[progman]

If you want to teach FP you should use the very first and most simple FP languages --- Lisp and Scheme. Despite their extreme simplicity, they provide an extremely expressive power (through their macros) which is still unmatched in most other languages.

[drb91]

I wouldn’t characterize either as FP, though—both of them still actively encourage maintenace of mutable state and use of macros.

They may be “simple” in that they are very analyzable but you’re teaching a whole bag of skills, and the most FP part of lisp/scheme is just the closure.

[baby]

These languages are horrible, filled with parenthesis and not fun. I had to learn these in school, like many other people, and I stayed away from FP languages for a long time because of that (like most people).

Try to learn Erlang or Ocaml, it's fun.