Proposal: merge either into transformers

David Feuer david.feuer at
Mon Jan 2 07:39:57 UTC 2017

On Mon, Jan 2, 2017 at 2:14 AM, Erik de Castro Lopo
<mle+hs at> wrote:
> Combinators in C.M.T.Either but not in C.M.T.Except:
>    bimapEitherT :: Functor m => (e -> f) -> (a -> b) -> EitherT e m a -> EitherT f m b

It's not a very pretty substitute, but note that

bimapEitherT f g = mapExceptT (fmap (bimap f g))

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