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

[Andreas Abel]

Seems like the partition function would subsume the others?!

   partitionByKeys :: Ord k => Set k -> Map k a -> (Map k a, Map k a)

Would there be impressive speed gains for a native

   fst . partitionByKeys set

?

On 25.07.2016 20:59, David Feuer wrote:
> A final question:
>
> Both `restrictKeys` and `withoutKeys` are special cases of
> `filterWithKey` (although they should be considerably more efficient
> than implementations using that function). Do we also want a
> `partition` special case, in which a map is partitioned into the keys
> that are in a set and the ones that are not?
>
> On Mon, Jul 25, 2016 at 1:10 PM, Edward Kmett <ekmett at gmail.com> wrote:
>> Good enough for me.
>>
>> On Mon, Jul 25, 2016 at 12:11 PM, David Feuer <david.feuer at gmail.com> wrote:
>>>
>>> I got distracted from this discussion for a bit. Based on input from
>>> the list, and Ross Paterson's remark about argument order, I'm
>>> currently thinking
>>>
>>> restrictKeys :: Ord k => Map k a -> Set k -> Map k a
>>>
>>> and
>>>
>>> withoutKeys :: Ord k => Map k a -> Set k -> Map k a
>>>
>>> Are there any major objections?
>>>
>>> On Thu, Jul 14, 2016 at 12:54 PM, Alexey Vagarenko <vagarenko at gmail.com>
>>> wrote:
>>>> How about `keepKeys`?
>>>>
>>>> 2016-07-14 21:36 GMT+05:00 Daniel Trstenjak
>>>> <daniel.trstenjak at gmail.com>:
>>>>>
>>>>> On Thu, Jul 14, 2016 at 12:02:51PM -0400, David Feuer wrote:
>>>>>> If you name it, it will come!
>>>>>
>>>>> intersectKeys and differentiateKeys
>>>>>
>>>>> or
>>>>>
>>>>> intersectionWithSet and differenceWithSet
>>>>>
>>>>> or ;)
>>>>>
>>>>> intersectionOfKeys and differenceOfKeys
>>>>>
>>>>>
>>>>> Greetings,
>>>>> Daniel
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>>>>
>>>>
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>>
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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/