impure fn parse_item_tag(parser p) -> @ast.item {
+fn parse_item_tag(parser p) -> @ast.item {
     auto lo = p.get_lo_pos();
     expect(p, token.TAG);
     auto id = parse_ident(p);
@@ -2112,7 +2106,7 @@ impure fn parse_item_tag(parser p) -> @ast.item {
     ret @spanned(lo, hi, item);
 }
 
-impure fn parse_opacity(parser p) -> ast.opacity {
+fn parse_opacity(parser p) -> ast.opacity {
     alt (p.peek()) {
         case (token.ABS) {
             p.bump();
@@ -2125,7 +2119,7 @@ impure fn parse_opacity(parser p) -> ast.opacity {
     fail;
 }
 
-impure fn parse_layer(parser p) -> ast.layer {
+fn parse_layer(parser p) -> ast.layer {
     alt (p.peek()) {
         case (token.STATE) {
             p.bump();
@@ -2143,18 +2137,14 @@ impure fn parse_layer(parser p) -> ast.layer {
 }
 
 
-impure fn parse_effect(parser p) -> ast.effect {
+fn parse_auth(parser p) -> ast._auth {
     alt (p.peek()) {
-        case (token.IMPURE) {
-            p.bump();
-            ret ast.eff_impure;
-        }
         case (token.UNSAFE) {
             p.bump();
-            ret ast.eff_unsafe;
+            ret ast.auth_unsafe;
         }
-        case (_) {
-            ret ast.eff_pure;
+        case (?t) {
+            unexpected(p, t);
         }
     }
     fail;
@@ -2164,8 +2154,6 @@ fn peeking_at_item(parser p) -> bool {
     alt (p.peek()) {
         case (token.STATE) { ret true; }
         case (token.GC) { ret true; }
-        case (token.IMPURE) { ret true; }
-        case (token.UNSAFE) { ret true; }
         case (token.CONST) { ret true; }
         case (token.FN) { ret true; }
         case (token.ITER) { ret true; }
@@ -2178,46 +2166,39 @@ fn peeking_at_item(parser p) -> bool {
     ret false;
 }
 
-impure fn parse_item(parser p) -> @ast.item {
-    let ast.effect eff = parse_effect(p);
+fn parse_item(parser p) -> @ast.item {
     let ast.opacity opa = parse_opacity(p);
     let ast.layer lyr = parse_layer(p);
 
     alt (p.peek()) {
         case (token.CONST) {
-            check (eff == ast.eff_pure);
             check (lyr == ast.layer_value);
             ret parse_item_const(p);
         }
 
         case (token.FN) {
             check (lyr == ast.layer_value);
-            ret parse_item_fn_or_iter(p, eff);
+            ret parse_item_fn_or_iter(p);
         }
         case (token.ITER) {
             check (lyr == ast.layer_value);
-            ret parse_item_fn_or_iter(p, eff);
+            ret parse_item_fn_or_iter(p);
         }
         case (token.MOD) {
-            check (eff == ast.eff_pure);
             check (lyr == ast.layer_value);
             ret parse_item_mod(p);
         }
         case (token.NATIVE) {
-            check (eff == ast.eff_pure);
             check (lyr == ast.layer_value);
             ret parse_item_native_mod(p);
         }
         case (token.TYPE) {
-            check (eff == ast.eff_pure);
             ret parse_item_type(p);
         }
         case (token.TAG) {
-            check (eff == ast.eff_pure);
             ret parse_item_tag(p);
         }
         case (token.OBJ) {
-            check (eff == ast.eff_pure);
             ret parse_item_obj(p, lyr);
         }
         case (?t) {
@@ -2227,7 +2208,7 @@ impure fn parse_item(parser p) -> @ast.item {
     fail;
 }
 
-impure fn parse_meta_item(parser p) -> @ast.meta_item {
+fn parse_meta_item(parser p) -> @ast.meta_item {
     auto lo = p.get_lo_pos();
     auto ident = parse_ident(p);
     expect(p, token.EQ);
@@ -2244,13 +2225,13 @@ impure fn parse_meta_item(parser p) -> @ast.meta_item {
     fail;
 }
 
-impure fn parse_meta(parser p) -> vec[@ast.meta_item] {
+fn parse_meta(parser p) -> vec[@ast.meta_item] {
     auto pf = parse_meta_item;
     ret parse_seq[@ast.meta_item](token.LPAREN, token.RPAREN,
                                    some(token.COMMA), pf, p).node;
 }
 
-impure fn parse_optional_meta(parser p) -> vec[@ast.meta_item] {
+fn parse_optional_meta(parser p) -> vec[@ast.meta_item] {
     alt (p.peek()) {
         case (token.LPAREN) {
             ret parse_meta(p);
@@ -2262,7 +2243,7 @@ impure fn parse_optional_meta(parser p) -> vec[@ast.meta_item] {
     }
 }
 
-impure fn parse_use(parser p) -> @ast.view_item {
+fn parse_use(parser p) -> @ast.view_item {
     auto lo = p.get_lo_pos();
     expect(p, token.USE);
     auto ident = parse_ident(p);
@@ -2274,7 +2255,7 @@ impure fn parse_use(parser p) -> @ast.view_item {
     ret @spanned(lo, hi, use_decl);
 }
 
-impure fn parse_rest_import_name(parser p, ast.ident first,
+fn parse_rest_import_name(parser p, ast.ident first,
                                  option.t[ast.ident] def_ident)
         -> @ast.view_item {
     auto lo = p.get_lo_pos();
@@ -2302,7 +2283,7 @@ impure fn parse_rest_import_name(parser p, ast.ident first,
     ret @spanned(lo, hi, import_decl);
 }
 
-impure fn parse_full_import_name(parser p, ast.ident def_ident)
+fn parse_full_import_name(parser p, ast.ident def_ident)
        -> @ast.view_item {
     alt (p.peek()) {
         case (token.IDENT(?ident)) {
@@ -2316,7 +2297,7 @@ impure fn parse_full_import_name(parser p, ast.ident def_ident)
     fail;
 }
 
-impure fn parse_import(parser p) -> @ast.view_item {
+fn parse_import(parser p) -> @ast.view_item {
     expect(p, token.IMPORT);
     alt (p.peek()) {
         case (token.IDENT(?ident)) {
@@ -2338,7 +2319,7 @@ impure fn parse_import(parser p) -> @ast.view_item {
     fail;
 }
 
