LLGPL License

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LLGPL License

Postby james » Tue Sep 22, 2009 4:50 pm

I've been looking at Clozure CL lately and wondering what the implications are of the license it's released under (LLGPL).
Not being a lawyer, I'm finding the licensing wording a bit of a challenge to understand and was wondering if someone here would perhaps
be able to help clarify a few things for me, particulary can Clozure CL be used as the basis of a closed-source product and what restrictions/rules are in place?


Re: LLGPL License

Postby findinglisp » Wed Sep 23, 2009 2:05 pm

IANAL either, but essentially, yes, you can link LGPL and LLGPL with closed-source code and not have to provide source to that code. Remember the lineage here...

LGPL was created for code (primarily libraries), where it was thought that there would be greater adoption of the LGPL code if it was not full GPL, where linking with GPL code would require all the linked code to be released as GPL. glibc is the obvious example here, which is used widely with closed-source programs as well as open source. The library itself is open source, and any modifications to the library must be open source, but linking doesn't automatically "taint" the other code that you link to.

LLGPL was conceived of by Franz to deal with some Lisp-specific issues related to the LGPL around dynamic linking. Essentially, the Lisp notion of "linking" is very different than the C notion of the same thing, and the LLGPL makes changes to the LGPL to take that into account. If this was not done, I believe under a strict reading of the LGPL, you could be forced to open source anything that would come in contact with a LGPL Lisp module. Specifically, LLGPL is designed to provide the same overall behavior (the library code is basically GPL, but it can be linked with closed-source code without tainting), but with Lisp-specific tweaks.

You can read more here: http://opensource.franz.com/preamble.html

As with everything, consult your lawyer to understand your specific situation and whether what you want to do is correct according to the legal interpretation of these licenses.
Cheers, Dave
Slowly but surely the world is finding Lisp. http://www.findinglisp.com/blog/
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