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Comment by wiradikusuma | Hacker News Reader

too bad they require JDK8 while App Engine supports only JDK7 :(

True Scala 2.12 generates byte code that requires a Java 8 VM. Scala 2.11 will be supported for a while longer, with as many as the 2.12 features implemented there first (those that don't require Java 8).

Java 8 was released almost 2.5 years ago. How long should they have to wait before they can use it? Java 9 was originally suppose to be released about now.

What does this mean?

They probably require JDK8 for compiling/building the class files, but can you target 1.7?

See target flag for javac ( http://stackoverflow.com/a/21206909 )

AFAIK no, 2.12 does a lot to be compatible with equivalent native features of JVM 8. The way to target JVM 7 bytecode is to stick with Scala 2.11.

You can only make use of the target flag when not making use of new bytecodes oder APIs introduced in a specific Java version.

Scala 2.12 is replacing some of their own code with Java 8 new features, so they rely on a Java 8 compatible JVM.

This will also prevent Scala 2.12 to target Android, because even Android N isn't 100% Java 8 compatible, specially the low level JVM features like invokedynamic and method handles are not supported on DEX format.

Try https://kotlinlang.org/.

It works with JDK 6+.

Scala 2.11 also supports 6

doesn't the Flexible Environment fit for you? https://cloud.google.com/appengine/docs

i haven't explored it, but from cursory look it's more "work" (and more expensive) than the one that comes out-of-the-box

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