-----------------------------------------------------------------------------
---
+-- |
-- Module : Data.IORef
-- 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 : portable
--
--- $Id: IORef.hs,v 1.3 2001/12/21 15:07:21 simonmar Exp $
---
-- Mutable references in the IO monad.
--
-----------------------------------------------------------------------------
module Data.IORef
- ( IORef -- abstract, instance of: Eq, Typeable
- , newIORef -- :: a -> IO (IORef a)
- , readIORef -- :: IORef a -> IO a
- , writeIORef -- :: IORef a -> a -> IO ()
- , modifyIORef -- :: IORef a -> (a -> a) -> IO ()
+ (
+ -- * IORefs
+ IORef, -- abstract, instance of: Eq, Typeable
+ newIORef, -- :: a -> IO (IORef a)
+ readIORef, -- :: IORef a -> IO a
+ writeIORef, -- :: IORef a -> a -> IO ()
+ modifyIORef, -- :: IORef a -> (a -> a) -> IO ()
#if !defined(__PARALLEL_HASKELL__) && defined(__GLASGOW_HASKELL__)
- , mkWeakIORef -- :: IORef a -> IO () -> IO (Weak (IORef a))
+ mkWeakIORef, -- :: IORef a -> IO () -> IO (Weak (IORef a))
#endif
) where
#endif
#endif /* __GLASGOW_HASKELL__ */
-#ifdef __HUGS__
-import IOExts ( IORef, newIORef, writeIORef, readIORef )
-import ST ( stToIO, newSTRef, readSTRef, writeSTRef )
-#endif
-
import Data.Dynamic
-#ifndef __PARALLEL_HASKELL__
+#if defined(__GLASGOW_HASKELL__) && !defined(__PARALLEL_HASKELL__)
+-- |Make a 'Weak' pointer to an 'IORef'
mkWeakIORef :: IORef a -> IO () -> IO (Weak (IORef a))
mkWeakIORef r@(IORef (STRef r#)) f = IO $ \s ->
case mkWeak# r# r f s of (# s1, w #) -> (# s1, Weak w #)
#endif
+#if defined __HUGS__
+data IORef a -- mutable variables containing values of type a
+
+primitive newIORef "newRef" :: a -> IO (IORef a)
+primitive readIORef "getRef" :: IORef a -> IO a
+primitive writeIORef "setRef" :: IORef a -> a -> IO ()
+primitive eqIORef "eqRef" :: IORef a -> IORef a -> Bool
+
+instance Eq (IORef a) where
+ (==) = eqIORef
+#endif /* __HUGS__ */
+
+-- |Mutate the contents of an 'IORef'
modifyIORef :: IORef a -> (a -> a) -> IO ()
modifyIORef ref f = writeIORef ref . f =<< readIORef ref