I'm going to dodge the breaking changes discussion, since it's a huge tangent, suffice to say that I greatly dislike _breaking_ changes and want languages that make it possible to avoid them or at least provide a migration path via incremental deprecation prior to removal. Go fails here in many ways. All I meant to do was point out that exhaustiveness checks are not without their tradeoffs.

> I was visualising something like

OK then. We're in agreement on that point. This is what Clojure has in it's destructuring syntax, and, as I said, it's great.