It's not very strict; it's the raison d'être of the GPL. The LGPL was written precisely to allow libraries without copyleft. A big chunk of CRAN is library-base

It's not very strict; it's the raison d'être of the GPL. The LGPL was written precisely to allow libraries without copyleft. A big chunk of CRAN is library-based and depends on a binary interface to R, and is GPL'ed. The FSF also does not think that whether the GPL'ed program is a separate process or not determines whether the bundle as a whole is GPL'ed or not. In their opinion, if you bundle the whole thing and it acts as a whole, and the communication between the GPL'ed components and the non-free parts are "intimate enough"[1], then the whole bundle is copylefted. It seems to me that bundling R with SQL server and tightly coupling the two, even across different processes, could well qualify. Of course, if the R developers do not want to enforce their copyleft, none of this matters. [1] https://www.gnu.org/licenses/gpl-faq.html#MereAggregation https://www.gnu.org/licenses/gpl-faq.html#MereAggregation