[project @ 2005-10-13 11:09:50 by ross]

[haskell-directory.git] / Data / STRef.hs

diff --git a/Data/STRef.hs b/Data/STRef.hs
index b3c4888..10853be 100644 (file)
--- a/Data/STRef.hs
+++ b/Data/STRef.hs
@@ -2,19 +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)
 --
--- $Id: STRef.hs,v 1.4 2002/04/24 16:31:40 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
@@ -25,10 +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