Merge pull request #3805 from erickt/incoming

Variety of small cleanups

15 files changed, 102 insertions, 103 deletions

diff --git a/src/libcore/dvec.rs b/src/libcore/dvec.rs
index 1540eb30fe5..1b6a7522864 100644
--- a/src/libcore/dvec.rs
+++ b/src/libcore/dvec.rs
@@ -56,7 +56,7 @@ pub enum DVec<A> {
 }
 
 /// Creates a new, empty dvec
-pub fn DVec<A>() -> DVec<A> {
+pub pure fn DVec<A>() -> DVec<A> {
     DVec_({mut data: ~[]})
 }
 
diff --git a/src/libcore/extfmt.rs b/src/libcore/extfmt.rs
index 5acb45fdf1a..d41393c2393 100644
--- a/src/libcore/extfmt.rs
+++ b/src/libcore/extfmt.rs
@@ -329,11 +329,11 @@ pub mod rt {
         // For strings, precision is the maximum characters
         // displayed
         let mut unpadded = match cv.precision {
-          CountImplied => s.to_unique(),
+          CountImplied => s.to_owned(),
           CountIs(max) => if max as uint < str::char_len(s) {
             str::substr(s, 0u, max as uint)
           } else {
-            s.to_unique()
+            s.to_owned()
           }
         };
         return unsafe { pad(cv, move unpadded, PadNozero) };
diff --git a/src/libcore/io.rs b/src/libcore/io.rs
index fd0fcbbe1c1..77f7b5023df 100644
--- a/src/libcore/io.rs
+++ b/src/libcore/io.rs
@@ -37,7 +37,7 @@ pub trait Reader {
     // FIXME (#2004): Seekable really should be orthogonal.
 
     // FIXME (#2982): This should probably return an error.
-    fn read(buf: &[mut u8], len: uint) -> uint;
+    fn read(bytes: &[mut u8], len: uint) -> uint;
     fn read_byte() -> int;
     fn unread_byte(int);
     fn eof() -> bool;
@@ -65,32 +65,32 @@ pub trait ReaderUtil {
 
 impl<T: Reader> T : ReaderUtil {
     fn read_bytes(len: uint) -> ~[u8] {
-        let mut buf = vec::with_capacity(len);
-        unsafe { vec::raw::set_len(&mut buf, len); }
+        let mut bytes = vec::with_capacity(len);
+        unsafe { vec::raw::set_len(&mut bytes, len); }
 
-        let count = self.read(buf, len);
+        let count = self.read(bytes, len);
 
-        unsafe { vec::raw::set_len(&mut buf, count); }
-        move buf
+        unsafe { vec::raw::set_len(&mut bytes, count); }
+        move bytes
     }
     fn read_line() -> ~str {
-        let mut buf = ~[];
+        let mut bytes = ~[];
         loop {
             let ch = self.read_byte();
             if ch == -1 || ch == 10 { break; }
-            buf.push(ch as u8);
+            bytes.push(ch as u8);
         }
-        str::from_bytes(buf)
+        str::from_bytes(bytes)
     }
 
     fn read_chars(n: uint) -> ~[char] {
         // returns the (consumed offset, n_req), appends characters to &chars
-        fn chars_from_bytes<T: Reader>(buf: &~[u8], chars: &mut ~[char])
+        fn chars_from_bytes<T: Reader>(bytes: &~[u8], chars: &mut ~[char])
             -> (uint, uint) {
             let mut i = 0;
-            let buf_len = buf.len();
-            while i < buf_len {
-                let b0 = buf[i];
+            let bytes_len = bytes.len();
+            while i < bytes_len {
+                let b0 = bytes[i];
                 let w = str::utf8_char_width(b0);
                 let end = i + w;
                 i += 1;
@@ -100,12 +100,12 @@ impl<T: Reader> T : ReaderUtil {
                     loop;
                 }
                 // can't satisfy this char with the existing data
-                if end > buf_len {
-                    return (i - 1, end - buf_len);
+                if end > bytes_len {
+                    return (i - 1, end - bytes_len);
                 }
                 let mut val = 0;
                 while i < end {
-                    let next = buf[i] as int;
+                    let next = bytes[i] as int;
                     i += 1;
                     assert (next > -1);
                     assert (next & 192 == 128);
@@ -119,8 +119,8 @@ impl<T: Reader> T : ReaderUtil {
             }
             return (i, 0);
         }
-        let mut buf: ~[u8] = ~[];
-        let mut chars: ~[char] = ~[];
+        let mut bytes = ~[];
+        let mut chars = ~[];
         // might need more bytes, but reading n will never over-read
         let mut nbread = n;
         while nbread > 0 {
@@ -130,15 +130,15 @@ impl<T: Reader> T : ReaderUtil {
                 // we're split in a unicode char?
                 break;
             }
-            buf.push_all(data);
-            let (offset, nbreq) = chars_from_bytes::<T>(&buf, &mut chars);
+            bytes.push_all(data);
+            let (offset, nbreq) = chars_from_bytes::<T>(&bytes, &mut chars);
             let ncreq = n - chars.len();
             // again we either know we need a certain number of bytes
             // to complete a character, or we make sure we don't
             // over-read by reading 1-byte per char needed
             nbread = if ncreq > nbreq { ncreq } else { nbreq };
             if nbread > 0 {
-                buf = vec::slice(buf, offset, buf.len());
+                bytes = vec::slice(bytes, offset, bytes.len());
             }
         }
         move chars
@@ -154,12 +154,12 @@ impl<T: Reader> T : ReaderUtil {
     }
 
