[allertonm]

It's not true of Java - the bytecode generated by javac is very robust in the face of new JVM versions. This is one of the reasons that Java has had to move so slowly in terms of language features.

Neither Scala or Clojure's compilers generate byte code that is expected to work with that from another version of the respective compiler or with a different version of the language runtime.

In the case of Clojure this is mitigated by the fact that (since it is a dynamic language) that applications and libraries are generally delivered in source form and "ahead of time" compilation is seen as an optimization rather than a code delivery mechanism.