All of this is just a (succesful) marketing stunt by Anthropic.

A garbage collected language does this automatically. Rust still requires thinking about and tracking memory lifecycles, but the borrow checker will complain and keep you from doing it wrong. That's why LLMs like Rust. It gives immediate feedback on what to fix. By-default constant reference parameters helps prevent major performance problems.

Even with the huge amount of "unsafe" rust currently in bun? https://news.ycombinator.com/item?id=48967630

You can just do that, and then Zig is really no less robust than Rust. But if you want to do "managed language" style allocation patterns (like what llms generally prefer), it doesn't make sense to use it.

Is this because Codex is written in Rust and not JS? I dunno. I think it's more just "lighter" in general, or it certainly feels that way. It's probably possible to make something with a similar feel in JS, just perhaps not with the big honking mess they've created.

Anthropic seems to be all in on 100% AI code.

When I started, I discovered to my shock that it was by far the worst TUI I had ever touched. Rendering glitches, keyboard input screwups, and just all-around jankiness.

Despite that awful baseline, I have to agree that it's gotten noticably worse in the past week or so.

It's started mangling my terminal sessions somehow, so that not all characters I input are visible in the UI.

Backgrounding it, doing a 'reset', then re-foregrounding seems to fix it.

Of course when I asked it to diagnose the problem, it assured me that Claude has no such big and it must be something else I'm running.

All I'm running is tmux and Claude, though, and the behavior surfaced while I was running Claude.

So, yeah - if they just recently updated Claude to use the Rust rewrite, this increased crappiness might actually be due to that. It does seem to at least roughly correlate.

"At the time of writing, about 4% of Bun's Rust code sits inside an unsafe block (~13,000 unsafe keywords across ~27,000 lines / ~780,000 lines), and 78% of those blocks are a single line — a pointer that came from C++, or one call into a C library. I expect this number to go down over time as we refactor from a faithful Zig port (which had no greppable unsafe keyword) to idiomatic Rust, but we are going to continue using C & C++ libraries like JavaScriptCore so it will always have more unsafe than pure Rust projects."

It was unpleasantly surprised when I learned the hard way that LLMs are not much better at translating than writing from scratch.

The more you look into how they work, the more you see that it doesn't really give them a huge advantage, if the classes are big enough. You can tell them to break each function up and translate them one-by-one, but the errors compound, you can't test most of it until you have a lot done, and in the end, it really isn't much faster (and sometimes it seems to be a lot slower) then just telling them to start over from scratch.

The downside is... If you have a system that already works, you don't want to start from scratch and test everything all over again...

Heck, a buddy and I once chatted about the likelihood of k8s running as the control plane in a prototype autonomous vehicle.

top/btop/htop on the mac are always fun to run and see what's up.

Proves LLMs don’t help with taste.

Claude Code isn't the only user of Bun (it's probably not even the only user of it internally at Anthropic), and this way they get to keep the Javascript runtime (and other tooling) that their coding models may one day, if not already, prefer to use when given the opportunity. For those kind of apps, you'll probably also eventually find that--what do you know!--Anthropic also has their own cloud offering (instead of Bun being the one to build one) that specializes in running and managing those applications for you. Even if all they get is a community of developers that choose to use Bun over other options, that gives them power and seats at tables they wouldn't have if they just rewrote Claude Code in Rust.

That'd be my best guess, anyhow.

The same tool, in the hands of someone that doesn't know how to handle it? I'll let you finish that

Basically, a good developer can handle the tool better by asking the proper questions, setting good guardrails and tweaking the output where needed

I actually used to have issues with run away memory leaks causing my computer to hang which often required a reboot to recover from. I haven't experienced that in a couple of weeks now. Too early to say just yet but I think its definitely possible that the rust port fixed a bunch of memory leaks that have tangibly improved the experience atleast for me.

It becomes completely unresponsive to any input except scrolling. I can't select options or even cancel out.

(I am in no way implying this is related to Bun)

Of course they’ll iterate and remove the unsafe bits which were necessary for the transition

It's not about making the dev experience better than node, that use-case is now secondary.

Now it is a Deno clone, both without anything enticing over node.js.

At that point, even Bun itself doesn't matter. All intermediate tools don't matter if LLMs can reliably write something large.

The problem is that LLM is not quite there yet. The rewrite was only possible because they mostly stick to 1-to-1 translation resulting in non-idiomatic Rust code. So, what from there? I don't think they can really build up a sane codebase from that state. They only shot themselves with a bigger gun.

I cannot take this seriously as tutorials on robust Zig Allocation Pools will store a deinit method for each item within the pool, so when the pool deinits, all internal objects can be deinit'd.

That is just RAII & dtors from first principles, except with extra overhead of manually storing fat pointers yourself (and the bugs that come with this). Instead of using a language with builtin guarantees & optimizations around handling this so your object pools don't need to carry around a bunch of function pointers. C++ has aggressive de-virtualization passes so at runtime a lot of the 'complex object hierarchies' can be flattened to purely static function calls.

Though most will be forgiven to not reading it since well it's all AI anyways. I don't know how I feel about all this yet, maybe someday.. ooof

They chose it early on, it works, and it makes obscene amounts of revenue. End of story. That doesn't mean it was the "greatest" choice, or has a perfect technical architecture.

Rewrites are never easy, even the bun rewrite. But a non-UI developer tool with a rigid API surface contract (and associated tests) will always be easier to trust after a rewrite than a partially tested UI tool with ambiguous functionality.

I'm sure there was some logical reason for shoehorning web technology into this stack given that we have a good 40 years or so of experience with interactive terminal programs that use curses/ncurses, alongside emacs, vim, almost the entirety of MS-DOS, and so on.

I suspect user facing/fast moving code (UX layer) will move to dynamic systems with fast iteration times. Infra layer will move towards safe systems level environments like Rust. I'm not sure where Java/C# lands in all of this - it's kind of the middle ground between these two worlds but the tradeoffs change drastically with LLMs - my gut feeling says that TS/Python is good enough for UX work and Rust is better for systems work so it gets less popular going forward.

[1] https://avi.press/posts/2026-07-10-after-7-years-in-producti...

Yeah, good question. OpenAI decided to rewrite Codex in Rust about a year ago[0].

In fact, since rewrites are that easy, what do we need Bun for? Why doesn't everybody just port all of their Javascript code into Rust?

[0] https://github.com/openai/codex/discussions/1174

I've read and heard in videos that Javascript is a pretty good language for AI to write code in. Apparently this is because there is so much training data out there. Also Javascript avoids problems of multi threading and memory management that can mess up the AI in other "more performant" languages.

So maybe Javascript is not the worst choice for writing software fast with AI

I think a JS runtime is fine because the ecosystem of tools is very large and plugins are easy.

Then you must know that the hardest part of software development is getting clear requirements...

> everyone on this planet could create a software for themselves exactly as how they wanted

Even with perfect AGI this will never happen because people will never be able to express clear requirements

Incredibly naive take when these models are closed behind (for now subsidized) paywalls.

This "democratization" argument is so nauseating, seems like the Bun port to Rust as a marketing piece (the primary motivator) sold it well!

If nothing prints "Segmentation fault", this just sounds like a hang

Is all you need to know to consider how much of an abomination it is

“bun the JavaScript runtime ” is not dead though.

