diff --git a/src/libcore/hash.rs b/src/libcore/hash.rs
index da684c8fab5..0e9c9110c8e 100644
--- a/src/libcore/hash.rs
+++ b/src/libcore/hash.rs
@@ -15,6 +15,7 @@
 
 import io::Writer;
 import io::WriterUtil;
+import to_bytes::IterBytes;
 
 export Streaming, State;
 export default_state;
@@ -33,6 +34,21 @@ export hash_u16;
 export hash_u8;
 export hash_uint;
 
+/// Types that can meaningfully be hashed should implement this.
+trait Hash {
+    pure fn hash_keyed(k0: u64, k1: u64) -> u64;
+}
+
+// When we have default methods, won't need this.
+trait HashUtil {
+    pure fn hash() -> u64;
+}
+
+impl <A: Hash> A: HashUtil {
+    #[inline(always)]
+    pure fn hash() -> u64 { self.hash_keyed(0,0) }
+}
+
 /// Streaming hash-functions should implement this.
 trait Streaming {
     fn input((&[const u8]));
@@ -43,38 +59,97 @@ trait Streaming {
     fn reset();
 }
 
-fn keyed(k0: u64, k1: u64, f: fn(s: &State)) -> u64 {
-    let s = &State(k0, k1);
-    f(s);
-    s.result_u64()
-}
-
-pure fn hash_bytes_keyed(buf: &[const u8], k0: u64, k1: u64) -> u64 {
-    unchecked { keyed(k0, k1, |s| s.input(buf)) }
-}
-pure fn hash_str_keyed(s: &str, k0: u64, k1: u64) -> u64 {
-    unsafe {
-        do str::as_buf(s) |buf, len| {
-            do vec::unsafe::form_slice(buf, len) |slice| {
-                hash_bytes_keyed(slice, k0, k1)
+impl <A: IterBytes> A: Hash {
+    #[inline(always)]
+    pure fn hash_keyed(k0: u64, k1: u64) -> u64 {
+        unchecked {
+            let s = &State(k0, k1);
+            for self.iter_le_bytes |bytes| {
+                s.input(bytes);
             }
+            s.result_u64()
         }
     }
 }
+
+// implementations
+
+pure fn hash_keyed_2<A: IterBytes,
+                     B: IterBytes>(a: &A, b: &B,
+                                   k0: u64, k1: u64) -> u64 {
+    unchecked {
+        let s = &State(k0, k1);
+        for a.iter_le_bytes |bytes| { s.input(bytes); }
+        for b.iter_le_bytes |bytes| { s.input(bytes); }
+        s.result_u64()
+    }
+}
+
+pure fn hash_keyed_3<A: IterBytes,
+                     B: IterBytes,
+                     C: IterBytes>(a: &A, b: &B, c: &C,
+                                   k0: u64, k1: u64) -> u64 {
+    unchecked {
+        let s = &State(k0, k1);
+        for a.iter_le_bytes |bytes| { s.input(bytes); }
+        for b.iter_le_bytes |bytes| { s.input(bytes); }
+        for c.iter_le_bytes |bytes| { s.input(bytes); }
+        s.result_u64()
+    }
+}
+
+pure fn hash_keyed_4<A: IterBytes,
+                     B: IterBytes,
+                     C: IterBytes,
+                     D: IterBytes>(a: &A, b: &B, c: &C, d: &D,
+                                   k0: u64, k1: u64) -> u64 {
+    unchecked {
+        let s = &State(k0, k1);
+        for a.iter_le_bytes |bytes| { s.input(bytes); }
+        for b.iter_le_bytes |bytes| { s.input(bytes); }
+        for c.iter_le_bytes |bytes| { s.input(bytes); }
+        for d.iter_le_bytes |bytes| { s.input(bytes); }
+        s.result_u64()
+    }
+}
+
+pure fn hash_keyed_5<A: IterBytes,
+                     B: IterBytes,
+                     C: IterBytes,
+                     D: IterBytes,
+                     E: IterBytes>(a: &A, b: &B, c: &C, d: &D, e: &E,
+                                   k0: u64, k1: u64) -> u64 {
+    unchecked {
+        let s = &State(k0, k1);
+        for a.iter_le_bytes |bytes| { s.input(bytes); }
+        for b.iter_le_bytes |bytes| { s.input(bytes); }
+        for c.iter_le_bytes |bytes| { s.input(bytes); }
+        for d.iter_le_bytes |bytes| { s.input(bytes); }
+        for e.iter_le_bytes |bytes| { s.input(bytes); }
+        s.result_u64()
+    }
+}
+
+pure fn hash_bytes_keyed(val: &[const u8], k0: u64, k1: u64) -> u64 {
+    val.hash_keyed(k0, k1)
+}
+pure fn hash_str_keyed(val: &str, k0: u64, k1: u64) -> u64 {
+    val.hash_keyed(k0, k1)
+}
 pure fn hash_u64_keyed(val: u64, k0: u64, k1: u64) -> u64 {
-    unchecked { keyed(k0, k1, |s| s.write_le_u64(val)) }
+    val.hash_keyed(k0, k1)
 }
 pure fn hash_u32_keyed(val: u32, k0: u64, k1: u64) -> u64 {
-    unchecked { keyed(k0, k1, |s| s.write_le_u32(val)) }
+    val.hash_keyed(k0, k1)
 }
 pure fn hash_u16_keyed(val: u16, k0: u64, k1: u64) -> u64 {
-    unchecked { keyed(k0, k1, |s| s.write_le_u16(val)) }
+    val.hash_keyed(k0, k1)
 }
 pure fn hash_u8_keyed(val: u8, k0: u64, k1: u64) -> u64 {
-    unchecked { keyed(k0, k1, |s| s.write_u8(val)) }
+    val.hash_keyed(k0, k1)
 }
 pure fn hash_uint_keyed(val: uint, k0: u64, k1: u64) -> u64 {
-    unchecked { keyed(k0, k1, |s| s.write_le_uint(val)) }
+    val.hash_keyed(k0, k1)
 }
 
