Proposal: add fromRight and fromLeft to Data.Either

Edward Kmett ekmett at
Sat May 21 12:55:09 UTC 2016

I'm personally -1 on this.

A large portion of the community is vehemently against adding new partial
functions, and they have to share base with the rest of us. I'd say more
people want to remove fromMaybe, head, tail, etc. than want to double down
on the pattern at this time.


On Fri, May 20, 2016 at 4:08 PM, Anton Felix Lorenzen <anfelor at>

> When working with Either,
> I am often missing two simple functions:
> fromRight :: Either a b -> b
> fromLeft  :: Either a b -> a
> It has been implemented a couple of times:
> But I don't want to depend on yet another library
> for such a basic function.
> Could it be added?
> Anton
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