erlang

I recently started looking into the erlang language. It is a functional language somewhat like lisp, but concurrency is built into the language in a very fundamental way. Has anyone out there worked with erlang before? Any opinions on the language?

From what I have seen, erlang would be rather useful for writing control systems. Each concurrently running function could represent portions of the system. As input comes in, each erlang process could communicate with other erlang processes to get something done. The IPC between erlang process seems very easy. If your system ever needed to do a low level operation, you can always call external executable programs using the following:

os:cmd("program and arguments here").

Lastly, if you ever deployed a system using erlang, you can field upgrade it with 0% down time. You insert the new code into the running system, and it switches to the new code live.

erlang looks like a powerful tool. However, I am more used to designs using languages like C and Java. I bet it takes a different mind set to design a system using a functional language.