Three functional programming languages

Scala is a functional programming language that is designed to work well with Java. That doesn't come free, of course. The language makes some compromises to play well with legacy Java code and the JVM, but it does make Scala a very good Java 2.0. If you are interested in functional programming and want a language that you may actually get to use professionally, Scala is the safe bet. But it will not cure your cynicism.

Programming in Scala

Lisp was shot in the head a generation ago by Algol-style syntax, but like Lisbeth Salander, it never quite died. A tenacious band of enthusiasts keeps insisting the language is special, and has never been proved wrong. If you want to learn a timeless classic of a language with a reputation for changing the way you look at programming, Lisp is a good choice. Also, Paul Graham will send you a mash note.

Practical Common Lisp

Haskell is a pure functional programming language known for extreme expressivity. SkyNet would be 300 lines in Haskell, tops. Its relentlessly orthodox functional nature will force you to confront, interrogate, and ultimately deconstruct the imperative paradigm you have been trained in. You will see imperative coding for the fire-lit cave that it is and depart for a sun-bright world of functional programming. (Actual results may vary -- Platonic enlightenment not guaranteed.)

Learn You a Haskell for Great Good