 pure fn hash_bytes(val: &[const u8]) -> u64 { hash_bytes_keyed(val, 0, 0) }
@@ -89,10 +164,13 @@ pure fn hash_uint(val: uint) -> u64 { hash_uint_keyed(val, 0, 0) }
 // Implement State as SipState
 
 type State = SipState;
+
+#[inline(always)]
 fn State(k0: u64, k1: u64) -> State {
     SipState(k0, k1)
 }
 
+#[inline(always)]
 fn default_state() -> State {
     State(0,0)
 }
@@ -109,6 +187,7 @@ struct SipState {
     mut ntail: uint;  // how many bytes in tail are valid
 }
 
+#[inline(always)]
 fn SipState(key0: u64, key1: u64) -> SipState {
     let state = SipState {
         k0 : key0,
@@ -129,6 +208,7 @@ fn SipState(key0: u64, key1: u64) -> SipState {
 impl &SipState : io::Writer {
 
     // Methods for io::writer
+    #[inline(always)]
     fn write(msg: &[const u8]) {
 
         macro_rules! u8to64_le (
@@ -235,10 +315,12 @@ impl &SipState : io::Writer {
 
 impl &SipState : Streaming {
 
+    #[inline(always)]
     fn input(buf: &[const u8]) {
         self.write(buf);
     }
 
+    #[inline(always)]
     fn result_u64() -> u64 {
         let mut v0 = self.v0;
         let mut v1 = self.v1;
@@ -269,7 +351,6 @@ impl &SipState : Streaming {
         return (v0 ^ v1 ^ v2 ^ v3);
     }
 
-
     fn result_bytes() -> ~[u8] {
         let h = self.result_u64();
         ~[(h >> 0) as u8,
@@ -290,6 +371,7 @@ impl &SipState : Streaming {
         return s;
     }
 
+    #[inline(always)]
     fn reset() {
         self.length = 0;
         self.v0 = self.k0 ^ 0x736f6d6570736575;
@@ -385,7 +467,7 @@ fn test_siphash() {
     while t < 64 {
         debug!("siphash test %?", t);
         let vec = u8to64_le!(vecs[t], 0);
-        let out = hash_bytes_keyed(buf, k0, k1);
+        let out = buf.hash_keyed(k0, k1);
         debug!("got %?, expected %?", out, vec);
         assert vec == out;
 
diff --git a/src/libcore/to_bytes.rs b/src/libcore/to_bytes.rs
index 6a5558e0236..f4305a74917 100644
--- a/src/libcore/to_bytes.rs
+++ b/src/libcore/to_bytes.rs
@@ -2,22 +2,314 @@
 #[forbid(deprecated_mode)];
 #[forbid(deprecated_pattern)];
 
