SE-0494: Add `isIdentical(to:)` Methods for Quick Comparisons to Concrete Types

[ksluder (Kyle Sluder)]

@xwu

I think @John_McCall is right that it wouldn't be in the spirit of the proposed API here.

The proposal author seems to disagree:

@vanvoorden

I would reference back to this earlier example:

@ksluder

The whole point of this tangent was to illustrate a plausible implementation of isIdentical(to:) for which it would not be accurate to say that the two SubSets have the same representation, because one could use positive indexing while the other uses negative indexing.

@xwu

In any case we are reviewing the APIs proposed for the specific concrete types here.

In evaluating whether “representation” is a good term for what this operation compares, my example is still relevant, as it explicitly intends for two instances with completely different values (and therefore different representations in memory) to compare “identically.”