> Well, I've been trying for about three years, but to be fair I'm a pretty slow programmer so you may have better luck.

Well, your own link proves it, doesn't it? Kotlin has nominal subtyping, contravariance, and generics, therefore its type system is undecidable.

> I think it needs to be a generic type in Kotlin for this to work, because otherwise it will dispatch to a single method.

That's the whole point - the type system has to decide which overload to dispatch it to at compile time, which it can only do by performing an arbitrarily complex computation. I ported that code directly to Kotlin and it doesn't compile but it "should", which, well, I don't know what you were expecting or what you'd accept as proof when we've already got an academic paper that proves the point.