diff --git a/src/libcore/dvec.rs b/src/libcore/dvec.rs
index 2a5df0ea1563..bdbdb6cef16b 100644
--- a/src/libcore/dvec.rs
+++ b/src/libcore/dvec.rs
@@ -76,7 +76,7 @@ fn unwrap<A>(-d: dvec<A>) -> ~[mut A] {
 }
 
 impl private_methods<A> for dvec<A> {
-    fn check_not_borrowed() {
+    pure fn check_not_borrowed() {
         unsafe {
             let data: *() = unsafe::reinterpret_cast(self.data);
             if data.is_null() {
@@ -119,11 +119,13 @@ fn swap(f: fn(-~[mut A]) -> ~[mut A]) {
     }
 
     /// Returns the number of elements currently in the dvec
-    fn len() -> uint {
-        do self.borrow |v| {
-            let l = v.len();
-            self.return(v);
-            l
+    pure fn len() -> uint {
+        unchecked {
+            do self.borrow |v| {
+                let l = v.len();
+                self.return(v);
+                l
+            }
         }
     }
 
@@ -172,6 +174,13 @@ fn shift() -> A {
             result
         }
     }
+
+    // Reverse the elements in the list, in place
+    fn reverse() {
+        do self.borrow |v| {
+            vec::reverse(v);
+        }
+    }
 }
 
 impl extensions<A:copy> for dvec<A> {
@@ -229,23 +238,25 @@ fn append_iter<A, I:iter::base_iter<A>>(ts: I) {
      *
      * See `unwrap()` if you do not wish to copy the contents.
      */
-    fn get() -> ~[A] {
-        do self.borrow |v| {
-            let w = vec::from_mut(copy v);
-            self.return(v);
-            w
+    pure fn get() -> ~[A] {
+        unchecked {
+            do self.borrow |v| {
+                let w = vec::from_mut(copy v);
+                self.return(v);
+                w
+            }
         }
     }
 
     /// Copy out an individual element
     #[inline(always)]
-    fn [](idx: uint) -> A {
+    pure fn [](idx: uint) -> A {
         self.get_elt(idx)
     }
 
     /// Copy out an individual element
     #[inline(always)]
-    fn get_elt(idx: uint) -> A {
+    pure fn get_elt(idx: uint) -> A {
         self.check_not_borrowed();
         ret self.data[idx];
     }
@@ -271,7 +282,7 @@ fn grow_set_elt(idx: uint, initval: A, val: A) {
 
     /// Returns the last element, failing if the vector is empty
     #[inline(always)]
-    fn last() -> A {
+    pure fn last() -> A {
         self.check_not_borrowed();
 
         let length = self.len();
@@ -285,13 +296,12 @@ fn last() -> A {
     /// Iterates over the elements in reverse order
     #[inline(always)]
     fn reach(f: fn(A) -> bool) {
-        let length = self.len();
-        let mut i = 0u;
-        while i < length {
-            if !f(self.get_elt(i)) {
-                break;
-            }
-            i += 1u;
-        }
+        do self.swap |v| { vec::reach(v, f); v }
+    }
+
+    /// Iterates over the elements and indices in reverse order
+    #[inline(always)]
+    fn reachi(f: fn(uint, A) -> bool) {
+        do self.swap |v| { vec::reachi(v, f); v }
     }
 }
diff --git a/src/libcore/vec.rs b/src/libcore/vec.rs
index 475f15576102..60e3373fdbe0 100644
--- a/src/libcore/vec.rs
+++ b/src/libcore/vec.rs
@@ -71,7 +71,7 @@
 export swap;
 export reverse;
 export reversed;
-export iter, iter_between, each, eachi;
+export iter, iter_between, each, eachi, reach, reachi;
 export iter2;
 export iteri;
 export riter;
@@ -204,12 +204,12 @@ fn reserve_at_least<T>(&v: ~[const T], n: uint) {
 }
 
 /// Produces a mut vector from an immutable vector.
-fn to_mut<T>(+v: ~[T]) -> ~[mut T] {
+pure fn to_mut<T>(+v: ~[T]) -> ~[mut T] {
     unsafe { ::unsafe::transmute(v) }
 }
 
 /// Produces an immutable vector from a mut vector.
-fn from_mut<T>(+v: ~[mut T]) -> ~[T] {
+pure fn from_mut<T>(+v: ~[mut T]) -> ~[T] {
     unsafe { ::unsafe::transmute(v) }
 }
 
@@ -1038,6 +1038,42 @@ fn reverse<T>(v: ~[mut T]) {
     }
 }
 
+/**
+ * Iterates over a vector's elements in reverse
+ *
+ * Return true to continue, false to break.
+ */
+#[inline(always)]
+pure fn reach<T>(v: &[T], blk: fn(T) -> bool) {
+    do vec::unpack_slice(v) |p, n| {
+        let mut i = 1;
+        while i <= n {
+            unsafe {
+                if !blk(*ptr::offset(p, n-i)) { break; }
+            }
+            i += 1;
+        }
+    }
+}
+
+/**
+ * Iterates over a vector's elements and indices in reverse
+ *
+ * Return true to continue, false to break.
+ */
+#[inline(always)]
+pure fn reachi<T>(v: &[T], blk: fn(uint, T) -> bool) {
+    do vec::unpack_slice(v) |p, n| {
+        let mut i = 1;
+        while i <= n {
+            unsafe {
+                if !blk(n-i, *ptr::offset(p, n-i)) { break; }
+            }
+            i += 1;
+        }
+    }
+}
+
 /**
  * Iterates over two vectors simultaneously
  *