[istvan__]

Right. Let me take this from a different angle. I like to hear about projects moving away from technology much more than jumping onto a band wagon. Right now, Scala feels to me as a band wagon. Some of the guys who moved to use Scala from Java just simply moved back because they realized that almost all of the features are available (emphasis on almost) in Java (especially in Java 8). On the other hand, learning Scala takes time so for a while you are writing inefficient code. On the top of that you need to make sure everybody is on the same page in your team, that is also additional effort. All of these were driving projects (like Kafka) away from Scala (look at the new producer code).

To summarize: Scala to me is just a better Java with too many trade offs.

[lmm]

To my mind the bandwagon has been and gone, with those companies moving away from Scala being those who arrived on the bandwagon and departed with it. But I guess it looks different from the inside.

If you're treating Scala as "just a better Java" then you're not writing inefficient code; you're writing code that could be better Scala code but is still better than the Java you would otherwise have written. Even if you never move beyond the "Java without semicolons" stage, hey, it saved you writing all those semicolons.

But Scala absolutely is a full language and not just a better Java; Java 8 barely scratches the surface of what you can do in Scala. I don't think I could bear to work in a language without higher-kinded types again.

Kafka has some very particular constraints that I don't think apply in general; remember they're making a framework rather than an application.

[justthistime_]

That's interesting, because weren't Kotlin and Ceylon created because people wanted to have "just a better Java", which Scala is not really interested in being?

> they realized that almost all of the features are available

Interesting too. Looking at the stuff I'm currently doing, there is plenty of stuff which is just impossible in Java.

By the way, isn't "Scala has such a nice type system that it blows out OCaml from the water" already the case?

[lmm]

> weren't Kotlin and Ceylon created because people wanted to have "just a better Java", which Scala is not really interested in being?

Scala was that at first. Arguably that's still Typesafe's primary interest.

> By the way, isn't "Scala has such a nice type system that it blows out OCaml from the water" already the case?

Yes and no. It's more featureful (higher-kinded types are really nice), but less elegant and type inference works less well (in part because scala has both inheritance and typeclasses).