[Haskell-cafe] Re: what is inverse of mzero and return?
jmaessen at alum.mit.edu
Mon Jan 24 21:25:54 EST 2005
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
return 4 >> return 5
=== (definition of >>)
return 4 >>= \_ -> return 5
=== (monad laws)
(\_ -> return 5) 4
=== (beta reduction)
We don't need to know anything about the semantics, etc. of any other
actions the monad might happen to define.
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