It’s important to understand that there is 2 tool introduced:
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Jack: A new compiler to replace the complicated javac + proguard + dx
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Jill: A library linker that will be able to link currently compiled libraries (.class) and more.
See http://tools.android.com/tech-docs/jackandjill
So it sounds like there is 2 separate problem here:
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Scala compatibility:
Scala will not be supported by Jack, as Jack compiles Java source code.
However Scala 2.11 compiles to Java 1.6 bytecode and therefore Jill will be able to pick that code and convert to jack files to feed the Jack compiler.
See Android N Java 8 features (Jack compiler) and Kotlin interop (Kotlin as the same issue as Scala as it’s a JVM language) -
Java 8, and therefore Scala 2.12+, compatibility:
This part is under development, if Jack/Jill supports Java 8, then it will also support Scala 2.12+ (through Jill). If not, Java 8 developers are in the same boat as Scala 2.12 developers.
In the case Jack supports Java 8 but not Jill, then Java 8 libraries developers will be in the same boat as Scala 2.12 developers.
See https://www.guardsquare.com/blog/DroidconLondon2015