Drilling into the original article where Jarred explained the reasoning behind the change, It's pretty clear that under zig the team was doing things by hand that are automatic in rust.
Humans and agents share one thing: they are both non-deterministic. He talks about the issue of tracking memory lifecycles manually in zig so it can be explicitly freed. As expected, this leads to a long list of bugs where people missed things.
Rust does this automatically. It removes an entire class of errors from his backlog. From an engineering management perspective, this looks like a pretty good trade.
The bonus here is that compiler errors are exactly the kind of deterministic guardrail you need to put around coding agents. Claude works really well if you give it a way to test for correctness and "make it compile" is a pretty good target.
There's a general version of this: the artifact you expose plus the test you run on it. Deterministic tests turn stochastic output into a hard guarantee. Wrote it up here if useful: https://michael.roth.rocks/blog/verification-surface/
awesan 9 hours ago [-]
Zig (like C) is simply not a good language to use if you're going to do many small allocations with uncorrelated lifetimes. To write robust Zig (or C) code, you must manage lifetimes yourself, for example by grouping allocations on an arena or by having fixed buffers of "things".
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.
hugmynutus 8 hours ago [-]
This reads like cope because you're re-inventing RAII from first principles.
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.
jstimpfle 7 hours ago [-]
I've argued elsewhere some things that are wrong with RAII and C++ objects in general.
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?
hugmynutus 7 hours ago [-]
> I don't see what should ever be wrong with a function pointer. [...]Care to explain what's the issue here?
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.
jstimpfle 6 hours ago [-]
1. No, you're not writing code you don't have to. It's not different to implementing this as non-virtual methods, in fact I'd argue doing simple functions is more straightforward.
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?
mrothroc 8 hours ago [-]
[dead]
BearOso 8 hours ago [-]
> Rust does this automatically.
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.
Diggsey 22 minutes ago [-]
You're getting confused between lifetimes (the static analysis that prevents use after free and similar errors) and lifecycles (more commonly discussed under the heading of ownership) which determines when objects (and thus memory) are allocated and deallocated.
Ownership is automatic. You don't have to explicitly drop things when they go out of scope. (although the responsibility for that is split between the compiler and the library code).
Lifetimes are not automatic, but also have no effect on memory allocation. They are purely a static analysis path and you can make a functioning rust compiler that completely ignores lifetimes.
gchamonlive 8 hours ago [-]
> Rust does this automatically. It removes an entire class of errors from his backlog.
As opposed to every commit abd line of code being unsafe? They use a lot of C/C++ libraries with their own code so unsafe isn't even a a problem in most places they use it.
theshrike79 6 hours ago [-]
You think it’ll all stay there?
Of course they’ll iterate and remove the unsafe bits which were necessary for the transition
bluegatty 32 minutes ago [-]
Good thing there are tons of languages that do that out of the box, and which are frankly quite fast.
portly 5 hours ago [-]
LLMs catch memory bugs quite easily in my experience.
All of this is just a (succesful) marketing stunt by Anthropic.
latortuga 8 hours ago [-]
I seem to recall this Rust rewrite is all "unsafe" meaning it really doesn't automatically eliminate those issues.
mrothroc 8 hours ago [-]
Relevant passage from Jarred's post:
"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."
gabrieledarrigo 16 hours ago [-]
Bah.
Personally my take on the entire affair is quite negative, whatever Jarred or Simonw says about it.
I think Bun owned by Anthropic and the entire rewrite with AI is not the real point (even if it's quite interesting, though).
My take is that Jarred, and Bun,didn't demonstrate a serious, adult approach, from "this is my branch, you are overreacting" message to just proceeding with a 1mil+ PR merged in less than month.
The communication is the issue, and it was handled very badly, in a way that impacted trust and divisions.
Was it so difficult to adopt the approach that the TS team adopted for 7.0?
baq 16 hours ago [-]
I guess the point is none of it matters, CC users didn't notice or don't care except an exceptionally small minority.
15 hours ago [-]
conartist6 16 hours ago [-]
Haha TS7 is the next biggest example of, "Let's just do a line by line port to another language instead of seriously examining our architecture"
raincole 7 hours ago [-]
This is the correct approach (I dare to say the only correct approach) when porting to another language. You can examining the architecture later.
dirtbag__dad 2 hours ago [-]
If you can lock down a test suite that ensures parity, then who cares what shape the lift ultimately looks like.
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
zarzavat 15 hours ago [-]
Indeed as much I dislike the approach Bun took, at least the port appears to be working. TS7 is going to cause problems for downstream users because Go is the wrong language to use for something that has to run in WASM.
nicce 14 hours ago [-]
> TS7 is going to cause problems for downstream users because Go is the wrong language to use for something that has to run in WASM.
Is there a huge need to run that typechecking on browsers?
conartist6 14 hours ago [-]
First, yes, the demand to be able to code natively in a browser is, I have reason to suspect, very large. It's just difficult to measure demand when nobody has ever offered a really compelling product. In engineering terms it's like getting a full-scale reading. The real level could be 1% above a full-scale reading, or the real level could be 100x higher than the full-scale reading.
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.
skydhash 10 hours ago [-]
> 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.
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.
conartist6 10 hours ago [-]
All great examples, but ones that do require installation. Their website is just where you download the product, I'm talking about making the website the product.
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.
anon7000 12 hours ago [-]
NodeJS can strip types internally without a straight TS dependency. I don’t think this matters, TS was a huge bottleneck for many build pipelines because it never parallelized well
shepherdjerred 10 hours ago [-]
It is incredibly useful
15 hours ago [-]
cush 2 hours ago [-]
There's literally nothing stopping anyone from continuing the Zig version if they want to
CrimsonRain 11 hours ago [-]
[flagged]
amazingman 11 hours ago [-]
Normal users, anti-AI dinosaurs / zig fanatics, and no one else. That's a nice echo chamber you have going there.
Sammi 10 hours ago [-]
"Normal users" haven't even heard of Bun and are still on Node.
weakfish 12 hours ago [-]
Maybe I’m taking crazy pills, but I’m still stuck on “why the hell does a TUI need to run in terminal React by way of JavaScript”
The fact that Anthropic felt the need to buy a runtime so they could make their TUI better speaks more to the quality of engineering than anything else IMO.
If rewrites are so easy, why not rewrite CC in a native language? Would’ve been a hell of a lot cheaper.
switz 11 hours ago [-]
It largely works and it's a massive business success. This is the classic engineer asking the 'why this technology?' to what amounts to a business question.
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.
coldtea 11 hours ago [-]
>It largely works and it's a massive business success. This is the classic engineer asking the 'why this technology?' to what amounts to a business question.
Your counter argument would be valid for a 2000 or a 2020 business decision about some tech stack.
But the whole point of their product is that it supposedly nullifies such "business" concerns around the use of technology, by making it cheap and fast to build whatever you like automatically.
That they wont, or worse, couldn't, speaks against that.
pdimitar 10 hours ago [-]
> But the whole point of their product is that it supposedly nullifies such "business" concerns around the use of technology, by making it cheap and fast to build whatever you like automatically.
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.
hyperpape 9 hours ago [-]
> $168k
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.
sscaryterry 5 hours ago [-]
If only paying the $168k was some sort of a guarantee. Vibing doesn't give you that.
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.
nomel 4 hours ago [-]
It's going to take an order of magnitude longer though, delaying any of that revenue significantly. I'm sorry, but we're talking 11 days here. What does "maintainable" even mean with impossible time-scales like this now!?
sscaryterry 3 hours ago [-]
The new normal is there is no normal. No common sense, FOMO, YOLO, everything combined is what we're living right now :)
nkrisc 3 hours ago [-]
Perpetual complete rewrites. When there’s more bugs the LLM can fix, rewrite the whole codebase. Repeat ad infinitum.
pdimitar 2 hours ago [-]
True on the premise, remains to be seen if that's what's going to happen in practice.
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.
throwaway7783 2 hours ago [-]
.. by hiring the right humans - which is not always a given
pdimitar 2 hours ago [-]
Even worse: it's much safer to assume you'll hire the wrong humans, most of the time.
pdimitar 9 hours ago [-]
Yep, same thought. And it seems Anthropic agrees.
NDizzle 9 hours ago [-]
The company I work for is about 15mm into what is effectively a rewrite. Just a lone data point…
NuclearPM 5 hours ago [-]
Millimeters?
ak39 4 hours ago [-]
I read "man months".
ariwilson 4 hours ago [-]
15 million dollars
malkia 1 hours ago [-]
15 million mollars :)
mobelkh 4 hours ago [-]
can't imagine rewriting a runtime to be easier than a coding harness
usef- 3 hours ago [-]
You might be surprised. Runtimes can be easier to test than UI for AI, and the bun rewrite was almost line-for-line translation, whereas CC likely uses many more libraries that cannot be ported directly.
It's really not about a PL runtime vs. an agent harness, it's about how spaghetti and complex the code is. I do get your point though.
TurdF3rguson 3 hours ago [-]
It has to have been purely a marketing move. There's no other way that acquiring a software product for millions and then completely rewriting it makes any sense.
pdimitar 3 hours ago [-]
Maybe it's one of the cases when techies call the shots?
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.
TurdF3rguson 3 hours ago [-]
The rewrite makes sense, it's all their dog food at that point. It's the acquisition that doesn't make sense. Why didn't Anthropic just rewrite it themselves?
pdimitar 3 hours ago [-]
Good question. I'd guess they didn't want community split?
tonyhart7 3 hours ago [-]
"Why didn't Anthropic just rewrite it themselves?"
they rewrite themselves, Bun team is under Antrophic umbrella
coldtea 9 hours ago [-]
>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.
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.
jbvlkt 5 hours ago [-]
Lets see what happens in the future. From my experience cost of maintaining this amount of shitty code explodes pretty quickly. We will see in a few years if SW development in all phases using agents is that much automated and easy as people now predict.
hluska 7 hours ago [-]
Do you know their entire roadmap? If not, maybe different people prioritize things differently when they see their full strategic position.
coldtea 6 hours ago [-]
How is that relevant to my response?
The argument I responded to argued that cost might be the prohibiting factor. I'm saying that for them, the costs mentioned are negligible.
pdimitar 2 hours ago [-]
I didn't claim that the cost is the prohibiting factor at all. Obviously they gave Jarred free Fable access and to do as his pleases. The cost was an FYI tidbit and nothing more.
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.
pdimitar 8 hours ago [-]
I don't work for them and I don't know their priorities. I can only speculate they're not okay with it but no idea why exactly.
shafyy 7 hours ago [-]
> 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.
Does anybody really believe that it only took 11 days, one engineer and $168k in tokens?
simonw 6 hours ago [-]
It played out in public on the GitHub repository, so yes.
pdimitar 7 hours ago [-]
I know what Fable did for just 5x6h sessions, singular agent, for my professional work.
Jarred used many agents and they worked 24/7. It tracks for me.
So yes, I do believe it. What makes you skeptical?
BedVibe_Studios 1 hours ago [-]
[flagged]
weakfish 10 hours ago [-]
Yeah, this is what I’m trying to get at.
There’s two arguments in competition:
1. LLMs make it cheap (in the time sense) and easy to build
2. Rewrites and/or writing something in a native app or program is harder and more time consuming
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.
I just don’t see how one can say that building things reliably good is easy now when the company providing these tools can’t even do it well.
coldtea 9 hours ago [-]
>2. Rewrites and/or writing something in a native app or program is harder and more time consuming
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.
pdimitar 10 hours ago [-]
> I just don’t see how one can say that building things reliably good is easy now when the company providing these tools can’t even do it well.
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".
weakfish 1 hours ago [-]
Going to give a short reply to one point because I’m about to go to sleep (I try to make an effort to be honest as to why I’m not fully engaging with the entire comment) but re: strawman, I don’t think so. When Dario Amodei is saying SWEs will be replaced soon [0], I think it follows that then he believes Claude can write a native app as well as a native app dev.
CEOs love to promise the sky and the stars. Color me unimpressed.
Now whether they can do it -- that's a separate, and a much more interesting, discussion.
KronisLV 10 hours ago [-]
> by making it cheap and fast to build whatever you like automatically.
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).
arijun 10 hours ago [-]
Can't have been that cheap if they thought buying Bun for an undisclosed amount of money was cheaper.
tracerbulletx 7 hours ago [-]
I don't think they bought them just for the claude-code gui harness as it is now. it's to have strategic control over some software runtime they can use to do other things related to verification, deployment, and end to end value delivery. Same reason other companies are buying up dev tools.
arijun 1 hours ago [-]
Yeah it was a little tongue-in-cheek--I think the estimate I saw was over $100M for bun, which would have been enough to pay Donald Knuth to rewrite Claude Code, let alone AI.
madeofpalk 7 hours ago [-]
How much extra money do you think they would make if Claude Code wasn’t JavaScript?
piker 7 hours ago [-]
Right now? Zero.
