diff --git a/src/comp/front/creader.rs b/src/comp/front/creader.rs
index 8ef75e5460ad..42bc51304068 100644
--- a/src/comp/front/creader.rs
+++ b/src/comp/front/creader.rs
@@ -35,18 +35,18 @@ type str_def = fn(str) -> ast.def_id;
 
 type pstate = rec(str rep, mutable uint pos, uint len);
 
-fn peek(@pstate st) -> char {
-    if (st.pos < st.len) {ret st.rep.(st.pos) as char;}
-    else {ret ' ';}
+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) -> char { // ?? somehow not recognized as impure
+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;
-    ret ch as char;
+    ret ch as u8;
 }
 
-fn parse_ty_str(str rep, str_def sd) -> @ty.t {
+impure fn parse_ty_str(str rep, str_def sd) -> @ty.t {
     auto len = _str.byte_len(rep);
     auto st = @rec(rep=rep, mutable pos=0u, len=len);
     auto result = parse_ty(st, sd);
@@ -61,7 +61,7 @@ impure fn parse_ty(@pstate st, str_def sd) -> @ty.t {
 
 impure fn parse_mt(@pstate st, str_def sd) -> ty.mt {
     auto mut;
-    alt (peek(st)) {
+    alt (peek(st) as char) {
         case ('m') {next(st); mut = ast.mut;}
         case ('?') {next(st); mut = ast.maybe_mut;}
         case (_)   {mut=ast.imm;}
@@ -70,13 +70,13 @@ impure fn parse_mt(@pstate st, str_def sd) -> ty.mt {
 }
 
 impure fn parse_sty(@pstate st, str_def sd) -> ty.sty {
-    alt (next(st)) {
+    alt (next(st) as char) {
         case ('n') {ret ty.ty_nil;}
         case ('b') {ret ty.ty_bool;}
         case ('i') {ret ty.ty_int;}
         case ('u') {ret ty.ty_uint;}
         case ('M') {
-            alt (next(st)) {
+            alt (next(st) as char) {
                 case ('b') {ret ty.ty_machine(common.ty_u8);}
                 case ('w') {ret ty.ty_machine(common.ty_u16);}
                 case ('l') {ret ty.ty_machine(common.ty_u32);}
@@ -92,13 +92,15 @@ impure fn parse_sty(@pstate st, str_def sd) -> ty.sty {
         case ('c') {ret ty.ty_char;}
         case ('s') {ret ty.ty_str;}
         case ('t') {
-            check(next(st) == '[');
+            check(next(st) as char == '[');
             auto def = "";
-            while (peek(st) != '|') {def += _str.from_char(next(st));}
+            while (peek(st) as char != '|') {
+                def += _str.unsafe_from_byte(next(st));
+            }
             st.pos = st.pos + 1u;
             let vec[@ty.t] params = vec();
-            while (peek(st) != ']') {
-                params = _vec.push[@ty.t](params, parse_ty(st, sd));
+            while (peek(st) as char != ']') {
+                params += vec(parse_ty(st, sd));
             }
             st.pos = st.pos + 1u;
             ret ty.ty_tag(sd(def), params);
@@ -108,23 +110,24 @@ impure fn parse_sty(@pstate st, str_def sd) -> ty.sty {
         case ('P') {ret ty.ty_port(parse_ty(st, sd));}
         case ('C') {ret ty.ty_chan(parse_ty(st, sd));}
         case ('T') {
-            check(next(st) == '[');
+            check(next(st) as char == '[');
             let vec[ty.mt] params = vec();
-            while (peek(st) != ']') {
-                params = _vec.push[ty.mt](params, parse_mt(st, sd));
+            while (peek(st) as char != ']') {
+                params += vec(parse_mt(st, sd));
             }
             st.pos = st.pos + 1u;
             ret ty.ty_tup(params);
         }
         case ('R') {
-            check(next(st) == '[');
+            check(next(st) as char == '[');
             let vec[ty.field] fields = vec();
-            while (peek(st) != ']') {
+            while (peek(st) as char != ']') {
                 auto name = "";
-                while (peek(st) != '=') {name += _str.from_char(next(st));}
+                while (peek(st) as char != '=') {
+                    name += _str.unsafe_from_byte(next(st));
+                }
                 st.pos = st.pos + 1u;
-                fields = _vec.push[ty.field]
-                    (fields, rec(ident=name, mt=parse_mt(st, sd)));
+                fields += vec(rec(ident=name, mt=parse_mt(st, sd)));
             }
             st.pos = st.pos + 1u;
             ret ty.ty_rec(fields);
@@ -139,7 +142,7 @@ impure fn parse_sty(@pstate st, str_def sd) -> ty.sty {
         }
         case ('N') {
             auto abi;
-            alt (next(st)) {
+            alt (next(st) as char) {
                 case ('r') {abi = ast.native_abi_rust;}
                 case ('c') {abi = ast.native_abi_cdecl;}
             }
@@ -147,22 +150,23 @@ impure fn parse_sty(@pstate st, str_def sd) -> ty.sty {
             ret ty.ty_native_fn(abi,func._0,func._1);
         }
         case ('O') {
-            check(next(st) == '[');
+            check(next(st) as char == '[');
             let vec[ty.method] methods = vec();
-            while (peek(st) != ']') {
+            while (peek(st) as char != ']') {
                 auto proto;
-                alt (next(st)) {
+                alt (next(st) as char) {
                     case ('W') {proto = ast.proto_iter;}
                     case ('F') {proto = ast.proto_fn;}
                 }
                 auto name = "";
-                while (peek(st) != '[') {name += _str.from_char(next(st));}
+                while (peek(st) as char != '[') {
+                    name += _str.unsafe_from_byte(next(st));
+                }
                 auto func = parse_ty_fn(st, sd);
-                methods = _vec.push[ty.method]
-                    (methods, rec(proto=proto,
-                                  ident=name,
-                                  inputs=func._0,
-                                  output=func._1));
+                methods += vec(rec(proto=proto,
+                                   ident=name,
+                                   inputs=func._0,
+                                   output=func._1));
             }
             ret ty.ty_obj(methods);
         }
@@ -174,7 +178,7 @@ impure fn parse_sty(@pstate st, str_def sd) -> ty.sty {
 impure fn parse_int(@pstate st) -> int {
     auto n = 0;
     while (true) {
-        auto cur = peek(st);
+        auto cur = peek(st) as char;
         if (cur < '0' || cur > '9') {break;}
         st.pos = st.pos + 1u;
         n *= 10;
@@ -184,16 +188,15 @@ impure fn parse_int(@pstate st) -> int {
 }
 
 impure fn parse_ty_fn(@pstate st, str_def sd) -> tup(vec[ty.arg], @ty.t) {
-    check(next(st) == '[');
+    check(next(st) as char == '[');
     let vec[ty.arg] inputs = vec();
-    while (peek(st) != ']') {
+    while (peek(st) as char != ']') {
         auto mode = ast.val;
-        if (peek(st) == '&') {
+        if (peek(st) as char == '&') {
             mode = ast.alias;
             st.pos = st.pos + 1u;
         }
-        inputs = _vec.push[ty.arg]
-            (inputs, rec(mode=mode, ty=parse_ty(st, sd)));
+        inputs += vec(rec(mode=mode, ty=parse_ty(st, sd)));
     }
     st.pos = st.pos + 1u;
     ret tup(inputs, parse_ty(st, sd));