Rust is awesome if you want to follow along and see how the bread is made. One of the best things about being involved in Rust since it was announced is being able to recount all the different paths it's taken and the reasoning behind them. It has taught me a lot about good language design, validated and sometimes destroyed some of my ideas about programming concepts and overall provided a great environment for questioning how things work.

I come from a C background however which is a little closer to Rust than Java/Javascript/R but I don't think you would hvae that much trouble if you put your mind to it. Java is a similarly large language if a bit removed from the metal.