[Haskell-cafe] GPL License of H-Matrix and prelude numeric

[wren ng thornton]

On 1/26/11 5:51 AM, Maciej Piechotka wrote:
> Some projects (like Linux) remove this clause and I'm not sure how many
> projects are marked on hackage as GPL2 being GPL2-only.

Technically GPLx and GPLy are incompatible for all x and y such that x 
/= y. The problem is that *technically* the phrasing of the viral clause 
prohibits dual licensing, despite the obvious intention. This is why the 
recommended verbiage states that that the work is "licensed under GPLx 
or any later version". That disjunction isn't saying that you're 
allowing for revisions of refinements to the license, it's a disjunction 
of licenses so that others can choose the license that's compatible with 
their needs. Which is also why, if the "or any later version" part is 
omitted then the GPLx code can't be combined with GPLy (for y > x).

Aka, "GPL2-only" stuff cannot depend on "GPL3(or later)" stuff. The only 
time this really matters is when dealing with the linux kernel (and few 
other projects) since they have specific objections to the GPL3 and 
intentionally sought to disallow licensing of kernel code under it.

-- 
Live well,
~wren