By way of analogy I'll compare languages to languages, specifically spoken and programming. Going from Java to Kotlin is like going from French to Spanish. Goin

By way of analogy I'll compare languages to languages, specifically spoken and programming. Going from Java to Kotlin is like going from French to Spanish. Going from Java to Scala, is like going from French to Klingon. More concretely, Scala actually had very little in common with Java. Yes it ran on the JVM, but that was where the similarities stopped, its functional layer and type system were effectively incompatible with Java or the Java standard library. Actually Scala was so badly made, its functional pieces weren't even really compatible with its own OO pieces, if you tried to mix and match the two it caused all kinds of problems. Kotlin in contrast is almost entirely compatible with Java. There are a couple rough spots, mostly around when frameworks depend very heavily on reflection and bytecode manipulation (particularly around annotations), but those can be worked around from both sides without too much trouble, and the rest of the time it's pretty much completely transparent.