Proposal: add fromRight and fromLeft to Data.Either

lennart spitzner lsp at
Mon May 30 07:29:01 UTC 2016

On 30/05/16 03:40, Edward Kmett wrote:
> The main annoyance with the total versions is that the existing fromJust
> has the wrong convention.
> Oh well. Consistency is overrated.

So you don't mind the breaking change in the `either` package?

For the lazy; `either` defines:

> Data.Either.Combinators.fromLeft  :: a -> Either a b -> a 
> Data.Either.Combinators.fromLeft' :: Either a b -> a
(~Right similarly)

Also, packages `MissingH` and `extra` define the consistent

> fromLeft :: Either a b -> a

(don't know if user numbers of those count as significant in any way.)

-1 on both partial and inconsistent total

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