In 2 years? A well-engineered TUI could be the difference between the Blackberry and the iPhone for all we know.
TurdF3rguson 3 hours ago [-]
Claude is better at Javascript than those other languages though so maybe it would be worse in a better language.
squidbeak 7 hours ago [-]
Perhaps over those two years they'll reach the same conclusion and change the engineering?
coldtea 6 hours ago [-]
Perhaps by then it can be too little, too late, too?
piker 7 hours ago [-]
Perhaps.
lacy_tinpot 7 hours ago [-]
>making it cheap and fast to build whatever you like automatically
This can be true, while "nullifies such "business" concerns" can be false. Both are not dependent on each other.
Automation doesn't "nullify business concerns", it just changes them.
harrisonjackson 9 hours ago [-]
By the same argument, why does it matter from the technology stack side? It doesn't just nullify the business concerns - it largely nullifies the tech stack concerns. Your preference doesn't matter if you aren't touching the code and the product works for your user base.
jstummbillig 6 hours ago [-]
> But the whole point of their product is that it supposedly nullifies such "business" concerns around the use of technology, by making it cheap and fast to build whatever you like automatically.
Eventually? I am sure they would agree. Currently it's you (and lots of people like you) who are doing the supposing, not Anthropic.
yojo 9 hours ago [-]
I have been working all day every day in Claude. I loathe their bug-ridden UI. Every release is a new crop of bugs, sometimes the old ones get fixed, usually not.
Any kind of scrolling back, copying text, using their menu system - basically anything that isn’t typing characters has had/still has unaddressed bugs.
OpenAI shipped a competitive model and I’m over in Codex now. I have yet to hit a bug.
If you’re holding the SOTA crown, people will put up with your buggy mess. As soon as that crown slips your pile of trash becomes a huge liability.
cvadict 10 minutes ago [-]
> I loathe their bug-ridden UI.
So weird that the same exact people telling you that programming careers are now obsolete are the same group who haven't been able to fix screen flickering bugs for like a year...
BoppreH 5 hours ago [-]
> basically anything that isn’t typing characters has had/still has unaddressed bugs.
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.
yojo 9 hours ago [-]
Oh, and the memory use! I run a lot of concurrent sessions. 3 gigs for a terminal window is ludicrous.
neutronicus 2 hours ago [-]
The vim mode in that text box was a mess for sure
tripleee 11 hours ago [-]
They succeeded in spite of their tech choices. Their model outshone it, which is an extremely rare thing to happen and not something they could've counted on. In any other timeline they could've/would've been hurt by their choices.
It's like "why did you go all in on buying scamcoin 3.0 as your investment strategy?" -- "I 5xed my money! End of story! It was fine!"
benoau 11 hours ago [-]
> They succeeded in spite of their tech choices.
Or those choices just don't matter, it's fundamentally just "tabs vs spaces".
pdimitar 9 hours ago [-]
As much as an enthusiast dev like myself hates it -- this is innately true, way too often.
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).
georgemcbay 6 hours ago [-]
> I still have trouble to admit to myself sometimes that people make dozens of millions with PHP
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.
pdimitar 1 hours ago [-]
I hear you on the worry, I have the same (and probably so do most devs even).
But IMO the endless churning of code will slow down, if it has not already. Quantity does not equal quality as we know, it even erodes it. There are already consulting companies that are "vibe-code fixers".
I am also not sure it's about "elegant" code. What we might call elegant has multiple measurable axii f.ex. well-isolated effectful code layer so you can easily static-code-check it, domains and enforcement of boundaries between them, bespoke linting to enforce business processes and standing code discipline, and many others.
groundzeros2015 8 hours ago [-]
Apply this reasoning to any other industry. Yes the average person is not the judge of the quality of a doctor or engineer. That doesn’t invalidate it. You want a doctor who cares about medicine , not whatever will accomplish a business goal.
azeirah 10 hours ago [-]
Eh, the rendering of Claude Code is genuinely such a mess. I have quit claude code over it because when used as a terminal in PHPStorm it sometimes gets so bad that it becomes hard to use.
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.
lucumo 10 hours ago [-]
> when used as a terminal in PHPStorm
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.
jamienicol 10 hours ago [-]
That may be so but Claude code certainly has rendering glitches in other terminals too.
vips7L 5 hours ago [-]
You don’t have to use these “tools”.
tripleee 8 hours ago [-]
If they don't matter why isn't GTA6 being built in React?
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.
enraged_camel 11 hours ago [-]
>> They succeeded in spite of their tech choices.
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.
anamexis 11 hours ago [-]
What do you mean in spite of their tech choices? When have the tech choices ever been an issue in the lifespan of Claude Code? From where I sit, it seems like their tech choices enabled them to create an industry-defining product.
dnautics 11 hours ago [-]
for about half a year claude code had this obnoxious flicker problem. i almost quit and went to codex over it.
tripleee 8 hours ago [-]
I mean people are using Claude Code because of their underlying LLM - they'll put up with Claude Code. There's no other real option to get Opus at a reasonably affordable price without CC.
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.
anamexis 6 hours ago [-]
I may not be the standard case, but I use Claude Code over Codex, OpenCode, Amp, etc primarily because of the UX, not the models or pricing.
nozzlegear 10 hours ago [-]
> When have the tech choices ever been an issue in the lifespan of Claude Code?
This is just blatantly ignoring all of the glaring issues Claude Code has had over its lifespan.
solumunus 9 hours ago [-]
I think the point is that people still continued to use it above everything else regardless.
troupo 8 hours ago [-]
Because there's no legal way to use Claude Code on subscription otherwise
solumunus 6 hours ago [-]
Exactly. Their tech choices were not an issue because other things mattered more to users.
galangalalgol 11 hours ago [-]
The criticism didn't appear to me to be that the solution didn't work, just that many of the working solutions we are selecting are dangerously overcomplicated due to shortsighted decisionmaking. The benefits of throwing redundant stacks of abstraction atop each other in terms of time to market are questionable, and obviously absent in every other metric.
bwfan123 11 hours ago [-]
So, you have a vibe-coded TUI which happens to work, and then, as a workaround you vibe-translate its engine to make it more performant. Where does that leave you ? Basically, fully dependent on AI to fix whatever breaks. Workaround on a workaround is the way I see it, and it aligns with the AI design mentality in general. For a variety of usecases, this might still be a win in terms of overall cost. But, for software that is intended to be built to last, I dont see this approach working out.
galangalalgol 11 hours ago [-]
That does seem to be the way many use it. I'd be very surprised if they didn't have to insert a rule to prevent opus from constantly asking why they didn't just use ncurses. I just asked sonnet for design options for a tui to onteract with llms to perform sw dev tasks. After describing the tui it immediately suggested ratatui and crossterm as the tech stack. I feel like they must have ignored even the advice of their own llm to come up with this solution.
Edit, the sonnet question shouldn't be taken as proof, it knows I'm a rust dev.
simonw 11 hours ago [-]
They decided on the tech stack for Claude Code over a year and a half ago.
tough 2 hours ago [-]
ratatui was still an excellent choice over a year and a half ago.
Nobody but a JS dev would choose react-on-terminal shenanigans over it
I could see CC getting a ratatui port eventually actually
jeremyjh 11 hours ago [-]
Bun was not ported to Rust for performance reasons and its not clear to me how anyone can think it was. The reason they've given is memory safety.
galaxyLogic 2 hours ago [-]
Plus 1) There's much more reusable open source code written in Rust than in Zig 2) There are more Rust developers than Zig developers.
vips7L 5 hours ago [-]
It was ported for vibe reasons.
simonw 11 hours ago [-]
I'm going to guess Anthropic are OK with "fully dependent on AI to fix whatever breaks".
jubilanti 11 hours ago [-]
> for sw that is intended to be built to last, I dont see this working out.
the era in which the tech industry built software to last was over long before LLMs, especially VC-backed startups.
zdragnar 11 hours ago [-]
Did it really exist? I remember buying games on discs as a kid that had bugs in them that prevented you from actually finishing the game at all.
I'm pretty sure "built to last" was only ever more true in specific contexts, and wasn't particularly more true than today.
nozzlegear 10 hours ago [-]
The era in which the [VC-backed, SV area] tech industry built software to last was over long before LLMs.
weakfish 11 hours ago [-]
Correct
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.
losvedir 7 hours ago [-]
This reply makes no sense in this context, though. Sure, it exploded in popularity based on whatever random tech choices were made. But now, when apparently they're deciding there's a problem there, why unleash $150k of tokens to rewrite a JS runtime wrapper from Zig to a million lines of rust, rather than simply rewrite Claude Code itself to rust?
galaxyLogic 2 hours ago [-]
This speaks for the benefits of JavaScript runtimes like Bun and Node.js. JavaScript is a dynamically typed language which makes it a good choice for explorative programming. It is a Lisp in sheeps' clothing.
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.
jolux 7 hours ago [-]
They probably should rewrite it in Rust, but also, I think the Bun guy wanted to rewrite it in Rust because he thinks Rust is a better choice for Bun, independent of Bun being used by Claude Code.
adastra22 9 hours ago [-]
Claude code still can’t handle scrolling history without corruption. It is embarrassingly broken.
tacitusarc 6 hours ago [-]
This is the “eating yogurt with a hammer” argument. Yes, of course you can do that. Yes, the yogurt gets eaten. It’s just… you see someone eating yogurt with a hammer and it’s hard not to wonder wtf is going on.
geraneum 7 hours ago [-]
> It largely works and it's a massive business success.
The engineer is suggesting that it could be done cheaper and maybe with better outcome. Ironically, this is a classic business case.
dd8601fn 7 hours ago [-]
...while proving their technology has finally reduced these questions down to what's best, instead of "how much effort will it take to be good enough".
If you have unlimited access to the magical development tool, then why would you not?
But they haven't.
solid_fuel 7 hours ago [-]
> It largely works and it's a massive business success.
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.
burner54828182 11 hours ago [-]
> “It largely works”
A ringing endorsement!
vips7L 5 hours ago [-]
Any choice would have made obscene money in this market. It doesn’t make it a good choice.
groundzeros2015 8 hours ago [-]
As an industry we are responsible for making our part good. So yes a business can succeed in spite of bad tech choices, but that doesn’t make it good tech.
behnamoh 2 hours ago [-]
No, it's because they wanted a unified pipeline in claude code, claude app, and their website. All of them use more or less the same claude features (claude code has artifacts, claude website has "Ask User a Question" tool, etc.).
Much less fragmented compared to "write the app 3 times in 3 different languages".
femiagbabiaka 8 hours ago [-]
It doesn’t work, it performs horribly and is full of bugs. Serious people use open harnesses.
5 hours ago [-]
realusername 7 hours ago [-]
> It largely works and it's a massive business success.
I'd argue these tech companies got popular because they have good models, nothing else.
Even OpenAI took two years to fix basic chat scrolling.
DoesntMatter22 4 hours ago [-]
This is far less so in this case because this is thier hot path. Everything runs through it and tens of billions in revenue depends on it. It needs to be as fast and solid as possible
wonnage 6 hours ago [-]
This is a useless post-hoc rationalization. "It worked out, so it doesn't matter". You're trying to galaxy brain yourself into ignoring the obvious conclusion.
The point is that if you were starting a new TUI LLM harness today, you would basically use CC's architectural decisions as a guide for what not to do.
pjmlp 10 hours ago [-]
So Claude isn't great for everything?!?
reinitctxoffset 8 hours ago [-]
I think it makes sense that when you've outlawed competition for many/most users of your product's matching service that you would cheap out on it if you were maximally extractive and took no pride in your work, sure.
But the "coding is mostly solved" narrative kinda doesn't match right? If good, correct, high-performance software is like, free now? Wouldn't you want it to be slick as hell, really reliable, all that? Even a little breakage costs a lot of money at that scale and pricing, it would be better than a wash if you put the magic code thing on the case.
"Claude. Do all employee work. Make no mistake. Notify in slack when revenue is double."
nullsanity 9 hours ago [-]
[dead]
ljm 12 hours ago [-]
I never knew that running an interactive program in my terminal would absolutely rinse my CPU and battery but that's what Claude, OpenCode and Ghostty have colluded to achieve. Even when the laptop is asleep overnight it's practically melting.
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.
vmg12 10 hours ago [-]
The fundamental problem with all Js based apps is how they are very single threaded.
