[Haskell-cafe] Exceptions

[Dominic Steinitz]

I'd be cautious about using exceptions too liberally. When I implemented 
a Haskell equivalent to traceroute, I wanted to stop sending packets 
when a certain condition occurred. It was very tempting to throw an 
exception and catch it at the top level. However, I think the code below 
is easier for the maintainer (me) to understand.

Dominic.

sequenceWhile_ :: Monad m => (a -> Bool) -> [m a] -> m ()
sequenceWhile_ p [] =
   return ()
sequenceWhile_ p (x:xs) =
   x >>= \c -> if (p c) then sequenceWhile_ p xs else return ()