Re: [Haskell-cafe] Concurrent Haskell Actions with Timeout

30 May 2009


      2009/5/30 Cetin Sert 
...
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
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UIN: 44640862