-impure fn parse_export(parser p) -> @ast.view_item {
+fn parse_export(parser p) -> @ast.view_item {
     auto lo = p.get_lo_pos();
     expect(p, token.EXPORT);
     auto id = parse_ident(p);
@@ -2347,7 +2328,7 @@ impure fn parse_export(parser p) -> @ast.view_item {
     ret @spanned(lo, hi, ast.view_item_export(id));
 }
 
-impure fn parse_view_item(parser p) -> @ast.view_item {
+fn parse_view_item(parser p) -> @ast.view_item {
     alt (p.peek()) {
         case (token.USE) {
             ret parse_use(p);
@@ -2371,7 +2352,7 @@ fn is_view_item(token.token t) -> bool {
     ret false;
 }
 
-impure fn parse_view(parser p, ast.mod_index index) -> vec[@ast.view_item] {
+fn parse_view(parser p, ast.mod_index index) -> vec[@ast.view_item] {
     let vec[@ast.view_item] items = vec();
     while (is_view_item(p.peek())) {
         auto item = parse_view_item(p);
@@ -2382,7 +2363,7 @@ impure fn parse_view(parser p, ast.mod_index index) -> vec[@ast.view_item] {
     ret items;
 }
 
-impure fn parse_native_view(parser p, ast.native_mod_index index)
+fn parse_native_view(parser p, ast.native_mod_index index)
     -> vec[@ast.view_item] {
     let vec[@ast.view_item] items = vec();
     while (is_view_item(p.peek())) {
@@ -2395,7 +2376,7 @@ impure fn parse_native_view(parser p, ast.native_mod_index index)
 }
 
 
-impure fn parse_crate_from_source_file(parser p) -> @ast.crate {
+fn parse_crate_from_source_file(parser p) -> @ast.crate {
     auto lo = p.get_lo_pos();
     auto m = parse_mod_items(p, token.EOF);
     let vec[@ast.crate_directive] cdirs = vec();
@@ -2409,7 +2390,7 @@ impure fn parse_crate_from_source_file(parser p) -> @ast.crate {
 //
 // Each directive imperatively extends its environment with 0 or more items.
 
-impure fn parse_crate_directive(parser p) -> ast.crate_directive
+fn parse_crate_directive(parser p) -> ast.crate_directive
 {
     auto lo = p.get_lo_pos();
     alt (p.peek()) {
@@ -2417,10 +2398,10 @@ impure fn parse_crate_directive(parser p) -> ast.crate_directive
             p.bump();
             auto n = parse_path(p, GREEDY);
             expect(p, token.EQ);
-            auto e = parse_effect(p);
+            auto a = parse_auth(p);
             auto hi = p.get_hi_pos();
             expect(p, token.SEMI);
-            ret spanned(lo, hi, ast.cdir_auth(n, e));
+            ret spanned(lo, hi, ast.cdir_auth(n, a));
         }
 
         case (token.META) {
@@ -2510,7 +2491,7 @@ impure fn parse_crate_directive(parser p) -> ast.crate_directive
 }
 
 
-impure fn parse_crate_directives(parser p, token.token term)
+fn parse_crate_directives(parser p, token.token term)
     -> vec[@ast.crate_directive] {
 
     let vec[@ast.crate_directive] cdirs = vec();
@@ -2523,7 +2504,7 @@ impure fn parse_crate_directives(parser p, token.token term)
     ret cdirs;
 }
 
-impure fn parse_crate_from_crate_file(parser p) -> @ast.crate {
+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 cdirs = parse_crate_directives(p, token.EOF);
diff --git a/src/comp/front/token.rs b/src/comp/front/token.rs
index 078467b5d0e..cdc6b5031e5 100644
--- a/src/comp/front/token.rs
+++ b/src/comp/front/token.rs
@@ -100,8 +100,7 @@ tag token {
     STATE;
     GC;
 
-    /* Effect keywords */
-    IMPURE;
+    /* Unsafe-block keyword */
     UNSAFE;
 
     /* Type qualifiers */
@@ -273,8 +272,7 @@ fn to_str(token t) -> str {
         case (STATE) { ret "state"; }
         case (GC) { ret "gc"; }
 
-        /* Effect keywords */
-        case (IMPURE) { ret "impure"; }
+        /* Unsafe-block keyword */
         case (UNSAFE) { ret "unsafe"; }
 
         /* Type qualifiers */
diff --git a/src/comp/middle/fold.rs b/src/comp/middle/fold.rs
index 6f1d6493e04..ef592fc8ab3 100644
--- a/src/comp/middle/fold.rs
+++ b/src/comp/middle/fold.rs
@@ -61,7 +61,6 @@ type ast_fold[ENV] =
          vec[ast.ty_method] meths) -> @ty)        fold_ty_obj,
 
      (fn(&ENV e, &span sp,
-         ast.effect eff,
          ast.proto proto,
          vec[rec(ast.mode mode, @ty ty)] inputs,
          @ty output) -> @ty)                      fold_ty_fn,
@@ -299,7 +298,7 @@ type ast_fold[ENV] =
          ast.proto proto,
          &block body) -> ast._fn)                 fold_fn,
 
-     (fn(&ENV e, ast.effect effect,
+     (fn(&ENV e,
          vec[arg] inputs,
          @ty output) -> ast.fn_decl)              fold_fn_decl,
 
@@ -398,12 +397,12 @@ fn fold_ty[ENV](&ENV env, ast_fold[ENV] fld, @ty t) -> @ty {
         case (ast.ty_obj(?meths)) {
             let vec[ast.ty_method] meths_ = vec();
             for (ast.ty_method m in meths) {
-                auto tfn = fold_ty_fn(env_, fld, t.span, m.effect, m.proto,
+                auto tfn = fold_ty_fn(env_, fld, t.span, m.proto,
                                       m.inputs, m.output);
                 alt (tfn.node) {
-                    case (ast.ty_fn(?eff, ?p, ?ins, ?out)) {
+                    case (ast.ty_fn(?p, ?ins, ?out)) {
                         _vec.push[ast.ty_method]
-                            (meths_, rec(effect=eff, proto=p, inputs=ins,
+                            (meths_, rec(proto=p, inputs=ins,
                                          output=out with m));
                     }
                 }
@@ -416,8 +415,8 @@ fn fold_ty[ENV](&ENV env, ast_fold[ENV] fld, @ty t) -> @ty {
             ret fld.fold_ty_path(env_, t.span, pth_, ref_opt);
         }
 
