Functional programming for the JVM

Dear Java, my good old friend, there is something I need to tell you. You've been my only one for over 10 years, but now I have trouble staying faithful. It's not you, it's me. And no, I am not moving out, not just yet, because I can't afford to leave all your stuff behind.

But you don't satisfy all my needs anymore!

I know you are trying, dear, and good people try to help you - here Neal Gafter is working hard to give you closure support, Ricky Clarkson, a true alpha-geek who played with the first prototype of Neal's work, has blogged the results. But, sorry love, I can't wait until the big makeover in Java 7. What do you expect me to do with all these JVM languages around? These languages inter-operate (well, to certain extent) with your libraries, so I can enjoy all the usual stuff but I can also be more expressive. Here is an example of hooking up JRuby with Velocity and another one of writing servlets in Scala under Tomcat.

You wanna know who they are? Among the young ones, Scala deserves to be mentioned first, alongside Ruby, JavaScript and Python to name just a few. Classic ones include several Lisp dialects (e.g. Clojure and Common Lisp), Scheme and OCaml implemented over the JVM as well. Either there is a compiler that produces bytecode, or there's a JVM scripting engine, and sometimes both. I hope one day to make a deeper study and produce a proper comparison table, maybe then you'll understand.

You think that closures alone aren't good enough reason to have a little flirt on the side with another language? Hmm, consider the fact that "the other language" may offer me hot-swapping of classes, mix-ins, better modularity, pattern matching, better concurrency model and dynamic typing support ... who can blame me for being tempted.

Still loving you, yours truly but... not entirely.