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

[amindfv at gmail.com]

+1 to the function, +1 to 'restrictKeys' or 'intersectKeys'

Tom


> El 14 jul 2016, a las 11:01, Iavor Diatchki <iavor.diatchki at gmail.com> escribió:
> 
> I've also needed this in the past, so +1.
> 
> I think the bike-shed should be colored:  intersectKeys or restrictKeys
> 
> -Iavor
> 
>> On Thu, Jul 14, 2016 at 6:39 AM, Edward Kmett <ekmett at gmail.com> wrote:
>> +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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>>> >> >
>>> >>
>>> >>
>>> >> --
>>> >> 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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>> 
>> 
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