Elisp licensing

Elisp licensing

[Christopher Howard]

Hi, if there is a long thread on this question already, please send me the link to that.

I was wondering if somebody could clarify, from a legal perspective, and from the perspective of the Gnu project, what is acceptable licensing for Elisp code? In my personal observations, finding Elisp in the wild, it seems like most people are labeling their Elisp as GPLv3+, not counting the code that doesn't have any license attached at all. But recently I came across an Elisp library marked LGPLv3+, and also another project that was under an ISC license.

My understand was that nearly all Elisp programs heavily utilize the Gnu Emacs API and libraries, and so they should be also licensed under GPLv3+. Maybe with exceptions for programs written for Guile Elisp or one of the non-Gnu Emacs clones that are being developed, like Gypsum or Rune. Actually, I believe Rune is marked GPL-3.0 and Gypsum is AGPL-3.0, though I haven't looked closely at their licensing comments.

-- 
📛 Christopher Howard
🚀 gemini://gem.librehacker.com
🌐 http://gem.librehacker.com

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Re: Elisp licensing

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
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  > I was wondering if somebody could clarify, from a legal perspective,
  > and from the perspective of the Gnu project, what is acceptable
  > licensing for Elisp code?

Those two perspectives make two different questions -- which are you
asking?

                              In my personal observations, finding Elisp
  > in the wild, it seems like most people are labeling their Elisp as
  > GPLv3+,

That is what we recommend.

            not counting the code that doesn't have any license attached
  > at all.

A nontrivial file with no license is nonfree.  That is the default under
copyright law.

When you see an instance of that, please point this out to the auhor
and ask per to add a GPLv3+ license header.

  >  But recently I came across an Elisp library marked LGPLv3+,

LGPLv3+ is basically the same as GPLv3+ ecept that it gives some
additional perissions.  (Please read it for yourself so you will see:
https://gnu.org/licenses/lgpl-3.0.txt.)  So it is no problem.

  > and also another project that was under an ISC license.

That is a weak, permissive license, compatible with everything.  We do
not recommend it but its use is not a problem.

  > My understand was that nearly all Elisp programs heavily utilize the
  > Gnu Emacs API and libraries, and so they should be also licensed under
  > GPLv3+.

Legally they need to be under licenses compatible with GPLv3+,
if they are meant for use in combination with GNU Emacs.
Morally, it is always good to use GPLv3+, and there is rarely
a good reason to use anything else.  

I suggest you read https://gnu.org/licenses/license-compatibility.html
to learn about license compatibility issues.

  >  Maybe with exceptions for programs written for Guile Elisp

That is rather vague, so I won't say it is absurd, but why would
it ever be better to use a weaker license for Emacs Lisp code?
Copyleft supports freedom, so in general it is better to copyleft
a program than not to.

                                                                or
  > one of the non-Gnu Emacs clones that are being developed, like Gypsum
  > or Rune.

What are those?   Why would they make it better not to uee copyleft?

-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)

Re: Elisp licensing

[Christopher Howard]

Thank you for your response. Thank you also for your pivotal work in
launching the free software movement and developing the wonderful Gnu
Emacs software.

To clarify: myself personally, I would prefer to see all Elisp code
licensed under the GPLv3+. Rather than wanting to encourage using other
licenses for Elisp program, I was actually concerned about how to relate
to Elisp projects I've found that that are released under other
licenses, in particular non-copyleft free software licenses.

I was wondering, since Emacs is licensed under the GPLv3+, if Elisp
programs legally must also be released under the GPLv3+. It appears you
answer that question with this statement:

> Legally they need to be under licenses compatible with GPLv3+,
> if they are meant for use in combination with GNU Emacs.
> Morally, it is always good to use GPLv3+, and there is rarely
> a good reason to use anything else.

So, Elisp programs "if they are meant for use in combination with GNU
Emacs" legally must be released under a GPLv3+ compatible license, but
not necessarily the GPLv3+ itself?

>   >  Maybe with exceptions for programs written for Guile Elisp
>
> That is rather vague, so I won't say it is absurd, but why would
> it ever be better to use a weaker license for Emacs Lisp code?
> Copyleft supports freedom, so in general it is better to copyleft
> a program than not to.
>
>                                                                 or
>   > one of the non-Gnu Emacs clones that are being developed, like Gypsum
>   > or Rune.
>
> What are those?   Why would they make it better not to uee copyleft?

Again, to emphasize, I would prefer that all Elisp programs would be
released under the GPLv3+. I understand you to be saying that this is
not legally necessary, though it is legally necessary that all Elisp
programs be released under a GPLv3+ compatible license "if they are
meant for use in combination with GNU Emacs". From my understanding, all
Elisp programs are meant for use in combination with GNU Emacs, except
for the following possible exceptions:

- Elisp code that was meant to be run only by the Guile Scheme
  interpreter, which is able to run code from some other programming
  languages
- Elisp code that was meant to be run only by one of the Emacs clones
  not produced by the Gnu Emacs project. Two such projects I am aware of
  are "Gypsum", which attempts to be a from-scratch clone of Gnu Emacs,
  but built on Guile Scheme; and secondly there is Rune, which also
  attempts to be a from-scratch clone of Gnu Emacs, but is built on Rust
  instead of on C.

Actually Rune is released under the GPL-3.0 and Gypsum is released under
the AGPL-3. But in theory at least one could have an Emacs clone,
capable of running Elisp, that is not released under a GPL license.

-- 
Christopher Howard

Re: Elisp licensing

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > I was actually concerned about how to relate
  > to Elisp projects I've found that that are released under other
  > licenses, in particular non-copyleft free software licenses.

the main question is whether those licenses are compatible
with GPLv3.  See https://gnu.org/licenses/license-list.html
for that information.

If they are compatible with GPLv3, you can use that code
in GNU Emacs  with no difficulty.

  > So, Elisp programs "if they are meant for use in combination with GNU
  > Emacs" legally must be released under a GPLv3+ compatible license, but
  > not necessarily the GPLv3+ itself?

Yes.

-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)