Proposal: merge either into transformers

[Ross Paterson]

On Mon, Dec 10, 2012 at 04:17:23PM +0000, Mario Blažević wrote:
> On 12-12-07 04:44 AM, Roman Cheplyaka wrote:
> > I propose to add the sole module of the 'either' package[1],
> > Control.Monad.Trans.Either, to the transformers package.
> 
> +1. Then I can drop the EitherFunctor type from the monad-coroutine package.

That's not the same thing:

newtype EitherT e m a = EitherT { runEitherT :: m (Either e a) }

data EitherFunctor l r x = LeftF (l x) | RightF (r x)