+import io::Writer;
+
+type Cb = fn(buf: &[const u8]) -> bool;
+
+trait IterBytes {
+    fn iter_le_bytes(f: Cb);
+    fn iter_be_bytes(f: Cb);
+}
+
+impl u8: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) {
+        f([
+            self,
+        ]);
+    }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) {
+        f([
+            self as u8
+        ]);
+    }
+}
+
+impl u16: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) {
+        f([
+            self as u8,
+            (self >> 8) as u8
+        ]);
+    }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) {
+        f([
+            (self >> 8) as u8,
+            self as u8
+        ]);
+    }
+}
+
+impl u32: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) {
+        f([
+            self as u8,
+            (self >> 8) as u8,
+            (self >> 16) as u8,
+            (self >> 24) as u8,
+        ]);
+    }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) {
+        f([
+            (self >> 24) as u8,
+            (self >> 16) as u8,
+            (self >> 8) as u8,
+            self as u8
+        ]);
+    }
+}
+
+impl u64: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) {
+        f([
+            self as u8,
+            (self >> 8) as u8,
+            (self >> 16) as u8,
+            (self >> 24) as u8,
+            (self >> 32) as u8,
+            (self >> 40) as u8,
+            (self >> 48) as u8,
+            (self >> 56) as u8
+        ]);
+    }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) {
+        f([
+            (self >> 56) as u8,
+            (self >> 48) as u8,
+            (self >> 40) as u8,
+            (self >> 32) as u8,
+            (self >> 24) as u8,
+            (self >> 16) as u8,
+            (self >> 8) as u8,
+            self as u8
+        ]);
+    }
+}
+
+impl i8: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) { (self as u8).iter_le_bytes(f) }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) { (self as u8).iter_be_bytes(f) }
+}
+
+impl i16: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) { (self as u16).iter_le_bytes(f) }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) { (self as u16).iter_be_bytes(f) }
+}
+
+impl i32: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) { (self as u32).iter_le_bytes(f) }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) { (self as u32).iter_be_bytes(f) }
+}
+
+impl i64: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) { (self as u64).iter_le_bytes(f) }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) { (self as u64).iter_be_bytes(f) }
+}
+
+#[cfg(target_word_size = "32")]
+impl uint: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) { (self as u32).iter_le_bytes(f) }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) { (self as u32).iter_be_bytes(f) }
+}
+
+#[cfg(target_word_size = "64")]
+impl uint: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) { (self as u64).iter_le_bytes(f) }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) { (self as u64).iter_be_bytes(f) }
+}
+
+impl int: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) { (self as uint).iter_le_bytes(f) }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) { (self as uint).iter_be_bytes(f) }
+}
+
+impl ~[const u8]: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) { f(self); }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) { f(self); }
+}
+
+impl @[const u8]: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) { f(self); }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) { f(self); }
+}
+
+impl<A: IterBytes> &[const A]: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) {
+        for self.each |elt| {
+            do elt.iter_le_bytes |bytes| {
+                f(bytes)
+            }
+        }
+    }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) {
+        for self.each |elt| {
+            do elt.iter_be_bytes |bytes| {
+                f(bytes)
+            }
+        }
+    }
+}
+
+fn iter_le_bytes_2<A: IterBytes, B: IterBytes>(a: &A, b: &B, f: Cb) {
+    let mut flag = true;
+    a.iter_le_bytes(|bytes| {flag = f(bytes); flag});
+    if !flag { return; }
+    b.iter_le_bytes(|bytes| {flag = f(bytes); flag});
+}
+
+fn iter_be_bytes_2<A: IterBytes, B: IterBytes>(a: &A, b: &B, f: Cb) {
+    let mut flag = true;
+    a.iter_be_bytes(|bytes| {flag = f(bytes); flag});
+    if !flag { return; }
+    b.iter_be_bytes(|bytes| {flag = f(bytes); flag});
+}
+
+fn iter_le_bytes_3<A: IterBytes,
+                   B: IterBytes,
+                   C: IterBytes>(a: &A, b: &B, c: &C, f: Cb) {
+    let mut flag = true;
+    a.iter_le_bytes(|bytes| {flag = f(bytes); flag});
+    if !flag { return; }
+    b.iter_le_bytes(|bytes| { flag = f(bytes); flag});
+    if !flag { return; }
+    c.iter_le_bytes(|bytes| {flag = f(bytes); flag});
+}
+
+fn iter_be_bytes_3<A: IterBytes,
+                   B: IterBytes,
+                   C: IterBytes>(a: &A, b: &B, c: &C, f: Cb) {
+    let mut flag = true;
+                       a.iter_be_bytes(|bytes| {flag = f(bytes); flag});
+    if !flag { return; }
+                       b.iter_be_bytes(|bytes| {flag = f(bytes); flag});
+    if !flag { return; }
+                       c.iter_be_bytes(|bytes| {flag = f(bytes); flag});
+}
+
+impl &str: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) {
+        do str::byte_slice(self) |bytes| {
+            f(bytes);
+        }
+    }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) {
+        do str::byte_slice(self) |bytes| {
+            f(bytes);
+        }
+    }
+}
+
+impl ~str: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) {
+        do str::byte_slice(self) |bytes| {
+            f(bytes);
+        }
+    }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) {
+        do str::byte_slice(self) |bytes| {
+            f(bytes);
+        }
+    }
+}
+
+impl @str: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) {
+        do str::byte_slice(self) |bytes| {
+            f(bytes);
+        }
+    }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) {
+        do str::byte_slice(self) |bytes| {
+            f(bytes);
+        }
+    }
+}
+impl<A: IterBytes> &A: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) {
+        (*self).iter_le_bytes(f);
+    }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) {
+        (*self).iter_be_bytes(f);
+    }
+}
+
+impl<A: IterBytes> @A: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) {
+        (*self).iter_le_bytes(f);
+    }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) {
+        (*self).iter_be_bytes(f);
+    }
+}
+
+impl<A: IterBytes> ~A: IterBytes {
+    #[inline(always)]
+    fn iter_le_bytes(f: Cb) {
+        (*self).iter_le_bytes(f);
+    }
+    #[inline(always)]
+    fn iter_be_bytes(f: Cb) {
+        (*self).iter_be_bytes(f);
+    }
+}
+
+
 trait ToBytes {
-    fn to_bytes() -> ~[u8];
+    fn to_le_bytes() -> ~[u8];
+    fn to_be_bytes() -> ~[u8];
 }
 
