diff --git a/Data/HashMap/Base.hs b/Data/HashMap/Base.hs
--- a/Data/HashMap/Base.hs
+++ b/Data/HashMap/Base.hs
@@ -31,6 +31,7 @@
 
       -- * Transformations
     , map
+    , mapWithKey
     , traverseWithKey
 
       -- * Difference and intersection
@@ -313,7 +314,7 @@
         | otherwise = runST (two s h k x hy ky y)
     go h k x s t@(BitmapIndexed b ary)
         | b .&. m == 0 =
-            let ary' = A.insert ary i $! Leaf h (L k x)
+            let !ary' = A.insert ary i $! Leaf h (L k x)
             in bitmapIndexedOrFull (b .|. m) ary'
         | otherwise =
             let !st  = A.index ary i
@@ -695,6 +696,7 @@
                            A.map' (\ (L k v) -> L k (f k v)) ary
 {-# INLINE mapWithKey #-}
 
+-- | /O(n)/ Transform this map by applying a function to every value.
 map :: (v1 -> v2) -> HashMap k v1 -> HashMap k v2
 map f = mapWithKey (const f)
 {-# INLINE map #-}
diff --git a/Data/HashMap/Lazy.hs b/Data/HashMap/Lazy.hs
--- a/Data/HashMap/Lazy.hs
+++ b/Data/HashMap/Lazy.hs
@@ -56,6 +56,7 @@
 
       -- * Transformations
     , HM.map
+    , mapWithKey
     , traverseWithKey
 
       -- * Difference and intersection
diff --git a/Data/HashMap/Strict.hs b/Data/HashMap/Strict.hs
--- a/Data/HashMap/Strict.hs
+++ b/Data/HashMap/Strict.hs
@@ -56,6 +56,7 @@
 
       -- * Transformations
     , map
+    , mapWithKey
     , traverseWithKey
 
       -- * Difference and intersection
@@ -92,7 +93,7 @@
 import qualified Data.HashMap.Base as HM
 import Data.HashMap.Base hiding (
     adjust, fromList, fromListWith, insert, insertWith, intersectionWith,
-    map, singleton, unionWith)
+    map, mapWithKey, singleton, unionWith)
 import Data.HashMap.Unsafe (runST)
 
 -- $strictness
@@ -330,6 +331,7 @@
         Collision h $ A.map' (\ (L k v) -> let !v' = f k v in L k v') ary
 {-# INLINE mapWithKey #-}
 
+-- | /O(n)/ Transform this map by applying a function to every value.
 map :: (v1 -> v2) -> HashMap k v1 -> HashMap k v2
 map f = mapWithKey (const f)
 {-# INLINE map #-}
diff --git a/benchmarks/Benchmarks.hs b/benchmarks/Benchmarks.hs
--- a/benchmarks/Benchmarks.hs
+++ b/benchmarks/Benchmarks.hs
@@ -191,39 +191,29 @@
 
             -- fromList
           , bgroup "fromList"
-            [ bgroup name
-              [ bgroup "long"
-                [ bench "String" $ whnf fl1 elems
-                , bench "ByteString" $ whnf fl2 elemsBS
-                , bench "Int" $ whnf fl3 elemsI
-                ]
-              , bgroup "short"
-                [ bench "String" $ whnf fl1 elemsDup
-                , bench "ByteString" $ whnf fl2 elemsDupBS
-                , bench "Int" $ whnf fl3 elemsDupI
-                ]
+            [ bgroup "long"
+              [ bench "String" $ whnf HM.fromList elems
+              , bench "ByteString" $ whnf HM.fromList elemsBS
+              , bench "Int" $ whnf HM.fromList elemsI
               ]
-            | (name,fl1,fl2,fl3)
-                 <- [("Base",HM.fromList,HM.fromList,HM.fromList)
-                    ,("insert",fromList_insert,fromList_insert,fromList_insert)]
+            , bgroup "short"
+              [ bench "String" $ whnf HM.fromList elemsDup
+              , bench "ByteString" $ whnf HM.fromList elemsDupBS
+              , bench "Int" $ whnf HM.fromList elemsDupI
+              ]
             ]
-            -- fromList
+            -- fromListWith
           , bgroup "fromListWith"
-            [ bgroup name
-              [ bgroup "long"
-                [ bench "String" $ whnf (fl1 (+)) elems
-                , bench "ByteString" $ whnf (fl2 (+)) elemsBS
-                , bench "Int" $ whnf (fl3 (+)) elemsI
-                ]
-              , bgroup "short"
-                [ bench "String" $ whnf (fl1 (+)) elemsDup
-                , bench "ByteString" $ whnf (fl2 (+)) elemsDupBS
-                , bench "Int" $ whnf (fl3 (+)) elemsDupI
-                ]
+            [ bgroup "long"
+              [ bench "String" $ whnf (HM.fromListWith (+)) elems
+              , bench "ByteString" $ whnf (HM.fromListWith (+)) elemsBS
+              , bench "Int" $ whnf (HM.fromListWith (+)) elemsI
               ]
-            | (name,fl1,fl2,fl3)
-                 <- [("Base",HM.fromListWith,HM.fromListWith,HM.fromListWith)
-                    ,("insert",fromListWith_insert,fromListWith_insert,fromListWith_insert)]
+            , bgroup "short"
+              [ bench "String" $ whnf (HM.fromListWith (+)) elemsDup
+              , bench "ByteString" $ whnf (HM.fromListWith (+)) elemsDupBS
+              , bench "Int" $ whnf (HM.fromListWith (+)) elemsDupI
+              ]
             ]
           ]
         ]
@@ -334,18 +324,3 @@
 
 deleteIM :: [Int] -> IM.IntMap Int -> IM.IntMap Int
 deleteIM xs m0 = foldl' (\m k -> IM.delete k m) m0 xs
-
-------------------------------------------------------------------------
--- * Reference implementations
-
-fromList_insert :: (Eq k, Hashable k) => [(k, v)] -> HM.HashMap k v
-fromList_insert = foldl' (\ m (k, v) -> HM.insert k v m) HM.empty
-#if __GLASGOW_HASKELL__ >= 700
-{-# INLINABLE fromList_insert #-}
-#endif
-
-fromListWith_insert :: (Eq k, Hashable k) => (v -> v -> v) -> [(k, v)] -> HM.HashMap k v
-fromListWith_insert f = foldl' (\ m (k, v) -> HM.insertWith f k v m) HM.empty
-#if __GLASGOW_HASKELL__ >= 700
-{-# INLINABLE fromListWith_insert #-}
-#endif
diff --git a/unordered-containers.cabal b/unordered-containers.cabal
--- a/unordered-containers.cabal
+++ b/unordered-containers.cabal
@@ -1,5 +1,5 @@
 name:           unordered-containers
-version:        0.2.3.3
+version:        0.2.4.0
 synopsis:       Efficient hashing-based container types
 description:
   Efficient hashing-based container types.  The containers have been
@@ -14,7 +14,7 @@
 maintainer:     johan.tibell@gmail.com
 Homepage:       https://github.com/tibbe/unordered-containers
 bug-reports:    https://github.com/tibbe/unordered-containers/issues
-copyright:      2010-2012 Johan Tibell
+copyright:      2010-2014 Johan Tibell
                 2010 Edward Z. Yang
 category:       Data
 build-type:     Simple