alt Hacker NewsZig Creator Calls Spade a Spade, Anthropic Blows Smoke
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I think like most people, I don’t have a problem with Andrew “calling a spade a spade,” even if I find his reasoning motivated. The bigger problem with the post is that it talks out of both ends of the mouth: it’s clearly meant as a personal attack, but also insists that it isn’t.
When I read the post, my first thought was that I wouldn’t want to build things in Zig, because any technical decision I make, good or bad, might subject me to this kind of article from their BDFL. I can’t conceive of the leadership of the Python or Rust or any other community I’ve ever worked with doing something like that.
I stand with Andrew.
As someone who's been following Sumner's work closely for years, Kelley's accusations are very much true even if unkind. While the results are useful and cool, it a wankfluencer op from start to finish. I dare you to refute thus.
And I say all this as someone who does agentic development 8hrs a day and someone who always pestered my team to opt for Rust and Deno instead of Node. Call a spade a spade, the rewrite was poorly justified and one in a long lines of successful psyops Dario and co. cooked and delivered.
Now, would Andrew's message have been better received if it had better "decorum"? Maybe. But I'm glad he stayed honest to himself instead and didn't have a PR team ghostwrite his thoughts. You have to appreciate that.
Did we read the same Anthropic and Andrew Kelly's posts? Anthropic is not in the programming language market; their post about rewriting Bun in Rust is full of technical details that led to improving the end product for their users. Zig's response is a sour opinion piece full of personal attacks.
For context, I'm using Codex and have no interest in either Zig or Rust, so just observing this drama from the sidelines.
What I have been missing in all this debate is substance. I don't care that Bun was ported to Rust; I don't care that Andrew wrote a hit piece about it; I don't care that Anthropic sells shovels in the gold rush.
What I do care about is technical details. Jared shared some motivation as to why they ported to Rust, and I think they look valid (even if provided with sparse evidence). But I have not seen any sort of refutation from Andrew that these are not actually issues or how they should be solved in Zig canonically. I'd really like to see an exploration of these arguments, specifically pertaining to the Zig code as it was written for Bun.
I agree with some of Kelley’s takes, but the issue is the tone.
Does anyone think that if Bun had been rewritten from Rust to Zig that a member of the Rust core team would have written a personal hit piece against Sumner (while pretending it isn’t a hit piece)? Probably not.
Kelley can write what he wants, but as the BDFL of a rising programming language, people are allowed to react if they don’t agree with the public image being portrayed by Zig.
Thank you. I was left confused after people praised the Bun to Rust blog post eventhough it contained very actual technical substance. No clear evaluation of options, very biased report on impact, missing figures. It absolutely didn't feel like an engineering blog post.
Maybe people were more interested in the agentic part more than the actual rationale for the port in the first place, because it was very disappointing from a technical standpoint.
> Management eagerly approved the Rust rewrite option because it was a great marketing opportunity to showcase their new Fable model, Anthropic already uses Rust, and Zig is openly against using Anthropic’s products.
Yeah, don't discount how powerful "marketing" is to management/executives, and also don't discount how absolutely ridiculously petty people can be, especially people who end up like CEOs and similar, requires a particular person. I can definitively see reason #1 and #3 from that to basically already set in stone that Bun had to be rewritten in Rust.
Why are we even discussing stuff like work hour expectations in a story about language switch drama?
Even if the guy is a terrible manager this still comes across as a determined attempt to find something negative to say.
To me it’s telling how little focus there is on the technical merits of the rewrite from zig side. Anthropic claimed a bunch of victories and as best as I can tell nobody has even attempted to refute them.
If I was running a project and someone threw it into an LLM rewrite and it comes out with improvements and silence on downsides I’d be pretty worried and try to address that. Instead we’re talking about working hours somehow
I think the only point that matters is that having Anthropic owning a project which is written in a programming language where the community (or at least the leaders of it) have come out as openly hostile to AI generated code is a clear conflict of interest. I think Andrew Kelley might have been better to say just that and leave it - the comments about Bun's founders energy and motivations don't really add anything worth adding in my opinion.
