[Haskell-cafe] Splitting off many/some from Alternative

[Ross Paterson]

The current definition says that some and many should be the least
solutions of the equations

    some v = (:) <$> v <*> many v
    many v = some v <|> pure []

We could relax that to just requiring that they satisfy these equations
(which I think is what John wants).  In that case there would be another
possible definition for Maybe:

    some Nothing = Nothing
    some (Just x) = Just (repeat x)

    many Nothing = Just []
    many (Just x) = Just (repeat x)