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

[Jorge Adriano Aires]

(Sorry about the recurrent self answers)

> Maybe (not sure) it is sensible to
> sapecify return::(a -> IO a), as an action with no side effects such that

> return x === return x  iff  x === x. 
return x === return y iff x === y    <-- this is what I meant to write.

But even that is not enough, should be:
"return x is an action with no side effects and that always returns x" 

The previous specification is be a consequence of this one, and it failed to 
specify that the returned value was always x.

J.A.