Re: proposal #4095: add Applicative instance for Either

Ashley Yakeley writes:

I currently have my own implementations for these:

instance Foldable Identity instance Traversable Identity instance Applicative Identity

The transformers package has such instances (but currently for a different Identity type).

instance Foldable (Either p) instance Traversable (Either p) instance Applicative (Either p)

instance Foldable ((,) p) instance Traversable ((,) p)

The Applicative one is proposed here. The others should also be added.