> I work on Bun and this is my branch
  >
  > This whole thread is an overreaction. 302 comments about code that does not work. We haven’t committed to rewriting. There’s a very high chance all this code gets thrown out completely.
  >
  > I’m curious to see what a working version of this looks, what it feels like, how it performs and if/how hard it’d be to get it to pass Bun’s test suite and be maintainable. I’d like to be able to compare a viable Rust version and a Zig version side by side.

https://tsz.dev

Rust is perfect for writing all of code using LLM. It's strict type system makes is less likely to make very dumb mistakes that other languages might allow.

Also want to note that writing the code using LLM doesn't remove the need to have a vision for the design and tradeoffs you make as you build a project. So Jarred and his team are the right kind of people to be able to leverage LLMs to write huge amounts of code.

Bun has had an extremely high amount of crashes/memory bugs due to them using Zig, unlike Deno which is Rust.

Of course, if Bun's Rust port has tons of `unsafe`, it won't magically solve them all, but it'll still get better

They fork Zig to utilize LLM rewrites and build something the Zig team clearly disregarded (non-deterministic compiling)

And now like a whiny baby they LLM rewrite to Rust. There is a very real chance that Zig design philosophy got them to the point where they are now by enforcing to make the tough but precise decisions and the Rust rewrite is the start of the downfall.

It’s purely politics-based not technical, but it seems like bun is full on pampered by Claude. So much that I wouldn’t wonder that the next marketing piece of Anthropic is. Claude Mythos rewrote leading 950k LOC JS Runtime to Rust.

It's going to be hard to compete with someone or a company that has more compute. They will just be able to do things you can't.

https://blog.katanaquant.com/p/your-llm-doesnt-write-correct...

But the timescale still gives me pause… just because AI lets us convert a codebase in 6 days doesn’t mean it’s wise. There are surely a lot of downstream implications! It’s always felt a little like Bun is making up a plan as it goes along (and maybe that’s unfair), this seems to underline the point.

So much of the fundamental dynamics of the industry and the job have changed in so little time. Basically over night.

Some days I am so excited at how much I can do now. You can build anything you want, in basically no time! 100% of my software dreams can be a reality.

Some days I am terrified at what's going to happen to the job market.

Suddenly you can get so much with so little. The world only needs so much software.

Is every company that sells software as their core business model going to go out of business?

What will happen if only certain companies or governments get access to the best models?

Many find it distasteful, and many finding liberating. I think it's broadly correlates with how they feel about expressing themselves in english vs say C++.

As a side question, is there anyone who's using LLMs primarily in non-english mode to program? I suspect there's quite a few people using mandarin, but can someone share first-hand account.

OK, they've got a working prototype, congrats! Now it needs to be put into shape so that all the unsafe blocks are eliminated (maybe with a few tiny exceptions), and the code is turned into maintainable, readable, reasonably idiomatic Rust.

I wonder how long is it going to take.

Some commenters have remarked they only heard of Zig because of Bun, therefore this is bad for Zig. Not so. In my opinion, there has always been a mismatch. I say with no ill will that a divorce is likely better for both parties. I genuinely believe Bun will be better software once fully converted to Rust.

As far as I understand the situation in the US (sorry, no idea where he is located), output from LLMs, once published, is essentially in the Public Domain, since there isn't any human who owns it.

However, in some sense, this is also a machine-assisted translation from one computer language into another, so one could argue that the ownership of the original code base still applies to the new one.

Which one is it? Is there any way to find out before a similar case goes to court?

Thanks for the sharing

My question is, to people even older than me (and I'm certainly not young), does anyone remember this much enthusiasm about people rewriting C code into (C++/Java/Whatever was new and hot)? Because I don't, but maybe I missed it.

Cannot imagine this agent rewrite had anyone review any the code (you can’t at that speed).

I’m positive this will go extremely well :p

If this succeeds, there is no stopping AI given it will have crossed the rubicon of human bottlenecks.

But in all honesty, I don't understand the extremism in Rust engineers that reject any other language.

Few big popular projects use Zig, if they start to move away from it, what Zig's future will look like?

---

I wonder how much of this is original size vs rust requiring verbosity vs the LLM being verbose in general.

Not a criticism, I do believe language translation it's the one field that AI is mature enough to near one shot projects.

Off: I'm wondering if now when more JS finds place on our machines and bundle size is 2nd place for most, would a revival of prepack or projects in the same vein would be worth it, especially with agents.

Developers use LLMs to migrate a million line codebase to a language that they have much less experience with in such a short amount of time that they likely do not have a good mental model of the migrates code.

At least the tests pass.

Only one person drove the migration, so the number of people that understand the new code is ~0.5 under the assumption there's no way the sole dev could build a mental model of fresh 1m code in 6 days.

This is code for a language runtime.

It's great that the tests pass but it's really hard for me to interpret this as anything other than horrible mismanagement of a promising project. When you sit this low in the stack this is grossly irresponsible and I have no idea why anyone would use Bun after this. You'd be literally adopting a runtime the devs presumably don't understand, keep in mind they now somehow need to evolve and maintain this in the future.

Hopefully this remains an experiment, or Bun has some plan for re-upping dev knowledge of the codebase. Sorry but a component with massive blast radius like a runtime isn't really a good candidate for vibe coding, no matter how good the AI is. I'd like the maintainers to actually understand their runtime, thanks.

(in a VAE-ish way, kl div on the embeddings?)

I don’t see how this is a good look for Bun?

inb4 .unwrap() / slice / etc hell + livelocks & deadlocks + resource leaks & toctou bugs + larger exposure to supply chain attacks

Still, ~1M LOC ported in a work week (400 LOC/min, wtf?) and almost all of it working is pretty wild. I hope the guy managed to maintain normal function, cause I found that getting into the flow but with AI is even more self-consuming and intoxicating than without it, which was already potentially rather rough.

And on the seventh day Claude ended His work which He had done, and He rested on the seventh day from all His work which He had done

"I am so tired of worrying about & spending lots of time fixing memory leaks and crashes and stability issues"

bun was zig's poster child. if it moves away, it becomes yet another random language like nim or crystal.

As expected, Modula-2 / Objective Pascal like safety was great during the last century, before automatic resource management, and improved type system became common in this century.

Naturally also have to note, wasn't this supposed to be only an experiment, nothing serious?

The Rust rewrite now passes 99.8% of Bun’s pre-existing Linux x64 glibc test suite.