X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FSTRef.hs;h=10853bea34caa8a0814820391435bf6356542721;hb=a0d7892da0d00fee781a550ef353df8734be5884;hp=deaa209575e6e8131bec0a681eae69b353a3ccfe;hpb=746ef6a7fd71bb1e9ebe3cd107c5f9f79f3b7a68;p=haskell-directory.git

diff --git a/Data/STRef.hs b/Data/STRef.hs
index deaa209..10853be 100644
--- a/Data/STRef.hs
+++ b/Data/STRef.hs
@@ -2,17 +2,18 @@
 -- |
 -- Module      :  Data.STRef
 -- Copyright   :  (c) The University of Glasgow 2001
--- License     :  BSD-style (see the file libraries/core/LICENSE)
+-- License     :  BSD-style (see the file libraries/base/LICENSE)
 -- 
 -- 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 ST monad.
+-- Mutable references in the (strict) ST monad.
 --
 -----------------------------------------------------------------------------
 
 module Data.STRef (
+	-- * STRefs
 	STRef,		-- abstract, instance Eq
 	newSTRef,	-- :: a -> ST s (STRef s a)
 	readSTRef,	-- :: STRef s a -> ST s a
@@ -23,10 +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