[haimez]

Excellent summary. A lot of the API's are definitely built scala-first, then adapted for Java. Usually this isn't too bad, but it can cause some headaches around things like the logger interfaces, etc.

We run a fairly complex java system in the same process as play (similar to an in-process database) for performance reasons, so given the amount of code already in java and not having the time to learn scala, java interop, AND build in the web bindings, we went the Java route.

It's definitely easier to use than something like Spring if you're approaching both for the first time.

[erwanl]

It's not that it's "Scala adapted to Java", but more like a choice to do async and functional programming even in Java. That makes stuff a bit verbose sometimes because to pass a function you have to pass an anonymous class.

That will become better with Java 8 and lambdas without having to break compatibility with older Java versions (they will still use anonymous classes).