-        case (ast.ty_fn(?eff, ?proto, ?inputs, ?output)) {
-            ret fold_ty_fn(env_, fld, t.span, eff, proto, inputs, output);
+        case (ast.ty_fn(?proto, ?inputs, ?output)) {
+            ret fold_ty_fn(env_, fld, t.span, proto, inputs, output);
         }
 
         case (ast.ty_chan(?ty)) {
@@ -433,7 +432,7 @@ fn fold_ty[ENV](&ENV env, ast_fold[ENV] fld, @ty t) -> @ty {
 }
 
 fn fold_ty_fn[ENV](&ENV env, ast_fold[ENV] fld, &span sp,
-                   ast.effect eff, ast.proto proto,
+                   ast.proto proto,
                    vec[rec(ast.mode mode, @ty ty)] inputs,
                    @ty output) -> @ty {
     auto output_ = fold_ty(env, fld, output);
@@ -443,7 +442,7 @@ fn fold_ty_fn[ENV](&ENV env, ast_fold[ENV] fld, &span sp,
         auto input_ = rec(ty=ty_ with input);
         inputs_ += vec(input_);
     }
-    ret fld.fold_ty_fn(env, sp, eff, proto, inputs_, output_);
+    ret fld.fold_ty_fn(env, sp, proto, inputs_, output_);
 }
 
 fn fold_decl[ENV](&ENV env, ast_fold[ENV] fld, @decl d) -> @decl {
@@ -894,7 +893,7 @@ fn fold_fn_decl[ENV](&ENV env, ast_fold[ENV] fld,
         inputs += vec(fold_arg(env, fld, a));
     }
     auto output = fold_ty[ENV](env, fld, decl.output);
-    ret fld.fold_fn_decl(env, decl.effect, inputs, output);
+    ret fld.fold_fn_decl(env, inputs, output);
 }
 
 fn fold_fn[ENV](&ENV env, ast_fold[ENV] fld, &ast._fn f) -> ast._fn {
@@ -1187,10 +1186,10 @@ fn identity_fold_ty_obj[ENV](&ENV env, &span sp,
 }
 
 fn identity_fold_ty_fn[ENV](&ENV env, &span sp,
-                            ast.effect eff, ast.proto proto,
+                            ast.proto proto,
                             vec[rec(ast.mode mode, @ty ty)] inputs,
                             @ty output) -> @ty {
-    ret @respan(sp, ast.ty_fn(eff, proto, inputs, output));
+    ret @respan(sp, ast.ty_fn(proto, inputs, output));
 }
 
 fn identity_fold_ty_path[ENV](&ENV env, &span sp, ast.path p,
@@ -1530,10 +1529,9 @@ fn identity_fold_block[ENV](&ENV e, &span sp, &ast.block_ blk) -> block {
 }
 
 fn identity_fold_fn_decl[ENV](&ENV e,
-                              ast.effect effect,
                               vec[arg] inputs,
                               @ty output) -> ast.fn_decl {
-    ret rec(effect=effect, inputs=inputs, output=output);
+    ret rec(inputs=inputs, output=output);
 }
 
 fn identity_fold_fn[ENV](&ENV e,
@@ -1638,7 +1636,7 @@ fn new_identity_fold[ENV]() -> ast_fold[ENV] {
          fold_ty_tup     = bind identity_fold_ty_tup[ENV](_,_,_),
          fold_ty_rec     = bind identity_fold_ty_rec[ENV](_,_,_),
          fold_ty_obj     = bind identity_fold_ty_obj[ENV](_,_,_),
-         fold_ty_fn      = bind identity_fold_ty_fn[ENV](_,_,_,_,_,_),
+         fold_ty_fn      = bind identity_fold_ty_fn[ENV](_,_,_,_,_),
          fold_ty_path    = bind identity_fold_ty_path[ENV](_,_,_,_),
          fold_ty_chan    = bind identity_fold_ty_chan[ENV](_,_,_),
          fold_ty_port    = bind identity_fold_ty_port[ENV](_,_,_),
@@ -1708,7 +1706,7 @@ fn new_identity_fold[ENV]() -> ast_fold[ENV] {
              bind identity_fold_native_item_ty[ENV](_,_,_,_),
          fold_item_tag  = bind identity_fold_item_tag[ENV](_,_,_,_,_,_,_),
          fold_item_obj  = bind identity_fold_item_obj[ENV](_,_,_,_,_,_,_),
-       
+
          fold_view_item_use =
              bind identity_fold_view_item_use[ENV](_,_,_,_,_,_),
          fold_view_item_import =
@@ -1720,7 +1718,7 @@ fn new_identity_fold[ENV]() -> ast_fold[ENV] {
 
          fold_block = bind identity_fold_block[ENV](_,_,_),
          fold_fn = bind identity_fold_fn[ENV](_,_,_,_),
-         fold_fn_decl = bind identity_fold_fn_decl[ENV](_,_,_,_),
+         fold_fn_decl = bind identity_fold_fn_decl[ENV](_,_,_),
          fold_mod = bind identity_fold_mod[ENV](_,_),
          fold_native_mod = bind identity_fold_native_mod[ENV](_,_),
          fold_crate = bind identity_fold_crate[ENV](_,_,_,_),
diff --git a/src/comp/middle/metadata.rs b/src/comp/middle/metadata.rs
index 31aec74d872..fee3b30f7ee 100644
--- a/src/comp/middle/metadata.rs
+++ b/src/comp/middle/metadata.rs
@@ -521,8 +521,8 @@ fn create_index[T](vec[tup(T, uint)] index, fn(&T) -> uint hash_fn)
     ret buckets;
 }
 
-impure fn encode_index[T](&ebml.writer ebml_w, vec[vec[tup(T, uint)]] buckets,
-                          impure fn(io.writer, &T) write_fn) {
+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);
@@ -553,16 +553,16 @@ impure fn encode_index[T](&ebml.writer ebml_w, vec[vec[tup(T, uint)]] buckets,
 }
 
 
-impure fn write_str(io.writer writer, &str s) {
+fn write_str(io.writer writer, &str s) {
     writer.write_str(s);
 }
 
-impure fn write_int(io.writer writer, &int n) {
+fn write_int(io.writer writer, &int n) {
     writer.write_be_uint(n as uint, 4u);
 }
 
