--
-------------------------------------------------------------------------------
+#ifdef __GLASGOW_HASKELL__
#include "Typeable.h"
+#endif
module System.Timeout ( timeout ) where
-#if __NHC__
-timeout :: Int -> IO a -> IO (Maybe a)
-timeout n f = fmap Just f
-#else
-
+#ifdef __GLASGOW_HASKELL__
import Prelude (Show(show), IO, Ord((<)), Eq((==)), Int,
- (.), otherwise, fmap)
+ 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 (Exception, handleJust, throwTo, bracket)
-import Data.Dynamic (Typeable, fromDynamic)
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
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
(bracket (forkIO (threadDelay n >> throwTo pid ex))
(killThread)
(\_ -> fmap Just f))
-#endif
+#else
+timeout n f = fmap Just f
+#endif /* !__GLASGOW_HASKELL__ */