I really don't understand what Andrew Kelly hopes to achieve here. Even the non-programmers at r/programming who usually piles on any type of anti-AI posts called it out.
I'm trying to not let this affect my thoughts about Zig as a language but it's hard.
The thing is, it's possible to call a spade a spade without resorting to ad hominem. Andrew's post would've been more effective if he focused more on the Rust port being for marketing, and the shortcomings of Bun's Zig implementation.
Instead, the first half of it solely consists of personal attacks.
> From my perspective, Anthropic is the party we need to hold accountable here.
It's insane that Ray Myers thinks that Anthropic did anything related to this port that requires holding them accountable; the fact that he used those words makes me want to prevent him from having any influence over AI policy.
> It would be inconvenient if maintainability still mattered because their products default to making it worse.
I think this is the most important line from this piece.
Incentives matter. The AI companies are incentivized to have us believe that LLMs are the new compiler. That’s ridiculous (a coding LLM is a very very leaky abstraction) but I hear coders, especially coders with poor fundamentals, say it all the time.
This entire AI period has been a study in marketing disguised as futurism.
I say this as one who uses and teaches AI. What fantastic, amazing, unreliable tools. Extraordinary in the right hands, but engines of cognitive and technical debt.
I'm not involved in this community, but I watched Andrew's interview with JetBrains a few weeks ago and I was really impressed. I don't currently have a project that would benefit from zig, but it's a language I want to explore when I have a good use case for it. I view his take as blunt but entirely reasonable.
Bun's rewrite has made me nervous about using it. I do have a project that would theoretically benefit from it, but that amount of vibe coding just makes me nervous. I'm not saying I'd never use it, but personally I'd rather wait for the dust to settle on it a bit. I feel like rewriting to a new language is going to be buggy no matter what (even if the tests pass), but an AI rewrite in a very short time makes me extra concerned. Just my 2 cents.
Also, one thing I want to highlight in the article because I agree hard with it:
> My advice? Don’t work for people that brag about 90 hour weeks. Work for people who will defend your ability to sleep at night.
I used to work in the games industry, where crunch was the norm, and I don't think crunching really helped at all past a couple weeks. I'm not particularly old (early 40s), but my performance falls off a cliff if I sleep poorly or don't practice self care. To me, people working ultra-long hours for marathon periods of time are making a grave mistake. It usually ends up being productivity theater rather than real productivity. Taking care of yourself is really important for being productive.
| how their AI was powerful enough to do this rewrite (even though it was not powerful enough to catch a use-after-free)
This, I don't think enough people pointed this out. We have been sold the "coding is solved" and "software engineering is over" shit by Anthropic folks for a while now. The discourse should have revolved around claude's capabilities and instead it became a Jared vs Andrew thing.
Andrew may be a little bit grating to some (including me at times), but I value the perspectives that he brings.
There is a lot of discussion about the exact tone and phrasing, etc, of Andrew's post. There's something there - we expect perfectly composed writing, never getting emotional, never saying how we actually feel about a specific individual's behaviour. Meanwhile, in private, we often let those emotions fly, name names, etc.
I think Andrew gave us an actual look into how he feels about Jarred -- ambivalent, largely.
Every one feels a bit wrong here.
Zig’s author, Andrew Kelley is out of line here.
> We made futile attempts to guide them towards better programming practices. There were a few exceptional heroes who did their very best in a dysfunctional company. You know who you are. But you can't stop a rising tide.
https://andrewkelley.me/post/my-thoughts-bun-rust-rewrite.ht...
So not only is Zig written by amateurs, but these amateurs also don’t know how to run a company?
Who is Andrew to say this, Oven got an exit. As far as their investors and owners are concerned that’s the only real reason to exist.
Assuming ( big assumption to be fair) all the early Bun employees got a fair amount of equity they’re all rich now. That’s a much better outcome than most startups.
At my first startup we had 6 day work weeks. I still remember staying up until 2 or 3am manually installing Postgres again and again. All we got was a paycheck. Although for me I went from a minimum wage earning college dropout to a 6 figure software engineer( at a new company).
As for actual coding… LLMs will always do better work in a well known stable language than something relatively new.
I had to give up on trying to get LLMs to write working Haxe code. Haxe is too niche for LLMs to handle.