 
-impure fn encode_metadata(@trans.crate_ctxt cx, @ast.crate crate)
+fn encode_metadata(@trans.crate_ctxt cx, @ast.crate crate)
         -> ValueRef {
     auto string_w = io.string_writer();
     auto buf_w = string_w.get_writer().get_buf_writer();
diff --git a/src/comp/middle/ty.rs b/src/comp/middle/ty.rs
index 0f527a33921..06fbf76ef3c 100644
--- a/src/comp/middle/ty.rs
+++ b/src/comp/middle/ty.rs
@@ -54,8 +54,8 @@ tag sty {
     ty_task;
     ty_tup(vec[mt]);
     ty_rec(vec[field]);
-    ty_fn(ast.proto, vec[arg], @t);                 // TODO: effect
-    ty_native_fn(ast.native_abi, vec[arg], @t);     // TODO: effect
+    ty_fn(ast.proto, vec[arg], @t);
+    ty_native_fn(ast.native_abi, vec[arg], @t);
     ty_obj(vec[method]);
     ty_var(int);                                    // ephemeral type var
     ty_local(ast.def_id);                           // type of a local var
diff --git a/src/comp/middle/typeck.rs b/src/comp/middle/typeck.rs
index 9a7fe79abc2..87c11a7b90a 100644
--- a/src/comp/middle/typeck.rs
+++ b/src/comp/middle/typeck.rs
@@ -267,7 +267,7 @@ fn ast_ty_to_ty(ty_getter getter, &@ast.ty ast_ty) -> @ty.t {
             sty = ty.ty_rec(flds);
         }
 
-        case (ast.ty_fn(_, ?proto, ?inputs, ?output)) {
+        case (ast.ty_fn(?proto, ?inputs, ?output)) {
             auto f = bind ast_arg_to_arg(getter, _);
             auto i = _vec.map[ast.ty_arg, arg](f, inputs);
             sty = ty.ty_fn(proto, i, ast_ty_to_ty(getter, output));
diff --git a/src/comp/middle/typestate_check.rs b/src/comp/middle/typestate_check.rs
index 4603fce94de..7d7108ff82a 100644
--- a/src/comp/middle/typestate_check.rs
+++ b/src/comp/middle/typestate_check.rs
@@ -277,7 +277,7 @@ fn mk_fn_info(_fn f) -> fn_info {
   ret res;
 }
 
-/* extends mk_fn_info to an item, side-effecting the map fi from 
+/* extends mk_fn_info to an item, side-effecting the map fi from
    function IDs to fn_info maps */
 fn mk_fn_info_item_fn(&_fn_info_map fi, &span sp, ident i, &ast._fn f,
                  vec[ast.ty_param] ty_params, def_id id, ann a) -> @item {
@@ -888,14 +888,14 @@ fn find_pre_post_expr(&_fn_info_map fm, &fn_info enclosing, &expr e) -> () {
     }
 }
 
-impure fn gen(&fn_info enclosing, &ann a, def_id id) -> bool {
+fn gen(&fn_info enclosing, &ann a, def_id id) -> bool {
   check(enclosing.contains_key(id));
   let uint i = (enclosing.get(id))._0;
 
   ret set_in_postcond(i, (ann_to_ts_ann_fail_more(a)).conditions);
 }
 
-impure fn gen_poststate(&fn_info enclosing, &ann a, def_id id) -> bool {
+fn gen_poststate(&fn_info enclosing, &ann a, def_id id) -> bool {
   check(enclosing.contains_key(id));
   let uint i = (enclosing.get(id))._0;
 
@@ -976,7 +976,7 @@ fn find_pre_post_state_item(_fn_info_map fm, @item i) -> bool {
   fail;
 }
 
-impure fn set_prestate_ann(ann a, prestate pre) -> bool {
+fn set_prestate_ann(ann a, prestate pre) -> bool {
   alt (a) {
     case (ann_type(_,_,?ts_a)) {
       check (! is_none[@ts_ann](ts_a));
@@ -990,7 +990,7 @@ impure fn set_prestate_ann(ann a, prestate pre) -> bool {
 }
 
 
-impure fn extend_prestate_ann(ann a, prestate pre) -> bool {
+fn extend_prestate_ann(ann a, prestate pre) -> bool {
   alt (a) {
     case (ann_type(_,_,?ts_a)) {
       check (! is_none[@ts_ann](ts_a));
@@ -1003,7 +1003,7 @@ impure fn extend_prestate_ann(ann a, prestate pre) -> bool {
   }
 }
 
-impure fn set_poststate_ann(ann a, poststate post) -> bool {
+fn set_poststate_ann(ann a, poststate post) -> bool {
   alt (a) {
     case (ann_type(_,_,?ts_a)) {
       check (! is_none[@ts_ann](ts_a));
@@ -1016,7 +1016,7 @@ impure fn set_poststate_ann(ann a, poststate post) -> bool {
   }
 }
 
-impure fn extend_poststate_ann(ann a, poststate post) -> bool {
+fn extend_poststate_ann(ann a, poststate post) -> bool {
   alt (a) {
     case (ann_type(_,_,?ts_a)) {
       check (! is_none[@ts_ann](ts_a));
@@ -1029,7 +1029,7 @@ impure fn extend_poststate_ann(ann a, poststate post) -> bool {
   }
 }
 
-impure fn set_pre_and_post(&ann a, pre_and_post pp) -> () {
+fn set_pre_and_post(&ann a, pre_and_post pp) -> () {
     alt (a) {
         case (ann_type(_,_,?ts_a)) {
             check (! is_none[@ts_ann](ts_a));
@@ -1068,7 +1068,7 @@ fn find_pre_post_state_exprs(&_fn_info_map fm,
   ret changed;
 }
 
-impure fn pure_exp(&ann a, &prestate p) -> bool {
+fn pure_exp(&ann a, &prestate p) -> bool {
   auto changed = false;
   changed = extend_prestate_ann(a, p) || changed;
   changed = extend_poststate_ann(a, p) || changed;
@@ -1363,7 +1363,7 @@ fn fixed_point_states(_fn_info_map fm, fn_info f_info,
   }
 }
 