     fn read_c_str() -> ~str {
-        let mut buf: ~[u8] = ~[];
+        let mut bytes: ~[u8] = ~[];
         loop {
             let ch = self.read_byte();
-            if ch < 1 { break; } else { buf.push(ch as u8); }
+            if ch < 1 { break; } else { bytes.push(ch as u8); }
         }
-        str::from_bytes(buf)
+        str::from_bytes(bytes)
     }
 
     // FIXME deal with eof? // #2004
@@ -191,9 +191,9 @@ impl<T: Reader> T : ReaderUtil {
     }
 
     fn read_whole_stream() -> ~[u8] {
-        let mut buf: ~[u8] = ~[];
-        while !self.eof() { buf.push_all(self.read_bytes(2048u)); }
-        move buf
+        let mut bytes: ~[u8] = ~[];
+        while !self.eof() { bytes.push_all(self.read_bytes(2048u)); }
+        move bytes
     }
 
     fn each_byte(it: fn(int) -> bool) {
@@ -226,8 +226,8 @@ fn convert_whence(whence: SeekStyle) -> i32 {
 }
 
 impl *libc::FILE: Reader {
-    fn read(buf: &[mut u8], len: uint) -> uint {
-        do vec::as_mut_buf(buf) |buf_p, buf_len| {
+    fn read(bytes: &[mut u8], len: uint) -> uint {
+        do vec::as_mut_buf(bytes) |buf_p, buf_len| {
             assert buf_len <= len;
 
             let count = libc::fread(buf_p as *mut c_void, 1u as size_t,
@@ -250,7 +250,9 @@ impl *libc::FILE: Reader {
 // duration of its lifetime.
 // FIXME there really should be a better way to do this // #2004
 impl<T: Reader, C> {base: T, cleanup: C}: Reader {
-    fn read(buf: &[mut u8], len: uint) -> uint { self.base.read(buf, len) }
+    fn read(bytes: &[mut u8], len: uint) -> uint {
+        self.base.read(bytes, len)
+    }
     fn read_byte() -> int { self.base.read_byte() }
     fn unread_byte(byte: int) { self.base.unread_byte(byte); }
     fn eof() -> bool { self.base.eof() }
@@ -297,39 +299,41 @@ pub fn file_reader(path: &Path) -> Result<Reader, ~str> {
 }
 
 
-// Byte buffer readers
-
-pub type ByteBuf = {buf: &[const u8], mut pos: uint};
+// Byte readers
+pub struct BytesReader {
+    bytes: &[u8],
+    mut pos: uint
+}
 
-impl ByteBuf: Reader {
-    fn read(buf: &[mut u8], len: uint) -> uint {
-        let count = uint::min(len, self.buf.len() - self.pos);
+impl BytesReader: Reader {
+    fn read(bytes: &[mut u8], len: uint) -> uint {
+        let count = uint::min(len, self.bytes.len() - self.pos);
 
