Proposal to solve the `EitherT` problem.

David Luposchainsky dluposchainsky at
Tue Aug 13 10:36:16 CEST 2013


Another discussion that didn't reach conclusion: "Proposal to solve the
`EitherT` problem." Let's do some proposal cleanup :-)

On 2013-06-16 23:52, Gabriel Gonzalez wrote:

> Approach 2: Add `EitherT` to `transformers` alongside `ErrorT` and
have them both implement `MonadError`.

That's the one I would recommend.

- Doesn't break anything, and gets rid of the "exception-vs-error"

- Not all uses of Either are to distinguish between success and failure,
sometimes it's just a convenient way of short-circuiting.

- Fits in well with all the other transformers of type "MonadT".

- MonadError instance makes possible use as throw-catch-y transformer clear.


More information about the Libraries mailing list