-impure fn check_states_expr(fn_info enclosing, &expr e) -> () {
+fn check_states_expr(fn_info enclosing, &expr e) -> () {
   let precond prec    = expr_precond(e);
   let prestate pres   = expr_prestate(e);
 
diff --git a/src/comp/pretty/pp.rs b/src/comp/pretty/pp.rs
index b7b0c64a17e..85651c78c3c 100644
--- a/src/comp/pretty/pp.rs
+++ b/src/comp/pretty/pp.rs
@@ -48,14 +48,14 @@ fn mkstate(io.writer out, uint width) -> ps {
            mutable potential_brk=false);
 }
 
-impure fn write_spaces(ps p, uint i) {
+fn write_spaces(ps p, uint i) {
   while (i > 0u) {
     i -= 1u;
     p.out.write_str(" ");
   }
 }
 
-impure fn push_context(ps p, contexttype tp, uint indent) {
+fn push_context(ps p, contexttype tp, uint indent) {
   before_print(p, false);
   _vec.push[context](p.context, rec(tp=tp, indent=indent));
   p.start_of_box = true;
@@ -65,13 +65,13 @@ fn pop_context(ps p) {
   _vec.pop[context](p.context);
 }
 
-impure fn add_token(ps p, token tok) {
+fn add_token(ps p, token tok) {
   if (p.width == 0u) {direct_token(p, tok);}
   else if (p.scanning == scan_none) {do_token(p, tok);}
   else {buffer_token(p, tok);}
 }
 
-impure fn direct_token(ps p, token tok) {
+fn direct_token(ps p, token tok) {
   alt (tok) {
     case (brk(?sz)) {write_spaces(p, sz);}
     case (word(?w)) {p.out.write_str(w);}
@@ -80,7 +80,7 @@ impure fn direct_token(ps p, token tok) {
   }
 }
 
-impure fn buffer_token(ps p, token tok) {
+fn buffer_token(ps p, token tok) {
   p.buffered += vec(tok);
   auto col = p.scancol;
   p.scancol = col + token_size(tok);
@@ -114,14 +114,14 @@ impure fn buffer_token(ps p, token tok) {
   }
 }
 
-impure fn check_potential_brk(ps p) {
+fn check_potential_brk(ps p) {
   for (boxtype tp in p.scandepth) {
     if (tp != box_h) {ret;}
   }
   p.potential_brk = true;
 }
 
-impure fn finish_scan(ps p, bool fits) {
+fn finish_scan(ps p, bool fits) {
   auto buf = p.buffered;
   auto front = _vec.shift[token](buf);
   auto chosen_tp = cx_h;
@@ -145,7 +145,7 @@ impure fn finish_scan(ps p, bool fits) {
   for (token t in buf) { add_token(p, t); }
 }
 
-impure fn start_scan(ps p, token tok, scantype tp) {
+fn start_scan(ps p, token tok, scantype tp) {
   p.buffered = vec();
   p.scancol = p.col;
   p.scanning = tp;
@@ -174,7 +174,7 @@ fn box_is(boxtype a, boxtype b) -> bool {
   else {ret false;}
 }
 
-impure fn do_token(ps p, token tok) {
+fn do_token(ps p, token tok) {
   auto start_of_box = p.start_of_box;
   p.start_of_box = false;
   alt (tok) {
@@ -223,14 +223,14 @@ impure fn do_token(ps p, token tok) {
   }
 }
 
-impure fn line_break(ps p) {
+fn line_break(ps p) {
   p.out.write_str("\n");
   p.col = 0u;
   p.spaces = cur_context(p).indent;
   p.start_of_line = true;
 }
 
-impure fn before_print(ps p, bool closing) {
+fn before_print(ps p, bool closing) {
   if (p.start_of_line) {
     p.start_of_line = false;
     if (closing) {p.spaces = base_indent(p);}
@@ -254,14 +254,14 @@ fn token_size(token tok) -> uint {
   }
 }
 
-impure fn box(ps p, uint indent) {add_token(p, open(box_hv, indent));}
-impure fn abox(ps p) {add_token(p, open(box_align, 0u));}
-impure fn vbox(ps p, uint indent) {add_token(p, open(box_v, indent));}
-impure fn hbox(ps p, uint indent) {add_token(p, open(box_h, indent));}
-impure fn end(ps p) {add_token(p, close);}
-impure fn wrd(ps p, str wrd) {add_token(p, word(wrd));}
-impure fn cwrd(ps p, str wrd) {add_token(p, cword(wrd));}
-impure fn space(ps p) {add_token(p, brk(1u));}
-impure fn spaces(ps p, uint n) {add_token(p, brk(n));}
-impure fn line(ps p) {add_token(p, brk(0u));}
-impure fn hardbreak(ps p) {add_token(p, hardbrk);}
+fn box(ps p, uint indent) {add_token(p, open(box_hv, indent));}
+fn abox(ps p) {add_token(p, open(box_align, 0u));}
+fn vbox(ps p, uint indent) {add_token(p, open(box_v, indent));}
+fn hbox(ps p, uint indent) {add_token(p, open(box_h, indent));}
+fn end(ps p) {add_token(p, close);}
+fn wrd(ps p, str wrd) {add_token(p, word(wrd));}
+fn cwrd(ps p, str wrd) {add_token(p, cword(wrd));}
+fn space(ps p) {add_token(p, brk(1u));}
+fn spaces(ps p, uint n) {add_token(p, brk(n));}
+fn line(ps p) {add_token(p, brk(0u));}
+fn hardbreak(ps p) {add_token(p, hardbrk);}
diff --git a/src/comp/pretty/pprust.rs b/src/comp/pretty/pprust.rs
index 470ecefdc1c..cf606d9e6f1 100644
--- a/src/comp/pretty/pprust.rs
+++ b/src/comp/pretty/pprust.rs
@@ -15,7 +15,7 @@ type ps = @rec(pp.ps s,
                option.t[vec[lexer.cmnt]] comments,
                mutable uint cur_cmnt);
 
-impure 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),
@@ -59,39 +59,39 @@ fn pat_to_str(&@ast.pat p) -> str {
     ret writer.get_str();
 }
 
