X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FSTRef.hs;h=10853bea34caa8a0814820391435bf6356542721;hb=74bc2d04fdbae494bcf4839c4ec5e6ec1d0bf600;hp=e25e8b5efcf11c897514836e17daf6dab3059ae0;hpb=9812e0a321ec0ed8f9e53eb2febfb14c79564200;p=haskell-directory.git

diff --git a/Data/STRef.hs b/Data/STRef.hs
index e25e8b5..10853be 100644
--- a/Data/STRef.hs
+++ b/Data/STRef.hs
@@ -6,7 +6,7 @@
 -- 
 -- Maintainer  :  libraries@haskell.org
 -- Stability   :  experimental
--- Portability :  non-portable (requires non-portable module ST)
+-- Portability :  non-portable (uses Control.Monad.ST)
 --
 -- Mutable references in the (strict) ST monad.
 --
@@ -24,14 +24,18 @@ module Data.STRef (
 import Prelude
 
 #ifdef __GLASGOW_HASKELL__
+import GHC.ST
 import GHC.STRef
 #endif
 
 #ifdef __HUGS__
 import Hugs.ST
-#endif
-
-import Data.Dynamic
+import Data.Typeable
 
-#include "Dynamic.h"
+#include "Typeable.h"
 INSTANCE_TYPEABLE2(STRef,stRefTc,"STRef")
+#endif
+
+-- |Mutate the contents of an 'STRef'
+modifySTRef :: STRef s a -> (a -> a) -> ST s ()
+modifySTRef ref f = writeSTRef ref . f =<< readSTRef ref