Should we have both operators and named functions/methods for set operations?

[bmcdonald3]

Python has all of the Chapel operators and additionally an equivalent named method as well, but Chapel today only supports the operators. The named methods could be more attractive/understandable to some users and also potentially be a gain when FCFs are more fully featured.

Set operators

Chapel	Python Operator	Python method
|	|	union()
+,add()	--	add()
&	&	intersection()
-	-	difference()
^	^	symmetric_difference()
<=	<=	issubset()
<	<	--
>=	>=	issuperset()
>	>	--

Before implementing this, the decision of whether or not to have these be functions (intersection(a,b)) or methods (a.intersection(b)). The challenge with having them be methods is deciding if we want the method to update the calling set or return a new set, where the answer with functions is more clear, that a new set wold be returned. (Python methods return a new set FWIW).

[bradcray]

Good summary of the issue! Adding a quick note that this is a non-breaking change, so could be done after Chapel 2.0 if need be.