module Data.IORef
(
IORef,
newIORef,
readIORef,
writeIORef,
modifyIORef,
atomicModifyIORef,
#if !defined(__PARALLEL_HASKELL__) && defined(__GLASGOW_HASKELL__)
mkWeakIORef,
#endif
) where
#ifdef __HUGS__
import Hugs.IORef
#endif
#ifdef __GLASGOW_HASKELL__
import GHC.Base
import GHC.STRef
import GHC.IORef hiding (atomicModifyIORef)
import qualified GHC.IORef
#if !defined(__PARALLEL_HASKELL__)
import GHC.Weak
#endif
#endif /* __GLASGOW_HASKELL__ */
#ifdef __NHC__
import NHC.IOExtras
( IORef
, newIORef
, readIORef
, writeIORef
, excludeFinalisers
)
#endif
#if defined(__GLASGOW_HASKELL__) && !defined(__PARALLEL_HASKELL__)
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
modifyIORef :: IORef a -> (a -> a) -> IO ()
modifyIORef ref f = readIORef ref >>= writeIORef ref . f
atomicModifyIORef :: IORef a -> (a -> (a,b)) -> IO b
#if defined(__GLASGOW_HASKELL__)
atomicModifyIORef = GHC.IORef.atomicModifyIORef
#elif defined(__HUGS__)
atomicModifyIORef = plainModifyIORef
where plainModifyIORef r f = do
a <- readIORef r
case f a of (a',b) -> writeIORef r a' >> return b
#elif defined(__NHC__)
atomicModifyIORef r f =
excludeFinalisers $ do
a <- readIORef r
let (a',b) = f a
writeIORef r a'
return b
#endif