But this is HN, a subsection of which places a high importance on what language something is written in, moreso than what it does (feels like).

I feel weird having to defend reality; reality being that it was merged nearly 2 months ago and tons of people have had their pitchforks out without a shred of actual evidence that this made bun worse in any measurable way. But they still insist it was a mistake.

I’ve never met Jared or the bun team but I don’t understand all the personal attacks, I just feel the need to correct the facts. Literally who cares what language a JS toolset is written in?

It’s not like they ported JavaScriptCore (the actual JS runtime) to rust even. All that stuff is largely untouched.

Claude Code seems to be an insanely complex program will all manner of cutesy features and telemetry features. The net result is approximately the same as Codex, but it’s pretty common in software engineering to find a simple thing and a complex thing that do more or less the same thing.

(I was actually half way through writing about something related, when I thought it would be interesting to see if I could prove that I had the Rust version of Bun on my laptop already.)

Faster startup

Typescript support out of the box

Better stdlib than node

Stdlib includes yaml, sqlite etc so you need to pull in fewer deps, so you can avoid the left-pad/is-even node_modules explosion problem to a greater extent

> If projects like Bun can be substantially rewritten and shipped to millions of users, it suggests we're entering a very different phase of software development.

exactly. this wasn't a technical project. this was a marketing stunt that worked on you.

Much less fragmented compared to "write the app 3 times in 3 different languages".

In Chrome or Firefox, a segfault is usually automatic CVE and in most cases a bounty of thousands of dollars…

Also GHC has an interpreter. It powers the REPL. No need to compile everything if you’re just experimenting. I do find that in the Haskell world the REPL is criminally underused compared to Python.

And the rest of your comment doesn’t make sense; this shop is rewriting their infra (not UI) from Haskell to Python.

You can make anything work when you have enough money to buy and radically change the entire runtime you’re relying on.

One must suspect that if they did not have insane amounts of money to burn, they could have tried other approaches to fixing the problems. Maybe engineering, perhaps.

The latest frontier models are competent at Rust and Swift and all manner of other less widely used languages.

The more important factor is how good they language's compiler is at kicking out actionable error messages, since one-shot code generation isn't as important once you have a coding agent loop.

With js you get 1 thread at 100% utilization. Power usage and heat scale non-linearly with cpu utilization and 100% utilization on a single threaded js app means you will have ui lag. Other languages like golang would split work across 8 threads and have 8 threads at 20% utilization and this would result in less power usage. Claude Code would have been better off performance wise being an electron app because it would be offloading rendering to the browser and gpu.

Also, the architecture of Open Code is actually a lot better here than Claude Code. ClaudeCode does everything, including rendering in a single thread and it's all in js. OpenCode has a zig based tui renderer it offloads that work onto.

But I will also say these coding agent tuis do get unfairly maligned because they launch subprocesses and those subprocesses tend to be expensive. If you are using Rust analyzer with claude code, it's rust analyzer that's causing the majority of your problems.

From what I could tell it looked like it was in JS code that had been JIT compiled. I haven't attempted to troubleshoot further beyond setting all my future Claude Code instances to pipe their stderr to disk so that I don't lose the stack trace next time.

Here I would just like to mention that if you have to rely on "de-virtualization" passes, you're in a miserable situation architecturally. If you have code where the overhead of virtual function calls might be too much to pay, don't do virtual functions then. End of story.

To deconstruct a pool of objects, I don't see what should ever be wrong with a function pointer. The overhead of loading the function pointer will get divided by the number of objects being deconstructed. Care to explain what's the issue here?

We'll develop faster and better tech. We'll find resources to feed that. Use that to build better. Access better resources. We'll mine asteroids. We'll harness much more from the sun. The factory must grow.

That’s patently false, just read Jarred’s own blog post describing how that was the first stage only, they went through many more to get the amount of non idiomatic, unsafe Rust code to an acceptable level.

It would have made far more sense, for reliability, efficiency, cost, etc., every metric really, to use or write a source to source translator that preserves as much structure from the original code as possible. Typically if you do a rewrite there are lessons learned from the existing code base that you want to take into account when doing the rewrite; using a bunch of agents to do the porting file-by-file buys you none of that. In either case the code will be an unidiomatic translation, just with LLMs you get an added source of indeterminism and a huge bill at the end of the month.

Eventually? I am sure they would agree. Currently it's you (and lots of people like you) who are doing the supposing, not Anthropic.

Programs which need more stability and performance than exploration are better done in statically typed languages like Rust. Therefore Bun is a platform for JavaScript programming, but itself is written in Zig or Rust.

It is rarely the case that technology choice is the make-or-break when it comes to whether a product is successful and achieves widespread adoption. Some choices are less ideal than others, but at the end of the day if you manage to make something that people want, the rest won't matter much.

If you have unlimited access to the magical development tool, then why would you not?

But they haven't.

Oh, that's buggy too. I just tried Claude Code on win10 powershell, and the first typed character goes in the wrong spot and can't be backspaced.

It is by far the the least reliable program on my machine, and every time I have to interact with it I feel like walking in eggshells.

The secret is individual humans are already largely irrelevant to our society. That's how we got here. The trend will only continue.

And the question of “if AI is so amazing, shouldn’t it enable easy development of a native TUI even if JS is easier at first?”

Don’t get me wrong I find great value in coding agents daily. Just finding the hype cycle tiring.

And I can believe you because I’ve seen JavaScript-heavy Safari tabs crash.

It's true that we don't know exactly which, and whether or not there are any other changes added on, but that is the case for every single release of Claude Code that has used bun.

Stay your pitchforks.

Maybe you're being coy by asking a rhetorical question you already know the answer to but I'll answer as if you asked sincerely...

There are 2 different groups interacting with software products:

(1) end-users : this is where the "Who cares what language it's written in?!?" is usually applicable. E.g. The finance guys using MS Excel don't care whether it's written in assembly, BASIC, or C Language.

(2) code contributors and/or programming language enthusiasts who see other projects as "validation" of the whatever language they've invested in: these people definitely care.

For all the decades that computer languages have been debated, Group (2) will always discuss projects language choices. E.g. reddit.com switching from Lisp to Python, the Linux kernel fiercely debating future Rust contributions , the Typescript compiler switching from Javascript to Go, Bun switching from Zig to Rust, etc.

People try to lecture others in Group 2 about "don't make a programming language your identity" ... but people are human and they can't look at all the above language choices as totally detached observers. They like to talk about it!

If one is a Zig coder that contributed to the previous Bun Zig codebase, we can't expect them to be neutral observers.

Issues on GitHub was mass closed claiming zig is no longer relevant without fixing the real issues.

And like, this is just the beginning of the port. They did a mechanical port basically line by line, next step is to make it idiomatic rust.

I thought by now people would’ve learned to stop betting against this rewrite.

Or those choices just don't matter, it's fundamentally just "tabs vs spaces".

This is a spectrum, it's not just 0% vs 100%. Even Fable frakked up a few things really badly in my professional work (though to its credit after a very detailed 2h chat it self-corrected and fixed all the blunders).

I would also challenge "fast" -- Fable (and I assume Mythos) are wicked fast and efficient and even they can't compensate for f.ex. slow recompilations or test suite reruns or security scans, linters etc.

