You won't be able to implement type classes. There might be something in that direction after 1.0; still, Kotlin is not supposed to be a contender with Scala w.

You won't be able to implement type classes. There might be something in that direction after 1.0; still, Kotlin is not supposed to be a contender with Scala w.r.t. expressive power. It is just Java with more concise syntax, and with most design patterns turned into language features: singleton, delegates, lambdas/sam, "utils" classes (extension methods).