-        let view = vec::const_view(self.buf, self.pos, self.buf.len());
-        vec::bytes::memcpy(buf, view, count);
+        let view = vec::view(self.bytes, self.pos, self.bytes.len());
+        vec::bytes::memcpy(bytes, view, count);
 
         self.pos += count;
 
         count
     }
     fn read_byte() -> int {
-        if self.pos == self.buf.len() { return -1; }
-        let b = self.buf[self.pos];
+        if self.pos == self.bytes.len() { return -1; }
+        let b = self.bytes[self.pos];
         self.pos += 1u;
         return b as int;
     }
     // FIXME (#2738): implement this
     fn unread_byte(_byte: int) { error!("Unimplemented: unread_byte"); fail; }
-    fn eof() -> bool { self.pos == self.buf.len() }
+    fn eof() -> bool { self.pos == self.bytes.len() }
     fn seek(offset: int, whence: SeekStyle) {
         let pos = self.pos;
-        self.pos = seek_in_buf(offset, pos, self.buf.len(), whence);
+        self.pos = seek_in_buf(offset, pos, self.bytes.len(), whence);
     }
     fn tell() -> uint { self.pos }
 }
 
-pub fn with_bytes_reader<t>(bytes: &[u8], f: fn(Reader) -> t) -> t {
-    f({buf: bytes, mut pos: 0u} as Reader)
+pub pure fn with_bytes_reader<t>(bytes: &[u8], f: fn(Reader) -> t) -> t {
+    f(BytesReader { bytes: bytes, pos: 0u } as Reader)
 }
 
 pub fn with_str_reader<T>(s: &str, f: fn(Reader) -> T) -> T {
@@ -602,10 +606,10 @@ impl<T: Writer> T : WriterUtil {
         self.write_str(&"\n");
     }
     fn write_int(n: int) {
-        int::to_str_bytes(n, 10u, |buf| self.write(buf))
+        int::to_str_bytes(n, 10u, |bytes| self.write(bytes))
     }
     fn write_uint(n: uint) {
-        uint::to_str_bytes(false, n, 10u, |buf| self.write(buf))
+        uint::to_str_bytes(false, n, 10u, |bytes| self.write(bytes))
     }
     fn write_le_uint(n: uint) {
         u64_to_le_bytes(n as u64, uint::bytes, |v| self.write(v))
@@ -687,34 +691,34 @@ pub fn print(s: &str) { stdout().write_str(s); }
 pub fn println(s: &str) { stdout().write_line(s); }
 
 pub struct BytesWriter {
-    buf: DVec<u8>,
+    bytes: DVec<u8>,
     mut pos: uint,
 }
 
 impl BytesWriter: Writer {
     fn write(v: &[const u8]) {
-        do self.buf.swap |buf| {
-            let mut buf <- buf;
+        do self.bytes.swap |bytes| {
+            let mut bytes <- bytes;
             let v_len = v.len();
-            let buf_len = buf.len();
+            let bytes_len = bytes.len();
 
-            let count = uint::max(buf_len, self.pos + v_len);
-            vec::reserve(&mut buf, count);
-            unsafe { vec::raw::set_len(&mut buf, count); }
+            let count = uint::max(bytes_len, self.pos + v_len);
+            vec::reserve(&mut bytes, count);
+            unsafe { vec::raw::set_len(&mut bytes, count); }
 
             {
-                let view = vec::mut_view(buf, self.pos, count);
+                let view = vec::mut_view(bytes, self.pos, count);
                 vec::bytes::memcpy(view, v, v_len);
             }
 
             self.pos += v_len;
 
-            move buf
+            move bytes
         }
     }
     fn seek(offset: int, whence: SeekStyle) {
         let pos = self.pos;
-        let len = self.buf.len();
+        let len = self.bytes.len();
         self.pos = seek_in_buf(offset, pos, len, whence);
     }
     fn tell() -> uint { self.pos }
@@ -730,21 +734,25 @@ impl @BytesWriter : Writer {
     fn get_type() -> WriterType { (*self).get_type() }
 }
 
-pub fn BytesWriter() -> BytesWriter {
-    BytesWriter { buf: DVec(), mut pos: 0u }
+pub pure fn BytesWriter() -> BytesWriter {
+    BytesWriter { bytes: DVec(), mut pos: 0u }
 }
 