Reminder that the Bun's Zig-to-Rust rewrite took 11 days with dozens of agents working 24/7 and the author put the cost they'd pay (if they had to pay) at about $168k.

Cheaper, but not free (if you don't buy into the marketing promises too much). The bigger the project, the bigger the cost, even with a discount.

At the same time, the early versions weren't very good and you can be sure that any rewrite will also need to be similarly iterated upon until it is also good enough and polished.

If you do that and don't spend enough effort on making it be something polished --> your competitors have a better product and you lose.

If you pause feature development to give enough effort to the initiative, you don't get to add new features quickly enough --> your competitors have a better product and you lose.

Maybe their priorities lay elsewhere, like how I've noticed that the desktop app version of Claude Code has gotten both faster (no 2-4 second lag when switching conversations), more stable and usable over time, to where I enjoy using the models because of it, not in spite of it (though not that they haven't had bumps along the way, like that one cache invalidation issue, or how people didn't like the auto accept timeout thing). I don't doubt that you can get pretty far with gradual patches and improvements, instead of only big rewrites.

Honestly it's really cool for me to see Kimi having their own CLI too, same with OpenCode, Pi, Hermes (well more of an agent than just a coding harness but you get the idea) - there's so many competing solutions out there, each good or bad in unique ways.

Just wish we'd see similarly many GUI solutions, for now OpenCode GUI seems like the one I've settled on (cross platform and supports most models), though it's not exactly ideal either (feels a bit barebones, especially in regards to sub-tasks and progress/plan tracking, even ZCode seems a bit better in that regard, it was actually surprisingly good after they pushed out some updates).

This does not even speak to it pegging my CPU and keeping the fans running on full blast even when the laptop is supposed to be idle overnight.

Like Ada or Ocaml or Haskell or something.

Or even require like MC / DC testing or MISRA C verification.

Or even some of the languages that apply Hoare checks, like Ada SPARK or FRAMA-C or VALE or whatever.

I don't have the budget to test how that would work but it seems interesting.

Bad coding is just bad coding.

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ChatGPT written script for counting here: https://gist.github.com/simonw/b1015bcadcedd1a781cedb7af9cbb...

As it is now, your post is meaningless to me.

So, from the start, people will be skeptical of a "we rewrote xyz in Rust" because it rarely works out. But there's a lot more to this, in fact it's a little bit loaded with "tech bro" ideas:

- Rewriting in Rust

- Rewriting using AI

- Making terminal apps in JS

- Zig (a lot of people's dear language) is involved somehow

This attracts every single skeptical developer. The only thing missing is maybe blockchain, if that was still cool. It just hits all the "what? why?" spots.

I was already writing a comment, when I realized that what I wanted to write had already been said by the top comment. I suppose that's why comments read so similarly.

I think even this is largely beside the point. The acquisition of any project by Big Capital (whether tech or VC) is usually a killing blow.

At this point, charging is the least of your issues.

Tabs vs spaces makes no tradeoffs. Tech choices do

They couldn't even fix flickering in their TUI and their new renderer is complete garbage.

They succeeded despite their tech.

You could test this by running "yes > /dev/null" in Ghostty. In Activity Monitor on my Macbook it shows `yes` using 100% and Ghostty using 0.5% of cpu.

I don't see why either of those would be true. The project isn't dead just because it's in a different language now, and for liveness purposes it doesn't matter how it got to that different language.

Anthropic, apparently, not the least because they blanket-closed all issues submitted before the rewrite. If the language were irrelevant, it shouldn’t matter for the existing unfixed issues.

Now it's smaller, faster and has fewer bugs. Also its every potential memory issue is neatly annotated by an unsafe block so you can go and refactor them out one by one with confidence.

All this seems like a pretty huge improvement to me. Why is this an abomination in your eyes?

> What is the governance structure for Bun by the way? Couldn't find any documents/explanations about how it's supposed to work. I'm guessing it's essentially just "Anthropic decides what gets done and accepted" today?

And this is a valid question. You are not "defending reality" by refusing to listen to it.

In summary and based solely on my understanding:

- Jared misled people about the intentions of the migration. It's not the worst thing in the world, but it's certainly worthy of criticism.

- Jared has commented before about locking out human contributors from open source projects. Whether he was making a larger point is irrelevant as his comment stands on its own.

- Other Bun contributors, past and future, outside of those employed by Anthropic, did not and likely will not have equal access to the model Jared used for the rewrite.

Jared, working in the public Bun repository, used tooling not available to his community to experiment with a signficant migration. He dismissed all concerns and told people it's just a bit of fun, and that it shouldn't be taken seriously. Most of the controversy would have been avoided were the experiment done in private.

None of this is a big scandal but questions about the project are entirely justified.

Is there a huge need to run that typechecking on browsers?

This is even more interesting given that prewar Bun was not a well respected code base. This matters if the code was bad, were the tests bad / not comprehensive as well? If so, the translation to rust whose sole / primary target was test-passing will have a fair amount of undocumented bugs in it.

> poster child for Zig programming language actually being the prime example of How Not To Write Zig Code

https://andrewkelley.me/post/my-thoughts-bun-rust-rewrite.ht...

I think it’s valid to object to. If 1.4 is good enough to be used by Claude, why not us?

This is just blatantly ignoring all of the glaring issues Claude Code has had over its lifespan.

> The most recent release of Bun on GitHub is currently v1.3.14 from May 12th, so that v1.4.0 version number in Claude supports them shipping a preview of a not-yet-released Bun version.

> And so, the FOSS project "Bun" silently dies

There’s no implication that it’s because of the switch to Rust.

Billions of dollars of annual revenue go through Claude Code, and the people who work on it must be a lot of millions in headcount.

The time matters a fair bit, it's probably time someone can't spend breaking things in the name of new features, but if rewriting the stack had even a tiny impact on retention or driving higher usage, it would pay back that $168k.

Does anybody really believe that it only took 11 days, one engineer and $168k in tokens?

I am 46 y/o and still excited to code and solve problems with code and I still have trouble to admit to myself sometimes that people make dozens of millions with PHP and the tech hardly matters when you can throw bodies at the problem (and when that throwing of bodies at the problem actually solves it, of course).

Most people would choose to swim a lap through a pool of pee to get a billion dollars at the end. The pool of pee itself wasn't the once in a lifetime opportunity (for most).

Sorry, I'm bad at analogies.

This isn't a minor nitpick, it's a pretty major UX issue.

Not saying it's like a massive business downside because I'm just one of a few users, maybe this affects their bottom line a little bit, but probably not by much.

Regardless, switching to pi has been a nice breath of fresh air. It just renders well and smoothly and handles terminal resizes well, which is especially important when used in a terminal window in PHPStorm.

In 2 years? A well-engineered TUI could be the difference between the Blackberry and the iPhone for all we know.

For an entity like Anthropic that's not even the cost of a single developer for a year. It's closer to what they pay a chef on premises.

That the showstopper for a better Claude agent is that they'd need to pay $168k or event $1M or even $10M in costs, can't be used as an excuse.

You can see my list of previous weekly blog sponsors here: https://simonwillison.net/dashboard/sponsor-history/

None of them get any influence on my content. That would hurt my credibility, and my credibility is the reason my site is worth sponsoring in the first place.

Honestly, if OpenAI or Anthropic offered to sponsor I'd probably turn them down. The optics of taking sponsorship from companies that I frequently write about are not great.

