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
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