Re: [Haskell-beginners] About monad

Excerpts from Trung Quang Nguyen's message of Thu Dec 20 22:07:02 +0800 2012:

Hi all,

I saw this

1. instance Monad Maybe where 2. return x = Just x 3. Nothing >>= f = Nothing 4. Just x >>= f = f x 5. fail _ = Nothing

I am wondering about the implementation of function (>>=). Why don't it be *Just x >>= f = Just (f x)*?

Try it; it won't typecheck. Cheers, Edward