Why would it be harder and/or more time consuming rather than the opposite? It's like having full specs and a full test-suite to match against the result you want.

I don't know how you can't see it, to me it's blindingly obvious: risk aversion.

Let's say the risk for a problem is 1%; hell, let's put it at 0.1% even. For a company at this scale even that amount of risk is too much.

I trust Opus/Fable to drive prod database migrations and backfills. I don't trust it with our financial ledger. I trust it with part of the infra. I don't trust it with backups. Etc.

You and others are arguing against a premise that nobody defended, namely "Claude can rewrite everything, for free and with zero mistakes". A bit of a straw man, don't you think?

And that's not even touching the fact that writing a GUI app is difficult for LLMs due to difficulties in it getting feedback and a "feel" whether it delivered what was asked (though I know people are working on it).

> I think I am willing to take it as an axiom that a native version of CC would be superior from a user perspective. Performance, etc.

How does that follow, and from where? I never once noticed any visual jank/lag in the TUI; not in iTerm2, not in Kitty, not in Alacritty, not in WezTerm and not in Ghostty. And even if we exclude those two, me and many other devs are quite fine with a TUI and don't miss a GUI program for everyday coding.

Not saying that our preference is superior -- but it'd be strange to blatantly claim: "for dev purposes, GUI > TUI/CLI".

from strings:

   bun-v1.4.0
   f6d0fcd24abd48061873c2f1a6fb2a67eee487b8
    Upgraded.
   Welcome to Bun's latest canary build!

(In contrast, earlier builds that I have locally have commit IDs that can be found in the public repo). I don't think it's particularly damning for them to vendor a canary release, mind you.

1. You're writing code you don't have to

2. That adds runtime overhead

3. That when you screw up has non-trivial security & resource management side effects

This is objectively indefeasible in nearly any vaguely professional context.

Edit, the sonnet question shouldn't be taken as proof, it knows I'm a rust dev.

It's also all cpu bound work. The majority of the stuff on your screen is being rendered by the gpu.

the era in which the tech industry built software to last was over long before LLMs, especially VC-backed startups.

> they need a high powered game engine rendering loop

Don't believe the bs on twitter. Claude code source was leaked, there is no high powered game engine rendering loop.

> It needs to stream text to stdout

These apps are doing real work taking text that is streaming in and doing syntax highlighting, calculating diffs, and rendering markdown. If the work was split across threads they would not use anywhere close to as much power and there would not be a slow ui.

If you think this is actually nothing, prove it. Put the code up on github that shows taking a constant random stream of markdown, code, and diffs and displays it in the terminal can be done cheaply on a single thread.

The reason the computer gets hot and uses more power is because the cpu is getting close to 100% utilization.

As with all transpile ports, the true test will be how well it can be extended and maintained over time. Historically working with the output of a transpile is not pleasant and requires heavy rework to get it to the point where you can be comfortable enough to extend it.

The existing community is now either going to need to learn Rust or new Rust developers are going to have to join the project and they may not invested enough to refactor the transpiled output when they could work on something else like Boa.

A full rewrite in different language that fails to be idiomatic is a step backward operationally, even if you stand to gain on issues the new language just eats for free

In the current world of cyber weaknesses everywhere, infrastructure must be solid and rust is a better choice than zig for something like bun.

In other words, bun is not a demo of zig programming that happens to do useful things. Bun does useful things, and must do them securely. That is its number one priority, language is secondary, inasmuch as it helps doing useful things securely.

You just AI generated 1 millions lines of code claiming it's for safety. Who exactly is to make any kind of security guarantees about this?

There are not nearly enough disenfranchised Bun-on-Zig contributors to make a dent in this conversation. There are lots of Group 3s in every similar convo, for any combination of technology, project, and acquirer you can name.

> Rob Pike, an unsafe guy, may insist that a small language and garbage collection are enough. But the typesafe visionary Grzegorz Wielbodłąński understands the deeper truth: every invalid state permitted by a compiler is a tiny act of civilizational sabotage.

https://x.com/typememetics/status/2078572052680790237

There is no sense pretending anymore that languages with as many gotchas as C and Zig are "simple". Quite simply, they are not. The complexities lie in what's left unspoken, unaddressed, and of course undefined; failure to comprehend these completely can be catastrophic. Rust is so thoroughly and obviously the correct thing that using anything less correct should be taken as a sign of engineering incompetence.

If anyone else did that on HN, they would be accused of slop with their domain blacklisted.

You can tell what will happen when they release it before sorting out all the new bugs introduced by the not-exactly-line-by-line port.

Jarred used many agents and they worked 24/7. It tracks for me.

So yes, I do believe it. What makes you skeptical?

Never had to dig through the xterm bug tracker to figure something out. I don't even know what version I'm running, or even what the versioning scheme looks like. I haven't changed the configuration since the first time I set it up. It just works.

Or many billions. eg. Facebook was originally written in PHP.

As a 52 y/o who cares deeply about software development as an art I don't have trouble admitting that the tech hardly matters relative to the economics, that was obvious to me very early in my career.

I have just never really cared because there has always been a path where you can have a decent career being paid to work on and with good technology in spite of the fact that the technology wasn't important to the economics.

I do fear that the rapid adoption of LLMs will probably cause the path I took to narrow considerably. There will likely be less companies willing to pay people to work on elegant technology when they are all competing against endless code generation machines (and this is assuming software companies can exist at all in this future). But at my age that's more of a concern for younger people than me.

The major open harnesses are in the ~800k lines of code size ( https://simonwillison.net/2026/Jul/15/grok-build/ ) and CC is the oldest and quite-likely largest judging by features.

[1] https://news.ycombinator.com/item?id=48967630

Similar to the Claude Code 60s timeout incident [1] it could just be "Jarade decides what gets done and accepted"

[1]: https://news.ycombinator.com/item?id=48949942

Or they will not… how could you possibly know.

It seems like when some folks see “open source” they think the project maintainers owe them something.

An open source MIT license of the source code is very different from being the original copyright holder.

the language is relevant for political not technical reasons. you could say, blanket closing the Issues, getting rid of this thing called Jarred from your stack, etc., is really an attack on the GitHub and the GitHub Agitator Lifestyles, which is why so many commenters on Hacker News actually care.

who claimed that? Are you suggesting that the rewrite did not introduce any new bugs? The correct answer is, by the way, that no one knows since it's millions of lines of code no one has properly read.

> smaller, faster

I thought this has already been debunked. You could just write better zig and make it smaller, faster (and have fewer bugs!)

2. And the code being compiled is abstract & generic, it won't be instantiated for every type and bloat the executable or instruction cache.

3. Security concerns: With C++ virtual methods every object carries a mutable pointer too (to a vtable containing function pointers). What resource management side effects please?

I'm pretty sure "built to last" was only ever more true in specific contexts, and wasn't particularly more true than today.

Casey Muratori addressed this years ago with the windows terminal drama, https://github.com/cmuratori/refterm

You'll need a citation for that. While I'm still not sure whether Claude Code's issue tracker is worth much (Anthropic doesn't seem to engage with individual issues a while lot), it still has 5k+ open issues ranging back to March 2025. Bun also still has all of its Zig-timeline issues, all 5k+ of them. So what's this about?

