I don't know. The experiments in the post only shows a limit set of examples. My hunch is that if you are using a modern compiler/IDE, you will not be coding -

I don't know. The experiments in the post only shows a limit set of examples. My hunch is that if you are using a modern compiler/IDE, you will not be coding -> compiling -> running that frequently. I typically code a lot before I actually actually run anything, so I'm not usually waiting around on a compiler. I don't even notice, at all, Java's incremental compilation when coding in IntelliJ. I refactor like a madman. Also, Kotlin is not very ambiguous, and the type inference that it does enable does not escape the scope of a function so the compiler doesn't have to do that much work. (functions require strict typing). I would guess much of that lambda work gives it a small headache, but probably not that much worse than Java's. If Kotlin grows mainstream, it's already pretty good compiler, will only get better. Of course, that is all a hunch. :)