I personally can’t stand Rust, it feels like it’s designed for machines to write. Zig is designed for humans. Outside of a 200k+ job offer you won’t see me learning Rust.
Zig is rather pleasant. I can imagine writing a side project with it.
Finally, my QA background is screaming in rage. You expect me to trust a project that you basically vibe coded in a week as a key part of my workflow?
You know it works because the automated tests ( which I guess you also vibe coded) pass ?
By that logic say I don’t like Rust, can I spend a few thousand in Fable tokens and ship DinnerRoll( Bun in D).
Is that enough to raise a VC round?
I really don't understand what's the big deal here. Anthropic converted Bun from Zig to Rust using Fable and used that for marketing, but do people blindly trust them? Also isn't Zig still unstable and from that perspective regardless of how they did it, wouldn't it make sense to migrate it to a stable language?
Anthropic migrated Bun from Zig to Rust, they probably tried writing it in Zig using AI and ran into issues because there isn't enough Zig training data. A year ago, most LLMs couldn' t code reliably in Rust, But were fluent in Python, C, and web tech.
Wow. Wonderful post; best read this year so far. Lots of gold in this one. I like the way the author slowly undressed the - social media influenced - hype to reveal both Anthropic and Bun as they are: awfully basic
There are a lot of posts going on, but let me just post this link to a specific file of the bun zig code base so you can have your own impression:
https://github.com/oven-sh/bun/blob/bun-v1.1.42/src/bundler/...
My take is they vibe coded too close to the sun
what I don't understand is, given the anthropic narrative, why on earth rewrite bun to rust, and not claude code to rust? why use typescript at all when the whole point is that languages don't matter anymore? I suppose it is solely because it would be a bad look on them to rewrite claude itself - it means they failed - but rewriting bun is a much better narrative - claude is fine! it's just his runtime we need fixing. and here is that token heavy story!
so weird people are not commenting on this.
it's like.. I dunno, rewrite linux in rust, because bun uses glibc, this will somehow make it better, so claude code somehow can run better?
hell, start with UEFI.
I think two things can be true at once....It was obviously a great marketing story for anthropic but that doesn't automatically mean that engineering work had no value. Companies have always turned interesting technical projects into marketing.
if I had to pick a side, I would pick Andrew but I don't think his side matters as much. IMO, it doesn't matter the technical reason why Jared ported Bun, it's his project, his wanting to do so is enough. I think the issue is that Jared turned it into a technical subtle reason of why "Zig is bad" without meaning to, and Andrew goes on the defense.
All that said, the coolest thing is that Jared did so, I don't care if it came out a bit worse with Rust, the interesting thing is here is what can be done with AI/LLM/Agents today. Yes, it might be worse, but on a reasonable enough timeline, it will get better. Folks get upset about these things. I did AOC in 2024 with LLM, my goal was not to top the leaderboard, but to see how good LOCAL LLMs could keep up. I did it with Qwen2.5-Coder-32B locally, and solved about 50%. Folks were often upset when I shared that, called it cheating, etc, even tho I often started about 8hrs after the competition due to timezone. It was so good, I suspected the cloud models would probably solve 75-80% and I concluded after my experiment that in 2025, LLM can solve it 100%. I didn't bother to try and the models were an order or magnitude better locally.
No matter the take on AI, they are very capable tools and we are only beginning to figure out how they can be used. I don't think we should stop, surely it's frightening on what that would mean if it can really "takeoff". This fight is multi layered, Zig vs Rust, Writing good code vs bad code, having good development standard vs not, being honest and transparent in technical disclosure, attacking Zig vs attacking Jared, AI good vs AI not, etc.
This paragraph is written by AI. I did not notice it earlier in the piece:
> The piece about the migration process is very cool, with details that are reusable. No complaints, I think that’s the real contribution here. I particularly like the honesty in explaining that this was a port to unsafe Rust, allowing a literal file-by-file migration to minimize risk, paving the way for redesign in future steps. That’s a sensible move explained well.
Sarcasm hat on - You know what, if LLMs were so infallible at coding and engineers useless for hands-on, then why even bother with anything except asm or even skip the mnemonics completely and go straight for the binary? Why even bother with abstract code when abstraction is now your LLM.
