[Dune] license again

[Ansgar Burchardt]

On Tue, 2020-12-01 at 08:43 -0600, Edscott Wilson wrote:
Actually, if your colleagues are just going to compile and run your
code, GPL is fine: There is no restriction to publishing results
> derived from compiling and executing GPL code.

Now, if you are going to give your colleagues an executable produced
from your code and the Dune toolbox, first consider:

a) if your code is in any way a modification of the code in any Dune
module, you *must* provide a copy of your code to your colleagues, or
if it
is in published somewhere, tell them where they can download it. The
licence you put on it must follow the GPL guidelines for free, i.e.,
any subsequent modification of the code must remain in the free
> realm.

The changes must be licensed under terms compatible with the GPL; they
don't have to be under the GPL.  Using a more permissive license is
fine.

Practically changes will often be only useful with the original code,
so it is most practical to just distribute them under the same terms,
including additional permissions (DUNE has a special exception in
addition the the GPL).

b) if your code in no way is a modification of the code in any Dune
module, you may use an open but non-free license such as BSD. The
> guys at GNU consider the BSD license as non-free, because it will
> allow your colleagues to modify your code and not share it back with
> you.

No, the GNU project / the FSF considers the BSD license a free software
license[1].

  [1]: https://www.gnu.org/licenses/license-list.html#ModifiedBSD

The GPL also doesn't require to share modifications: you can just
modity code and not share it back with other people, see for example
[2]. (You only have to share source code if you distribute binaries,
but for research that's often not done.)

  [2]:
https://www.gnu.org/licenses/gpl-faq.html#GPLRequireSourcePostedPublic

> Furthermore, the BSD license will allow them to do so and not even
> give you any credit. Windows uses a lot of BSD code and does not
> credit the University of California at Berkeley.

The BSD license requires to reproduce the copyright notice which really
is the only notice giving credit to the creator.  GPL doesn't require
more credit.  Commercial users, including Microsoft, do usually comply
with that, but usually copyright notices aren't shown prominently in
most applications (they are very, very long; see this[3] 1000 page PDF
as an example).

  [3]: https://docs.oracle.com/cd/E60864_01/doc.3390/om_license.pdf

Ansgar