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.
wild_egg 8 hours ago [-]
No, the fundamental problem of these apps is that they are, for no reason, pretending they need a high powered game engine rendering loop. They don't. It's a text printout of history with some hotkeys for mode switches and such. "rendering in a single thread" should never be an issue because it should never be "rendering". It needs to stream text to stdout. That's been a solved problem for 50 years and now it takes 2GB of memory to be done poorly with broken scrollback.
vmg12 8 hours ago [-]
Drawing to the terminal / rendering / whatever, this is all arguing semantics and very uninteresting and not insightful.
> 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.
wild_egg 7 hours ago [-]
There are two different arguments here.
> 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.
vmg12 6 hours ago [-]
The argument is that doing it all on a single thread will result in high cpu utilization and that is what makes the power usage spike and the pc feel hot. Thats it.
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.
hahahaa 4 hours ago [-]
Yeah I don't get it we had terminals on single core machines. In early 2000s I am sure they could handle the UI of Claude (probably IO too).
wild_egg 4 hours ago [-]
Early 2000s tech could absolutely handle LLM agents as a client. They output like 1-2kbps and even dial up modems would have plenty of capacity for other traffic.
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.
mixmastamyk 6 hours ago [-]
Stuff doable on a pentium 90, and before that, just slowly.
hahahaa 4 hours ago [-]
I wonder if those were fast enough nostalgia says yes but I bet it was dog slow if we tried today with 2026 lens.
mixmastamyk 3 hours ago [-]
My Turbo Pascal programs could calculate and print to the screen faster than could be read, on a 486. With DOS however.
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.
wild_egg 2 hours ago [-]
"The most amazing achievement of the computer software industry is its continuing cancellation of the steady and staggering gains made by the computer hardware industry."
— Henry Petroski
nnmg 7 hours ago [-]
I don't think any of that seriously counts as real work.
The heck? It does all that rendering for a tiny fraction of the total amount of time that the TUI is running. The streaming is IO bound, there’s no way that it’s outputting nearly enough text to tax the CPU that much.
anthk 8 hours ago [-]
Sorry, but nope; Golang there would be there a beast doing that in a much, much faster way. Not to mention C/C++ with NCurses.
vmg12 7 hours ago [-]
> 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.
Put up the code and prove it. We already know exactly how fast golang is in comparison to nodejs on basic numeric computations, it's roughly 40 to 50% faster.
I'm not concerned with CPU use/wakeups while actively using it, but with it sitting idle doing nothing.
skydhash 9 hours ago [-]
That’s not really a big issue. In major OS like the BSD, SMP implementation are not that old. If we can have a full OS running in single core mode, we can have an application being performant too. I’m currently running OpenBSD on 4 cores and it’s basically 99% idle.
Bad coding is just bad coding.
vmg12 8 hours ago [-]
It's basically idle because it's not doing anything. If you are streaming in markdown and code and then doing syntax highlighting on this code in real time, then rendering it on the screen you are doing actual work.
It's also all cpu bound work. The majority of the stuff on your screen is being rendered by the gpu.
wild_egg 3 hours ago [-]
> If you are streaming in markdown and code and then doing syntax highlighting on this code in real time, then rendering it on the screen you are doing actual work.
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.
skydhash 2 hours ago [-]
Processors today are very fast. If you are spiking it on rendering diffs, you’re doing it wrong. I can’t even stress it building openbsd’s kernel.
senderista 11 hours ago [-]
Why are you implicating ghostty? Have you compared its CPU usage to any other terminal?
ljm 11 hours ago [-]
Of course I have. If I see ghostty constantly consuming the most energy and helping reduce my battery life to barely 2 or 3 hours, the first thing I'm going to do is switch terminal to see if I can improve that situation. The built in terminal and WezTerm have been fine and I've had much more reasonable battery life since.
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.
andruby 8 hours ago [-]
This seems a suspicious. How do you measure the CPU load of Ghostty? Is the measure/reporting method just attributing the cpu load of the commands/programs you're running in Ghostty to Ghostty?
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.
benrutter 7 hours ago [-]
If you're looking for a non-ghostty recommendation (not that I have anything against ghostty) I use alacritty + zellij and it works fantastic. It doesn't seem to impact battery, I certainly get good battery usage on both my work and home laptops.
mtlmtlmtlmtl 4 hours ago [-]
I've messed around with pretty much all the fancy new terms to varying extents. Ghostty, wezterm, alacritty, etc. And I'm all in favour of people innovating in this space again. But at the end of the day, I always end up back with xterm. It's reasonably lightweight, runs and is packaged absolutely everywhere, I never have to muck about with termcap files and/or $TERM on remote hosts, and I've never had it break, crash, or exhibit any kind of bug or strange behaviour in over a decade of using it. The only TUI that has some quirks in xterm is Emacs, but Emacs has weird quirks in every term I've tried to run it in, and different quirks in every case somehow, so I just chalk that up to Emacs being weird. I'm sure xterm has some bugs buried in it still, but I bet all of them are in codepaths that are almost never reached nowadays, or at least are extremely niche. It does lack some features like ligature fonts(I just decided not to care), sixels and similar graphics things(again, don't really care) and panes/tabs/yadda yadda(tmux or screen or whatever you like can do all of that anyway).
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.
st3fan 10 hours ago [-]
Same. I really want to file a proper bug report for this but I haven't been able to really dig into the details and the last thing I want is a "ghostty is a cpu hog" kind of report without useful info on how to debug that.
agrippanux 11 hours ago [-]
I don't know if its still the case anymore since 1.3 but Ghostty did have a documented issue with Claude causing resource issues.
tdhz77 11 hours ago [-]
I think the author is saying everything that touches llm.
11 hours ago [-]
myaccountonhn 11 hours ago [-]
Its so wasteful, but that tracks with the modus operandi of AI companies.
onlyrealcuzzo 1 hours ago [-]
> If rewrites are so easy, why not rewrite CC in a native language? Would’ve been a hell of a lot cheaper.
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...
rafaelmn 7 hours ago [-]
I recently saw a blog post [1] about a famous Haskel shop moving away from Haskell to Python because the iteration speed with LLMs was just that much better. There is so much React in training data, TS compile times are minimal compared to Rust and similar.
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.
That blog post doesn’t make sense to me at all. The author is going from full modern Haskell (since he mentioned Servant and Beam, you could tell almost every file uses dozens of GHC extensions beyond what Haskell2010 gives you) to Python with dynamic types. He could instead rewrite the Haskell to use less modern type system features and get so much faster compilation speed.
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.
frollogaston 4 hours ago [-]
Python was faster to iterate on than Haskell even before LLMs
jmspring 2 hours ago [-]
I think Moore's Law and related have made programming sloppy. AI is building on that. There was a time where accounting for memory, footprint, stability, and speed mattered. Your point shows we are well passed that aside from certain areas.
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.
dmix 12 hours ago [-]
Codex CLI and Grok Build are both in Rust. OpenAI’s web still use react. Previously their CLI was React Ink until they ported most of it to Rust
abc42 5 hours ago [-]
>If rewrites are so easy, why not rewrite CC in a native language? Would’ve been a hell of a lot cheaper.
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?
Code verbosity and complexity still matter with LLM coding
pianopatrick 5 hours ago [-]
As a counter argument - I assume that Anthropic is using AI to write Claude Code.
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
simonw 5 hours ago [-]
I feel like a year ago JavaScript and Python were the best languages for coding agents to use because of their heavier presence in the training data, but I'm not sure that's true any more now.
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.
pianopatrick 4 hours ago [-]
Sometimes I think that if we are willing to burn tokens and rely on compilers in a loop we should be using languages that can catch as many errors as possible at compile time.
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.
hexasquid 2 hours ago [-]
I presume haskell applications similar to claude code are well represented in the training data.
pianopatrick 2 hours ago [-]
There was a post recently from a guy who used Haskell with AI agents. If I remember correctly he said the type checking did catch errors. The problem was the compiler was very slow, which slowed down the feedback loop and output. I think he switched to Python.
yoyohello13 7 hours ago [-]
It is kind of mind boggling. They could have chosen anything and decided to implement it in the slowest jankiest way possible.
Proves LLMs don’t help with taste.
johnfn 11 hours ago [-]
Why would rewriting Claude code, an app which probably has 30-40 (I might be significantly underestimating) extremely active contributors be easier than rewriting Bun, which has fewer contributors and almost certainly also less lines of code?
weakfish 11 hours ago [-]
Because I’ve been told that Fable can do anything :-)
My question is moreso “why was it ever JS in the first place”
& the cost of a native rewrite would be cheaper than acquiring Bun no matter how you shake it
jm4 9 hours ago [-]
Probably because it consumes the same APIs originally developed for a web app and the same front end engineers likely created Claude Code. People assume Anthropic set out to create Code as a product and went through a normal design phase. I think it’s more likely it started as an internal tool or someone’s side project and blew up as a product when they released it to the public.
w4der 5 hours ago [-]
But isn't the point of an API that it abstracts away the language(s) in which your application is written?
AndrewKemendo 11 hours ago [-]
>Because I’ve been told that Fable can do anything
I hear some version of this anecdote constantly
yet despite using all these prompting tools since 2019 I have never once heard a lab or professional say “x model can do anything”
Can you provide me whatever specific source you heard for this?
coldtea 10 hours ago [-]
>I have never once heard a lab or professional say “x model can do anything”
Yeah, they "merely" say that they're about to break the singularity in a couple of years, that it's too capable to be safe to release, that it's going to take 50% (or all, depening on the day and audience) of programmers out of work, that it's smarter than Nobel prize winners, that their programmers don't write anything themselves anymore, and things to that effect.
AndrewKemendo 10 hours ago [-]
Who is “they?”
Again… provide me a quote from someone doing this every day that says: “they're about to break the singularity in a couple of years”
The only people saying this stuff are random Internet commenters, breathless reporters and reactionaries.
The only person on record for a statement like this was Geoff Hinton about radiologists and he has since walked back his statement
weakfish 10 hours ago [-]
It’s hyperbolic and intended to generalize the sentiment I perceive from others.
Dario Amodei said in January that he expected software engineers to be replaced [0], so I suppose the quote should be extended to “can do anything… a software engineer can do”
And I think we can all agree that SWE is on the more complex end of all white collar jobs. So, my thinking is that if SWE can hypothetically be replaced, so can many other jobs. Hence, the claim the models can “do anything” intending to capture the majority of white collar work.
This, of course, is if you take their claim at face value - which I certainly do not.
Code is the killer app for LLMs so software developers are the easiest to replace.
weakfish 10 hours ago [-]
Code isn’t what the majority of software engineering is.
Kiro 9 hours ago [-]
Pointless nitpicking that completely missed my point. Software developers are not the hardest to replace, so your presumption that everything else should be easier is wrong.
weakfish 8 hours ago [-]
[flagged]
7 hours ago [-]
AndrewKemendo 10 hours ago [-]
So then nobody actually has ever said that and its explicitly hyperbole
So then its misleading in the extreme to say “I’ve been told AI can do anything”
It amplifies hype when people make claims like this by including hyperbolic statements as though they are reflective of the state of the discussion.
weakfish 10 hours ago [-]
Alright, sure, my bad. I thought it was clear that it was meant tongue in cheek, but I’ll accept it was unclear.
That said, with respect what I clarified, I’m curious your thoughts.
loosescrews 9 hours ago [-]
I'm doubtful that it has fewer lines of code, but even so, it is almost certainly less tricky and simpler code. You could also rewrite it in a higher level and more forgiving language than Rust (e.g. Go) and get huge improvements. The improvements would probably be much bigger than the improvements they have achieved at the JavaScript runtime level.
jayd16 4 hours ago [-]
I don't think people are saying it's easier, they're saying the results would be better.
ronniebasak 11 hours ago [-]
this. /s
jchw 8 hours ago [-]
Yknow, I really didn't mind Claude Code that badly, but subjectively speaking I really do like Codex more after using it for a couple weeks. Feels a bit snappier and lighter weight. I know with OpenAI you can actually use third party tools with the subscription so there's less of a draw to using Codex, but I still find myself preferring it now.
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.
amluto 7 hours ago [-]
Codex appears to be a mildly complex, somewhat-but-not-outrageously-sloppy Rust program (yes, I’ve poked around at its source — thank you OpenAI for making it more or less open source). It has lots of features, mostly related all the fancy web features of Codex.
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 don’t doubt his expertise, I just am not convinced it’s the right tool.
To me it comes back to the premise I hear a lot from AI hype men (of which I do not subscribe but it’s worth clarifying that I find great value in using it for code) that the code doesn’t matter anymore. I just don’t know how to square that claim with the idea that we’re limited still by JS/TS being easier to use or approachable despite inferior TUI toolsets.
8 hours ago [-]
8 hours ago [-]
hellohello2 11 hours ago [-]
I'm confused as well, could someone who knows how TUIs work explain what's the point of React-style diffing in this context? I thought you need to clean and full redraw if anything changs anyways?
tredre3 10 hours ago [-]
> I thought you need to clean and full redraw if anything changs anyways?
