When talking about JVM languages suitable for building systems, Jython isn't generally mentioned for the reasons you give, nor is Apache Groovy. Those two are g

When talking about JVM languages suitable for building systems, Jython isn't generally mentioned for the reasons you give, nor is Apache Groovy. Those two are good for scripting, e.g. testing Java classes, build scripts, glue code. Besides Java, languages like Clojure, Scala, and Kotlin are usually considered as systems languages on the JVM.