Re: [Haskell-cafe] Re: what is inverse of mzero and return?

But only some instances (such as []) satisfy this:

(mplus a b) >>= c = mplus (a >>= c) (b >>= c)

Other instances (IO, Maybe) satisfy this:

mplus (return a) b = return a

I think mplus should be separated into two functions.

How would we implement the first kind in the Maybe instance of MonadPlus? J.A.