Unless you use an ancient teletype, you don't have to redraw everything. That would make any interactive applications way too slow/flickery.
You can move the cursor arbitrarily in the terminal and start overwriting characters from there. So you need to track state to know what is "dirty" and needs refreshing. Occasionally you issue a full redraw to catch missed artifacts left behind or when the terminal is resized (SIGWINCH).
9 hours ago [-]
qudat 10 hours ago [-]
You can do damage tracking for TUIs. Printing to the terminal is done by moving the cursor and redrawing the line the cursor is on.
delusional 11 hours ago [-]
Ncurses is how people used to do it.
11 hours ago [-]
frollogaston 4 hours ago [-]
And the TUI fights the terminal on basic things like copy/paste. I end up telling Claude to write all outputs to a tmp file.
tokioyoyo 8 hours ago [-]
Cause it works, most users are fine with it, people don't migrate off it because of the codebase, and easier to maintain if the dev team is familiar with code flow.
This is close to the same "why Spotify is a chromium embed?" question. Because it works, and users are ok with it.
mischief6 53 minutes ago [-]
i got annoyed by this especially the memory use and non portability aspect of bun so I had claude (lol) and kiro cook up my own agent. it runs on linux, openbsd and even on omnios and esp32. it's just a personal project so there are probably rough edges, but I am using it on my clockworkpi uconsole daily now. https://github.com/mischief/clm
bushbaba 7 hours ago [-]
JavaScript is very fast and easy for UI rendering. If it works for web apps it’d also work for the terminal. Sure it’s bloated but it’s fine. The dev velocity of JavaScripts is orders better than rust.
cozzyd 9 hours ago [-]
Otherwise an idle TUI wouldn't halve my laptop's battery life. Maybe that's an exaggeration but not that much, based on looking at wakeups in powertop.
sroussey 11 hours ago [-]
So the code for the web, the desktop app, and the cli where largely similar.
qudat 10 hours ago [-]
The component trees have to be rewritten, only the non-view related JS code can be reused.
groundzeros2015 8 hours ago [-]
The answer is those are the tools their lead engineers knew, so they repurposed them rather than learning other paradigms .
antonvs 2 hours ago [-]
To the man with a hammer…
golergka 1 hours ago [-]
I’m not sure what else can you use to share the same business logic between website frontend, desktop gui and tui apps and backend
onetrickwolf 9 hours ago [-]
> why not rewrite CC in a native language?
It's hell to maintain for not much gain (for a use case like this at least). As much as it's become a meme, JS and web tech in general has become extremely portable and stable.
I also don't think Anthropic bought bun to make their TUI better. They could have forked it, they bought bun because it incidentally was excellent for the way agents prefer to work and they wanted to capture that audience.
vips7L 8 hours ago [-]
I thought maintenance was free with LLMs???
tayo42 55 minutes ago [-]
I don't think it's that kind of maintenance like code.you need to test cross compiling and running on different platforms. I guess js acts like how the jvm is
simonw 9 hours ago [-]
I think they bought Bun because it was a supply chain risk for them.
Their new flagship product (earning them billions of dollars in revenue per month) was dependent on a platform maintained by a tiny startup.
Buying Bun was a very rational way to reduce that risk, epically since it also got them some top tier engineering talent.
Thinking about that further, I wonder if that was part of the rationale for switching from Zig to Rust that they haven't talked about?
Zig is a much riskier bet for your multi-billion dollar cash cow than Rust is.
But saying that out loud would be rude - they took steps to NOT openly criticize Zig, even after Zig's founder did not show them the same courtesy.
keeganpoppen 7 hours ago [-]
it is kinda mystifying bc from what i understand their engineering ethos is very much "if it's not working, just regenerate it" (which i completely understand).
12 hours ago [-]
newswasboring 9 hours ago [-]
Anything that can be written in JavaScript will be written in JavaScript. That's just how it is it seems.
api 7 hours ago [-]
Lots of devs know how to code in it, and the AI models have more training in JavaScript than any other language.
It's like asking "why does everything run on Windows?" Because everything runs on Windows.
miroljub 7 hours ago [-]
> Maybe I’m taking crazy pills, but I’m still stuck on “why the hell does a TUI need to run in terminal React by way of JavaScript”
No, you are not crazy. They do crazy things with unlimited budget, and still their chat app flickers when using.
They should just port pi-tui from pi coding agent, since they have no clue.
deadbabe 9 hours ago [-]
Should have done it in C++ with SDL3.
voidhorse 11 hours ago [-]
Probably because claude suggested some kind of wack react based setup early on (because react dominates the training data) and it's be blasphemy worthy of termination for the Anthropic employees to question the sacred pronouncements of the llm.
ozgrakkurt 12 hours ago [-]
If you think that way I would recommend just keeping away from these topics. It is just useless arguing and speculating about things don’t matter.
I have been trying to keep away in the last couple weeks and it was all win for me. I still come down here sometimes when I am stressed with real work since it is a strong addiction to see “how terrible the plebs are doing”.
fny 11 hours ago [-]
JavaScript is dynamic and supports live reload which means iterations are far faster than would be in a compiled language--even for LLMs.
This is especially useful when you're trying to evaluate behaviors while changing state surgically.
amoss 10 hours ago [-]
If you are relying on live updates to change state in a dynamic language then you are not doing it "surgically", unless there is some other definition that means hitting it softly with a large rock.
pjmlp 10 hours ago [-]
There are several compiled languages with live reloading, including C++.
nozzlegear 10 hours ago [-]
There's no surgery when you're a company with a trillion dollar hammer and every problem looks like a big ass nail.
embedding-shape 16 hours ago [-]
> For me this outputs Bun v1.4.0 (macOS arm64). 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 in darkness and is now something completely else. I'm glad I still had "Investigate if Bun is worth it" on my TODO list and hadn't yet gotten to it.
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?
junon 16 hours ago [-]
Why does changing to Rust kill the project? I don't understand the point here.
atonse 16 hours ago [-]
It’s made absolutely no negative difference, as we’ve seen in the real world in the last 60 days since the merge.
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.
jasode 15 hours ago [-]
>Literally who cares what language a JS toolset is written in?
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.
estearum 15 hours ago [-]
I think you're missing group 3, which is the "assume bad faith and/or bad outcome from any possible change to anything, and especially changes to open source projects that can be interpreted as exogenous, e.g. from an acquirer, and especially if that acquirer is a gigantic commercial entity."
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.
atonse 11 hours ago [-]
I think most of the naysayers are in group 3 because there’s a lot of anger but never a single link to a blog post or analysis done by anyone to demonstrate a regression. not one. There are some that analyzed the quality of the initial rust code and use of unsafe but Claude has been chewing through those as I understand.
It was a PR issue more than anything else. It is also a proxy for Pro AI and Anti AI sentiment.
And for most part I don't think it was communicated well apart from the last blog post.
rjzzleep 15 hours ago [-]
What about Group x.
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?
tokioyoyo 8 hours ago [-]
What was your safety guarantee pre-rewrite? If CVE scanners and aggregators is your answer, then well, this applies to post-rewrite as well.
10 hours ago [-]
10 hours ago [-]
conartist6 14 hours ago [-]
Don't forget the group asking really dumb pointless questions like "who legally owns the rewritten code"
ethbr1 13 hours ago [-]
Afaik, under current US law (Thaler v. Perlmutter 2025^), "the Copyright Act of 1976 requires all eligible work to be authored in the first instance by a human being".
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.
Couldn't it be argued that Bun-Rust is still MIT licensed, because the old implementation was "in the first instance" authored by a human? All the machine did was translate it.
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?
simonw 6 hours ago [-]
"If the LLM trained on GPL-derived code, what does that mean for the end result?"
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.
conartist6 5 hours ago [-]
Yeah you could argue that, but it's a messy argument. I'm wiling to imagine that they hadn't used AI to do the rewrite to Rust. It wouldn't have been all that hard to do with plain old syntax tree transformation (my expertise). The trickier question for me is the ownership at the boundary where prompts were turned into Zig code. That is not a process that could have been done with syntax tree transformation: creative freedom was given to the model as to how to do the work at that stage, and so that is the stage at which I'm least sure they could legally defend their claim to ownership.
layer8 15 hours ago [-]
> who cares what language a JS toolset is written in?
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.
pronik 6 hours ago [-]
> blanket-closed all issues submitted before the rewrite
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?
skybrian 14 hours ago [-]
[dead]
doctorpangloss 11 hours ago [-]
imagine being the leadership of the one of most valuable US private companies in the world. then you have to make something called a "pull request" that gets "reviewed" by someone named "Jarred" to make improvements to your stuff. do you see how that is untenable?
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.
12 hours ago [-]
jgalt212 14 hours ago [-]
> It’s made absolutely no negative difference, as we’ve seen in the real world in the last 60 days since the merge.
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
Issues on GitHub was mass closed claiming zig is no longer relevant without fixing the real issues.
atonse 11 hours ago [-]
Whole classes of bugs WERE fixed by moving to rust. wouldn’t that result in mass closures of classes of bugs that were no longer relevant in rust? What would you prefer?
jdiff 33 minutes ago [-]
Whole classes of bugs are fixed by safe rust. This is not safe rust. As a line-by-line translation with unsafe forced anywhere necessary to make it compile, this should result in no classes of bugs fixed by moving to rust.
re-thc 9 hours ago [-]
I would prefer they confirm before closing. It's AI / bot anyway. Instead it's just mass keyword zig = close. The bug can still exist post-port. None of it got "fact-checked".
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".
vermilingua 15 hours ago [-]
Except that it hasn’t yet hit the real world, the live release is still 1.13.4, the last Zig version. Anthropic does not operate in the real world.
Tadpole9181 12 hours ago [-]
The canary build has been Rust for over a month, available to anyone. In that time it has been used in production for Claude Code and Prisma Compute.
atonse 11 hours ago [-]
Not sure why this purely factual post got downvoted. Upvoted it.
zzzeek 13 hours ago [-]
this whole AI era has put the topic of "do we believe actual reality, or what we hoped/assumed/continue to insist would be reality" front and center. Every discussion is like this these days.
bbg2401 15 hours ago [-]
The crux is:
> 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.
cube00 14 hours ago [-]
> I'm guessing it's essentially just "Anthropic decides what gets done and accepted" today?
Similar to the Claude Code 60s timeout incident [1] it could just be "Jarade decides what gets done and accepted"
Sometimes the questions aren't justified, though, like when someone else’s project is someone else’s project.
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.
bmitc 12 hours ago [-]
The outrage was more how the rewrite was communicated and defended, which was objectively poor.
pronik 6 hours ago [-]
Which was completely bonkers -- it happened completely in the open, people were just outraged that something like this happens without asking them and not on a schedule they perceive as adequate. Most of them haven't really grasped what was happening and why. Many still don't.
cube00 3 hours ago [-]
> it happened completely in the open
You don't create PRs like this when you're working "completely in the open"
It wasn't out in the open. It was never announced or discussed ahead of time. It was just done because the company who purchased Bun wanted it done, and they only communicated it was happening once they started.
I don't consider the following comment to be good, honest, and open communication:
> 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.
bmitc 4 hours ago [-]
He knew he wasn't going to throw out the code when he made that comment.
simonw 2 hours ago [-]
I think he didn't know. We are at an impasse.
well_ackshually 16 hours ago [-]
[flagged]
CrimsonRain 15 hours ago [-]
What a load of bs.
> Inevitable collapse
According to who? You? The well ackshually guy?
> Low in trust before acquisition
Cite your sources.
> Unreleased version
v140 is the canary version which has been available for a long time.
What is actually going on with that tag? It has files uploaded in Jul 29, 2024 and files uploaded "6 hours ago" (some hours after Simon first published his blog post). Do they not do proper releases with immutable tags and instead use one tag kind of like a git branch that mutates and changes over time?
simonw 14 hours ago [-]
Yeah, it looks like they constantly repoint the "canary" tag at whatever they think should be the new canary release.
I don't like that, personally. I think the project would be easier to reason about if they shipped alpha versions instead.
bikeshedpelicun 14 hours ago [-]
[flagged]
simonw 13 hours ago [-]
Did you create a burner account just to accuse me of bikeshedding Bun's release tag process?
stymaar 16 hours ago [-]
Rust as a language is irrelevant to this discussion, the problem is that bun was vibe coded by a single dude without any open source community involvement. “bun the open source project” is basically dead at that point: don't expect any of the zig enthusiasts who had their code being forcibly rewritten in a language they don't like to follow Jared.
“bun the JavaScript runtime ” is not dead though.
