I meant I was planning to, unless there's some disaster. I'm working on it now. Anyone have any preference for licenses? BSD? Or should I not have asked that...
From what I've seen, projects that go GPL tend to be more community-focused, and seem to more readily gather a contributor community around them. I think contributors tend to like the idea of their contribution being free in perpetuity.
MIT-licensed projects, OTOH, tend to be mostly worked-on by their creator (again, FWICT). That is, there are fewer individuals willing to contribute code to a project which could simply be scooped up and put into some company's closed-source product. I get the impression that MIT-licensed projects are always looking to be popular, and feel entitled to be so, since users can basically do whatever they want with the code.
A lot of careful thought by lawyers, the community, and the FSF has gone into the most current GPL. I'd suggest that it's worth considering.
Being Arc a language, I think you would like to remain the head of its development, so maybe the Artistic License [3][4]would be right. Like Perl does.
It's far more complicated than the simple ones, but it would make easier to differentiate between the Vanilla Arc and the Straciatella Arc.
For the GPL[5], I think it is better suited for programs than for languages.
[0] http://www.opensource.org/licenses/category
[1] http://www.opensource.org/licenses/bsd-license.php
[2] http://www.opensource.org/licenses/mit-license.php
[3] http://www.opensource.org/licenses/artistic-license.php
[4] http://www.opensource.org/licenses/artistic-license-2.0.php
Choosing a license to fight imagined evils seems like the short route to a DRM'd license.
Incidentally, the last thing the FSF is worried about is popularity, yet look at how popular GCC, Emacs, bash, and other GPL'd software is.
Licensing your software with a very liberal license may help make your software more popular with some large companies who are in a position to take advantage of it (and I suspect timing is important here as well), but I'm not so sure it makes your software popular with the developer community.
One thing that's important for languages like Tcl is that they can be embedded within other projects, and for that reason a liberal license was very important. Of course, it's certainly not the only thing you need. The GPL is probably ok for "finished product" sorts of things that you don't need to link against to utilize it.
I prefer GPL over BSD strictly for the reason that if someone makes a modified version of Arc publicly available, then we all get to see (and maybe use) the modifications.
The license should be Affero GPL.
they seem like ostensibly the same thing.
GPLv2 requires modified public distributions to also be under GPLv2, so you could both see the fix/change and use it (in the sense that you won't be infringing on copyright).
GPLv3 adds patent protection, so someone adding a fix/change that they have also patented explicitly grants a license for that patent.
I think GPLv3 is the most comprehensive way to keep fixes/changes of others available for reuse.
http://www.apache.org/licenses/LICENSE-2.0
OTOH, it's a big, long license, and perhaps the BSD license would be simpler, which is always an advantage.
"Do What The Fuck You Want To Public License"
It's actually not a joke: http://sam.zoy.org/wtfpl/
Some ideas I've got floating around are to use it for scripting (instead of, say, LUA or XSLT) and for config files (instead of XML) in existing apps. Also, lisp seems fantastically placed for HTML generation, so if I embed it in an IIS or Apache site, then great!