On 2010-05-25 05:41, Ross Paterson wrote:
The proposal is to add this instance to Control.Applicative:
instance Applicative (Either e) where pure = Right Left e<*> _ = Left e Right f<*> r = fmap f r
This is not the only possible instance for Either, but this one is compatible with the usual Monad instance.
Deadline: 15th June 2010
I currently have my own implementations for these: instance Foldable Identity instance Traversable Identity instance Applicative Identity instance Foldable (Either p) instance Traversable (Either p) instance Applicative (Either p) instance Foldable ((,) p) instance Traversable ((,) p) Do any of these others already exist? -- Ashley Yakeley