If you're talking about sets, then yes. Doing that on lists would be awful. Lists don't have the same guarantees as sets, so the operator would have plenty of b

If you're talking about sets, then yes. Doing that on lists would be awful. Lists don't have the same guarantees as sets, so the operator would have plenty of behavioral ambiguity. You'd have to learn the convention of the operator for edge cases where the operation is not well defined.