Matl 15 hours ago [-]
I agree, it's unfortunate the headlines seem to have become 'rewritten in Rust' (not a bad thing) and not 'vibecoded in a week without review' (a bad thing).
rane 13 hours ago [-]
"Vibecoded" is not an accurate description of what actually happened. LLMs are extremely good at porting code from one language to another while preserving semantics. Which is why how everything turned out so well was not very surprising.
endospore 12 hours ago [-]
"Preserving semantics" by casting pointers to aliasing refs in Rust, ignoring lints and errors in the process.
Can't help laughing at this point.
mpyne 12 hours ago [-]
I don't know, did the prior vibe-coded Zig code not ever have pointers aliased to data? Might be preserving semantics too well, if anything.
endospore 12 hours ago [-]
The Zig one uses raw pointers. These are bad and get out of hand quickly but at least don't have constraints like "you must never have two &mut on the same value". You may refer to c2rust to see how "semantics preserving transformation" without new UBs looks like.
uecker 11 hours ago [-]
Rust as a language is not relevant, but the Rust community still helped to popularize the idea that trashing a community by a rewrite is ok if it serves some "higher goal". This rewrite is just a striking example why this is problematic.
Dylan16807 14 hours ago [-]
Surely a lot of review has happened in the last two months?
endospore 12 hours ago [-]
Reviewing is meaningless while they are still keeping the 10433 (sorry it has become 10503 since last week) unsafe blocks, most unsound and none encapsulated.
Any review would get to the simple conclusion that this should not be released before all the obvious bads are sorted out.
Tadpole9181 12 hours ago [-]
This feels like such an absurd, bad faith take I keep hearing.
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?
ambicapter 11 hours ago [-]
What's the point of rewriting it to Rust if you're going to, on purpose, disable the most prominent benefits of using Rust?
Tadpole9181 9 hours ago [-]
It isn't disabled, it has exclusions. Now that they have it, they can close the gaps. It was literally impossible to have ANY coverage before, now they are mostly, covered and have an avenue for remediation.
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.
fleventynine 7 hours ago [-]
I like Rust and use it full-time professionally. Unsafe is not the same as unsound. Unsound means that the unsafe code is not maintaining the aliasing invariants on references required by the language, and thus undefined behavior can leak into safe code (that is, the safe code can be miscompiled).
Known unsound code should not be merged, let alone released to production. If you have good enough tests and run them under MIRI or ASAN, maybe you can get away with it for a time, but most Rust experts would not sign-off on such a project.
If somebody put a gun to my head and told me to make the best of such a codebase, I would try to figure out how to turn off the LLVM optimizations that assume the Rust references don't alias. With these optimizations this codebase is scarier than most C or C++ code.
skydhash 11 hours ago [-]
I'm not a rust dev. But I've been once asked to take care of a TypeScript codebase and the thing was littered with so many casts to `any`, you're wondering why they bothered with TypeScript in the first place. Some people do choose tech on a vibe and not any real analysis.
endospore 11 hours ago [-]
My conclusion was formed in my two months long tracking of the repo activities. They have done absolutely nothing in that front. (Well, to be precise they tried to fix exactly one thing that was pointed out but that's it)
> 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.
lunar_mycroft 6 hours ago [-]
> Deno for instance have ~0.2x as many unsafes.
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).
Tadpole9181 9 hours ago [-]
> I'd remind you the current new version is not an improvement compared to the previous one, both in terms of correctness and maintainability.
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.
endospore 3 hours ago [-]
> nobody has really pointed to a single actual issue
I personally know 3 categories of newly introduced issues spanning the code base with 200+ occurrences, that leads to undefined behavior and memory issues. Not doing any contributions to the code is my conscious decision, which includes not pointing to the specific problems in public.
It's nice to hear that people are doing the same.
ljm 12 hours ago [-]
> bun was vibe coded by a single dude without any open source community involvement.
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.
Dylan16807 14 hours ago [-]
Is the idea that a code base reset makes something stop being open source? Or that the number of people doing the reset matters?
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.
avianlyric 14 hours ago [-]
I think the point is that an “open source project” is more than just the code and license, it’s also the community that builds and maintains it.
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.
Tadpole9181 12 hours ago [-]
Just so everyone know, Bun is and has always been owned by a YC funded org with full time employees. The overwhelming majority of commits came from them.
Dylan16807 13 hours ago [-]
A reset is very different from not being open source any more. If losing most of the community would mark a project dead in open source terms, then every new project would be dead on arrival. And that would just be silly.
CrimsonRain 15 hours ago [-]
That's just like your opinion...? More power to Jared (and anyone else) if they can "vibe code" useful projects like bun.
_pdp_ 16 hours ago [-]
I am impartial on the matter, but I think one of the reasons Bun became a thing in the first place was because of Zig attracted a small but very active developer community. Switching from Zig to Rust effectively alienates that community.
petcat 16 hours ago [-]
I think the Zig people are really just worried that maybe Zig itself is a DOA language before it has even reached 1.0 because it doesn't offer enough over C for any serious use and their flagship project has now abandoned it.
pmarreck 16 hours ago [-]
Anyone actually using it knows it is better. The C interop is so good that there is no use-case where C is the better option IMHO
59nadir 15 hours ago [-]
You, by your own admission, haven't even written a single line of Zig despite having ~31 Zig projects on GitHub. I don't think your knowledge of the language is to be trusted in almost any capacity. This might seem harsh but I don't trust someone who's experience with a language amounts to slopping out 30+ repositories and not even engaging with the language normally.
lstodd 11 hours ago [-]
By my own admission I wrote ~100K loc in zig-head. Having a background in linux kernel development of all things I can tell you that Zig is so much better than C or Rust, that I think linux kernel rush to rust is misguided.
59nadir 9 hours ago [-]
I haven't even stated whether I agree with the opinion that Zig is worth it, in fact I do think Zig is worth it for a large set of problems and I wrote Zig for years, I am stating simply that I would never trust anyone who's self-admitting that they don't even write the language they're arguing for when it comes to opinions on whether it's good or not. It's not really about whether Zig is good, it's about someone who doesn't even write the language and doesn't even know it, not having a valuable opinion on it.
pjmlp 10 hours ago [-]
Industry standards, existing team knowledge, use after free story is the same as C already has.
bitwize 13 hours ago [-]
Zig is a DOA language for other reasons though. The reason why Rust enthusiasts act so morally superior is because they are:
> 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.
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.
K0nserv 11 hours ago [-]
> 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.
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.
yeah rust has no footguns. just dont try to mix clone with iter.
K0nserv 8 hours ago [-]
Of course Rust has a few footguns too, that's not my point.
skydhash 11 hours ago [-]
There are many things in life that are "fine" only when you take extreme care (knives, cars, industrial machinery,...). The thing is something like C has many usages and you can't just say "use Rust" and be done with it. Using Rust is not cost-free.
K0nserv 8 hours ago [-]
I'm not saying "never use C". The thing I dislike is the false dichotomy between "(Zig|C|Go) is simple unlike Rust, which is complex". A statement like that makes it sound like writing correct code in the former is easier when it's, in fact harder.
pjmlp 10 hours ago [-]
There is more to it even, the UNIX and C founders arrived to Go, before retirement, after a few other interactions.
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?
BigTTYGothGF 7 hours ago [-]
> And then we have a bunch of folks assuming they know better about C that its own authors?
Barthes aside, C's changed a lot in the years since they left.
pjmlp 5 hours ago [-]
Yes they stopped caring after C89, Plan 9 C compiler was a mix of C89 with extensions.
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.
BigTTYGothGF 2 hours ago [-]
> kind of proves the point
I don't think it proves anything other than the wanted to work on something else.
csb6 4 hours ago [-]
The post you linked to seems to jump to conclusions, to say the least. For example:
> 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.
phoghed 15 hours ago [-]
If this were true the very small but active community of Zig contributors could just fork it and you could all return to the happy times of not using Bun anyway.
CrimsonRain 14 hours ago [-]
Bun became a thing because it provided some specific benefit to js ecosystem. Zig enabled the rapid development. The people who contributed were definitely helpful but they can still choose to help or not and new people will step up too
OJFord 16 hours ago [-]
Emphasis on the FOSS project. The v1.4 mentioned is not (yet?) open source, Claude Code is essentially using a proprietary fork, was GP's point.
atonse 16 hours ago [-]
You can install it now we with bun upgrade —-canary it something along those lines.
NuclearPM 15 hours ago [-]
I think you’re missing a word or two.
layer8 15 hours ago [-]
Based on comments elsethread, I think what was meant is: You can install it now with “bun upgrade --canary”, or something along those lines.
However, people also report that the canary version doesn’t identify itself as version 1.4.
OJFord 10 hours ago [-]
It's extremely obvious what they meant, even if it/or wasn't a common phone autocorrect typo.
CrimsonRain 12 hours ago [-]
And GP is full of shit as the main branch is the v1.4.0. it is not "released" yet as it is not finished. It is available as canary version.
croes 11 hours ago [-]
So Anthropic ships with unfinished version of bun.
Doesn’t sound like responsible software deployment
CrimsonRain 2 hours ago [-]
They can ship with whatever they want as long as it works.
croes 40 minutes ago [-]
Given the permissions Claude Code gets on many systems they should be more professional.
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?
10 hours ago [-]
11 hours ago [-]
12 hours ago [-]
goo0000fy 16 hours ago [-]
[flagged]
OJFord 16 hours ago [-]
From the article:
> For me this outputs Bun v1.4.0 (macOS arm64). 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.
Which is still true as I write this comment.
simonw 16 hours ago [-]
The code is on GitHub in the "main" branch, it's only unreleased in that it hasn't been tagged with a version number yet.
OJFord 11 hours ago [-]
If it hasn't been tagged with a version yet, how do you know (or what makes you think) it's the same as this 'v1.4'?
simonw 11 hours ago [-]
I don't know for certain, but it seems likely that it is given that Jarred said "Claude Code v2.1.181 (released June 17th) and later use the Rust port of Bun".
What motive could he have for secretly maintaining a private fork of Bun that's shipped with Claude Code while simultaneously working on the open source repairs every day?
goo0000fy 15 hours ago [-]
yeah the word "unreleased" makes it sound so mysterious
i am a clankersceptic as much as the next guy and i hate "anthropic" for participating in the murder of innocent people (maven "smart" system, offers them as a provider to the pedo criminal unitedstatistan government)
but this whole "unreleased" framing is just manufacturing drama / lack of knowledge
kelnos 16 hours ago [-]
A charitable interpretation is that the version of bun inside Claude Code corresponds to some recent state of their public git repository, so if you clone that, you more or less get the same thing.
I don't see what it would buy Anthropic to have some sort of secret internal fork with special private code in it.
goo0000fy 15 hours ago [-]
bun upgrade --canary
hoppp 16 hours ago [-]
Bun is now mainly the runtime for claude code. All changes will go in to make claude code better.
It's not about making the dev experience better than node, that use-case is now secondary.
afavour 16 hours ago [-]
The objection isn’t to the language. It’s to Claude using a version of Bun that is not available to us. We don’t know what’s actually in it.
kstenerud 16 hours ago [-]
Why is that even a thing to object to? You're talking as if you placed stock in the bizarre idea that Anthropic would close source the project and start charging for it.
Stay your pitchforks.
afavour 15 hours ago [-]
I wouldn’t use language as strong as OPs but it is against the spirit of FOSS for a corporate owner to use a private prerelease version of their open source software.
I think it’s valid to object to. If 1.4 is good enough to be used by Claude, why not us?
kstenerud 15 hours ago [-]
So you wouldn't, for example, after doing a complete ground-up rewrite, perhaps spend a few months dogfooding it to work out the worst bugs before unleashing it upon the public, thus maximizing your initial velocity by minimizing the blast radius and support requests and triage during this phase?
realo 15 hours ago [-]
It's Anthropic. I am pretty sure they spent time dogfooding it to Mythos or an even more advanced model.
That might even be the reason why they switched to rust.
Don't worry too much.
afavour 15 hours ago [-]
> before unleashing it upon the public
…but they have? Claude users are public, no? If they were dogfooding internally I’d agree with you.
kstenerud 15 hours ago [-]
Yeah. One single project that they control. Not thousands of other people's projects breaking, I'm sure with a ton of HN outcry over releasing "this pile of vibe coded slop" upon the poor populace.
You just can't win.
afavour 15 hours ago [-]
> you just can’t win
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.
ithkuil 9 hours ago [-]
The irony. A company building models and tooling to automatically produce code being attacked for using automatically produced code in the very tools that allow people to automatically produce code, presumably by somebody who wants to use their tools to automatically produce code, possibly because they believe that their approach at ensuring that automatically produced code is properly reviewed by a responsible human has to be more thorough than whatever that company does because of course they were going too fast and thus it can't be good
kstenerud 13 hours ago [-]
How do you know it's vibe coded slop? Have you seen the source code?
ethbr1 13 hours ago [-]
> How do you know it's vibe coded slop? Have you seen the source code?