-pub fn with_bytes_writer(f: fn(Writer)) -> ~[u8] {
+pub pure fn with_bytes_writer(f: fn(Writer)) -> ~[u8] {
     let wr = @BytesWriter();
     f(wr as Writer);
-    wr.buf.check_out(|buf| move buf)
+    // FIXME (#3758): This should not be needed.
+    unsafe { wr.bytes.check_out(|bytes| move bytes) }
 }
 
-pub fn with_str_writer(f: fn(Writer)) -> ~str {
+pub pure fn with_str_writer(f: fn(Writer)) -> ~str {
     let mut v = with_bytes_writer(f);
 
-    // Make sure the vector has a trailing null and is proper utf8.
-    v.push(0);
+    // FIXME (#3758): This should not be needed.
+    unsafe {
+        // Make sure the vector has a trailing null and is proper utf8.
+        v.push(0);
+    }
     assert str::is_utf8(v);
 
     unsafe { move ::cast::transmute(move v) }
@@ -975,15 +983,17 @@ mod tests {
     fn bytes_buffer_overwrite() {
         let wr = BytesWriter();
         wr.write(~[0u8, 1u8, 2u8, 3u8]);
-        assert wr.buf.borrow(|buf| buf == ~[0u8, 1u8, 2u8, 3u8]);
+        assert wr.bytes.borrow(|bytes| bytes == ~[0u8, 1u8, 2u8, 3u8]);
         wr.seek(-2, SeekCur);
         wr.write(~[4u8, 5u8, 6u8, 7u8]);
-        assert wr.buf.borrow(|buf| buf == ~[0u8, 1u8, 4u8, 5u8, 6u8, 7u8]);
+        assert wr.bytes.borrow(|bytes| bytes ==
+            ~[0u8, 1u8, 4u8, 5u8, 6u8, 7u8]);
         wr.seek(-2, SeekEnd);
         wr.write(~[8u8]);
         wr.seek(1, SeekSet);
         wr.write(~[9u8]);
-        assert wr.buf.borrow(|buf| buf == ~[0u8, 9u8, 4u8, 5u8, 8u8, 7u8]);
+        assert wr.bytes.borrow(|bytes| bytes ==
+            ~[0u8, 9u8, 4u8, 5u8, 8u8, 7u8]);
     }
 }
 
diff --git a/src/libcore/logging.rs b/src/libcore/logging.rs
index d4f3c0ea272..958d1ac56ea 100644
--- a/src/libcore/logging.rs
+++ b/src/libcore/logging.rs
@@ -32,7 +32,7 @@ pub fn console_off() {
 #[cfg(notest)]
 #[lang="log_type"]
 pub fn log_type<T>(level: u32, object: &T) {
-    let bytes = do io::with_bytes_writer() |writer| {
+    let bytes = do io::with_bytes_writer |writer| {
         repr::write_repr(writer, object);
     };
     unsafe {
diff --git a/src/libcore/option.rs b/src/libcore/option.rs
index f8bafe29fdd..50489a82029 100644
--- a/src/libcore/option.rs
+++ b/src/libcore/option.rs
@@ -225,7 +225,7 @@ pub fn swap_unwrap<T>(opt: &mut Option<T>) -> T {
 
 pub pure fn unwrap_expect<T>(opt: Option<T>, reason: &str) -> T {
     //! As unwrap, but with a specified failure message.
-    if opt.is_none() { fail reason.to_unique(); }
+    if opt.is_none() { fail reason.to_owned(); }
     unwrap(move opt)
 }
 
diff --git a/src/libcore/repr.rs b/src/libcore/repr.rs
index ff29953f09a..b246adcb1d7 100644
--- a/src/libcore/repr.rs
+++ b/src/libcore/repr.rs
@@ -559,7 +559,7 @@ impl ReprPrinter {
         unsafe {
             self.align(sys::min_align_of::<T>());
             let value_addr: &T = transmute(copy self.ptr);
-            (*value_addr).write_repr(self.writer);
+            value_addr.write_repr(self.writer);
             self.bump(sys::size_of::<T>());
             true
         }
diff --git a/src/libcore/str.rs b/src/libcore/str.rs
index d59f36e0681..3122f3d7f32 100644
--- a/src/libcore/str.rs
+++ b/src/libcore/str.rs
@@ -2135,7 +2135,7 @@ pub trait StrSlice {
     pure fn trim() -> ~str;
     pure fn trim_left() -> ~str;
     pure fn trim_right() -> ~str;
-    pure fn to_unique() -> ~str;
+    pure fn to_owned() -> ~str;
     pure fn to_managed() -> @str;
     pure fn char_at(i: uint) -> char;
 }
@@ -2258,13 +2258,12 @@ impl &str: StrSlice {
     pure fn trim_right() -> ~str { trim_right(self) }
 
