2009/5/30 Cetin Sert <cetin.sert@gmail.com>

Hi how could one implement a function in concurrent haskell that either returns 'a' successfully or due timeout 'b'?

timed :: Int → IO a → b → IO (Either a b)
timed max act def = do

Something like (warning, untested code - no compiler atm).

timed timeout act fallback = do

res <- newEmptyMVar

tid <- forkIO $ act >>= writeMVar res

threadDelay timeout

stillRunning <- isEmptyMVar res

if stillRunning then killThread tid >> return fallback else takeMVar res

--
Sebastian Sylvan
+44(0)7857-300802
UIN: 44640862