fmap = (_t1::Functor f => (a -> b) -> f a -> f b)
fmap = (_t2::forall (f :: * -> *) a b.
             Functor f =>
             (a -> b) -> f a -> f b)
<*> = (_t3::forall (f :: * -> *) a b.
            Applicative f =>
            f (a -> b) -> f a -> f b)
<*> = (_t4::Applicative f => f (a -> b) -> f a -> f b)