There have been some discussions on this forum in the past about which programming language to learn after R (eg here), with some good suggestions.
However, I would like to probe you people with a more targeted question: which compiled programming language would it be best to learn after R for a data scientist interested in data engineering?
A bit of context. Where I work most development is done in C#. However, JVM languages seem to be a better choice for a data scientist who wants to expand his data engineering skills (think kafka and spark). So I have been thinking of learning a language that compiles to the JVM.
Here three choices appear: java, kotlin and scala. Both kotlin and scala are interoperable with java; kotlin seems like a "better java", while scala seems a more advanced, FP first language.