-impure fn hbox(ps s) {
+fn hbox(ps s) {
     pp.hbox(s.s, indent_unit);
 }
-impure fn wrd1(ps s, str word) {
+fn wrd1(ps s, str word) {
     wrd(s.s, word);
     space(s.s);
 }
-impure fn popen(ps s) {
+fn popen(ps s) {
     wrd(s.s, "(");
     pp.abox(s.s);
 }
-impure fn popen_h(ps s) {
+fn popen_h(ps s) {
     wrd(s.s, "(");
     pp.hbox(s.s, 0u);
 }
-impure fn pclose(ps s) {
+fn pclose(ps s) {
     end(s.s);
     wrd(s.s, ")");
 }
-impure fn bopen(ps s) {
+fn bopen(ps s) {
     wrd(s.s, "{");
     pp.vbox(s.s, indent_unit);
     line(s.s);
 }
-impure fn bclose(ps s) {
+fn bclose(ps s) {
     end(s.s);
     pp.cwrd(s.s, "}");
 }
-impure fn bclose_c(ps s, common.span span) {
+fn bclose_c(ps s, common.span span) {
     maybe_print_comment(s, span.hi);
     bclose(s);
 }
-impure fn commasep[IN](ps s, vec[IN] elts, impure fn(ps, &IN) op) {
+fn commasep[IN](ps s, vec[IN] elts, fn(ps, &IN) op) {
     auto first = true;
     for (IN elt in elts) {
         if (first) {first = false;}
@@ -99,7 +99,7 @@ impure fn commasep[IN](ps s, vec[IN] elts, impure fn(ps, &IN) op) {
         op(s, elt);
     }
 }
-impure fn commasep_cmnt[IN](ps s, vec[IN] elts, impure 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 i = 0u;
@@ -112,21 +112,21 @@ impure fn commasep_cmnt[IN](ps s, vec[IN] elts, impure fn(ps, &IN) op,
         }
     }
 }
-impure fn commasep_exprs(ps s, vec[@ast.expr] exprs) {
+fn commasep_exprs(ps s, vec[@ast.expr] exprs) {
     fn expr_span(&@ast.expr expr) -> common.span {ret expr.span;}
     auto f = print_expr;
     auto gs = expr_span;
     commasep_cmnt[@ast.expr](s, exprs, f, gs);
 }
 
-impure fn print_mod(ps s, ast._mod _mod) {
+fn print_mod(ps s, ast._mod _mod) {
     for (@ast.view_item vitem in _mod.view_items) {print_view_item(s, vitem);}
     line(s.s);
     for (@ast.item item in _mod.items) {print_item(s, item);}
     print_remaining_comments(s);
 }
 
-impure fn print_type(ps s, &@ast.ty ty) {
+fn print_type(ps s, &@ast.ty ty) {
     maybe_print_comment(s, ty.span.lo);
     hbox(s);
     alt (ty.node) {
@@ -159,7 +159,7 @@ impure fn print_type(ps s, &@ast.ty ty) {
         case (ast.ty_rec(?fields)) {
             wrd(s.s, "rec");
             popen(s);
-            impure fn print_field(ps s, &ast.ty_field f) {
+            fn print_field(ps s, &ast.ty_field f) {
                 hbox(s);
                 print_mt(s, f.mt);
                 space(s.s);
@@ -182,7 +182,7 @@ impure fn print_type(ps s, &@ast.ty ty) {
             bopen(s);
             for (ast.ty_method m in methods) {
                 hbox(s);
-                print_ty_fn(s, m.effect, 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);
@@ -190,8 +190,8 @@ impure fn print_type(ps s, &@ast.ty ty) {
             }
             bclose_c(s, ty.span);
         }
-        case (ast.ty_fn(?eff, ?proto,?inputs,?output)) {
-            print_ty_fn(s, eff, proto, option.none[str], inputs, output);
+        case (ast.ty_fn(?proto,?inputs,?output)) {
+            print_ty_fn(s, proto, option.none[str], inputs, output);
         }
         case (ast.ty_path(?path,_)) {
             print_path(s, path);
@@ -200,7 +200,7 @@ impure fn print_type(ps s, &@ast.ty ty) {
     end(s.s);
 }
 
-impure fn print_item(ps s, @ast.item item) {
+fn print_item(ps s, @ast.item item) {
     maybe_print_comment(s, item.span.lo);
     hbox(s);
     alt (item.node) {
@@ -278,7 +278,7 @@ impure fn print_item(ps s, @ast.item item) {
                 wrd(s.s, v.node.name);
                 if (_vec.len[ast.variant_arg](v.node.args) > 0u) {
                     popen(s);
-                    impure fn print_variant_arg(ps s, &ast.variant_arg arg) {
+                    fn print_variant_arg(ps s, &ast.variant_arg arg) {
                         print_type(s, arg.ty);
                     }
                     auto f = print_variant_arg;
@@ -295,7 +295,7 @@ impure fn print_item(ps s, @ast.item item) {
             wrd(s.s, id);
             print_type_params(s, params);
             popen(s);
-            impure fn print_field(ps s, &ast.obj_field field) {
+            fn print_field(ps s, &ast.obj_field field) {
                 hbox(s);
                 print_type(s, field.ty);
                 space(s.s);
@@ -337,7 +337,7 @@ impure fn print_item(ps s, @ast.item item) {
     line(s.s);
 }
 
-impure fn print_block(ps s, ast.block blk) {
+fn print_block(ps s, ast.block blk) {
     maybe_print_comment(s, blk.span.lo);
     bopen(s);
     for (@ast.stmt st in blk.node.stmts) {
@@ -359,7 +359,7 @@ impure fn print_block(ps s, ast.block blk) {
     bclose_c(s, blk.span);
 }
 
-impure fn print_literal(ps s, @ast.lit lit) {
+fn print_literal(ps s, @ast.lit lit) {
     maybe_print_comment(s, lit.span.lo);
     alt (lit.node) {
         case (ast.lit_str(?st)) {print_string(s, st);}
@@ -392,7 +392,7 @@ impure fn print_literal(ps s, @ast.lit lit) {
     }
 }
 
-impure fn print_expr(ps s, &@ast.expr expr) {
+fn print_expr(ps s, &@ast.expr expr) {
     maybe_print_comment(s, expr.span.lo);
     hbox(s);
     alt (expr.node) {
@@ -406,7 +406,7 @@ impure fn print_expr(ps s, &@ast.expr expr) {
             pclose(s);
         }
         case (ast.expr_tup(?exprs,_)) {
-            impure fn printElt(ps s, &ast.elt elt) {
+            fn printElt(ps s, &ast.elt elt) {
                 hbox(s);
                 if (elt.mut == ast.mut) {wrd1(s, "mutable");}
                 print_expr(s, elt.expr);
@@ -421,7 +421,7 @@ impure fn print_expr(ps s, &@ast.expr expr) {
             pclose(s);
         }
         case (ast.expr_rec(?fields,?wth,_)) {
-            impure fn print_field(ps s, &ast.field field) {
+            fn print_field(ps s, &ast.field field) {
                 hbox(s);
                 if (field.mut == ast.mut) {wrd1(s, "mutable");}
                 wrd(s.s, field.ident);
@@ -460,7 +460,7 @@ impure fn print_expr(ps s, &@ast.expr expr) {
             print_ident(s, ident);
         }
         case (ast.expr_bind(?func,?args,_)) {
-            impure 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)) {
                         print_expr(s, expr);
@@ -685,7 +685,7 @@ impure fn print_expr(ps s, &@ast.expr expr) {
     end(s.s);
 }
 
