written on March 05, 2026
Because code gets cheaper and cheaper to write, this includes re-implementations. I mentioned recently that I had an AI port one of my libraries to another language and it ended up choosing a different design for that implementation. In many ways, the functionality was the same, but the path it took to get there was different. The way that port worked was by going via the test suite.
Something related, but different, happened with chardet. The current maintainer reimplemented it from scratch by only pointing it to the API and the test suite. The motivation: enabling relicensing from LGPL to MIT. I personally have a horse in the race here because I too wanted chardet to be under a non-GPL license for many years. So consider me a very biased person in that regard.
Unsurprisingly, that new implementation caused a stir. In particular, Mark Pilgrim, the original author of the library, objects to the new implementation and considers it a derived work. The new maintainer, who has maintained it for the last 12 years, considers it a new work and instructs his coding agent to do precisely that. According to author, validating with JPlag, the new implementation is distinct. If you actually consider how it works, that’s not too surprising. It’s significantly faster than the original implementation, supports multiple cores and uses a fundamentally different design.
What I think is more interesting about this question is the consequences of where we are. Copyleft code like the GPL heavily depends on copyrights and friction to enforce it. But because it’s fundamentally in the open, with or without tests, you can trivially rewrite it these days. I myself have been intending to do this for a little while now with some other GPL libraries. In particular I started a re-implementation of readline a while ago for similar reasons, because of its GPL license. There is an obvious moral question here, but that isn’t necessarily what I’m interested in. For all the GPL software that might re-emerge as MIT software, so might be proprietary abandonware.
For me personally, what is more interesting is that we might not even be able to copyright these creations at all. A court still might rule that all AI-generated code is in the public domain, because there was not enough human input in it. That’s quite possible, though probably not very likely.
But this all causes some interesting new developments we are not necessarily ready for. Vercel, for instance, happily re-implemented bash with Clankers but got visibly upset when someone re-implemented Next.js in the same way.
There are huge consequences to this. When the cost of generating code goes down that much, and we can re-implement it from test suites alone, what does that mean for the future of software? Will we see a lot of software re-emerging under more permissive licenses? Will we see a lot of proprietary software re-emerging as open source? Will we see a lot of software re-emerging as proprietary?
It’s a new world and we have very little idea of how to navigate it. In the interim we will have some fights about copyrights but I have the feeling very few of those will go to court, because everyone involved will actually be somewhat scared of setting a precedent.
In the GPL case, though, I think it warms up some old fights about copyleft vs permissive licenses that we have not seen in a long time. It probably does not feel great to have one’s work rewritten with a Clanker and one’s authorship eradicated. Unlike the Ship of Theseus, though, this seems more clear-cut: if you throw away all code and start from scratch, even if the end result behaves the same, it’s a new ship. It only continues to carry the name. Which may be another argument for why authors should hold on to trademarks rather than rely on licenses and contract law.
I personally think all of this is exciting. I’m a strong supporter of putting things in the open with as little license enforcement as possible. I think society is better off when we share, and I consider the GPL to run against that spirit by restricting what can be done with it. This development plays into my worldview. I understand, though, that not everyone shares that view, and I expect more fights over the emergence of slopforks as a result. After all, it combines two very heated topics, licensing and AI, in the worst possible way.