I've been doing some programming in lisp/arc, which isn't exactly functional but I try to stay as side-effect-free as possible. And I've been having a lot of fu

I've been doing some programming in lisp/arc, which isn't exactly functional but I try to stay as side-effect-free as possible. And I've been having a lot of fun doing TDD. See, for example, http://github.com/akkartik/wart http://github.com/akkartik/wart which has about as many LoC in tests as in code.