-impure fn print_decl(ps s, @ast.decl decl) {
+fn print_decl(ps s, @ast.decl decl) {
     maybe_print_comment(s, decl.span.lo);
     hbox(s);
     alt (decl.node) {
@@ -724,11 +724,11 @@ impure fn print_decl(ps s, @ast.decl decl) {
     end(s.s);
 }
 
-impure fn print_ident(ps s, ast.ident ident) {
+fn print_ident(ps s, ast.ident ident) {
     wrd(s.s, ident);
 }
 
-impure fn print_for_decl(ps s, @ast.decl decl) {
+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));
@@ -738,7 +738,7 @@ impure fn print_for_decl(ps s, @ast.decl decl) {
     }
 }
 
-impure fn print_path(ps s, ast.path path) {
+fn print_path(ps s, ast.path path) {
     maybe_print_comment(s, path.span.lo);
     auto first = true;
     for (str id in path.node.idents) {
@@ -754,7 +754,7 @@ impure fn print_path(ps s, ast.path path) {
     }
 }
 
-impure fn print_pat(ps s, &@ast.pat pat) {
+fn print_pat(ps s, &@ast.pat pat) {
     maybe_print_comment(s, pat.span.lo);
     alt (pat.node) {
         case (ast.pat_wild(_)) {wrd(s.s, "_");}
@@ -772,18 +772,13 @@ impure fn print_pat(ps s, &@ast.pat pat) {
     }
 }
 
-impure fn print_fn(ps s, ast.fn_decl decl, str name,
+fn print_fn(ps s, ast.fn_decl decl, str name,
                    vec[ast.ty_param] typarams) {
-    alt (decl.effect) {
-        case (ast.eff_impure) {wrd1(s, "impure");}
-        case (ast.eff_unsafe) {wrd1(s, "unsafe");}
-        case (_) {}
-    }
     wrd1(s, "fn");
     wrd(s.s, name);
     print_type_params(s, typarams);
     popen(s);
-    impure fn print_arg(ps s, &ast.arg x) {
+    fn print_arg(ps s, &ast.arg x) {
         hbox(s);
         if (x.mode == ast.alias) {wrd(s.s, "&");}
         print_type(s, x.ty);
@@ -804,10 +799,10 @@ impure fn print_fn(ps s, ast.fn_decl decl, str name,
     }
 }
 
-impure fn print_type_params(ps s, vec[ast.ty_param] params) {
+fn print_type_params(ps s, vec[ast.ty_param] params) {
     if (_vec.len[ast.ty_param](params) > 0u) {
         wrd(s.s, "[");
-        impure fn printParam(ps s, &ast.ty_param param) {
+        fn printParam(ps s, &ast.ty_param param) {
             wrd(s.s, param);
         }
         auto f = printParam;
@@ -816,7 +811,7 @@ impure fn print_type_params(ps s, vec[ast.ty_param] params) {
     }
 }
 
-impure fn print_view_item(ps s, @ast.view_item item) {
+fn print_view_item(ps s, @ast.view_item item) {
     maybe_print_comment(s, item.span.lo);
     hbox(s);
     alt (item.node) {
@@ -825,7 +820,7 @@ impure fn print_view_item(ps s, @ast.view_item item) {
             wrd(s.s, id);
             if (_vec.len[@ast.meta_item](mta) > 0u) {
                 popen(s);
-                impure fn print_meta(ps s, &@ast.meta_item item) {
+                fn print_meta(ps s, &@ast.meta_item item) {
                     hbox(s);
                     wrd1(s, item.node.name);
                     wrd1(s, "=");
@@ -869,7 +864,7 @@ fn operator_prec(ast.binop op) -> int {
     fail;
 }
 
-impure fn print_maybe_parens(ps s, @ast.expr expr, int outer_prec) {
+fn print_maybe_parens(ps s, @ast.expr expr, int outer_prec) {
     auto add_them;
     alt (expr.node) {
         case (ast.expr_binary(?op,_,_,_)) {
@@ -907,7 +902,7 @@ fn escape_str(str st, char to_escape) -> str {
     ret out;
 }
 
-impure fn print_mt(ps s, &ast.mt mt) {
+fn print_mt(ps s, &ast.mt mt) {
     alt (mt.mut) {
         case (ast.mut)       { wrd1(s, "mutable");  }
         case (ast.maybe_mut) { wrd1(s, "mutable?"); }
@@ -916,17 +911,12 @@ impure fn print_mt(ps s, &ast.mt mt) {
     print_type(s, mt.ty);
 }
 
-impure fn print_string(ps s, str st) {
+fn print_string(ps s, str st) {
     wrd(s.s, "\""); wrd(s.s, escape_str(st, '"')); wrd(s.s, "\"");
 }
 
-impure fn print_ty_fn(ps s, ast.effect eff, ast.proto proto, option.t[str] id,
-                      vec[ast.ty_arg] inputs, @ast.ty output) {
-    alt (eff) {
-        case (ast.eff_impure) {wrd1(s, "impure");}
-        case (ast.eff_unsafe) {wrd1(s, "unsafe");}
-        case (_) {}
-    }
+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) {
@@ -934,7 +924,7 @@ impure fn print_ty_fn(ps s, ast.effect eff, ast.proto proto, option.t[str] id,
         case (_) {}
     }
     popen_h(s);
-    impure fn print_arg(ps s, &ast.ty_arg input) {
+    fn print_arg(ps s, &ast.ty_arg input) {
         if (middle.ty.mode_is_alias(input.mode)) {wrd(s.s, "&");}
         print_type(s, input.ty);
     }
@@ -962,7 +952,7 @@ fn next_comment(ps s) -> option.t[lexer.cmnt] {
     }
 }
 
