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|
-----------------------------------------------------------------------------
-- |
-- Module : Data.STRef
-- Copyright : (c) The University of Glasgow 2001
-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : libraries@haskell.org
-- Stability : experimental
-- Portability : non-portable (requires non-portable module ST)
--
-- 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 ()
modifySTRef -- :: STRef s a -> (a -> a) -> ST s ()
) where
import Prelude
#ifdef __GLASGOW_HASKELL__
import GHC.ST
import GHC.STRef
#endif
#ifdef __HUGS__
import Hugs.ST
#endif
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
|
