Add intersections and unions to Set

Tab Atkins Jr. jackalmage at gmail.com
Mon Mar 4 10:56:48 PST 2013


On Mon, Mar 4, 2013 at 10:08 AM,  <aleth at instantbird.org> wrote:
> It would be useful to be able to form the intersection and the union of
> two Sets. These are natural operations that are currently not part of
> the API
> (http://wiki.ecmascript.org/doku.php?id=harmony:simple_maps_and_sets).
>
> Similar methods would make sense for Map, but one would have to think
> about what to do in the case where the key but not the value matches.
>
> An intersection is equivalent to a particular filter, so an alternative
> might be to add a method like Array.filter to Sets instead.
>
> (I filed bug 847355 for this and was told this mailing list was the
> right place for this suggestion.)

Yes please, and also minus (remove from set A all elements it shares
with set B).  All three of these are fairly vital for a lot of code
using sets.

~TJ


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