Okay, I need to do a geek post.  I want to learn functional programming, I have heard lots of good stuff and lots of nasty stuff about it.  But I can't comment on it unless I have tasted it.  There are 3 I am interested in.  I heard lots of good things about Erlang, it's used in many production machines, it seems to have a strong following and it's designed in such a way that you can easily upgrade a system without stopping the program.  Then there is Haskell, it seems like it's made by the super academic for the super academic, it has a steep learning curve and is purely functional, it sounds nasty.  Then there is Ocaml, apparently it's comparable in speed to C/C++, it's a mix of functional and imperative programming and the size of your code is a bit shorter than C++.

Has anybody had any experience with any of these.  I want something that is easy, and fun, to code.  Is fast.  And gives me a good taste of functional programming.  I would also possibly be able to apply it to my work in some places.  Have you seen any of these languages used in the wild, outside of academia?  If so, where have you seen them used?  What are functional program like to maintain?  With this, I am asking what happens when you come back in 6 months to update the code, is it easy to update/refactor/optimise?