[Haskell-cafe] instance Alternative (Either [a])

[Ross Paterson]

On Thu, May 22, 2014 at 05:10:24PM +1000, Tony Morris wrote:
> AccValidation has an Applicative instance that accumulates on "Left" (Failure)
> as per the previous email. Therefore, it has no Monad.

This applicative is called Errors in the transformers package
(in Control.Applicative.Lift, of which it's a special case).