I just thought it was interesting. I'm a fan of TUIs, both positive and negative about JavaScript (the modern language is quite nice, given you avoid the historical warts, in my opinion - the ecosystem is unfortunate), and I think the best description for how I feel about LLMs is that I'm bearish. Also Simon is a fantastically prolific and intelligent person though, even though LLMs are not my cup of tea.

https://news.ycombinator.com/item?id=48960912 is a recent comment by someone I also respect related to how LLMs recreate human-like content (Widgets, really), making actual human-created content feel fake.

Sometimes it sure does feel like ELIZA is the main news source these days.

You might get more maintainable code for $168k by hiring humans, but if its something bespoke it isn't going to get you far (or far quickly).

Vibing is straight out gambling right now, the thing is, I don't know who the house is any more.

Truthfully, the terminal in Jetbrains IDEs just isn't that great. It's gotten a lot better with their rewrites (yes, plural) of the last years, especially on Windows, but it can still be pretty dodgy.

I was responding to your GP comment. For weeks, it was uproar over the blanket AI move to Rust and now it’s this reason. That’s why I said the goalposts are being moved.

I can understand people being more sold on Rust compared to Zig -- there are legitimate differences on the memory safety front and I can see how people will prefer one or the other.

Plus I believe Jarred (Bun's main dev) went out of his way to explain why he chose Rust over Zig in his blog post.

Of course the marketing angle might indeed be the explanation; not arguing against that, I simply followed with interest and Jarred seemed very reasonable to me.

https://doi.org/10.1007/s11869-026-01918-5

A fast rewrite of Bun in Rust has effectively alienated most of the people in the Bun community, so in that sense the “open source project” has died. It’s no longer a community project, it’s just become a personal project again.

You are really, really not. Not at LLM inference speeds at least. Frontier models output maybe 200 bytes per second on the fast end. I guarantee you that idle BSD box is still processing more than 200 bytes of whatever at any point in time. Streaming 200 bytes of LLM output through syntax highlighting, markdown rendering, and diff formatting, will still leave the box basically idle if done correctly. Claude Code has not done it correctly.

> These apps are doing real work taking text that is streaming in and doing syntax highlighting, calculating diffs, and rendering markdown.

The first argument is that these are expensive operations. They are not. And the second argument is the assumption that these are desirable things for an agent system to be doing. That's a personal preference but, personally, I don't want them and would appreciate a way to disable all of that to reduce CPU use.

Doesn’t sound like responsible software deployment

Secondly, WASM isn't the right target for the browser anyway, JS and the DOM have to be what you consider "native", for the most rigorous UI projects at least (which building an IDE is). If you want to build a cross-platform UI product that doesn't require installation and has Emacs-like levels of extensibility, JS is the end of the line in terms of language selection. There are no other candidates.

True.

> has fewer bugs

Nope, this is demonstrably false because Rust has its own invariants around its types and the codebase is violating a lot of them.

> every potential memory issue is neatly annotated by an unsafe block

"Potential memory issue" can originate in unsafe blocks and safe code that are able to alternate the input condition of these unsafe blocks. Guess what? That still counts towards 100% in this code base, hence the abomination remark.

> refactor them out one by one

Not as easy as it sounds. They are like threads in a yarn ball, if there are one or two ends visible it's easier to sort them out. The actual situation is more like we have tens of thousands of ends (all the raw pointer code that comes with every shared object), to fix them it's basically a requirement to unwind the whole thing (rewrite all the callees and reorder the data flow as needed, redesigning all the APIs during that).

It's too early to declare it as anything remotely close to a win, optimistically saying.

It's not just typechecking, the typescript library is also the reference parser for TypeScript and reference emit. Emitting JS from TypeScript is non-trivial and non-local.

It's not just in browsers, you might want to run the typescript library on the edge or in some restricted environment where JS/WASM is OK but native code is not.

You may want to use the typescript library as a dependency in your own package. TypeScript becoming non-pure JS means that your library also becomes non-pure JS.

However, people also report that the canary version doesn’t identify itself as version 1.4.

Tell you what I sometimes think about though: The fact it has clickable links and complex formatting rules for markdown, the most interactive and highest-quality clickable interface I've ever seen in a terminal, and somehow manages to work. That actually blows my mind.

THEN, I'm reminded that it's written in React, and I think "Huh, guess that does make it a ton easier than using ncurses or something."

And done.

Nobody but a JS dev would choose react-on-terminal shenanigans over it

I could see CC getting a ratatui port eventually actually

Rust protects against a rather small group of memory error, if and only if the unsafe sections are actually correct. And nobody knows if they are correct or not, plus there can be millions of logical errors that can be exploited.

See how many CVEs uutils has… quite a lot for a supposedly secure rewrite of GNU coreutils.

But look at your own disclosure page [0]: OpenAI paid you for your time at a GPT-5 preview, and you regularly get early access, embargoed previews, and free API credits from OpenAI, Anthropic, Gemini, and Mistral. So "I've made no money from Anthropic" is narrower than it sounds, access and preferential treatment are compensation too, even if cash didn't directly change hands.

Same goes for the sponsor list. Microsoft is OpenAI's investor and infrastructure (or was anyways, I've got no clue what the status of that is these days), Amazon and Google are both major Anthropic investors, and most of that list runs on Azure, AWS, or GCP, or sells tools built on these labs' models. Taking a Microsoft sponsorship isn't really separate from an OpenAI one, it's just a single hop removed. The entire software ecosystem and all the players in it are entangled in this bubble.

I'm not accusing you of consciously hyping any of them. Your posts are high quality even when I disagree with the contents of them. You often list downsides too, prompt injection, security, slop issues but the throughline still repeats: this is inevitable, get on board. Product-market fit found, November 2025 as the inflection point. That kinda framing shows up again and again throughout all your posts.

It's refreshing that you're upfront about the previews and credits and all that jazz, but surely you understand why some people stay skeptical even with that disclosed as it confirms the access exists.

Whether you realize it or not, I think they are indeed paying you in some sense, which is part of why I'm skeptical when your posts consistently land at the top of HN. Not because the writing isn't good, but because I think the same incentive shaping the coverage probably shapes some of that reach too.

[0] https://simonwillison.net/about/#disclosures:~:text=2024%2E-...

The argument I responded to argued that cost might be the prohibiting factor. I'm saying that for them, the costs mentioned are negligible.

This is I think a preview of the future of software development. LLMs are having the same effect as compilers, frameworks, etc - they are making new kinds of software development feasible which were not previously so.

Can't help laughing at this point.

Evidence: see the amount of nonsense in the postgres rewritten in Rust story - https://news.ycombinator.com/item?id=48841676 where there are two contradictory claims made:

"postgres is so stable I will never trust a rewrite."

"covering 100% of postgres regression suite doesn't guarantee you have replicated every behavior."

Folks who are okay with LLMs think the regression test suite is the spec and is the guarantee of stability. How else can it be? If you are depending on some behavior not covered in the regression tests, how do you know the next minor release won't break you?

Folks who are against seem to imagine a platonic ideal of PG which conveniently is the original PG implementation by tautological definition. So no rewrite can ever meet their bar.

Knowing Simon - he’s very much both :)

It's a shitposting, hyperbolic bait account. As funny as calling Andrew Kelley Smelley, it's not meant to be taken as gospel.

