fact: Definition EitherT_map {E M} `{Functor M} {X Y} (f : X -> Y) (x : EitherT E M X) : EitherT E M Y := (fmap[M] (fmap[Either E] f)) x.
imports: Hask.Prelude Hask.Control.Monad Hask.Control.Monad.Trans.Class Hask.Control.Monad.Morph