     #[inline]
-    pure fn to_unique() -> ~str { self.slice(0, self.len()) }
+    pure fn to_owned() -> ~str { self.slice(0, self.len()) }
 
     #[inline]
     pure fn to_managed() -> @str {
-        let v = at_vec::from_fn(self.len() + 1, |i| {
-            if i == self.len() { 0 } else { self[i] }
-        });
+        let bytes = as_bytes_slice(self);
+        let v = at_vec::from_fn(bytes.len(), |i| bytes[i]);
         unsafe { ::cast::transmute(v) }
     }
 
diff --git a/src/libstd/json.rs b/src/libstd/json.rs
index d170255b565..5f64389e583 100644
--- a/src/libstd/json.rs
+++ b/src/libstd/json.rs
@@ -897,7 +897,7 @@ pub impl Deserializer: serialization::Deserializer {
                 // FIXME(#3148) This hint should not be necessary.
                 let obj: &self/~Object = obj;
 
-                match obj.find_ref(&name.to_unique()) {
+                match obj.find_ref(&name.to_owned()) {
                     None => fail fmt!("no such field: %s", name),
                     Some(json) => {
                         self.stack.push(json);
diff --git a/src/libsyntax/attr.rs b/src/libsyntax/attr.rs
index d08edd7af1d..4bd1679600f 100644
--- a/src/libsyntax/attr.rs
+++ b/src/libsyntax/attr.rs
@@ -90,9 +90,7 @@ fn attr_meta(attr: ast::attribute) -> @ast::meta_item { @attr.node.value }
 
 // Get the meta_items from inside a vector of attributes
 fn attr_metas(attrs: ~[ast::attribute]) -> ~[@ast::meta_item] {
-    let mut mitems = ~[];
-    for attrs.each |a| { mitems.push(attr_meta(*a)); }
-    return mitems;
+    do attrs.map |a| { attr_meta(*a) }
 }
 
 fn desugar_doc_attr(attr: &ast::attribute) -> ast::attribute {
diff --git a/src/rustc/back/upcall.rs b/src/rustc/back/upcall.rs
index a2c864f6f46..45e7cd4e9d4 100644
--- a/src/rustc/back/upcall.rs
+++ b/src/rustc/back/upcall.rs
@@ -27,8 +27,7 @@ fn declare_upcalls(targ_cfg: @session::config,
     fn decl(llmod: ModuleRef, prefix: ~str, name: ~str,
             tys: ~[TypeRef], rv: TypeRef) ->
        ValueRef {
-        let mut arg_tys: ~[TypeRef] = ~[];
-        for tys.each |t| { arg_tys.push(*t); }
+        let arg_tys = tys.map(|t| *t);
         let fn_ty = T_fn(arg_tys, rv);
         return base::decl_cdecl_fn(llmod, prefix + name, fn_ty);
     }
diff --git a/src/rustc/metadata/decoder.rs b/src/rustc/metadata/decoder.rs
index f0911bd1aa2..1656efbd966 100644
--- a/src/rustc/metadata/decoder.rs
+++ b/src/rustc/metadata/decoder.rs
@@ -598,13 +598,12 @@ fn get_enum_variants(intr: @ident_interner, cdata: cmd, id: ast::node_id,
         let ctor_ty = item_type({crate: cdata.cnum, node: id}, item,
                                 tcx, cdata);
         let name = item_name(intr, item);
-        let mut arg_tys: ~[ty::t] = ~[];
-        match ty::get(ctor_ty).sty {
-          ty::ty_fn(f) => {
-            for f.sig.inputs.each |a| { arg_tys.push(a.ty); }
-          }
-          _ => { /* Nullary enum variant. */ }
-        }
+        let arg_tys = match ty::get(ctor_ty).sty {
+          ty::ty_fn(f) => f.sig.inputs.map(|a| a.ty),
+
+          // Nullary enum variant.
+          _ => ~[],
+        };
         match variant_disr_val(item) {
           Some(val) => { disr_val = val; }
           _         => { /* empty */ }
diff --git a/src/rustc/metadata/encoder.rs b/src/rustc/metadata/encoder.rs
index 0b25f0670b4..1579705dd0e 100644
--- a/src/rustc/metadata/encoder.rs
+++ b/src/rustc/metadata/encoder.rs
@@ -1162,7 +1162,7 @@ fn encode_metadata(parms: encode_parms, crate: @crate) -> ~[u8] {
 
