RE: Proposal: Add Applicative instances for the remaining monads in base

Bas van Dijk writes:

instance ArrowApply a => Applicative (ArrowMonad a) where pure = return (<*>) = ap

You don't actually need ArrowApply there: instance Arrow a => Applicative (ArrowMonad a) where pure x = ArrowMonad (arr (const x)) ArrowMonad f <*> ArrowMonad x = ArrowMonad (f &&& x >>> arr (uncurry id)) Of course for this and the Functor instance ArrowMonad is a poor name.