Licenses question (was: Re: port of prevayler)

goran.hultgren at goran.hultgren at
Mon Feb 17 14:34:56 UTC 2003


Hannes Hirzel <hannes.hirzel.squeaklist at> wrote:
> Hi Goran
> Thanks for answering
> goran.hultgren at wrote:
> > Combining GPL with MIT (or SqueakL for that matter) would undermine the
> > whole purpose of GPL. If I can do whatever I like with code (MIT) then
> > why should I ever want to use the more restricting license (GPL)?
> Thank you for this information that GPL is more restrictive than MIT!
> And it seems that MIT is compatible with Squeak-L.
> Could you post a summary or a pointer to a summary which briefly
> lists the pros and cons of these three licenses.

Well, I don't have any such pointer available but essentially it goes
like this (make some room here for subtle mistakes IANAL):

> Squeak-L

Squeak-L is the original license of Squeak from Apple. It is very
unrestricting and quite simple to understand. IMHO it is a
MIT/BSD-flavored license and was mostly intended to protect Apple I
guess. You can create software that even includes whole Squeak and
redistribute without source (read "sell commercial proprietary


MIT is the shortest license of all. It simply says "Do whatever you
like, just don't blame me and make sure to include this text when you

If we disregard any theoretical discussions about degrees of freedom for
second and third party in the distribution chain etc then MIT is as free
and simple as it gets. I like MIT. :-)


GPL is about making sure that whoever gets in contact with the software
(on its own or as a part of another program) in question also gets the
source code.

>From section 2 b of GPL:
"You must cause any work that you distribute or publish, that in whole
or in part contains or is derived from the Program or any part thereof,
to be licensed as a whole at no charge to all third parties under the
terms of this License."

This is what is commonly referred to the "viral" property of GPL. So if
I include code under GPL in my program then I am not free to choose my
own license anymore for my program.

Sidenote: The "at no charge" above got me confused - has GPL always had
this clause? I am having a hard time understanding that clause since I
was under the impression that I can carge whatever I like for software
under GPL - as long as I include the source.

Anyway, GPL is rather complex and Andrew Greenberg has repeatedly on
this list given advice that GPL (and LGPL too) really isn't written with
imagebased software systems like Smalltalk in mind.

Final notes:

- In the Squeak community we have (a long time ago, and repeatedly when
the question arises) agreed that base Squeak should only contain
software under Squeak-L.

- If you want to publish software so that the most people can reuse it
the way they like to then I urge you to dual-license it under Squeak-L
(to keep Squeakers happy) and MIT (to keep everyone else happy). This is
also an available option under SM.

regards, Göran

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