-impl ~[u8]: ToBytes {
-    fn to_bytes() -> ~[u8] { copy self }
-}
+impl<A: IterBytes> A: ToBytes {
+    fn to_le_bytes() -> ~[u8] {
+        let buf = io::mem_buffer();
+        for self.iter_le_bytes |bytes| {
+            buf.write(bytes)
+        }
+        io::mem_buffer_buf(buf)
+    }
+    fn to_be_bytes() -> ~[u8] {
+        let buf = io::mem_buffer();
+        for self.iter_be_bytes |bytes| {
+            buf.write(bytes)
+        }
+        io::mem_buffer_buf(buf)
+    }
 
-impl @~[u8]: ToBytes {
-    fn to_bytes() -> ~[u8] { copy *self }
-}
-
-impl ~str: ToBytes {
-    fn to_bytes() -> ~[u8] { str::to_bytes(self) }
-}
-
-impl @(~str): ToBytes {
-    fn to_bytes() -> ~[u8] { str::to_bytes(*self) }
 }
diff --git a/src/libcore/vec.rs b/src/libcore/vec.rs
index baf6c7c8601..1533b07861c 100644
--- a/src/libcore/vec.rs
+++ b/src/libcore/vec.rs
@@ -1168,7 +1168,7 @@ pure fn iter_between<T>(v: &[T], start: uint, end: uint, f: fn(T)) {
  * Return true to continue, false to break.
  */
 #[inline(always)]
-pure fn each<T>(v: &[T], f: fn(T) -> bool) {
+pure fn each<T>(v: &[const T], f: fn(T) -> bool) {
     do vec::as_buf(v) |p, n| {
         let mut n = n;
         let mut p = p;
@@ -1206,7 +1206,7 @@ pure fn each_mut<T>(v: &[mut T], f: fn(elem: &mut T) -> bool) {
  * Return true to continue, false to break.
  */
 #[inline(always)]
-pure fn eachi<T>(v: &[T], f: fn(uint, T) -> bool) {
+pure fn eachi<T>(v: &[const T], f: fn(uint, T) -> bool) {
     do vec::as_buf(v) |p, n| {
         let mut i = 0u;
         let mut p = p;
@@ -1916,12 +1916,12 @@ mod u8 {
 // This cannot be used with iter-trait.rs because of the region pointer
 // required in the slice.
 
-impl<A> &[A]: iter::BaseIter<A> {
+impl<A> &[const A]: iter::BaseIter<A> {
     pure fn each(blk: fn(A) -> bool) { each(self, blk) }
     pure fn size_hint() -> Option<uint> { Some(len(self)) }
 }
 
-impl<A> &[A]: iter::ExtendedIter<A> {
+impl<A> &[const A]: iter::ExtendedIter<A> {
     pure fn eachi(blk: fn(uint, A) -> bool) { iter::eachi(self, blk) }
     pure fn all(blk: fn(A) -> bool) -> bool { iter::all(self, blk) }
     pure fn any(blk: fn(A) -> bool) -> bool { iter::any(self, blk) }