     if (parms.tcx.sess.meta_stats()) {
 
-        do wr.buf.borrow |v| {
+        do wr.bytes.borrow |v| {
             do v.each |e| {
                 if *e == 0 {
                     ecx.stats.zero_bytes += 1;
@@ -1195,7 +1195,7 @@ fn encode_metadata(parms: encode_parms, crate: @crate) -> ~[u8] {
 
     (do str::as_bytes(&~"rust\x00\x00\x00\x01") |bytes| {
         vec::slice(*bytes, 0, 8)
-    }) + flate::deflate_bytes(wr.buf.check_out(|buf| buf))
+    }) + flate::deflate_bytes(wr.bytes.check_out(|buf| buf))
 }
 
 // Get the encoded string for a type
diff --git a/src/rustc/middle/trans/build.rs b/src/rustc/middle/trans/build.rs
index dfcc66adc3a..ea992600ae1 100644
--- a/src/rustc/middle/trans/build.rs
+++ b/src/rustc/middle/trans/build.rs
@@ -433,8 +433,7 @@ fn GEP(cx: block, Pointer: ValueRef, Indices: ~[ValueRef]) -> ValueRef {
 //
 // XXX: Use a small-vector optimization to avoid allocations here.
 fn GEPi(cx: block, base: ValueRef, ixs: &[uint]) -> ValueRef {
-    let mut v: ~[ValueRef] = ~[];
-    for vec::each(ixs) |i| { v.push(C_i32(*i as i32)); }
+    let v = do vec::map(ixs) |i| { C_i32(*i as i32) };
     count_insn(cx, "gepi");
     return InBoundsGEP(cx, base, v);
 }
diff --git a/src/rustc/util/common.rs b/src/rustc/util/common.rs
index 0c6ec267da8..123905adba1 100644
--- a/src/rustc/util/common.rs
+++ b/src/rustc/util/common.rs
@@ -34,9 +34,7 @@ type flag = HashMap<~str, ()>;
 fn field_expr(f: ast::field) -> @ast::expr { return f.node.expr; }
 
 fn field_exprs(fields: ~[ast::field]) -> ~[@ast::expr] {
-    let mut es = ~[];
-    for fields.each |f| { es.push(f.node.expr); }
-    return es;
+    fields.map(|f| f.node.expr)
 }
 
 // Takes a predicate p, returns true iff p is true for any subexpressions
diff --git a/src/rustc/util/ppaux.rs b/src/rustc/util/ppaux.rs
index 27ace283fa0..8207082cf20 100644
--- a/src/rustc/util/ppaux.rs
+++ b/src/rustc/util/ppaux.rs
@@ -282,8 +282,7 @@ fn ty_to_str(cx: ctxt, typ: t) -> ~str {
           _ => { }
         }
         s += ~"(";
-        let mut strs = ~[];
-        for inputs.each |a| { strs.push(fn_input_to_str(cx, *a)); }
+        let strs = inputs.map(|a| fn_input_to_str(cx, *a));
         s += str::connect(strs, ~", ");
         s += ~")";
         if ty::get(output).sty != ty_nil {
@@ -338,13 +337,11 @@ fn ty_to_str(cx: ctxt, typ: t) -> ~str {
       ty_unboxed_vec(tm) => { ~"unboxed_vec<" + mt_to_str(cx, tm) + ~">" }
       ty_type => ~"type",
       ty_rec(elems) => {
-        let mut strs: ~[~str] = ~[];
-        for elems.each |fld| { strs.push(field_to_str(cx, *fld)); }
+        let strs = elems.map(|fld| field_to_str(cx, *fld));
         ~"{" + str::connect(strs, ~",") + ~"}"
       }
       ty_tup(elems) => {
-        let mut strs = ~[];
-        for elems.each |elem| { strs.push(ty_to_str(cx, *elem)); }
+        let strs = elems.map(|elem| ty_to_str(cx, *elem));
         ~"(" + str::connect(strs, ~",") + ~")"
       }
       ty_fn(ref f) => {