MonadFail instance for Either

[Dannyu NDos]

What about?:

instance Read e => MonadFail (Either e) where
    fail = Left . read

2018년 10월 25일 (목) 오후 12:42, David Feuer <david.feuer at gmail.com>님이 작성:

> FWIW, I think I'm weakly opposed. Either is Haskell 98. MonadFail is
> solidly "standards-track" material, to the extent that designation is
> meaningful
> at the moment. IsString ... isn't.
> On Wed, Oct 24, 2018 at 10:44 PM Daniel Bergey <bergey at alum.mit.edu>
> wrote:
> >
> > Is there still consensus in favor of adding this instance?
> >
> >  instance IsString str => MonadFail (Either str) where
> >     fail = Left . fromString
> >
> > In 2016 there was some discussion, and my reading is that there was
> consensus in favor at the time:
> > Trac: https://ghc.haskell.org/trac/ghc/ticket/12160
> > libaries mailing list:
> https://mail.haskell.org/pipermail/libraries/2016-August/027248.html
> >
> > Does anyone know of a later decision not to add it, or was it simply no
> one's top priority?
> >
> > What is the next step to move this proposal forward?  Is more discussion
> in order?  Should I just submit a patch?
> >
> > Thanks,
> > bergey
> > _______________________________________________
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