Re: [Haskell-cafe] Possible bug in Control.Concurrent

[Neil Brown]

On 09/02/11 15:34, Krzysztof Skrzętnicki wrote:
Hello Cafe,
Here is a simple program that yields strange results:

module Main where

import Control.Concurrent
import Control.Concurrent.Chan
import Control.Monad

main = do
 c <- newChan
 writeChan c 1
 forkIO $ forever $ do
   i <- readChan c
   print ("forkio",i)
isEmptyChan c >>= print


Now, this is strange thing: we put single element into the channel. We 
take it out.

What your program does is put a single element into the channel, and 
then *repeatedly* try to take one out (notice the forever you have in 
there!).  Judging by the results, the program deadlocks, which seems 
like a reasonable outcome to me.

Thanks,

Neil.

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