Ashley Yakeley wrote:
For example:
class Functor f => Applicative f where return :: a -> f a ap :: f (a -> b) -> f a -> f b (>>) :: f a -> f b -> f b (>>) = liftA2 (const id)
for backwards compatibility of everyone who *uses* Applicative, (and arguably it is a less ugly notation,) : (<*>) = ap (and pure = return) I'm not sure, is the word "ap" even as well known as "<*>" right now? I wonder which one we'd prefer to use in Applicative?
class Applicative m => Monad m where (>>=) :: m a -> (a -> m b) -> m b fail :: String -> m a fail s = error s
I want to add to this Applicative=>Monad class: join :: m (m a) -> m a join mm = mm >>= id m >>= f = join (fmap f m) What do others think about that? (P.S. And I guess this hierarchy change is quite independent of the difficult task of removing "fail" from Monad, so I won't discuss that here/now) -Isaac