Rars: a Rust RAR implementation, mostly written by LLMs
I spent a fortnight using Claude to create specs for every version of RAR, then another using gpt-5.5 to write compressors in Rust. It's not fast and it's not pretty, but it works.
I spent a fortnight using Claude to create specs for every version of RAR, then another using gpt-5.5 to write compressors in Rust. It's not fast and it's not pretty, but it works.
Discussion Highlights (15 comments)
themafia
> But, it works, and the world now has a free software RAR implementation. Does it? How are you legally intending to use copyright to license this machine output? How would you know it's not encumbered in any way?
cactusplant7374
> and it almost earned me an OpenAI ban Were you flagged for a cybersecurity violation?
esafak
> It’s sloppy, it’s slow, it’s almost two megabytes in size and somewhat worse than WinRAR on compression. As mathematicians say, optimization is left as an exercise to the reader. You did the hard part.
Imustaskforhelp
Kudos, this is a really cool project (even if it might be AI generated), I have starred the repo, (3rd starrer here) One thing I have been curious at is are there any ways to stop a rar compression mid way and then continue it later? Like suppose I have a compression happening for a large file, then would there be a possibility with this project to shut down the computer mid compression and continue it after starting it again? I would really love it if you can add this functionality!
slopinthebag
How do we know it's actually correct?
xphos
Would it really take 5 years to develop rare compress and decompression that seems an extreme overestimate in time. I don't know of the compressor decompression but that seems really high
unixhero
Rar means weird in Norwegian and adorable in Swedish. Just for an anecdote.
npn
Rar is proprietary. Good luck.
rebolek
> "For the last 15 months or so my hobby has been shouting at Claude" How can you shout at Claude when it’s 1) foobaring, bamblabooing and fghrtawing all the time without telling you what’s going on 2) when it finally interacts, it’s asking for a permission you told it 30 seconds ago "yes and do not ever ask me again until heat death of the Universe" 3) and after all of that, it just spits out: "you’re out of tokens, give up your liver or wait until next Trump’s war"
periodjet
Finally, a sane and enjoyable read about a coding project. Feel like it’s been months since we had one of these that wasn’t filled to the brim with bluesky/mastodon-flavored whining about AI. Kudos to the author. A fun read, thank you for sharing.
dclavijo
It wonders me that a coupe of days ago I did the same with Unique and a single skill.md, repo: https://github.com/daedalus/uniq-reconstruction , on succes I tried with rar but failed. Kudos
spprashant
I have never attempted something so ambitious with AI, but this feels spot on in terms of experience. As you cede more control to the model, you will find yourself losing control on things like code quality and performance.
sntran
Good luck with keeping it online. Somebody built `rar-stream` with Rust, and its GitHub is no longer there.
rvz
> but it works. Are you sure "it works?"
p0w3n3d
First, isn't RAR compression algorithm proprietary somehow? Second, why compress to RAR if you can compress to 7z?