[Rd] Implications of a Dependency on a GPLed Package

[Christian Sigg]

Dear Marc

> 2. Can non-GPL compatible packages for R even be created (even if "pure R"), based upon the interpretation of the GPL that Christian has postulated?

I am not trying to offer my own interpretation of the GPL, which is entirely irrelevant. (If anyone is interested, I fall on the "pragmatic" side of the spectrum). I tried to give an accurate rendition of the interpretation of the FSF as stated in the GPL FAQ, which is relevant for the R project. Even though the legal basis of their reasoning seems unclear, to me, the argumentation as given in the GPL FAQ is quite clear and can be summarised as:

1. In an interpreted environment, using library/module/package functionality in a program implies dynamic linking of the library and the program.

2. Because of the dynamic linking, the library and the program effectively form a single program.

3. Therefore, if the library is released under the GPL (without any linking exception), the program has to be released under a GPL-compatible license.

Of course, others can disagree with my understanding the argument given in the GPL FAQ, and I might not have stated the FSF position correctly. 

If others read the same sections of the GPL FAQ and come to a different conclusion w.r.t. the FSF interpretation of the GPL, I would be interested to hear their reasoning, unless this is considered off-topic for R-devel.

Best regards,
Christian