Re: LilyPond, LilyPond snippets and the GPL

[David Kastrup]

Karsten Reincke <address@hidden> writes:

> On Wed, 2019-10-30 at 00:46 +0100, David Kastrup wrote:
>> [...]
>> 
>> I disagree with your assessment that calling any code/function makes
>> the
>> work doing so a derivative of that code (that would concern using
>> OpenLilyLib code). [...]
>
> I agree with you, that the question, when and how a piece of code
> definitely becomes a derivative work of another is not finally
> clarified, especially not judically. Therefore, we all have to argue
> and can finally only deliver more or less rational 'rule of thumbs'. I
> argue the following way:
>
> RMS has invented the LGPL to ensure that free code stays free. (weak
> copyleft effect). And he invented the GPL to ensure that no one can use
> the advantages of free software without let his own the advantages
> using software becoome free software too. (strong copyleft effect).
> This is the successful spirit of the free software world. (If you doubt
> this, please consider, why the AGPL has been invented)
>
> Hence, if I use a piece of software as library, snippet, or module,
> then I am using the advantage that I do not have to program that code
> by myself. I am saving costs and time. A very good indicator, that I am
> saving resources by using the prework of another programer, is the call
> of a function (or method or similar). Therefore, calling a function /
> method delivered by a GPL licensed software indicates that I create a
> derivative work and that the strong copyleft effect is triggered.

Which would imply that distributing your LilyPond input combined with
OpenLilylib code would require licensing your LilyPond input under the
GPL.

It doesn't cover the output of running your LilyPond code, namely the
PDF.

-- 
David Kastrup