Proposal: Add `restriction` to Data.Map and Data.IntMap

[Edward Kmett]

+1 on the functionality, not a fan of the name.

Bikeshed color: intersectionWithSet?

-Edward

On Thu, Jul 14, 2016 at 9:36 AM, Ivan Lazar Miljenovic <
ivan.miljenovic at gmail.com> wrote:

> On 14 July 2016 at 22:45, Jake McArthur <jake.mcarthur at gmail.com> wrote:
> > I like the function, but I'd like to bikeshed a bit. The name
> "restriction"
> > seems confusing to me, or at least I don't understand the etymology. As
> of
> > now I'd prefer something like "filterMember". filterMember is to (filter
> .
> > flip member) as concatMap is to (concat . map). That's not perfectly
> > consistent due to the flip, but I think it's close enough to motivate the
> > name.
>
> More possible bikeshed colours:
>
> * intersectionWith/setIntersection to reflect the similarity with the
> existing intersection functions
>
> * restrictTo (which may fit better with the proposed argument order
> than the ones above)
>
> If we keep this argument order, then I think a name similar to
> restriction as originally proposed makes more sense than an
> intersection one (as the arguments are flipped compared to the other
> similarly named functions).
>
> >
> >
> > On Thu, Jul 14, 2016, 5:39 AM Andreas Abel <abela at chalmers.se> wrote:
> >>
> >> +1.
> >>
> >> On 14.07.2016 06:45, David Feuer wrote:
> >> > Cale Gibbard proposes the following:
> >> >
> >> > Data.IntMap.restriction :: IntSet -> IntMap a -> IntMap a
> >> > Data.Map.restriction :: Ord k => Set k -> Map k a -> Map k a
> >> >
> >> > In each case, the map is filtered to contain only the keys that are
> >> > also found in the set. This can be implemented efficiently using a
> >> > slightly stripped-down version of Data.Map.intersection.
> >> >
> >> > David Feuer
> >> > _______________________________________________
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> >> > Libraries at haskell.org
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> >> >
> >>
> >>
> >> --
> >> Andreas Abel  <><      Du bist der geliebte Mensch.
> >>
> >> Department of Computer Science and Engineering
> >> Chalmers and Gothenburg University, Sweden
> >>
> >> andreas.abel at gu.se
> >> http://www2.tcs.ifi.lmu.de/~abel/
> >> _______________________________________________
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> >
> >
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> >
>
>
>
> --
> Ivan Lazar Miljenovic
> Ivan.Miljenovic at gmail.com
> http://IvanMiljenovic.wordpress.com
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