14 Sep
2008
14 Sep
'08
2:01 p.m.
Johannes Waldmann wrote:
I think the crux of the matter was that a monad is too general. Either there is a result or there is not. That's precisely the intended use of a Maybe.
Indeed "Monad m =>" is dangerous here because not every Monad has a reasonable definition of "fail".
But that seems to be a problem in the (current) definition of "Monad", and its solution was "MonadZero", no?
I agree that the MonadZero class with a useful 'zero' :: m a would be the right abstraction for views. But MonadZero is not part of base, mtl or any other common package, or am I missing something? Changing this is beyond a simple heap package ;) -- Früher hieß es ja: Ich denke, also bin ich. Heute weiß man: Es geht auch so. - Dieter Nuhr