We don't strictly *need* to add either of these functions. Users can use munzip from the MonadZip instance, and we can add a rewrite rule to turn

    munzip (fmap f xs)

into

    Data.Sequence.Internal.unzipWith f xs

On the other hand, MonadZip isn't a terribly well-known class, and unzipWith has always struck me as an obvious analogue of zipWith.

On Jan 11, 2018 10:32 PM, "Ivan Lazar Miljenovic" <ivan.miljenovic@gmail.com> wrote:

On 12 January 2018 at 13:28, David Feuer <david.feuer@gmail.com> wrote:
> Paolo G. Giarrusso (Blaisorblade) would like to add an unzip function to
> Data.Sequence. I agree. I propose adding
>
>   unzip :: Seq (a,b) -> (Seq a, Seq b)
>
>   unzipWith :: (x -> (a, b)) -> Seq x -> (Seq a, Seq b)
>
> Does anyone object?

I see no problem with this.  Though I think it's worth pointing out
that Data.List doesn't have unzipWith (though unzipWith f = unzip .
map f).

--
Ivan Lazar Miljenovic
Ivan.Miljenovic@gmail.com
http://IvanMiljenovic.wordpress.com

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