-impure fn maybe_print_comment(ps s, uint pos) {
+fn maybe_print_comment(ps s, uint pos) {
     while (true) {
         alt (next_comment(s)) {
             case (option.some[lexer.cmnt](?cmnt)) {
@@ -977,7 +967,7 @@ impure fn maybe_print_comment(ps s, uint pos) {
     }
 }
 
-impure fn maybe_print_line_comment(ps s, common.span span) -> bool {
+fn maybe_print_line_comment(ps s, common.span span) -> bool {
     alt (next_comment(s)) {
         case (option.some[lexer.cmnt](?cmnt)) {
             if (span.hi + 4u >= cmnt.pos) {
@@ -992,7 +982,7 @@ impure fn maybe_print_line_comment(ps s, common.span span) -> bool {
     ret false;
 }
 
-impure fn print_remaining_comments(ps s) {
+fn print_remaining_comments(ps s) {
     while (true) {
         alt (next_comment(s)) {
             case (option.some[lexer.cmnt](?cmnt)) {
@@ -1005,7 +995,7 @@ impure fn print_remaining_comments(ps s) {
     }
 }
 
-impure fn print_comment(ps s, lexer.cmnt_ cmnt) {
+fn print_comment(ps s, lexer.cmnt_ cmnt) {
     alt (cmnt) {
         case (lexer.cmnt_line(?val)) {
             wrd(s.s, "// " + val);
diff --git a/src/comp/rustc.rc b/src/comp/rustc.rc
index 8e57ff4d90f..f580edeaa14 100644
--- a/src/comp/rustc.rc
+++ b/src/comp/rustc.rc
@@ -45,37 +45,11 @@ mod util {
     mod typestate_ann;
 }
 
-auth driver.rustc.main = impure;
-auth front.creader.parse_ty_str = impure;
 auth front.creader.load_crate = unsafe;
 auth front.creader.get_metadata_section = unsafe;
-auth front.creader.lookup_def = impure;
-auth front.creader.get_type = impure;
-auth front.creader.get_symbol = impure;
-auth front.creader.get_tag_variants = impure;
-auth front.creader.impure_no_op = impure;
 auth middle.metadata = unsafe;
-auth middle.metadata.encode_index = impure;
-auth middle.metadata.encode_metadata = impure;
 auth middle.trans = unsafe;
-auth middle.trans.copy_any_self_to_alloca = impure;
-auth middle.trans.copy_args_to_allocas = impure;
-auth middle.trans.trans_block = impure;
-auth middle.trans.alloc_ty = impure;
-auth middle.typestate_check.log_expr = impure;
 auth lib.llvm = unsafe;
-auth pretty.pprust = impure;
-auth middle.typestate_check.find_pre_post_block = impure;
-auth middle.typestate_check.find_pre_post_state_block = impure;
-auth middle.typestate_check.find_pre_post_state_stmt = impure;
-auth middle.typestate_check.find_pre_post_state_expr = impure;
-auth middle.typestate_check.find_pre_post_state_exprs = impure;
-auth middle.typestate_check.find_pre_post_expr  = impure;
-auth middle.typestate_check.find_pre_post_stmt  = impure;
-auth middle.typestate_check.check_states_against_conditions = impure;
-auth middle.typestate_check.check_states_stmt   = impure;
-auth middle.typestate_check.log_stmt            = impure;
-auth util.typestate_ann.implies = impure;
 
 mod lib {
     alt (target_os) {
diff --git a/src/comp/util/typestate_ann.rs b/src/comp/util/typestate_ann.rs
index 9ccb87318f3..b1f12ffbc87 100644
--- a/src/comp/util/typestate_ann.rs
+++ b/src/comp/util/typestate_ann.rs
@@ -85,20 +85,20 @@ fn pps_len(&pre_and_post p) -> uint {
   ret p.precondition.nbits;
 }
 
-impure fn require_and_preserve(uint i, &pre_and_post p) -> () {
+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);
 }
 
-impure fn set_in_postcond(uint i, &pre_and_post p) -> bool {
+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);
   ret !was_set;
 }
 
-impure fn set_in_poststate(uint i, &pre_and_post_state s) -> bool {
+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);
@@ -107,35 +107,35 @@ impure fn set_in_poststate(uint i, &pre_and_post_state s) -> bool {
 
 // Sets all the bits in a's precondition to equal the
 // corresponding bit in p's precondition.
-impure fn set_precondition(&ts_ann a, &precond p) -> () {
+fn set_precondition(&ts_ann a, &precond p) -> () {
   bitv.copy(a.conditions.precondition, p);
 }
 
 // Sets all the bits in a's postcondition to equal the
 // corresponding bit in p's postcondition.
-impure fn set_postcondition(&ts_ann a, &postcond p) -> () {
+fn set_postcondition(&ts_ann a, &postcond p) -> () {
   bitv.copy(a.conditions.postcondition, p);
 }
 
 // Sets all the bits in a's prestate to equal the
 // corresponding bit in p's prestate.
-impure fn set_prestate(&ts_ann a, &prestate p) -> bool {
+fn set_prestate(&ts_ann a, &prestate p) -> bool {
   ret bitv.copy(a.states.prestate, p);
 }
 
 // Sets all the bits in a's postcondition to equal the
 // corresponding bit in p's postcondition.
-impure fn set_poststate(&ts_ann a, &poststate p) -> bool {
+fn set_poststate(&ts_ann a, &poststate p) -> bool {
   ret bitv.copy(a.states.poststate, p);
 }
 
 // Set all the bits in p that are set in new
-impure fn extend_prestate(&prestate p, &poststate new) -> bool {
+fn extend_prestate(&prestate p, &poststate new) -> bool {
   ret bitv.union(p, new);
 }
 
 // Set all the bits in p that are set in new
-impure fn extend_poststate(&poststate p, &poststate new) -> bool {
+fn extend_poststate(&poststate p, &poststate new) -> bool {
   ret bitv.union(p, new);
 }
 
@@ -150,7 +150,7 @@ fn ann_prestate(&ts_ann a) -> prestate {
 // returns true if a implies b
 // that is, returns true except if for some bits c and d,
 // c = 1 and d = 0
-impure fn implies(bitv.t a, bitv.t b) -> bool {
+fn implies(bitv.t a, bitv.t b) -> bool {
   auto tmp = bitv.clone(b);
   bitv.difference(tmp, a);
   ret bitv.is_false(tmp);