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How is the Bun rewrite in Rust going?

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Re: How is the Bun rewrite in Rust going?

#61

Post by oblio »

furyofantares wrote: post #49
benjiro29 wrote: post #41

I really do not understand how software developer think anymore. Using a LLM to translate a project in a short time, is by itself incredible. Just like one-shot whatever office clone. But what makes software is not the fast creation of a "product" but that actual development of its features. Figuring out how everything needs to work together, fixing the bugs, and the o so boring UI work. I have used LLMs to create st…

> I have used LLMs to create stuff like word clones just for fun. It was a disaster. Sure, it had the basic functionality. But the moment you started with page structure (harder then one non-stop scrolling page), tables, images, rotating, and so many details that make up just the basics of word. Not even the extended functionality. You see every LLM just fall on its face. What do you think of https://scramblequest.ap…

Are you comparing 2 relatively simple games with... Word?

Word is basically an operating system. Unix people like to make fun of Emacs for being one, but Word is basically one, too. And all the features in there are used, otherwise Microsoft wouldn't keep them around.

Re: How is the Bun rewrite in Rust going?

#62

Post by TaLiTr »

furyofantares wrote: post #49
benjiro29 wrote: post #41

I really do not understand how software developer think anymore. Using a LLM to translate a project in a short time, is by itself incredible. Just like one-shot whatever office clone. But what makes software is not the fast creation of a "product" but that actual development of its features. Figuring out how everything needs to work together, fixing the bugs, and the o so boring UI work. I have used LLMs to create st…

> I have used LLMs to create stuff like word clones just for fun. It was a disaster. Sure, it had the basic functionality. But the moment you started with page structure (harder then one non-stop scrolling page), tables, images, rotating, and so many details that make up just the basics of word. Not even the extended functionality. You see every LLM just fall on its face. What do you think of https://scramblequest.ap…

I think they might mean Word as in Microsoft Word. Just based on the feature list they were describing.

Re: How is the Bun rewrite in Rust going?

#63

Post by flohofwoe »

usef- wrote: post #26
SquareWheel wrote: post #20

I'm not sure how much insight we can glean from looking at the number of commits and release cadence here. In the aftermath of such a major refactor/rewrite, I would expect it to take some time to get back up to their usual development speed. Jared and the other developers are new to the Rust codebase, even if the structure is largely familiar. They're also likely focusing on other priorities right now such as tracki…

They also have made a release, in a sense, since they moved all Claude code users to it a month ago. (And apparently no one noticed). I think they're taking things "gradually" as they are under a lot of scrutiny and no rush for full release.

Claude Code most likely only uses a tiny fraction of Bun/Node features, so Claude Code switching to the Rust rewrite doesn't mean all that much.

Re: How is the Bun rewrite in Rust going?

#65

Post by pu_pe »

I am fascinated by the discourse around this Bun rewrite. I read a lot of drama and personal accusations, there are pieces like this one trying to extract clues, and it seems everyone has a deeper ideological concern behind whatever they are trying to say. For this article, it seems to be skepticism towards AI and how successful it can be at replacing programmers. Other takes, like the one from the Zig maintainer, were also along those lines but more about the open source ethics and the future of that in a LLM world.

I am mostly bullish on AI capabilities, so from my perspective I don't see why we should be skeptical that frontier LLMs guided by experienced devs can translate whole libraries like that. Good follow-up questions would be how expensive it currently is to do so, and whether we will see people branching into all-in on AI versus no-AI camps as happened in this case.

Re: How is the Bun rewrite in Rust going?

#66

Post by tribaal »

irishcoffee wrote: post #50
vessenes wrote: post #46

Earlier quoted context omitted.

Presumably lots of stuff wrapped in 'unsafe'. I'm not a rust guy or a rust fan, and the last time I wrote something with Rust was like 7 years ago, but to my memory, because of how Rust manages mutability there are many access patterns that are Rust-specific; idiomatic Rust is going to use this patterns but they would be unlikely to show up in a language with a different type system / borrow checker / etc. etc.

