Scala. It’s something I’ve been meaning to learn for about 8+ years now. Not the most exciting language these days for a lot of people I suppose, but I’ve already learned a ton about real world functional programming.
Yeah, I recently had the opportunity to use Java 8 on the job for the first time and solving problems in a functional way was a sort of Damascus road experience for me. Now I want to go farther so I'm learning Kotlin.