X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FSTRef.hs;h=10853bea34caa8a0814820391435bf6356542721;hb=b9b6e38a1ebb5f05b382609fe0776d91cdd1090b;hp=336a61fbd30aabfb79b2b2bb320f590cbbd5bea3;hpb=1819f73fc5bb82bf8e2a57905edfde81017d9167;p=haskell-directory.git

diff --git a/Data/STRef.hs b/Data/STRef.hs
index 336a61f..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.
 --
@@ -24,10 +24,18 @@ module Data.STRef (
 import Prelude
 
 #ifdef __GLASGOW_HASKELL__
+import GHC.ST
 import GHC.STRef
 #endif
 
-import Data.Dynamic
+#ifdef __HUGS__
+import Hugs.ST
+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