Does Scala see much use out of the big data niche nowadays? I've considered picking it up, but I'm always discouraged by someone telling me to use Kotlin instead, or stories of companies abandoning Scala for reasons like complexity and on-boarding.

Honestly I thought this about Java because people told me they thought this about Java, but once you try work with a language lacking libraries you need it’s a lot more appealing! Also I found things like Akka and JML make it even fun to write.

Do you have significant experience with Java?

Because I shared your views until I started working with it at a good team :-)

As I continued writing botj Java as well as other projects on other stacks Java became less and less annoying until today it is one of my two favorites.

Scala's type system is more expressive than Haskell's? I didn't know that. What makes it more expressive?