[Haskell-cafe] do you have to use fix with forkio?
derek.a.elkins at gmail.com
Thu Mar 5 19:26:46 EST 2009
On Thu, 2009-03-05 at 16:12 -0800, Jonathan Cast wrote:
> On Thu, 2009-03-05 at 15:36 -0800, Daryoush Mehrtash wrote:
> > In this chat server implementation
> > http://www.haskell.org/haskellwiki/Implement_a_chat_server
> > forkIO is used with fix as in:
> > reader <- forkIO $ fix $ \loop -> do
> > (nr', line) <- readChan chan'
> > when (nr /= nr') $ hPutStrLn hdl line
> > loop
> > Do you have to use fix? Or is there a way to write this with a "let"?
> You can certainly use let:
> reader <- forkIO $ let loop = do
> (nr', line) <- readChan chan'
> when (nr /= nr') $ hPutStrLn hdl line
> in loop
> But the version with fix is clearer (at least to people who have fix in
> their vocabulary) and arguably better style.
Both are poorish style.
reader <- forkIO $ forever $ do (nr', line) <- readChan; when (nr /= nr') $ putStrLn hdl line
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