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 loop 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