In fact a lot of "feature requests" like npm compatibility related or missing specs etc ALL also got closed for being "zig" because reproduction and suggested solution were of course zig.

Again doesn't mean it got "auto fixed".

~$ bun upgrade [2.42s] Upgraded.

Welcome to Bun's latest canary build!

Report any bugs:

    https://github.com/oven-sh/bun/issues

    https://github.com/oven-sh/bun/compare/f161e0311...98f664962

Nevertheless, the principles of open source never demanded more than providing the source upon request.

A lot of people go “js is bad” reflexively and they are right for the wrong reasons. Its not because js (specifically v8) is slow. I have many websites and web based apps open and none fuck up my laptop as hard as claude code.

Any review would get to the simple conclusion that this should not be released before all the obvious bads are sorted out.

AT&T was the one doing the Cyclone research.

And then we have a bunch of folks assuming they know better about C that its own authors?

Given the success of the port so far and the fact that CC is now running on rust Bun, that seems highly unlikely to me.

This is where I’ve arrived too. After nearly 20 years of programming I feel done with leaving foot guns lying around. Languages that are full of them, but “fine” as long as you take extreme care are not interesting to me. I’ve started calling this “simple as long as you avoid all the foot guns” idea the sword juggling fallacy[0].

It’s too bad about Zig because it has many nice ideas, in particular allocators, that I hope Rust or some future language will adopt.

0: https://hugotunius.se/2026/06/15/the-sword-juggling-fallacy....

(Unless photos of actual pelicans count as "AI" content now.)

I just shipped this filter UI so you can see my other non-AI-tagged content in one place: https://simonwillison.net/search/?exclude.tag=ai

> One probable outcome of an unsafe-language-dominant world is full Andrew communism, which is precisely what Andrew “Smelley” Kelley proposes: abolish ICE and replace the market economy with a globally distributed network of community-maintained allocators.

> Rather than a commercial product, software becomes a “public good,” ultimately provided by the Zig Software Foundation as manually managed digital infrastructure.

Calling him "smelley"? Really? Pulling in the political views of the founder of a language and claiming that they inform his language design as part of a grand conspiracy against Rust/capitalism? Where are they getting all of this? Free, open-source compilers and related tooling (both of which Rust and Zig have) are already public goods managed by global communities of mostly volunteers

> This future strikes me as a dystopian hellscape, but I have never met an unsafe-language advocate who could explain how this ecosystem is supposed to sustain itself without unpaid maintainers, ideological volunteers, subsidized infrastructure, and endless donations to compiler projects that still cannot protect users from basic memory errors.

How is Rust any different than Zig in this respect? Both are projects largely run by nonprofits relying on communities to promote, maintain, and improve them.

Frankly, that entire "Institute for Type Safe Memetic Research" seems like either an elaborate satire or an account run by genuinely insane people who think type and memory safety are paramount societal issues.

Earth is in a cooler period and it will get very warm. These crappy climate change activists will not get anything done but to hold us back. We need more power, more tech, and more abundance of things. We will need to engineer our way out of real climate change.

I'm just one person though, and have no problem with a move to language X, using tool Y, who cares?

For "goalpost are being moved" to be valid here, you have to be able to point to someone saying one thing at one point, then same person putting a different target later. You're folding a huge group of people into one person, when that's not really accurate to do.

they rewrite themselves, Bun team is under Antrophic umbrella

What I argued was that you seemed to have been arguing an extreme point i.e. LLMs can one-shot stuff in any PL and that it does not matter in what PL they'd rewrite Bun.

If I misunderstood -- my apologies.

Nobody is unbiased, no matter how hard they might try. I like to get my information from sources where I understand their motivations, so my approach is to try to make my motivations as clear as possible.

(That's why I spend an unreasonable amount of energy arguing with people on Hacker News who call me a shill!)

You don't create PRs like this when you're working "completely in the open"

  test ci #30412
  No description provided.

I'm not sure I'm following what you're saying here. In the rewrite blog post it has been stated that the Rust port landed in a place where it passes 100% of the existing test suite and does so without some of the known memory leaks of the Zig version that they were aware of and didn't know how to address.

Sure, there's no guarantee that the port didn't introduce new bugs and most likely it did, but the 1.4 version has not been released yet, so I don't think a direct comparison of a long-time "stable" version and the just-landed full rewrite is meaningfully helpful.

> "Potential memory issue" can originate in unsafe blocks and safe code that are able to alternate the input condition of these unsafe blocks. Guess what? That still counts towards 100% in this code base, hence the abomination remark.

But that just means that once you get rid of the unsafe block, you're pretty much guaranteed by the Rust compiler to be memory-safe. This means that all your potential memory landmines are annotated in the code and once you disarm them all, you're memory-safe.

I don't understand how what you're saying contradicts any of my statements.

> Not as easy as it sounds. They are like threads in a yarn ball, if there are one or two ends visible it's easier to sort them out.

Still easier than the Zig version, where all the same things you've mentioned apply, but also there's no visible indication of progress and issues are unmarked and could be pretty much anywhere.

> It's too early to declare it as anything remotely close to a win, optimistically saying.

Based on the rewrite blog post it's pretty clear that the Rust version is outperforming the Zig version by pretty much every measurable metric at this point.

I think the backlash is mostly focused on the ideological opposition to fully AI-authored 1MLOC+ PR approach they took.

calibre (with python+Qt) begs to differ. And I believe VLC runs on every current platforms. There's also Code::Blocks and Blender. Cross-platform UI is not rocket-science.

I don't consider the following comment to be good, honest, and open communication:

https://news.ycombinator.com/item?id=48016880#48019226

I picked the P90 because I remember running Linux ~1.0 and/or NT on it, with real multitasking and services etc. Those soaked up many of the cycles.

Another story, around Y2k/Win2k was asked to write a C program to record all the files/sizes on the C: in to file. Then something would be installed, my program run again, and the results diffed. Despite thousands of files the program was done before the enter key came back up. Boss told me that he thought the program was cheating.

That’s just how fast modern computers are these days, I said. When running C code anyway. That perf is still available today, compare astral’s uv to slow competitors. Just takes some investment, though probably less when boosted by VC bionics.

And for most part I don't think it was communicated well apart from the last blog post.

I'm not quite as optimistic. "Unpleasantness" might sound like subjective disgust, but it often relates to objective criteria like complexity, that increases the surface area open to bugs in a real way. Similarly, if reworking has a non-0 chance of bugs, its gonna have some form of risk, and a major one will of course be higher.

LLMs may be capable of a lot, and they miggt change what projects people can take on, but they definitely don't write bug free code.

The bun rewrite/transpile did use some neat ideas like lots of testing and per-file translations, so hopefully they have more in their toolbox than "LLMs hopefully won't be affected by complexity or write bugs"

In my work I have Fable/Opus add bespoke linters and tie them to verify/precommit tasks (including in CI) so nothing of the reworks and 15+ initiatives we have in flight ever regresses.

Some discipline will remove that worry of yours. It's not nice to immediately assume that the rewrite's orchestrator (Jarred) did not use discipline. He even outlined a few false starts.

Personally I chose not to disclose my findings in public to avoid this kind of outcome. Having a good laugh with others is not as important as keeping the result of this experiment undisturbed.

This also eliminates the chance of another round of marketing of LLM ability based on actual human contributions and I suggest everyone who is able to analyze the code to do the same - so that they cannot misattribute our ability to LLMs.

