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

[Ivan Lazar Miljenovic]

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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>> >
>>
>>
>> --
>> 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