[Haskell-cafe] Where is "minimumsBy"?

[Brandon Allbery]

Not exactly that, but you can use groupBy fst . sort, then the head of the
result list is your "minimumsBy" result.

On Wed, Sep 26, 2018 at 6:28 AM Tom Ellis <
tom-lists-haskell-cafe-2017 at jaguarpaw.co.uk> wrote:

> Data.List.minimumBy :: Foldable t => (a -> a -> Ordering) -> t a -> a
>
>
> https://www.stackage.org/haddock/lts-12.1/base-4.11.1.0/Data-List.html#v:minimumBy
>
> but there are many cases where that's quite unhelpful.  Actually what we
> want is more like
>
>     minimumsBy :: ... => (a -> a -> Ordering) -> t a -> [a]
>
> There can be many distinct minimizers.  For example when I want to get the
> collection of the youngest people from [(Age, Person)] I want
>
>     minimumsBy (compare `on` fst) [(12, alice), (15, balaji), (12, cho)]
>
> to return
>
>     [(12, alice), (12, cho)]
>
> Does "minimumsBy" exist somewhere reasonably standard?  Hoogle doesn't
> throw
> up anything obvious
>
>
> https://www.stackage.org/lts-12.1/hoogle?q=%28a+-%3E+a+-%3E+Ordering%29+-%3E+t+a+-%3E+%5Ba%5D
>
> Thanks,
>
> Tom
> _______________________________________________
> Haskell-Cafe mailing list
> To (un)subscribe, modify options or view archives go to:
> http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
> Only members subscribed via the mailman list are allowed to post.



-- 
brandon s allbery kf8nh
allbery.b at gmail.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/haskell-cafe/attachments/20180926/ac80bd28/attachment.html>