[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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