By far the most satisfying piece I've read in this saga. Favorite line:
> I’m not the one saying that their environment resulted in a buggy unmaintainable mess, Bun is the one saying that.
I have found myself wondering a lot lately about the alternative universe where all the effort and resources devoted to developing and using AI coding and debugging agents were instead simply dedicated to fuzzing human-generated code. How would the code quality and total usefulness of the results have compared?
Zig creator's article seems to have changed? I don't remember the bottom bit being there when I read it a few days ago.
> Ray’s story: Faced with a legitimate challenge of memory bugs, there were several viable options. Management eagerly approved the Rust rewrite option because it was a great marketing opportunity to showcase their new Fable model, Anthropic already uses Rust, and Zig is openly against using Anthropic’s products.
Kinda makes sense. They also tried to make a C compiler earlier in the year. Idk what happened to that.
I guess it's an experiment without much downside for Anthropic, if it works use it to make a point about AI assisted coding - if it doesn't bun users will learn a costly lesson but who cares, it will just be another case study to make their product better.
That said, I think it'd be great to see this actually work out.
> we still need good judgement and communcation in deciding where to go
I want to emphatically endorse this statement.
This is where the human workload will shift to: making good decisions... understanding why one path is preferred over another. And collaborating and communicating in constructive ways. More to the point, humans excel at being able to recognize when a chosen path is no longer fruitful, or where a conversation devolves into the unproductive.
We are constantly making decisions based on tradeoffs. We choose one approach over another, not so much because our chosen path is obviously superior, but because the peril on our chosen path is preferential to the peril on a different path.
I have used ai to great utility in my design process, to help me understand the tradeoffs within any given endeavor, greatly helping in choosing which path to take.
Thus far, I haven't seen an AI which can unilaterally be relied up on to always effect "good judgement" for the work it is tasked with completing.
But once good judgement, and the correct path, is codified in markdown files, ai can be exceedingly efficient in carrying it out.
The thing is - is it a self fulfilling prophecy?
We already know junior hiring an are down. And how many people are now excited to learn to code compared to 5years ago?
How many of those excited people are ACTUALLY learning to code and not just learning to prompt?
LLMs/agents will take over (or at least dominate) software dev even if they don’t get any better because humans will just get old and there’ll be no new humans who know how to do it.
Not to "glaze" the author as the kids say but this has to be one of the best written musings I've read on HN in a long time. I'm likely bias because it's written in "my style" but I feel like it's a rather fair and balanced approach to a nuanced and socially difficult topic.
I agree that both Andrew, and the author have numerous good points, and yet I see things differently.
- I too am a fan of Andrew, and Zig, although all of my future plans currently are tied to Rust.
- I think the crux is that we are talking about 2 Vibe-ish AI rewrites, one to Zig, and another to Rust. I believe the investment in both reasonably minimal beyond the cost of tokens.
- I think that more adherence to a Zig style guide would probably have been very beneficial to the final work product.
- I have high expectations that the Rust rewrite will yield a more stable work product out-of-the-box. I am looking forward to the post-analysis.
The more I interact with the real world and mature as a person the less respect I have for temper tantrums such as these. Even if everything you say is correct, coming across as emotional and petty just does not help your case. This just makes Zig look like a zealot fighting a turf war rather than a serious ecosystem.
"We wrap LLMs in Agent harnesses because AI isn’t enough."
This feels equivalent to saying you're not a real coder if you need a compiler to hold your hand. What, a human coder isn't enough?
Of course we're going to improve tools by building more tools on top of them. That's how we went from punch cards to assembly to high-level languages!
> Anthropic is actively campaigning to end software engineering
While this may be slightly overstated, my take on this is that AI progress should have us upgrade our view of the human brain rather than the opposite.
Wrote about it the other day:
https://livingsystems.substack.com/p/ai-progress-should-upgr...
In this whole discussion of what can be done with AI, I think a lot of people are missing the distinction between:
A. making consumer end-user apps, basic enterprise applications (making end products)
B. making tooling, libraries, languages (making things people build on top of)
What is the "software engineering" that AI will replace? A? Or both A and B?