Turnabout is fair play.

> Frankly, that entire "Institute for Type Safe Memetic Research" seems like either an elaborate satire or an account run by genuinely insane people who think type and memory safety are paramount societal issues.

You've been had. Your entire rant means the bait worked.

But I guess my opinion is null and void since I "slop-code"

That might even be the reason why they switched to rust.

Don't worry too much.

I think this deserves a real response.

First, an analogy. I drive along a cliff with no guardrail. How do I not drive off the cliff? By knowing how to drive. Sometimes people mess up and drive off the cliff

In practice people are operating Postgres as a machine, more than an abstract spec. Minor releases exist, but the changes are made by people operating the machine and who have a fear of making the machine break.

There are also performance characteristics that are part of an informal spec. While you can definitely write regression tests on performance, theres loads of value in stability of internals because people who have problems look into the machine and discuss it.

The internals might change, but there’s a lot of friction. So… you can have a lot of informal knowledge about.

If everyone working on a software stack is bathing in this informal knowledge, then the decision making is based on that. Things like what is meant to be in a minor or major release is understood. And people make those judgement calls.

After all, even if you have regression tests if you’re making changes you’ll need to write new tests! How do you know your new tests are right? That the new behavior is right?

PG is the entire machine. Fortunately we have version numbers, migration strategies, etc. But “here’s a new binary that passes the test suite and… maybe changes everything not covered by tests maybe doesn’t”. Why bother suffering when there are totally reasonable gradual rewrite strategies?

And of course… every bug in the world… got through despite a test suite! What software out there doesn’t have bugs?

And if the behavioral difference in the rewrite does affect people… I guess that’s something right? “Oh this isn’t a bug because it wasn’t covered in regression tests” is not that tenable.

Regardless of the technical choices, whether Rust is better or worse, whatever -- pgrust popped into existence thanks to one person driving an LLM through 7000 commits in ~2 weeks. It produced something that passes the regression tests. Even as an LLM-sceptic, I think that's amazing.

From that point, though, it appears to have been completely abandoned. There hasn't been a commit in a month, other than a brief tweak and a note that an as-yet unpublished version that's even betterer is in the works. IDK. I don't think we've acclimated to the shock of the change LLMs create, but if the outcome is a forest of exciting new projects that have a bus factor of 1 and little to no collaboration, I think that's a disservice to this profession.

Decades of intrinsic knowledge. Which a rewrite lacks.

imho the issue is the language used. AI rewrites are cheap and cheap exercises require a great deal of scrutiny and proof of correctness. Simply using regressions test lacks the intrinsic knowledge of a decades old codebase stuck in developers minds.

Claiming a rewrite is better because it passes all tests is a flex, a new version requires a boatload of evidence for people to accept it as an improvement and not just "passes tests, written in rust via LLM so it must be better". Run it in production for a year in a sufficiently large system and you might be somewhere.

With regards to AI-generated code, this means the copyrightability (at all, not with regard to who owns it) turns on whether or not a human was substantially involved in its creation.

Existing decisions require evidence of pretty heavy and continued human guidance to qualify.+

To wit, autonomous agent created code (prompt -> machine churns for hours -> output) is explicitly not eligible for copyright.

Functionally, this is a double-edged sword.

On the one hand, it means anything coded with autonomous agents by Meta, Google, et al. can be legally reused if it leaks (because no one could hold copyright on it).

On the other hand, it leaves copy-left open source licenses in a weird place. If you convert open source (even MIT/BSD-style) code into something else with an autonomous coding agent... the result has no copyright (nor can ever in the US).

In this instance, Bun was MIT-licensed, no? Then it was shoved mostly-autonomously through an LLM for the port.

Now Bun-Rust is technically still MIT licensed, but if push came to shove it seems like US law's current position is that Bun-Rust would now have no copyright license (because the manner in which it was developed renders it ineligible for copyright).

That's on the copyright side.

On the infringing usage side (i.e. whether you were entitled to shove a copyrighted work into a coding agent to produce something)... that's still TBD.

^ https://media.cadc.uscourts.gov/opinions/docs/2025/03/23-523...

+ https://garrettham.com/ai-generated-works-copyright/

Barthes aside, C's changed a lot in the years since they left.

In Zig, every single memory operation is unsafe.

And Bun must interface with C code that has no safe interface, necessitating a ton of boundary-level unsafe behaviors.

There's too much, sure, but can we at least be honest and reasonable?

…but they have? Claude users are public, no? If they were dogfooding internally I’d agree with you.

So. Rust evangelists ? :)

But yes, it is wild that people can honestly quote such drivel as evidence of the language and its philosophy being superior.

Each time I try to evaluate Rust, I do so on its own merits. Going online I am rapidly convinced that I don’t want to be in the same room as a large chunk of its userbase. Statements start to sound a bit like that one time I was dragged into a pentecostal meeting.

The UI itself requires laughably simple tech. The idea that a markdown renderer that can produce HTML at 50MB/s would use much CPU to process incoming hundreds of bytes per second is insane. CPU should be idle even if doing that constantly. Nevermind that between turns it has nothing to do whatsoever and should use zero CPU at all.

— Henry Petroski

They are basically testing the rust port on user machines.

Who come that since the rise of AI all principles of software development are thrown over board?

Version was changed in Bun in May 18

https://github.com/oven-sh/bun/commit/b18bf6d1d0a92238f240bf...

So it has been canary since then, most likely, if docs are accurate that latest main is canary.

https://news.ycombinator.com/item?id=48837877

I'd also like to inform you that

- the current success metrics solely consist of their advertisement, my eyes looking at the code strongly suggest otherwise

- the Bun team lacks knowledge to actually make it more idiomatic: none of the Bun team has written any Rust and relying on model knowledge is already proven insufficient.

The release decision itself is presumably driven by that tbh. It's only LGTM from there when nobody knows how to review unsafe Rust.

The "ai" tagged posts (2,100+) significantly outnumber "sighting" posts by orders of magnitude. Even searching HN, this post is the very first mention of it.

Perhaps that is why everyone here (except you) overlooks that or why we don't see much more of those sightings posts here either.

They can't mention what they don't know. And that's the exact reason I'm against this: doing a port without being able to tell what is correct is asking for a disaster, obviously.

I've checked their posts and blogs for a few times, and I'm quite sure they don't know any of these to write about them.

> the 1.4 version has not been released yet

Let's hope the repeated delays (it was scheduled for last week) are not for quality issues, otherwise I'll only be half correct. It appears that all the MIRI errors are not stopping them though. (They have a script to run it but most probably it just fails and they don't care. Personally I'm not executing any of bun's code to avoid summoning nasal demons, so I actually don't know for sure)

> get rid of the unsafe block

Would be possible if they are not disregarding everything else going for numbers. E.g. they are actively increasing the unsafe surface by rewriting some code in SIMD C++ (https://github.com/oven-sh/bun/pull/33032). As if no Rust solutions already exist.

> Still easier than the Zig version

Well, this is true but only realizable if they know how to deal with the new problems emerging during the process. My current conclusion is that they don't.

> ideological

For me it's methodological as explained above.

That being said I've found a case that doesn't do much harm even if it's fixed, and is technically not my contribution. You may take a look at that:

https://github.com/oven-sh/bun/pull/30794

The second that you start to introduce nonsensical axioms (or bugs in unsafe sections) all your proven correct theorems will be worthless.

