X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FSTRef.hs;h=3edfb871ae33310be20c2fe330e45b6b3438ef5d;hb=99a329d9b272925dcdf474ce2369e9421b51e51c;hp=747d5baad330b4fd90c53f19add570c39263edc7;hpb=5545727d5a6a1fc6d5d00f32a92a8fdf0fb7ca77;p=ghc-base.git

diff --git a/Data/STRef.hs b/Data/STRef.hs
index 747d5ba..3edfb87 100644
--- a/Data/STRef.hs
+++ b/Data/STRef.hs
@@ -1,33 +1,42 @@
 -----------------------------------------------------------------------------
--- 
+-- |
 -- 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)
 --
--- $Id: STRef.hs,v 1.2 2001/07/03 11:37:50 simonmar Exp $
---
--- 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
-	writeSTRef	-- :: STRef s a -> a -> ST s ()
+	writeSTRef,	-- :: STRef s a -> a -> ST s ()
+	modifySTRef	-- :: STRef s a -> (a -> a) -> ST s ()
  ) where
 
 import Prelude
 
 #ifdef __GLASGOW_HASKELL__
+import GHC.ST
 import GHC.STRef
 #endif
 
-import Data.Dynamic
+#ifdef __HUGS__
+import Hugs.ST
+#endif
 
-#include "Dynamic.h"
+import Data.Typeable
+
+#include "Typeable.h"
 INSTANCE_TYPEABLE2(STRef,stRefTc,"STRef")
+
+-- |Mutate the contents of an 'STRef'
+modifySTRef :: STRef s a -> (a -> a) -> ST s ()
+modifySTRef ref f = writeSTRef ref . f =<< readSTRef ref