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

On Jan 24, 2005, at 8:53 PM, Jorge Adriano Aires wrote:

And it would say nothing about things like: return 4 >> return 5 ==?== return 5 I can live with it.

I feel obliged to point out (because the repeated references to the question are driving me up the wall) that this simple equality holds in every monad: return 4 >> return 5 === (definition of >>) return 4 >>= \_ -> return 5 === (monad laws) (\_ -> return 5) 4 === (beta reduction) return 5 We don't need to know anything about the semantics, etc. of any other actions the monad might happen to define. -Jan-Willem Maessen