Sebastian Sylvan wrote:
Not quite the same complaint, but I've always been bothered by the inconsistent use of "=>". I would prefer "A => B" to mean "if A, then B". Accordingly:
class Monad m <= MonadPlus m
By your definition, couldn't what we have now (class Monad m => MonadPlus m) be read as "If m is in the Monad class, then the class MonadPlus can be defined for m thusly:...", which seems pretty clear to me.
Not to me. It's like saying "If f is a piece of furniture, then the set of chairs can be defined for f thusly", which seems equally unclear to me. If m is in the Monad class... then what? It's not necessarily in the MonadPlus class. No useful inference can be drawn this way. What we mean to say instead is "if m is in the MonadPlus class, then it is in the Monad class". -- Ashley Yakeley