-{-# OPTIONS -fglasgow-exts #-}
-------------------------------------------------------------------------------
-- |
-- Module : System.Timeout
--
-------------------------------------------------------------------------------
-module System.Timeout ( timeout ) where
+#ifdef __GLASGOW_HASKELL__
+#include "Typeable.h"
+#endif
-#if __NHC__
-timeout :: Int -> IO a -> IO (Maybe a)
-timeout n f = fmap Just f
-#else
+module System.Timeout ( timeout ) where
-import Prelude (IO, Ord((<)), Eq((==)), Int, (.), otherwise, fmap)
+#ifdef __GLASGOW_HASKELL__
+import Prelude (Show(show), IO, Ord((<)), Eq((==)), Int,
+ otherwise, fmap)
import Data.Maybe (Maybe(..))
-import Control.Monad (Monad(..), guard)
+import Control.Monad (Monad(..))
import Control.Concurrent (forkIO, threadDelay, myThreadId, killThread)
-import Control.Exception (handleJust, throwDynTo, dynExceptions, bracket)
-import Data.Dynamic (Typeable, fromDynamic)
+import Control.Exception (Exception, handleJust, throwTo, bracket)
+import Data.Typeable
import Data.Unique (Unique, newUnique)
+import GHC.Num
-- An internal type that is thrown as a dynamic exception to
-- interrupt the running IO computation when the timeout has
-- expired.
-data Timeout = Timeout Unique deriving (Eq, Typeable)
+data Timeout = Timeout Unique deriving Eq
+INSTANCE_TYPEABLE0(Timeout,timeoutTc,"Timeout")
+
+instance Show Timeout where
+ show _ = "<<timeout>>"
+
+instance Exception Timeout
+#endif /* !__GLASGOW_HASKELL__ */
-- |Wrap an 'IO' computation to time out and return @Nothing@ in case no result
-- is available within @n@ microseconds (@1\/10^6@ seconds). In case a result
-- I\/O or file I\/O using this combinator.
timeout :: Int -> IO a -> IO (Maybe a)
+#ifdef __GLASGOW_HASKELL__
timeout n f
| n < 0 = fmap Just f
| n == 0 = return Nothing
| otherwise = do
pid <- myThreadId
ex <- fmap Timeout newUnique
- handleJust (\e -> dynExceptions e >>= fromDynamic >>= guard . (ex ==))
+ handleJust (\e -> if e == ex then Just () else Nothing)
(\_ -> return Nothing)
- (bracket (forkIO (threadDelay n >> throwDynTo pid ex))
+ (bracket (forkIO (threadDelay n >> throwTo pid ex))
(killThread)
(\_ -> fmap Just f))
-#endif
+#else
+timeout n f = fmap Just f
+#endif /* !__GLASGOW_HASKELL__ */