> If you're okay with using old Java versions, it's not much of a stretch to say you'll be okay with old Scala versions.

No, because Scala doesn't offer forward binary or source compatibility. Maintainers of widely-used Java libraries can write and build for Java 6 and be confident their libraries will be usable by everyone (on Android and off). Maintainers of widely-used Scala libraries have no such option (for now they can write their code using the subset that works in Scala 2.11 and 2.12 and cross-build, but there's no guarantee that such a subset will be maintained in 2.13 and beyond).

> there's no guarantee that such a subset will be maintained

There's no guarantee about Java either. This class compiles with Java 7, but not with Java 8:

    class SampleClass {
        static class Baz<T> {
            public static java.util.List<Baz<Object>> sampleMethod(Baz<Object> param) {
                return null;
            }
        }
 
        private static void bar(Baz arg) {
            Baz element = Baz.sampleMethod(arg).get(0);
        }
    }

Like Java or any other good software, Scala will try to maintain backwards compatibility (particularly source compatibility).

> There's no guarantee about Java either. This class compiles with Java 7, but not with Java 8:

Ok, but you can compile it with the newer compiler by passing -source 1.7, right? And you can call into it from 1.8 code?

Yes, binary compatibility is maintained in this case.

Yep, 2.11.9 is the last planned release, but we would release another one for security fixes or anything as severe. If we get customer requests for backports, we (usually) also release those publicly.

Thanks for your support!