I wish the Clojure guys would come up with some clear and direct messaging around its license. When I started exploring Clojure one weekend a few months back, I found that it's the only language I've ever seen that uses the Eclipse Public License. In turn, the EPL is the only license I've ever seen where the FAQ is even more ambiguous and confusing than the license text itself!

I did some sniffing around to see what the practical effects (if any) are for applications written in Clojure, and on their own mailing list the topic is a bit of a mess:

https://groups.google.com/forum/#!topic/clojure/bpnKr88rvt8 https://groups.google.com/forum/#!topic/clojure/mGf_SuHsSGc

Everyone seems to agree that forking or modifying Clojure itself would trigger all sorts of license requirements (e.g. GPL-incompatibility, you might need to use the EPL, etc).

However, nobody on their mailing list seems to agree on what the licensing means for normal applications that happen to be written in Clojure and use its library at runtime. Is that a "derivative work", or not? Does the fact that you write applications in Clojure have any bearing on the licenses that you may choose?

I know that it's somewhat possible to mix the EPL with almost anything... because I've worked with some Aptana IDE's that are based on Eclipse, yet use GPL v3 with several paragraphs of caveats and exceptions. (http://www.aptana.com/legal , http://www.aptana.com/legal/aplgplex) Not sure about GPL v2.

I just don't want to have to think about this stuff AT ALL as an application developer who isn't making changes to the programming language or core runtime library. The murkiness on their own mailing list has definitely been a deterrent from my exploring Clojure more seriously.