1 -----------------------------------------------------------------------------
4 -- Copyright : (c) The University of Glasgow 2001
5 -- License : BSD-style (see the file libraries/core/LICENSE)
7 -- Maintainer : libraries@haskell.org
8 -- Stability : experimental
9 -- Portability : portable
11 -- Mutable references in the IO monad.
13 -----------------------------------------------------------------------------
16 ( IORef -- abstract, instance of: Eq, Typeable
17 , newIORef -- :: a -> IO (IORef a)
18 , readIORef -- :: IORef a -> IO a
19 , writeIORef -- :: IORef a -> a -> IO ()
20 , modifyIORef -- :: IORef a -> (a -> a) -> IO ()
22 #if !defined(__PARALLEL_HASKELL__) && defined(__GLASGOW_HASKELL__)
23 , mkWeakIORef -- :: IORef a -> IO () -> IO (Weak (IORef a))
29 #ifdef __GLASGOW_HASKELL__
30 import GHC.Base ( mkWeak# )
33 #if !defined(__PARALLEL_HASKELL__)
36 #endif /* __GLASGOW_HASKELL__ */
40 #if defined(__GLASGOW_HASKELL__) && !defined(__PARALLEL_HASKELL__)
41 mkWeakIORef :: IORef a -> IO () -> IO (Weak (IORef a))
42 mkWeakIORef r@(IORef (STRef r#)) f = IO $ \s ->
43 case mkWeak# r# r f s of (# s1, w #) -> (# s1, Weak w #)
47 data IORef a -- mutable variables containing values of type a
49 primitive newIORef "newRef" :: a -> IO (IORef a)
50 primitive readIORef "getRef" :: IORef a -> IO a
51 primitive writeIORef "setRef" :: IORef a -> a -> IO ()
52 primitive eqIORef "eqRef" :: IORef a -> IORef a -> Bool
54 instance Eq (IORef a) where
58 modifyIORef :: IORef a -> (a -> a) -> IO ()
59 modifyIORef ref f = writeIORef ref . f =<< readIORef ref
62 INSTANCE_TYPEABLE1(IORef,ioRefTc,"IORef")