I recommend this paper for info, it's very easy to follow:
http://www.haskell.org/~simonmar/papers/ext-exceptions.pdfhttp://www.haskell.org/%7Esimonmar/papers/ext-exceptions.pdf
Austin
That paper cleared up most of my issues and it is amazing that it is not amongst the papers that are referenced at the top of the the page describing Control.Exception. Anyway, there is one more problem I have related to exceptions that is about forcing strictness. It relates to option parsing. I have an option -t that says which track from a file of tracks to print. So I go data Flags = TrackNumber !Int deriving(Read, Show, Eq) makeTrackNumber :: String -> Flags makeTrackNumber str = TrackNumber $ read str options = [GetOpt.Option ['t'] ["tracknumber"] (GetOpt.ReqArg makeTrackNumber "tracknumber") "number of track to show"] Now my main goes main = do args <- getArgs opts <- evaluate $ GetOpt.getOpt GetOpt.RequireOrder options args print "done getting the opts" case opts of ... which of course first prints "done getting opts" and then throws an exception if I give it a flag -t abc. What would be the way to proceed here? Do I increase the strictness or do I write a handler around my complete main? Even if I map the exception in makeTrackNumber to my very own exception how do I find out which exact call gave a problem i.e. which is the call stack at the moment the exception was thrown -- I might use makeTrackNumber in other contexts too. Thanks in advance, Immanuel