[jorgemf]

> Kotlin is a smart subset of Scala

Yes, it is only the subset you need, nothing else. That is why is here to stay and Scala not.

Making the things more complex doesn't mean making them better. Do one thing, and do it right. Don't do a lot of things half good.

[pkolaczk]

Scala does all the features of Kotlin equally well, not half good.

Actually Kotlin inherited a few bad ideas from Scala as well - which Scala already dropped like procedure syntax.

And some features like null handling or coroutines in Kotlin are implemented as language features - special cases in the compiler, because the core of the language lacks abstraction mechanisms. This is making the language more complex than Scala.

Scala: minimal and powerful language core, the rest is in libraries.

Dotty: make this core even smaller

Kotlin: take a powerful language like Scala, remove almost all of the unnique abstraction features, leave only "better Java syntax" and then reimplement missing features by special cases directly in the language instead of libraries. Feels like VB of XXI century.

[jorgemf]

I have written Scala code and kotlin code, and it is much more legible the kotlin code. When I tried also there were problems calling Scala code from Java (I think there were problems with the type inference system that was giving me non-sense errors). Scala adds like 500kb to an Android app, kotlin only few kb. The compilation times are much faster with kotlin, the tooling support is also better. It is easier to become more productive with kotlin than with Scala.

> Scala already dropped like procedure syntax

Do you mean this?: https://groups.google.com/forum/#!topic/scala-internals/q1YX...

Kotlin does not do that.

> some features like null handling or coroutines in Kotlin are implemented as language features

null handling yes, and it is very well done. Coroutines so so, they added a couple of keywords to the language and most of the implementation is in the library. You can create your own coroutines: https://kotlinlang.org/docs/reference/coroutines.html

Go do coroutines quite good and they have also implemented in the language, why is it bad they use a couple of keywords for those special cases?

[pkolaczk]

> Scala adds like 500kb to an Android app

This is a lie. Please stop spreading these lies about Scala requiring a huge runtime. Scala runtime adds about 30 kB, which is nothing in 2017.

> the tooling support is also better.

Both use the same IDE from Jetbrains and both are officially supported. Hard to tell which one is really better, but Kotlin support has more issues in its bug tracker, despite being less popular :P

> (nulls) it is very well done.

It is not. It makes the type system more complex, and you can't abstract over optionals and other collection types. You also can't make your own flavor of optional-kinds, like Either or Try that would behave similar to the builtin nullability feature.

The biggest problem with builtin features is that you can't make your own slightly different ones. You're at mercy of one company controlling the language. With a smaller language + libraries, you can always fork a library and do modifications.