To reach maximal coherence we will, as a rule of thumb, only accept
new code that has the Simplified BSD license and existing code with a
permissive license such as MIT, Apache, BSD-3, etc. In
exceptional cases we may accept code with GPL or LGPL conditions. Such
code must be tagged using a license/1
directive (Prolog) or a call to
PL_license()
for foreign code and, if they are part of the core, the code must be
excluded using the --without-gpl or
--without-lgpl option.