Re: Proposal: merge either into transformers

A couple of these are in transformers already.

Combinators which I am used to using at work include:

firstEitherT :: Functor m => (x -> y) -> EitherT x m a -> EitherT y m a

https://hackage.haskell.org/package/transformers-0.5.2.0/docs/Control-Monad-...

secondEitherT :: Functor m => (a -> b) -> EitherT e m a -> EitherT e m b

This is just fmap -- Chris Wong (https://lambda.xyz) "I had not the vaguest idea what this meant and when I could not remember the words, my tutor threw the book at my head, which did not stimulate my intellect in any way." -- Bertrand Russell