Rise and fall of JVM languages

If the language designers keep their heads, Kotlin will slowly eat away at Java. Java itself is never going away: it's a Fortran or Cobol situation, only maybe three or four orders of magnitudes bigger.

Xtend never was alive, and it's clear Ceylon has lost at this point, even though it is arguably better designed than Kotlin. However, they made some bad syntactic decisions (not shedding enough of the Java verbosity, introducing new weird keywords), and when you're doing run the mill Java-like programming, it's just more gratifying to write/read Kotlin code.

Scala's development is somewhat unpredictable, but I think it's fair to say it's lineage is not going away either. New compilers are being developed by the original team (Dotty) and by Twitter (reasonable scala) with very different objectives. Currently, there simply aren't any many contenders in Scala's niche (very powerful statically typed programming languages with a pragmatic bend, i.e. not Haskell). C++ could fit the bill but pushes memory management and Cthulhu on you. The ML family could also fit the bill, but lacks momentum/hype. However Facebook is spearheading a revival with Reason ML. Scala's big trump card is the Java library ecosystem.

Scala is much more complex language. Kotlin is more complex, than Java, but its complexity is just enough to cover major Java pain points.

Scala brings its own huge library with features that I don't need. Billions of abstract collections, but all I need is HashMap and ArrayList. They generalize over builders, so `filter` can return some fancy underlying class, but all I need for filter is to return ArrayList or lazy sequence. Kotlin again hits sweet point: all it does is extending standard Java library with few utility methods and it adds lazy sequence type (interface with one method).

Due to Scala huge library it's hard to use on Android with its artificial 65k method restriction. Kotlin doesn't have this problem.

Last time I checked, Intelij Idea wasn't able to parse even standard Scala library without errors. May be it's better now, but my experience is that Kotlin beta plugin was better than Scala plugin. Doesn't relate to language directly, but complexity of the language is definitely influences tooling: simplest language Go has awesome tooling.

Compilation time was never an issue for me, but I guess for some projects it matters.

I don't care about corporate support, but I do care about dogfunding. I didn't see Hibernate being rewritten with Ceylon. But Jetbrains use their own language for their tasks, that means that they are unlikely to abandon it. Google support probably matters a lot for Android developers as well.

That said, Scala is mature language and I don't see it going anywhere soon. It has very rich set of features, it allows much better abstractions than Kotlin, it has huge projects, a lot of developers work as Scala developers. But Kotlin definitely has a momentum.

Not using scala or Kotlin. But if others think like me, I bet the scala syntax is stopping them from touching it with a stick.

Java was cool when I started using it "in anger" in 1995. It was going to be a totally new way of delivering software on the fly over the network (that's why all the package names look like reverse domain names). I moved to Python when Java gave up on the dream and became the new COBOL after the dotcom crash.

Kotlin can never replace Java as long as the JVM is relevant.

This is like trying to replace C on UNIX, C# on .NET, Erlang on BEAM, or JavaScript on the browser.