I believe you've just made your opponent's point for them.
kstenerud 13 hours ago [-]
Have I? I believe I've merely chased them around their moving goalposts. When it's closed source, that's nefarious because "they're not sharing" and that's against the whole spirit of open source. When it's dogfooding with a reduced audience, it's "shoving vibe coded slop on people" (this information gleaned through magical knowledge). When that unfounded assertion is called, lo and behold: It's closed source, so bad bad bad! It's called a logical fallacy for a reason.
But more to your point: Do you believe in "guilty until proven innocent"? Do you believe that they're doing bad things with the bun code, and you can't be convinced otherwise in your judgment of them until they release the code?
ethbr1 10 hours ago [-]
More to the point, because you've been chasing them around goalposts, you've both accepted that the question at hand is unknowable precisely because the source isn't available.
> Do you believe in "guilty until proven innocent"? Do you believe that they're doing bad things with the bun code, and you can't be convinced otherwise in your judgment of them until they release the code?
Hell yes, and anyone who trusts one of the AI labs for anything important is insane.
Whether it's their initial mass piracy and then lying about it, dealmaking with the US government, or continually shifting opt-out lines on what they are and aren't training on, they haven't earned the trust to skip the "but verify" step.
Their economic incentives are too transparently aligned with ends at any costs.
well_ackshually 16 hours ago [-]
You're running a closed source piece of software (claude code), running on an effectively closed source piece of software (bun), both of them updated daily by AI psychosis bros.
At this point, charging is the least of your issues.
kelnos 16 hours ago [-]
It may be available to us, in the form of a git checkout of their public repository.
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.
dgacmu 15 hours ago [-]
It's probably not. I tried to extract the commit hash from the version of bun packaged in claude code. the commit hashes from previous versions resolve, whereas the commit hash for the current 1.4.0 isn't available.
from strings:
bun-v1.4.0
f6d0fcd24abd48061873c2f1a6fb2a67eee487b8
Upgraded.
Welcome to Bun's latest canary build!
This build does have a different way of identifying itself than earlier builds so it's possible this string isn't correct.
(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.
jen20 7 hours ago [-]
That is also true of the rest of their codebase, no?
firesteelrain 16 hours ago [-]
Moving the goalposts?
afavour 16 hours ago [-]
No? I think OP’s comment was very clear:
> 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.
firesteelrain 16 hours ago [-]
> The objection isn’t to the language. It’s to Claude using a version of Bun that is not available to us.
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.
afavour 15 hours ago [-]
That seems illogical to me. We’re only allowed to have one objection to a project and once that’s used up we can’t air another? FWIW I don’t think people have forgotten the original objection either!
firesteelrain 15 hours ago [-]
You can; it feels contrived and very social justice warrior/anti Anthropic (which on HN is in of itself almost a meme now). The main reason was because of the blanket AI move which I could understand.
afavour 15 hours ago [-]
I think your perception of events is pretty heavily affected by personal bias here. Objecting to a hasty AI rewrite of an entire runtime and objecting to violating the spirit of FOSS is “very social justice warrior”?
What?
firesteelrain 15 hours ago [-]
Please re read your original comment. AI rewrite is one thing and objecting to FOSS/non FOSS is a new argument, anti-Anthropic etc is moving the goal posts. The main argument was the blanket rewrite to Rust using Claude.
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?
afavour 15 hours ago [-]
Airing two entirely separate objections to a project is not “moving the goalposts”. The original objection still stands! You’re using a phrase you’ve heard in an inappropriate context.
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.
14 hours ago [-]
firesteelrain 14 hours ago [-]
[dead]
embedding-shape 15 hours ago [-]
> 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'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.
Your point being? None of my comments in either of those state that I'm upset about it moving from Zig to Rust?
firesteelrain 14 hours ago [-]
I wasn’t referring to you and rather the general sentiment. Hence, goal posts have been moved again comment.
embedding-shape 13 hours ago [-]
My overall larger point (maybe poorly stated) was that unless you're engaged specifically in a 1-on-1 conversation with someone, accusing a whole community of "moving the goalpost" makes no sense, there is a whole host of arguments and points being made in different directions all the time, by different individuals.
firesteelrain 13 hours ago [-]
I see what you are saying. My comment is rooted in the fact that different people are foregrounding different objections to Anthropic/Bun, and taken together it looks like whatever launches, someone will find a reason to be upset
Cthulhu_ 16 hours ago [-]
Yeah same, according to one of the Zig team members, the original source code wasn't all that anyway.
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).
flohofwoe 16 hours ago [-]
An interesting tidbit is that large parts of the original Bun source code was a line-by-line port of esbuild from Go to Zig (mentioned here: https://bun.com/blog/bun-in-rust), tbh this lowered my respect for the project a bit (a line-by-line port simply isn't as interesting as original work), and it might also explain the subpar Zig code quality (a line-by-line port from Go to Zig simply won't result in idiomatic Zig). It also might explain why porting from Zig to Rust was done 'on a whim', the actual source code (and the idea of 'original work') never seemed to be all that important to the author (and I wouldn't be surprised if the project does more language-hopping in the future heh).
realo 14 hours ago [-]
I read your link, written by Bun's author and totally get his thinking.
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.
ambicapter 11 hours ago [-]
Are you really "doing things securely" when you use as many unsafe blocks as the Rust port of Bun does?
gipp 16 hours ago [-]
I don't think the GP had anything to do with the language change itself. More that it marks a clear point of Anthropic taking ownership and governance of the project in a less open direction.
amazingman 11 hours ago [-]
I didn't read OP as complaining about the rewrite, but about the (lack of clear) governance after being acquired by Anthropic.
pjmlp 16 hours ago [-]
Definitely, it was a possible reason why Zig actually matters in the industry.
Now it is a Deno clone, both without anything enticing over node.js.
16 hours ago [-]
foxes 16 hours ago [-]
As an open source - community driven project? Have you looked at the repo on github?
Theres thousands of PRs from claude agents or whatever.
Yeah really feels like a worthwhile place to contribute lol.
embedding-shape 15 hours ago [-]
> As an open source - community driven project? Have you looked at the repo on github?
FOSS as in FOSS - Free and Open Source Software. Has nothing to do with if it's community driven or not, I'm strictly talking about FOSS.
jeroenhd 16 hours ago [-]
My personal feelings about the matter is that having an LLM rewrite the entire thing as an experiment and then just going with it a few weeks later kills any incentive for a community to build up around it. It's a clear signal that every basic aspect of the runtime can change on a whim.
I don't care about meh Zig being rewritten to bad Rust if it does the same thing, but taking what is presented as" look at this funny experiment I did" and then taking that into production with barely any announcement is what kills off the interest to me.
Bun has been a great ad for whatever LLM they were using but the cool factor is gone now, and that's really what set it apart from basic NodeJS in my mind.
entrope 14 hours ago [-]
> taking that into production with barely any announcement is what kills off the interest to me.
Did Bun v1.4.0 release weeks ago and I missed it? I would call a formal release the point that it goes "into production", and I think dogfooding it via Claude Code is yet another form of testing Bun-in-Rust before the latter goes to casual users.
atonse 16 hours ago [-]
Which community specifically though? The overwhelming “user” community would be web developers and people writing JS/TS, right? Not zig/rust developers.
jdiff 16 hours ago [-]
There were very many open pull requests from the community that were all invalidated overnight for something that same community was assured was merely an experiment.
The normal process would be "hey, this experiment is going well, we've made this plan, come help us shake out the new codebase for the switchover in X time." None of that happened. There wasn't even an announcement, just a silent commit that trashed hard work from hundreds of community members.
CrimsonRain 11 hours ago [-]
None of that is needed. Nobody benefits from all that time wasting bureaucracy/corpo speak. Bun is quick to deliver new features and bug fixes. With this change, the hope is that'll only get faster.
All those PRs can be fed thru Claude and converted to rust and then manual polish can be added.
jdiff 10 hours ago [-]
Bun is riddled with bugs. That's what moving fast and breaking things gets you. It gets you famously bad codebases that are nightmares to work with and slow you down over time as your sins catch up with you. Vibecoding is not enough.
CrimsonRain 2 hours ago [-]
Then why do you care? If target users (developers) face issues with bun, they will stop using it. Go back to Node or switch to Deno.
Bun has bugs? yes. Do they affect vast majority of users? Not really. Been using bun for about 3 years; never had an issue with it.
jdiff 1 hours ago [-]
Are you interested in the discussion that was taking place before you popped in or are you just here to get outraged that something you clearly identify strongly with is getting criticism for making poor choices?
"Because the discussion was interesting" is why I care.
waisbrot 16 hours ago [-]
Developer community. "Open source" historically implied that an interested developer might hack on the code and submit their changes. But if the entire code-base is rewritten by the maintainer every year, then there's no developer community.
hibikir 16 hours ago [-]
It's like a couple of languages I know where there's still one real owner, and there's no real review, and PRs are unlikely to be merged, even with review: They might be open source, but it's more a source visible thing, because you are never going to get a change in, and the language will change directions at the creator's lone whim. The best you can get at times is "I didn't like your PR, so I implemented the feature you tried to add completely different". Typical community killers.
muglug 16 hours ago [-]
The language an application is authored in does not matter to me, as a user. I care that it is widely-used (safety in numbers), that it works, and that it is fast.
It's cool that the Zig project exists, but I'm unlikely to ever use Zig so that’s sort of orthogonal to my interests.
locknitpicker 16 hours ago [-]
> Why does changing to Rust kill the project? I don't understand the point here.
I'm concerned that the complete rewrite in an entirely different language is not a sound technical decision and instead is a ploy to shed copyright claims from past contributors.
Now, based on comments from this thread, the formerly FLOSS project is somehow granting special access to a corporation that apparently is invested in going way out of their way to push implementations that consume the complete rewrite before the world has access to it.
I for one won't be touching Bun. This doesn't pass the smell test. It feels like a bait-and-switch in progress.
brabel 16 hours ago [-]
> I'm concerned that the complete rewrite in an entirely different language is not a sound technical decision…
Even if this was a terrible technical decision, it is a good, maybe even unavoidable, business decision. And I don’t think moving to Rust was a bad technical decision at all, given Zig is unstable and constantly changing, and that it’s not memory safe, which is a big problem for something like a JS runtime!
The reason it’s a necessary business decision is that Bun is owned by an AI company and Zig has a policy to not accept AI assisted contributions, making it impossible for Anthropic to contribute to a language that is still evolving rapidly, not to mention the bad marketing of using a language that basically is hostile to your product.
CrimsonRain 11 hours ago [-]
A lot of hypotheticals, conjecture, speculation, personal feels devoid of any facts. That somehow kills the project. ok!
conartist6 16 hours ago [-]
of course they also gave away their own claim to be the copyright owner, but that's neither here nor there ; )
embedding-shape 16 hours ago [-]
I don't care about the language, but pre-releases the community don't get access to but released (Anthropic) applications do have access to, feels a bit too on the nose after the acquisition.
atonse 16 hours ago [-]
The whole point of the outrage was that 1.4 was merged into main. Publicly. So I’m not sure what you mean.
Everything is in the open: PR #30412
embedding-shape 16 hours ago [-]
> The whole point of the outrage
Ok, go ask those people what they think then, I feel no outrage over a project switching language or merging whatever. But when once-semi-transparent projects become more opaque after an acquisition, I'm starting to readjust anything to the project I had in mind.
jdiff 16 hours ago [-]
That PR is the rust rewrite. That's some time in the past now. As of this comment, there is no tagged 1.4 release. This is the present. Anthropic is using apparently a version of Bun that is not publicly available. This is orthogonal to it being Rust-based, as all Bun releases now will be.
That commit (and main) still purports to be 1.3.14, the version numbers haven't changed. Does that not still suggest Anthropic is using something else?
simonw 15 hours ago [-]
I think Bun/Anthropic should document which commit hash their "1.4" as shipped in Claude Code uses.
alexjurkiewicz 16 hours ago [-]
Come on, "not publicly available"? You know how git works right? Each Claude release probably has the HEAD of main compiled as "1.4.0" until there is a real official release.
jdiff 15 hours ago [-]
I do know how git works and in my experience, while the version number sometimes doesn't get bumped until just before a release is tagged, the version number comes from the codebase. If they're building something that says 1.4.0, then they have a codebase that disagrees with ours.
Lerc 13 hours ago [-]
Where is the previous version referred to in the codebase? I'm guessing that would be the place to look for changes.