So "unidiomatic" rust means, 'don't use these parts of the language even though they're first-class citizens?' How odd. Lot of mental gymnastics going on there.

It's mostly the same in any general purpose programming language though, parts of the language features are meant (or became seens as) tools to be used in very narrow cases, which people less familiar with the language tend to "overuse".

Eg. goto/jump, bare "except" statements in python, etc... In Rust, unsafe has its uses and is a first class language feature, but it certainly isn't idiomatic to use it to mimic access patterns from other languages (unless absolutely necessary).

Re: How is the Bun rewrite in Rust going?

#67

Post by jFriedensreich »

rienbdj wrote: post #44
losvedir wrote: post #32

I'm not sure Anthropic even cares about "releasing" the next version. The rust one has been in use in Claude Code for more than a month now, used by millions of people, and that's as far as they probably really worry about it. They bought Bun for Claude Code and I doubt the open source project matters to them otherwise.

Anyone know why? Can’t CC run on any JS runtime?

because their js code is so bad and slow that they need the bun performance hacks and optimisations.

Re: How is the Bun rewrite in Rust going?

#68

Post by furyofantares »

oblio wrote: post #61
furyofantares wrote: post #49

Earlier quoted context omitted.

> I have used LLMs to create stuff like word clones just for fun. It was a disaster. Sure, it had the basic functionality. But the moment you started with page structure (harder then one non-stop scrolling page), tables, images, rotating, and so many details that make up just the basics of word. Not even the extended functionality. You see every LLM just fall on its face. What do you think of https://scramblequest.ap…

Are you comparing 2 relatively simple games with... Word? Word is basically an operating system. Unix people like to make fun of Emacs for being one, but Word is basically one, too. And all the features in there are used, otherwise Microsoft wouldn't keep them around.

Haha, I misread as "word games" and was very confused about the claim.

Re: How is the Bun rewrite in Rust going?

#69

Post by TazeTSchnitzel »

irishcoffee wrote: post #38
reliabilityguy wrote: post #6

Many repeat the point of “$165k is cheaper than team of multiple engineers working on the rewrite for a year”, which I think is flawed — the team of engineers would have produced idiomatic rust, and it would take probably 100k+ of tokens more to make the bun in rust idiomatic rust.

> produced idiomatic rust I keep seeing this. What is "un-idiomatic" rust?

Rust contains the ability to do everything that C can, if you use `unsafe`. And a file-by-file rewrite in Rust from another language usually involves keeping the ABI and API between files very C-like (and unsafe). In practice this means that the result of a first pass this way has all the memory safety of C code, but with worse readability because Rust makes unsafe things less ergonomic.

To actually get the safety benefits of Rust in a real way you have to rework those files to not treat eachother as C code. This is the interesting and the difficult part of a rewrite in Rust, and one that an unsupervised LLM rewrite is probably not even going to attempt.

I don't think this latter stage has actually happened with Bun's codebase. The result of the Rust rewrite in Bun's case is actually less safe than the Zig it is replacing, especially because (I am told) a lot of the new Rust code is unsound (introducing UB).

Re: How is the Bun rewrite in Rust going?

#70

Post by flohofwoe »

davidgtonge wrote: post #22
rk06 wrote: post #14

Earlier quoted context omitted.

bun in zig was used by many companies. some were using it in prod. how many of those are using it in prod? none, because bun in rust is not released yet. Hence, the author concludes that rust rewrite is not complete as bun in rust is not released yet. I agree with author's POV.

The rust version is being used by Claude Code though - which is a fairly large product! I was hoping for more push back against https://bun.com/blog/bun-in-rust - which is pretty thorough and has some decent arguments and reasoning for why they did the rewrite.

How much of the Bun/Node API surface does Claude Code actually use though? Conceptually it's a relatively simple TUI application.
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