On Tue, Dec 13, 2011 at 10:23 PM, Gregory Crosswhite
This way users of the classes will know whether their type has well-defined instance for some and many or not.
But that's *precisely* what the Alternative class is already for! If you are writing an Alternative instance *at all*, then you are asserting that it *must* be possible and reasonable to replicate the existing behaviour of some and many. The fact that those functions are currently methods of the class is completely irrelevant, and perhaps this is a source of your confusion. They can be - *and used to be* - implemented as normal functions with Alternative class constraints, then at some point someone moved them into the class itself, solely to allow implementors to write faster versions. I think we should take any further discussion off-list. Your messages from last night betray a deep misunderstanding that I'm not sure everyone else needs to sit through :-)