Languages offer a lot more than syntax and compilers. They often have supporting libraries and special facilities that set them apart from other languages. Some languages offer special compiler support for a particular construct, like tail call optimization, for example. Others provide interesting library support or capabilities. In this presentation we will dive into 12 cool things we can do with different languages on the JVM, things that are either impossible or hard to do in Java, but are quite easy and useful to realize in other popular languages on the JVM. If mixing these languages is an option on your projects, you’ll have dozen more reasons after this presentation. Languages used: Java, Scala, Groovy, Kotlin.