Re: [Haskell-cafe] 1st attempt at parallelizing

26 Jul 2010

      2010/7/26 Felipe Lessa :
...
downloader :: TChan (Maybe Page) -> TChan (Page, Info) -> IO ()
downloader in out = do
 mp <- atomically (readTChan in)
 case mp of
   Nothing -> return ()
   Just p -> download p >>= atomically . writeTChan out
Oops!  Of course there should be recursion here!  (This is a bug the
typechecker probably wouldn't catch.)

downloader :: TChan (Maybe Page) -> TChan (Page, Info) -> IO ()
downloader in out = do
 mp <- atomically (readTChan in)
 case mp of
   Nothing -> return ()
   Just p -> download p >>= atomically . writeTChan out >> downloader in out

Cheers,

-- 
Felipe.