diff --git a/Control/DeepSeq.hs b/Control/DeepSeq.hs
--- a/Control/DeepSeq.hs
+++ b/Control/DeepSeq.hs
@@ -1,3 +1,6 @@
+#if __GLASGOW_HASKELL__ >= 701
+{-# LANGUAGE Safe #-}
+#endif
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Control.DeepSeq
@@ -42,7 +45,7 @@
 -- the wrong threads).
 --
 module Control.DeepSeq (
-     deepseq,
+     deepseq, ($!!), force,
      NFData(..),
   ) where
 
@@ -50,13 +53,10 @@
 import Data.Word
 import Data.Ratio
 import Data.Complex
-import Data.Map
-import Data.Set
-import Data.IntMap
-import Data.IntSet
-import Data.Tree
 import Data.Array
 
+infixr 0 $!!
+
 -- | 'deepseq': fully evaluates the first argument, before returning the
 -- second.
 --
@@ -79,6 +79,23 @@
 deepseq :: NFData a => a -> b -> b
 deepseq a b = rnf a `seq` b
 
+-- | the deep analogue of '$!'.  In the expression @f $!! x@, @x@ is
+-- fully evaluated before the function @f@ is applied to it.
+($!!) :: (NFData a) => (a -> b) -> a -> b
+f $!! x = x `deepseq` f x
+
+-- | a variant of 'deepseq' that is useful in some circumstances:
+--
+-- > force x = x `deepseq` x
+--
+-- @force x@ fully evaluates @x@, and then returns it.  Note that
+-- @force x@ only performs evaluation when the value of @force x@
+-- itself is demanded, so essentially it turns shallow evaluation into
+-- deep evaluation.
+
+force :: (NFData a) => a -> a
+force x = x `deepseq` x
+
 -- | A class of types that can be fully evaluated.
 class NFData a where
     -- | rnf should reduce its argument to normal form (that is, fully
@@ -130,21 +147,6 @@
 instance (NFData a, NFData b) => NFData (Either a b) where
     rnf (Left x)  = rnf x
     rnf (Right y) = rnf y
-
-instance (NFData k, NFData a) => NFData (Data.Map.Map k a) where
-    rnf = rnf . Data.Map.toList
-
-instance NFData a => NFData (Data.Set.Set a) where
-    rnf = rnf . Data.Set.toList
-
-instance NFData a => NFData (Data.Tree.Tree a) where
-    rnf (Data.Tree.Node r f) = rnf r `seq` rnf f
-
-instance NFData a => NFData (Data.IntMap.IntMap a) where
-    rnf = rnf . Data.IntMap.toList
-
-instance NFData Data.IntSet.IntSet where
-    rnf = rnf . Data.IntSet.toList
 
 instance NFData a => NFData [a] where
     rnf [] = ()
diff --git a/deepseq.cabal b/deepseq.cabal
--- a/deepseq.cabal
+++ b/deepseq.cabal
@@ -1,5 +1,5 @@
 name:		deepseq
-version:	1.1.0.2
+version:        1.2.0.0
 license:	BSD3
 license-file:	LICENSE
 maintainer:	libraries@haskell.org
@@ -23,13 +23,13 @@
 cabal-version:  >=1.6
 
 source-repository head
-    type:     darcs
-    location: http://darcs.haskell.org/packages/deepseq/
+    type:     git
+    location: http://darcs.haskell.org/packages/deepseq.git/
 
 library {
   exposed-modules: Control.DeepSeq
   build-depends: base       >= 3   && < 5, 
-                 containers >= 0.1 && < 0.5,
                  array      >= 0.1 && < 0.4
   ghc-options: -Wall
+  extensions: CPP
 }