If you can't find an update at that place in the codebase saying 1.4.0 you can ask where it is. It seems after doing that and not receiving an answer would be the appropriate time to start making the claims that people are throwing around.
v1.4 hasn't been tagged... No idea what the shipped binary corresponds to.
embedding-shape 15 hours ago [-]
Yeah, of course Anthropic making the version publicly available AFTER people notice it wasn't public, completely solves the issue ;)
simonw 15 hours ago [-]
Anthropic changed nothing since I wrote published this post a few hours ago - I updated my post to mention Bun canary since it was a point of confusion here on Hacker News.
So it has been canary since then, most likely, if docs are accurate that latest main is canary.
Lerc 15 hours ago [-]
You seem to be wrong about that
Nevertheless, the principles of open source never demanded more than providing the source upon request.
16 hours ago [-]
minraws 16 hours ago [-]
It's largely just what jarred is willing to accept this week afaik or not, and they did put the bun 1.4.0 version bump in the changelogs for claude code a while ago, over a month almost.
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
jdiff 16 hours ago [-]
> they did put the bun 1.4.0 version bump in the changelogs for claude code a while ago, over a month almost.
Where? Is see no CHANGELOG in the root. I do see LATEST, last modified 2 months ago, and it says 1.3.14
(Though that doesn't clarify that this is the Rust rewrite)
TheRoque 6 hours ago [-]
I had "investigate if bun is worth it" too, and decided not to use it, but instability was one of the reasons. So it feels it was the right move.
GuB-42 12 hours ago [-]
Why all the mess with Bun?
Couldn't they have rewritten Claude Code in Rust directly? No more need for a JS runtime, better performance, etc... If their agents can do Zig to Rust, why not JS to Rust?
jeremyjh 10 hours ago [-]
I know, its so confusing. Its almost as if the bun rewrite to Rust has absolutely fuck all nothing to do with Anthropic's product strategy.
59nadir 9 hours ago [-]
Well, yeah, it's just good marketing and Bun ultimately doesn't matter anyway, not to the wider ecosystem and especially not to Anthropic. The only purpose Bun had for Anthropic was as a way of getting attention, so that's what they used it for.
tbrockman 6 hours ago [-]
In isolation, yes, that does seem like it would have been the better decision for Claude Code, but it also would have severely diminished the value of their Bun/oven.sh acquisition.
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.
aurareturn 5 hours ago [-]
Is Claude Code bottlenecked by performance?
I think a JS runtime is fine because the ecosystem of tools is very large and plugins are easy.
thewhitetulip 1 hours ago [-]
Why is ecosystem of tools and plugins a bottle neck when they literally own Claude models and as per their boss, code is so cheap that anything us just an English sentence away?
aurareturn 42 minutes ago [-]
I knew this was going to be the first reply.
The answer is because you still need at least one human to develop and test any tool, integration, feature.
nirui 15 hours ago [-]
All the emotion of speculations aside, how it runs? It boots faster yeah, but what about RAM and CPU usage? Weird dead loop or dead locks?
If it run as good as before or even better, then that's kinda impressive.
I'm a developer so I really don't like it when AI might took my job, but if everyone on this planet could create a software for themselves exactly as how they wanted with just a few simple demands, that will change the world for the better.
Think of it as a democratization of technology. You don't want Microsoft stealing your data? Just ask a AI to write an OS for you. You don't want Google to listen to what you're saying? Just ask a AI to design a phone for you. If one day the AI ended up doing that, it will be the ultimate technology self-sufficient. In front of that, your job security is insignificant.
It is also why keeping the tech open source is that much important. Otherwise, it's still the same old shit again and again, and, you lose your job too.
phinnaeus 14 hours ago [-]
> I'm a developer
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
William_BB 9 hours ago [-]
It's not even about requirements. It's about responsibility. Someone has to take responsibility for the code and the product. Someone has to hotfix a bug that's costing millions of dollars an hour and someone has to be blamed for a bug that's consting millions of dollars an hour.
godwinson__4-8 3 hours ago [-]
Not really. The secret of our society is it wouldn't work if people with a controlling interest in things ever faced personal responsibility. Who got blamed for the Iraq war? How much did that cost? The theory is if you tried to blame someone then some future president wouldn't be able to declare war. You don't know how the law works apparently. Corporate law is pretty much the same. The economy doesn't boom if CEOs can actually be blamed for things. You don't blame a "someone" that's what incorporation does. If some code does a booboo just put a $ amount on it, withdraw the funds and move on. The media will focus on the humans because of the drama, but they are largely irrelevant. It doesn't come out of their pockets. A human is already window dressing in this status quo. A LLM has no reason to do the sorts of things that violate such legal protections, be it of a president (none really apply) or a CEO (good luck getting a CEO to take personal responsibility for anything short of outright fraud). If it suddenly goes haywire the law already has a concept of vis major.
The secret is individual humans are already largely irrelevant to our society. That's how we got here. The trend will only continue.
hvb2 14 hours ago [-]
A good tool, in the hands of a skilled craftsman gets great results.
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
slekker 14 hours ago [-]
> Think of it as a democratization of technology
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!
anematode 7 hours ago [-]
It's a "democracy", in which some people (Anthropic and co., and anyone willing to suck up to them) are more equal than others...
revengerwizard 14 hours ago [-]
It definitely worked as a marketing stunt for sure
Aeveus 14 hours ago [-]
Anecdotal, but I’ve been getting segfaults in Claude Code. I run inside Kitty tabs, and the entire tab becomes unusable when this happens. No response to inputs at all from that point.
When this happens, a link shows up to report the issue. It’s not clickable (likely due to the segfault), and perhaps more important: it’s encoded, so you can’t see what you would be sending in your report.
Hope it gets better.
MitziMoto 11 hours ago [-]
Something similar has been happening to me with Ghostty, but there is no error message or link and it only happens when Claude uses it's interactive questions interface.
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)
mort96 14 hours ago [-]
What makes you think it's a segfault? Does your shell print "Segmentation fault"? If so, you should be back at your shell and you should be able to recover the tab by typing 'reset' + enter (even if you can't see anything as you're typing it).
If nothing prints "Segmentation fault", this just sounds like a hang
javawizard 9 hours ago [-]
I just had this happen today. It was indeed a segfault.
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.
kccqzy 6 hours ago [-]
Bun does not have its own JIT compiler. Bun uses JSC made by Apple. So your blame should be directed to Apple.
And I can believe you because I’ve seen JavaScript-heavy Safari tabs crash.
root_axis 6 hours ago [-]
Same experience I have with bun in general. As an idea, it's the absolute best js runtime by a very large margin, but in terms of stability it's terrible and segfaults 20x as much as node (I base that number on newrelic telemetry)
nicce 4 hours ago [-]
> but in terms of stability it's terrible and segfaults 20x as much as node (I base that number on newrelic telemetry)
In Chrome or Firefox, a segfault is usually automatic CVE and in most cases a bounty of thousands of dollars…
nerdix 9 hours ago [-]
I run Ghostty and Claude Code on a work macbook and I haven't seen this yet.
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.
Philip-J-Fry 9 hours ago [-]
Segfaults were a thing with the Zig version. Purely based on the fact it's a line by line translation of the Zig code to unsafe Rust, all the Zig code that caused segfaults is going to also cause segfaults in the Rust version. The Rust code won't fix it until they get to the point of refactoring it into idiomatic and memory safe Rust.
vips7L 8 hours ago [-]
But if the segfaults are new that implies it’s from the LLM no?
Philip-J-Fry 6 hours ago [-]
Who said they're new? Also, you can encounter new segfaults in a codebase just by executing code paths you haven't seen before.
feverzsj 16 hours ago [-]
It's a transpile. And not even a good one. The generated code is far from idiomatic rust. Some may consider it an abomination.
daishi55 15 hours ago [-]
Seems to be working just fine though?
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.
cube00 14 hours ago [-]
> Seems to be working just fine though?
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.
daishi55 13 hours ago [-]
historically we didn’t have LLMs which don’t mind “unpleasant[ness]” and “heavy rework”.
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.
benrutter 7 hours ago [-]
> historically we didn’t have LLMs which don’t mind “unpleasant[ness]” and “heavy rework”.
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"
endospore 12 hours ago [-]
> next step is to make it idiomatic rust
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.
kccqzy 6 hours ago [-]
But Bun did not even release a new version of Bun written in Rust yet. It was still a canary version.
daishi55 10 hours ago [-]
Sorry you think they’re not going to continue developing and improving bun and making it more idiomatic?
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.
endospore 9 hours ago [-]
That's a stated goal, so nope. But releasing it before any cleanups is another story.
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.
daishi55 9 hours ago [-]
> the Bun team lacks knowledge to actually make it more idiomatic: none of the Bun team has written any Rust
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.
endospore 3 hours ago [-]
> Good engineers can work in any language
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.
simonw 9 hours ago [-]
One of the best Django engineers I ever worked with had hardly any Django or Python experience when we hired them, but had done plenty of Rails.
They were up and running and super-productive with Django within a week.
variadix 13 hours ago [-]
Yeah I don’t understand this port at all other than as a big marketing stunt.
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.
5 hours ago [-]
brabel 15 hours ago [-]
Can you show some examples of abominable Rust code they have?
amelius 15 hours ago [-]
Why not transpile directly into LLVM IR?
12 hours ago [-]
jqbd 14 hours ago [-]
I don't think AI or humans are trained well on it.
brown9-2 14 hours ago [-]
Is it important to be idiomatic if the project meets its goals around memory safety?
kikimora 14 hours ago [-]
No, but the project does not meet its goals around memory safety. It is usage Rust all the way down with same memory safety issues.
feverzsj 14 hours ago [-]
If it's not idiomatic, the memory safety won't be guaranteed.
alexandra_au 15 hours ago [-]
grep -nr 'unsafe' .
Is all you need to know to consider how much of an abomination it is
simonw 15 hours ago [-]
This comment inspired me to take a look at the trend of "unsafe" in the Bun code over time since the rewrite PR first landed - here are the commits where that number changed by at least 10:
The original code was one giant unsafe block with almost no tangible way to find or debug all the subtle memory bugs and leaks they had.
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?
endospore 12 hours ago [-]
> The original code was one giant unsafe block
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.
William_BB 9 hours ago [-]
> has fewer bugs
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!)
luckydata 9 hours ago [-]
given enough time and tokens, it will become that. I really don't understand how that is a problem in any way.
vips7L 8 hours ago [-]
LLM code has always been an abomination.
rekttrader 8 hours ago [-]
They’re just wildly successful terrible engineers who can describe problems well and have unlimited token budgets. If they were paying for their own token use, the software would be better, they simply don’t have financial incentive to be more performant.
A dirty secret of AI data centers are that they’re only getting 40-60% efficiency out of their GPU clusters and because the moneygun go brrrrr they just buy more.
You wonder why they’re so afraid of the Chinese competition… they can’t afford to be as wasteful
harrisi 6 hours ago [-]
Maybe I'm taking crazy pills, but I swore there have been very similar comments I've seen as the current top post by weakfish:
> Maybe I’m taking crazy pills, but I’m still stuck on “why the hell does a TUI need to run in terminal React by way of JavaScript”
> The fact that Anthropic felt the need to buy a runtime so they could make their TUI better speaks more to the quality of engineering than anything else IMO.
> If rewrites are so easy, why not rewrite CC in a native language? Would’ve been a hell of a lot cheaper.
It turns out, there's some similar sentiments in the last year ish:
I'm not a fan of any of the technologies, companies, or people related to this. I just couldn't shake the feeling that I've seen similar comments.
September and all.
vdfs 5 hours ago [-]
Maybe because the 1st thing any experienced technical person would think about? It's like rebuilding and optimizing the racing track to make F1 run faster.
harrisi 4 hours ago [-]
Perhaps. The thing I was trying to highlight more is comments (particularly disapproving ones) about the intersection of JavaScript (especially React, apparently), TUIs, and LLMs.
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.
scrollaway 2 hours ago [-]
I have ~24 years of experience coding and the LAST thing I think about when opening claude code is "why is this written in react".
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.
shimman 2 hours ago [-]
Okay and as someone who would rather just straight up use cursor than claude code, I'd rather have my software not crash out on me every 5 minutes. What sort of self respecting dev purposely uses broken software? Even opencode (use it on nonwork computers) is fully better at this point.
scrollaway 2 hours ago [-]
Disingenuous, much? I've only ever had claude code crash once (after it decided to spawn like 12 subagents and got my laptop swapping like mad).
