[int_19h]

That is precisely a key comparison issue. That is why I spoke about a tuple of two values; tuples by definition don't have a meaningful identity, so reference comparison is utterly meaningless for them.

Stringification is a very crude hack, and it doesn't even work in all cases - e.g. not if a part of your key still needs to be compared by reference. Say, it's a tuple of two object references, describing the association between those two objects.

Either way, the point is that this is really basic stuff that has been around in mainstream PLs for literally many decades now (you could do this in Smalltalk in 1980!).