I wrote an initial blog post about it a few months ago at https://redvice.org/2026/lunacy/ - I think at that point it was like 95% written by hand, because LLMs were simply too stupid to actually work on it effectively and would immediately break the JIT and then claim it was broken the entire time and never worked. Now they’re a bit better, and I’m able to have Claude Opus 5.5 do most of the programming work and refactoring which has been convenient. It definitely still makes commits doing things the wrong way, and most of its “suggestions” are things that actually completely defeat the JIT design or several important invariants so it still can’t be trusted to make any sort of decision, but for a fun side-project that I’m doing mostly to mess around with neat JIT techniques it’s been nice to have it do the mechanical work.

Do you have any public material about your JIT? I’d love to check it out!

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I’ve been working on Lunacy, my interpreter + JIT compiler for Lua, again recently. It’s now (very) fast, but I need to do a pass over all the Claude-slop quality code and rewrite the bad parts and all the comments. Then once I have all the new features cleaned up I can actually merge it into main and write a new blog post: I want to brag a bit!

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