while (hGetBuf h buf bufsize == bufsize) crc := updateCrc crc buf bufsize break if crc==0 print crc
inContT $ callCC $ \break -> do flip execStateT 0 $ do whileM (liftM (== bufsize) (hGetBuf h buf bufsize)) $ do modifyM (updateCrc buf bufsize) crc <- get when (crc == 0) (lift (break crc)) print crc
first. it's longer than original.
is it, though? what makes it longer are features that the original doesn't have, I think. so how about a less ambitious translation, with crc in an MVar and a while-loop that can be broken from the body as well as the condition: while (hGetBuf h buf bufzise .==. (return bufsize)) $ do crc =: updateCrc crc buf bufsize breakIf ((val crc) .==. (return 0)) `orElse` do printM (val crc) od using definitions roughly like this while c b = do { r <- c; when r (b >>= flip when (while c b)) } continueIf c m = c >>= \b-> if b then od else m breakIf c m = c >>= \b-> if b then return False else m orElse = ($) od :: Monad m => m Bool od = return True x .==. y = liftM2 (==) x y printM x = x >>= print v =: x = do { rx <- x; swapMVar v rx } val = readMVar not that I like that style;-) Claus