I would strongly recommend looking at Racket and/or Closure. I tried the Haskell world and what a hassle to get it working on more then one machine the same way. The package management in Haskell is still more painful then other systems and is overly taxing. I work at two locations both using the same exact Dell machine with OpenSUSE and both gave problems. I also tried it on two windows machines and ugh.

OCamal also suffers from portability issues but haven't tried that hard. I love the idea of OCamal but the practical/pragmatic side of me gets rubbed the wrong way.

Personally Racket has a ton to offer and has been growing its user base a lot recently. I love this language and you can amke it whatever you want to do. Racket is a progamming language for programming languages. Clojure gives you a more pragmatic functional language and running on the jvm with a very large community.