[copyleft-next] An interesting take on license compatibility

Richard Fontana fontana at sharpeleven.org
Wed May 22 05:05:31 UTC 2013


On Tue, May 21, 2013 at 05:54:44PM +0200, Antoine Pitrou wrote:
> IMHO, copyleft-next should be forward-compatible, not only with GPLv2
> and GPLv3, but also LGPL and perhaps MPL.

Originally I dismissed the idea of forward compatibility with LGPL
(though I naturally thought about it) because of the assumption that
copyleft-next would be a strong copyleft license in some very GPL-like
sense, plus (maybe this was more important) LGPL is itself
forward-compatible with GPL. 
 
> This implies to have a "weak" copyleft model, and I think that's the way
> to go, as noted in the previous discussion, given the increasing
> importance of libraries and dynamic languages in free software
> ecosystems.

It is clear that without intending this to have happened,
copyleft-next is showing signs of evolving into something 'weaker'
than I had originally conceived. This is somewhat disturbing (not in a
bad way necessarily) for various reasons. For one, I believe I
originally assumed that weak copyleft was actually the dead
category. For another, I thought Mozilla did a decent job with MPL
2.0. :)

As for forward compatibility with LGPL, though... this is easy to fix
but I am not sure it is really necessary. It is possible to interpret
LGPL as what I've now inaccurately described as inbound-compatible --
that is it is arguably compatible in the same sense that EPL is
arguably compatible. That may rest on a 'weak' interpretation of
LGPL. And as a policy matter it doesn't seem as compelling -- I take
your point about libraries and dynamic languages, indeed this has been
influencing a lot of my recent thinking, but LGPL is presumably
declining in use in that sphere.

- RF



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