I second that (using Scala), it's amazing. Totally compatible with Java and the JVM, but lets you mix in really concise functional programming, along with a do

I second that (using Scala), it's amazing. Totally compatible with Java and the JVM, but lets you mix in really concise functional programming, along with a dozen other big pluses and scores of little treats (for a long-time Java programmer like me). We're using it as the primary language for our start-up. I use the Emacs mode for syntax-highlighting and indentation (and I've fixed a couple annoyances). I use two Emacs shell-mode buffers for a scala prompt and a shell prompt to run build scripts (I don't use whatever facilities scala-mode has for those things).