Re: LilyPond, LilyPond snippets and the GPL

[Karsten Reincke]

On Wed, 2019-10-30 at 01:36 +0100, David Kastrup wrote:
> Karsten Reincke <address@hidden> writes:
> 
> > [...]
> > 
> > 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.
Yes, exactly. That's my point.
> 
> It doesn't cover the output of running your LilyPond code, namely the
> PDF.

I am afraid that this statement does judicially not hold:

LilyPond itself says that it works "[...] as a compiled system: [...] In some
ways, LilyPond is more similar to a programming language [...]". Hence the
viewpoint of Carl Sorensen seems to be valid: LilyPond is like the gcc. And even
in case of the gcc, the copyleft effect does not cover the outpout (the compiled
program).

But in case of a GPL licensed LilyPond snippet (sic!), the copyleft effetc is
triggered by the use of that snippet. And the GPLv3 is very clear: §4 and §5
require us also to distribute the code of the embedding / using work under the
terms of th GPL. And - under the title "Conveying Non-Source Forms" - §6 
requires
us also to distribute our non-source forms under the terms of the GPL.

Here, the analogy of gcc and Lilypond matches perfectly: As we are must 
distribute
binaries which are compiled by the gcc on the base a GPL licensed source code, 
we
must also distribute the binaries (png) which are compiled by LilyPond on the 
base
of a GPL licensed LilyPond score description. It is exactly the same case.

I regret to be the messenger of bad news. But there is a simple solution: Don't
use GPL licensed LilyPond snippets, if wou want to keep you rights. And perhaps
convince the OpenLilyLib developers to relicense their work.

with best reagards Karsten

-- 
  Karsten Reincke    /\/\   (+49|0) 170 / 927 78 57
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