Just because people can get away with using AI to make A apps that are "good enough" or pass test suites, does NOT meant that therefore people can get away with doing all software engineering with AI. B products require a whole other level of quality, stability, and extensibility.
I'm not saying doing A with AI is a good idea either, I just think that it's a fallacy to say that because you can do A with AI, you can do B.
I don't agree that Anthropic's position is AI is all you need. My interpretation is that it's about developer acceleration. I've been following their messaging closely and it's not that you can fire all of your developers. It's mostly their developers saying they are somewhat more productive. They have published papers showing that productivity gains are uneven.
I remember the uber db migration post and I can't help but wonder if the tone of these conversations would be different for bun if AI wasn't involved.
https://www.uber.com/us/en/blog/postgres-to-mysql-migration/
Interesting article, seems more balanced than Andrew Kelley's one that it links to.
The thing I still think is wrong: why are Anthropic rewriting a Javascript runtime from Zig to Rust? Why not rewrite Claude Code itself in Rust (or Go or whatever, lots of options there) and drop Bun completely. That actually seems like an easier solution (rather than having to create a performant, correct Javascript runtime, just rewrite your CLI console app in something else) and the final result is better (smaller and faster) although likely not on the most critical axes for them.
"A lot of reasonably good coders have never seen an example of a good manager, and have all kinds of weird ideas about what management is."
Banger of a quote that one.
I think Anthropic is putting too much time and energy into marketing (and politics) while competitors are catching up on the engineering side.
But what do I know, maybe your CTO bought this and now wants to fire half of the dev team and use Claude to convert your COBOL codebase to Rust...
I think Zig being a new and a low-resource language (not enough training data) is also one of the reasons Bun decided to use Rust as large language models will simply not be as good no matter how good the model is.
Anything that can be written in Rust will be written in Rust.
I'm using Rust as a placeholder for a language with excellent performance and safety characteristics. It may not be a good thing, but there's no way around it.
Those problems are partly attributable to Zig itself. If the project accepted AI-assisted contributions, this controversy might never have happened. Completely shutting out one side of the industry and taking a dogmatic position is not helpful, especially for a pre-1.0 language that is still relatively immature.
Now the Zig community is attacking one of the largest and best-known codebases ever built with the language. Anthropic’s motives are clearly promotional, but even so, I would not choose Zig for any project.
Great Article. I appreciate the amount of detail you went into here to give everyone a fair hearing. Will there be a recording of your talk at the software should work conference next week? Thanks!
Oh, they're converting Bun to unsafe rust. That's easy, but useless. That's the sort of thing c2rust does - transpile to an low level language which is unsafe Rust with a set of functions that unsafely emulate C pointer semantics. You don't need an LLM for that.
There's no point. It's not doing the job DARPA's TRACTOR program is trying to do - translate C to safe Rust. I've used c2rust. It works, but what you get out is like compiler output, not something you can work on.
> In the AI bubble, we are pressured to build things nobody wants, poorly. Pop the bubble.
I'm sooo waiting for this to happen. I miss the old times where simplicity, clarity, and good architecture mattered.
There's so much good stuff in this post.
Can't help to think of a recent HN post about most AI-generated projects being abandoned within months. Why?
Because value of a project is not in the code produced. It's in the amount of battle-testing that code has seen.
Battle-tested, mature code > fresh rewrite.
Existing Zig codebase has seen X amount of battle-testing. Rust rewrite: 0 (except -I'm assuming- passing test suites). Also:
"this was a port to unsafe Rust, allowing a literal file-by-file migration to minimize risk"
How is that better than the Zig codebase you started with?
Now if that's further migrated to safe Rust, put into production & gathered feedback from lots of users, yes then you have something. As it is, the impressive bit is do such a big rewrite & result seems to work ok. Are Bun users happy with this?
To me it reads like Bun was forked. Will the Zig version survive? Will the Rust one? Both? All options ok.
Edit: and fwiw, I don't think Zig community should get triggered on any of this. It says nothing about how suitable Zig is or isn't for project xyz, and Zig community is big enough to carry their own project & applications besides Bun.