Hey Mark,
How can I concisely compose these functions without having to write a cascade of case statements such as:
case f1 rec1 of Nothing -> return Nothing Just id1 -> do rec2 <- f2 id2 return $ case rec2 of Nothing -> return Nothing Just rec2' -> case f3 rec2' of .... I understand that if I was just dealing with Maybe I could use the fact that Maybe is a monad. Yes, you can write like this:
id2 <- f1 rec1 rec2 <- f2 id2 rec3 <- f3 rec2 return rec3 or, even shorter: id2 <- f1 rec1 rec2 <- f2 id2 f3 rec2
The cool thing of the Maybe monad is that it combines a result in such a way that it removes the plumbing of constantly checking for Nothing. I can definitely recommand you the following tutorials: http://www.nomaware.com/monads/html/index.html http://uebb.cs.tu-berlin.de/~magr/pub/Transformers.en.html Those two tutorials really helped me. Good luck, Chris