I think Clojure would probably make for a more interesting comparison because its syntax is more different from the other languages currently on there and it's less multi-paradigm than Scala is (it doesn't support OOP, it's more explicitly immutable-first). I think Scala is a lovely and cool language, but I'd be more interested in the Clojure comparison here.

Prolog night be interesting because I bet nobody is trying to train very hard on it, but I'm less directly interested in model performance with Prolog.