By restricting ourselves to the JVM, we can introduce Kotlin code gradually because it can run side-by-side with legacy Java code. Unlike the other JVM language

By restricting ourselves to the JVM, we can introduce Kotlin code gradually because it can run side-by-side with legacy Java code. Unlike the other JVM languages, Kotlin has been designed to work seamlessly with an IDE. It doesn't introduce as much extra symbol syntax as Scala so it's still readable. And it was designed to be statically-compiled from the ground up, unlike Clojure and Apache Groovy which both bolted on clumsy-looking static-typing annotations later on.