Actual, open and good functional programming language

I've been programming C# for quite some time now and the best part of it is its functional components - delegates, events, etc. C# is very inefficient when it comes to that and I was wondering if anyone could tell me what is a good functional languages. It must be free(open), have - big, or not - community.

I really liked node.js for its event driven and friendly for JavaScript developers.

Any more arguments for node.js, or for any other language?

In my very personal opinion, you might want to take a look at erlang.

It has very clear syntax, good documentation, and nice courses. There is a community and it has been actually used in real-life commercial applications. Unlike other languages that have never managed the step to leave universities or very small and specialized user circles.

I am not saying that other functional languages don't share maybe these same advantages, but erlang is a good point to start looking.

For starters, look at the stackoverflow questions tagged with "erlang" and you can get a first impression.