> There’s a very high chance all this code gets thrown out completely.

... and a few days later he decided that the code wouldn't get thrown out. That doesn't make the comment itself dishonest, he didn't have a crystal ball.

You can absolutely argue that the rewrite was not communicated clearly once they committed to it, but I don't think the comment you linked to there stands as evidence of poor communication at the time it was written.

And your "it's just ANSI escape codes" is the weirdest take on any kind of software.

What?

If you're crashing every 5 minutes, either you have a cursed build, or you need to do a memtest.

They are not informal AFAIK - https://github.com/PGPerfFarm. A lot of these heavy duty OS projects have explicit Perf testing/nighlites (see Lucene's at https://benchmarks.mikemccandless.com/)

If you are saying the PG regression suite doesn't cover these perf tests - that is fair. I consider perf to be part of the "regression framework" generally.

>> How do you know your new tests are right? That the new behavior is right?

This is a more generic question in the LLM world. Reliable verifiers is what drives LLM loops. If you don't have these, you have no idea if you are actually making progress or you just generated code that returns 42 for every question. You needs something to actually ground the LLM output against. For existing features, the reliable verification is the existing regression/perf suites. For new features, the regression/perf suites should expand to fit. There are ways to go at this that range from ad-hoc (line/branch coverage) to fully formalized (verification-aware languages like Dafny).

I do regret that I've also read the code though, otherwise I'd probably live a little happier with ignorance right now. Sadly as they don't know they don't know about the issues, there's no indication of those in the two public materials they have released.

I think it's the "infringing usage" question that is more interesting. If the LLM trained on GPL-derived code, what does that mean for the end result?

You mean the ones encoded in the regression suite? I think your argument is valid in many medium-to-faang firms where the application is going to have encoded business logic that isn't explicitly tested for. If anything, projects like PG are the exact opposite: no business context and regression suites that test every possible scenario due to the accumulation of bug fixes and context over many years.

>> Run it in production for a year in a sufficiently large system and you might be somewhere.

How do you know every release of PG doesn't break in the setting of "a year in a sufficiently large system"?

Still they are the authors, and withdrawing from WG14, going their own direction with Alef, Limbo, and finally Go, kind of proves the point they considered C done for its original purpose.

You just can't win.

> must interface with C code that has no safe interface

Yeah so the sane first step is to create encapsulated, safe interface for them, especially in a project like this. Deno for instance have ~0.2x as many unsafes.

And mind you if you haven't read the code, the vast majority of unsafe blocks in bun are for raw pointer access to local (Rust) objects because their ownership was a mess both before and after the rewrite. Also funnily enough a lot of the access patterns are wrong (in the Rust sense), leading to hundreds of new undefined behaviors.

> be honest and reasonable

Well, well. Talking about dishonest and unreasonable behavior, why is bun releasing a new version before solving any of those glaring issues? I'd remind you the current new version is not an improvement compared to the previous one, both in terms of correctness and maintainability.

I would be very surprised if one of my sightings posts made it to Hacker News. Maybe if I manage to snap a photo of an actual pelican perched on a bicycle some time.

BTW did you hear about this:

https://babylonbee.com/news/democrats-say-they-are-perfectly...

OR

https://www.youtube.com/watch?v=bXEddCLW3SM

Do you know how silly this sounds? Good engineers can work in any language. At the top companies (of which Anthropic is certainly one) they don’t have “C++ engineers” and “rust engineers” they just have engineers.

  Rewrite Bun in Rust #30412

This is a product by a company worth supposedly $1trillion and they can't even make one of their starship products not shit the bad within 5 minutes? These are the same engineers telling us for the last 3 years that coding is solved?

Like it's pathetic, and it's pathetic you're falling for it too. Have some standards, good grief.

Not sure why you’re trying to bring up experience as a justification for using React to render a tui and all the downsides that come with that.

It’ll most likely still do 99% of the things people need it to do, there’ll be a an issue created for that broken 1%, and eventually it’ll be iterated upon and fixed.

Unless you’re working on a security boundary of course, there you should treat it like maths.

Now, /you/ are trying to move the goalposts into an entirely different argument.

Very likely it’s just anti Anthropic altogether.

Like I said, a meme.

Anthropic hasn’t done anything wrong but if they move a single inch then people will complain. Perhaps it is just a preview version?

Either it means nothing at all, or it means that a substantial portion of the code produced at some of the world's most valuable companies over the last two and a half years is GPL.

Spend time enough with a codebase and you’ll know stuff about its behavior that is not encoded in a test suite. Especially when you need to adjust an integration tests due to the modification of an invariant in a dependency.

> How do you know every release of PG doesn't break in the setting of "a year in a sufficiently large system"?

Because the postgres team is professional and will take care of publishing a changelog for what has been modified since the last version.

there is a potential future where an llm with unbounded patience would have an easy time literally walking through the zig code looking for one of the footguns might miss a footgun in rust because it's abstracted away. the ones in the stdlib should give you pause. what is hiding in some third party library's code?

You could! You could not release a “pile of vibe coded slop” onto people’s machines. There don’t even appear to be any particular advantages to Claude upgrading early. If there are no one has been made aware of it.

I don't think it proves anything other than the wanted to work on something else.

Except, you know, multiple real companies saying that it is and using it in production. And the fact it closed all known memory leaks. And that nobody has a really pointed to a single actual issue the new version introduced after two months of endless, ceaseless bitching.

I'm also fascinated by all these people upset at Jarred for harming the readability of a codebase they've literally never cared about before it become drama. Bun has almost exclusively been maintained by Oven employees since it's inception.

> Deno for instance have ~0.2x as many unsafes.

A project written ground-up in Rust idiomatically, with a smaller surface area, still has an unsafe footprint within an order of magnitude compared to this automated rewrite from an unsafe language with different practices and known bugs? That's not exactly the slam you think it is.

Another point of comparison is density of unsafe: the number of unsafe blocks per line of code and/or file. By this metric, Deno has a bit over half the unsafe (because the bun rewrite is significantly more lines of code).

Given that they are investing their time into actually learning the language before diving into this mess. No, unsafe Rust isn't supposed to be something you can handle without prior knowledge.

Jarred was even asking in public how to use traits without runtime overhead during the rewrite. And the blog post phrased it like a normal problem to encounter while doing a million lines port... That's two months after the initial rewrite so you can guess if they learned.

They were up and running and super-productive with Django within a week.

I’m sorry but this is a nonsensical debate.

> Now, /you/ are trying to move the goalposts into an entirely different argument.

You said something and I responded to it. That’s invalid too now? There can only ever be one single objection in a conversation? I’m not permitted to react to the things said? Like I said, nonsense.

Take it from someone who, in those 24 years, has written UIs in jquery, react and ncurses (and yeah I've tried out Ink and it's great).

"all the downsides that come with that" yeah well, while you're stuck implementing your app in the Best Possible Library, millions of people are happy using claude code and it's crazy useful.

I don't understand why folk are having such a hard time understanding why you do large projects in multiple steps? 80/20 rule? Perfect is the enemy of good?

Was nobody here for moving billions of lines of JavaScript to Typescript? It starts with declarations, then turn on type checking gradually inside the codebase: piece by piece until done.