[primenum]

I'm a bit shocked by how people are equating recreating from copyright with recreating from copyleft. It's not the same thing... copyleft code is out in the open on purpose, with the condition that you share back in kind. People are latching onto the intellectual property angle of this article, but the point is way simpler than that: "The terms of that compact were: if you take this and build on it, you share back under the same terms."