If you're crashing every 5 minutes, either you have a cursed build, or you need to do a memtest.
slopinthebag 2 hours ago [-]
You’ve been writing code for 24 years and you don’t know that clickable links are a terminal emulator feature and not a Claude Code feature? Or that “markdown formatting” is just ansi escape codes, and possible with things other than React that don’t bring so many downsides?
scrollaway 2 hours ago [-]
Claude Code is able to hyperlink any kind of text, not just the native terminal emulator feature of hyperlinking anything starting with https://...
And your "it's just ANSI escape codes" is the weirdest take on any kind of software.
slopinthebag 2 hours ago [-]
Formatted hyperlinks are an escape code too. It has nothing to do with React.
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.
scrollaway 2 hours ago [-]
It sounds like you completely missed the point I was making: that actually implementing such a highly dynamic TUI application normally requires a significant amount of state tracking and it is significantly easier to write such apps using a functional, descriptive UI framework instead of something like ncurses.
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.
slopinthebag 2 hours ago [-]
CC is not even that complex of a TUI. It’s certainly not as complex as many of the GUI programs I use daily. And yet it’s by far the buggiest and worst performing. I don’t understand the desire to make excuses for this. The reason people use it is because it’s the only way they can afford to use Opus and Fable. If Anthropic let people use their subs with other harnesses their market share would plummet.
If they could migrate an entire runtime to Rust why can’t they migrate CC? It’s not as if React is the only way to do declarative UI.
harrisi 6 hours ago [-]
I don't want to edit this to change the narrative, but I wanted to clarify that I'm not not a fan of all of the technologies or people related to this. As far as compan{y,ies} go, though, well..
dundarious 4 hours ago [-]
What's the implication or inference based upon this? So you're seeing comments sharing a general attitude. And?
As it is now, your post is meaningless to me.
codethief 15 hours ago [-]
Incidentally, Claude Code has been very buggy for me lately (much more so than before). Lots of TUI rendering issues causing, e.g., the conversation history to be garbled etc.
NateEag 11 hours ago [-]
I've been (grudgingly) using Claude since February.
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.
PsylentKnight 14 hours ago [-]
Every time I resize my window now, the output is completely garbled. I often have to ask it to repeat itself just so I can see what it just said. This isn’t a new thing, but it feels like it’s gotten worse. This is on Windows
anematode 7 hours ago [-]
Same observation. One thing you can do is close out the session and `claude --resume`
LambdaComplex 11 hours ago [-]
Does exiting following by resuming the session fix it?
kilroy123 12 hours ago [-]
I'm far from being anti-AI, but these guys take it way too far IMO. It's straight-up AI slop. Like a real engineer still needs to be in the loop and drive the tool.
Anthropic seems to be all in on 100% AI code.
luciana1u 9 hours ago [-]
a terminal app now has a supply chain long enough to include a runtime acquisition. somewhere between "rewrote it in Rust" and "ship it" someone said "or we could just buy the company"
steveiliop56 7 hours ago [-]
Ah so that's why it has been crashing constantly for me.
softwaredoug 15 hours ago [-]
Whatever the headaches of the internals, I haven’t heard any substantive outcomes in hacker news that have been impacted by this change.
Yes if we had a Zig->Rust transpiler maybe it would produce similar output. But I can’t find one. We’d have to use an agent to build one first :)
bel8 16 hours ago [-]
Contrary to many, I have high hopes that Jarred and team will lapidate the ported codebase and it will continue to flourish as an open source project.
16 hours ago [-]
15 hours ago [-]
witx 15 hours ago [-]
What is the actual contribution and motivation of this post?
softwaredoug 15 hours ago [-]
People shouldn’t overthink blog posts. Just write what’s on your mind and have fun.
rvz 14 hours ago [-]
The motivation is obviously clear. No-one would be doing that for fun 24/7, only covering about AI and nothing else without getting paid for it.
If anyone else did that on HN, they would be accused of slop with their domain blacklisted.
> "only covering AI" - don't miss my wildlife photography!
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.
simonw 11 hours ago [-]
Yeah, wildlife photography is a new hobby - it used to be every few months, now it's several times a week.
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.
softwaredoug 14 hours ago [-]
There are many people with unbridled enthusiasm and an ability to write fast
Knowing Simon - he’s very much both :)
simonw 15 hours ago [-]
I thought it was interesting. I didn't write this with Hacker News in mind.
(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.)
sensanaty 10 hours ago [-]
I don't blame him, if I had Anthropic's money hose pointed directly into my pocket I'd be spamming HN non-stop too
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.
sensanaty 8 hours ago [-]
Fair, that rules out "Anthropic pays you directly."
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.
Your comment here is fair, and it's why I take my disclosures seriously.
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!)
8 hours ago [-]
owebmaster 15 hours ago [-]
At this point we all know the answer
14 hours ago [-]
aureate 16 hours ago [-]
The port of Bun, which has >5000 open github issues, is used in Claude Code, which has >11000 open github issues. Do people use Bun in things that are expected to work reliably? Have any such projects tried the upgrade yet?
ivanjermakov 15 hours ago [-]
11k in two years vs 5k in two weeks? You're right, numbers speak for themself.
entrope 14 hours ago [-]
Did Bun mass-close issues that predated the rewrite? It doesn't look like they did, as the oldest open issue is from 2021 and there are many from 2022, but maybe they did something that killed most of the old issues.
endospore 12 hours ago [-]
Their (public) project management is horrible, you can find fixed issues unclosed and unfixed issues closed. Not really surprising when that part of the work is completely taken over by LLM agents though.
4 hours ago [-]
effnorwood 4 hours ago [-]
My perl re-write is not very good.
preommr 12 hours ago [-]
I love bun - although disliked how Jarred did the conversion.
Project-wise, nothing has changed.
Bun was always great because of the fantastic dx - it was just really easy to use , with stuff like out of the box typescript (unreal that it took so long for node, and it's behind a super long flag, wtf...). And it didnt have the weirdness of deno, it maintained backwards compatability with node api, and it just worked.
But it was never stable. You'd have to be fool to believe that a single project could stably do everything bun covers. It's always been an insane project. It was built on top of zig, a langauge that hasn't reached 1.0, and is constantly changing, and throw in how he was rewriting his own custom zig stuff. Like c'mon, let's apply some common sense here.
For me, little has changed. I am still going to use bun as a nice dev tool, and use node for production.
reddalo 16 hours ago [-]
Damn, I should have not migrated to Bun. Should I revert back to Npm?
cromka 16 hours ago [-]
I am getting into the frontend dev and one thing that I don't understand is why people use bun in the first place? It's not much better preforming, it's not much safer, it's still not 100% compliant. Some tests show it's actually slower than node. Why bother switching, then?
awestroke 15 hours ago [-]
Faster package manager
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
vips7L 8 hours ago [-]
I don’t think you would use Bun for front end.
frollogaston 4 hours ago [-]
That's what Claude Code does at least
johnny22 16 hours ago [-]
i assume it's because of all the built in tooling that node doesn't ship with.
frollogaston 4 hours ago [-]
So much of JS dev is just saying no to random new stuff, Bun included
vaughnegut 16 hours ago [-]
There's always deno
jqbd 14 hours ago [-]
but it's written in Rust too /s
orf 16 hours ago [-]
What specific technical issues are you experiencing with running Bun that would justify a change?
15 hours ago [-]
lykahb 9 hours ago [-]
Is it easier to rewrite Bun than it is to rewrite Claude?
16 hours ago [-]
tappaseater 15 hours ago [-]
Anthropic bought Bun, so they kinda, sorta had to make this work. I am sure the cost at $145,000 in Claude time will get some attention.
I am curious how this will work going forward from FOSS perspective. Will humans be allowed to modify the generated code? Only the .md prompts for the agents? Or what?
forrestthewoods 5 hours ago [-]
It’s interesting that Bun was a human rewrite from Go to Zig. (I think?). Then rewritten from Zig to Rust.
AI is pretty good at rewrites and ports. Quite good infact.
LAC-Tech 5 hours ago [-]
Has all of this drama turned anyone else a bit sour on bun?
I have a long running side project I migrated to bun, and I'm starting to regret it. I don't want to build on top of this much churn.
baq 16 hours ago [-]
Turns out it was just a build step after all.
jason_s 9 hours ago [-]
TIL about Bun.
nottorp 15 hours ago [-]
So does that make Claude Code any better?
Can you select text with shift + arrow keys now in the command line client? :)
Debo_Jolaosho 5 hours ago [-]
For real
throwatdem12311 10 hours ago [-]
I despise this era we live in. Pushing rewrites like this upon millions of users, when the Bun rewrite has countless known issues and is likely a security nightmare. Every time I ‘brew outdated’ and I see a wall of updates I die a little inside knowing that most of this code has not been verified or even looked at. Yet we hear about massive supply chain attacks pretty much every week now and we’re still full steam ahead on this vibe coded nightmare. God help us. Claude Code in particular updates sometimes multiple times per day. Like I’m sorry but there is no way all this nonsense is safe.
hmokiguess 11 hours ago [-]
pi runs in TypeScript and I like it, the target language of the tool, for me, matters only such that I can extend it. I like writing extensions, plugins, things, in TypeScript so I'm cool with that!
Claude Code is closed source, doesn't let me extend it beyond hooks, and these I write in bash anyways.
That all said, why should I bother about this change? Feels like a nothing burger to me, as an end user. This should matter more for those that are internal to Claude Code and Bun developing it.
rs_rs_rs_rs_rs 16 hours ago [-]
It is absolutely amazing to me that this ai rewrite work so well, maybe claude is not really that much of a complicated tool to stress the bun runtime but still...
jqbd 14 hours ago [-]
It works well because they had tests, they could compare before and after. Likelihood of issues especially if you transpile to a safer language should be minimal.
IshKebab 16 hours ago [-]
This post is just "they didn't lie"...
23951276 8 hours ago [-]
Basically Anthropic can ship any trojan in underhanded Rust to any target because it is not possible to audit 1M lines of slop.
And the crowd is cheering.
thrance 16 hours ago [-]
Yeah, I noticed. I had Claude write a quick JS script for me a few days ago, it then tried to use Bun to run it. When it couldn't find it, it tried to install it with `sudo pacman`. I had to fucking tell it to use Node instead.
ooofydoofy 16 hours ago [-]
bun upgrade --canary
you are welcome
16 hours ago [-]
zuzululu 10 hours ago [-]
as it always should've been Rust was the right move
kburman 16 hours ago [-]
Honestly, I initially thought rewriting an entire codebase with AI would be a huge mistake. After reading this, I'm starting to think I was wrong.
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.
Today's AI-generated rewrites may not produce code that humans would consider high quality or maintainable. But I'm beginning to wonder whether that will even matter in a few months. If AI is the primary consumer, maintainer, and refactorer of code, human readability becomes far less important than correctness, performance, and the ability to iterate.
This feels like a shift where software may no longer exist as a long-lived artifact in its current form. Instead of writing and maintaining applications for years, we may generate, adapt, and discard them continuously for each use case.
esjeon 16 hours ago [-]
> But I'm beginning to wonder whether that will even matter in a few months.
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.
brabel 15 hours ago [-]
> The rewrite was only possible because they mostly stick to 1-to-1 translation resulting in non-idiomatic Rust code.
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.
klibertp 13 hours ago [-]
Somebody checked[1], and they discovered that the "stages" past the first had minimal impact on the unsafe blocks count. That's just one metric, but it makes me doubt your claim that there was/is a lot of work put into making the translated code idiomatic Rust.
Isn't it just: "while true {refactorIdiomatically(); fixErrors()}"
folkrav 13 hours ago [-]
/goal fix all bugs
rho138 16 hours ago [-]
That sounds like a massive waste of finite energy and compute resources.
CrimsonRain 11 hours ago [-]
That's like saying let's stay with horses.
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.
rho138 5 hours ago [-]
Is that before or after the earths atmosphere acidifies for humans and our bodies can’t hold enough phosphorus or calcium for basic metabolic tasks? You have until 2050:
these doom and gloom reports also said half the land will be under water by now and average temperature will be 40c. Didn't happen.
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.
whateveracct 11 hours ago [-]
> Honestly, I initially thought rewriting an entire codebase with AI would be a huge mistake. After reading this, I'm starting to think I was wrong.
> 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.
sdevonoes 16 hours ago [-]
We are the ones to get to decide. Do we want that? I don’t. But im just a single data point
molmos 6 hours ago [-]
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hkclawrence 14 hours ago [-]
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marsven_422 11 hours ago [-]
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luciana1u 16 hours ago [-]
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marsven_422 16 hours ago [-]
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dranan 7 hours ago [-]
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lazzlazzlazz 15 hours ago [-]
Seeing all the people up in arms that there was an automated rewrite of Bun to Rust has been very revealing and disappointing. Very silly behavior and denial over the inevitable.
znpy 16 hours ago [-]
> Startup got 10% faster on Linux but otherwise, barely anyone noticed.
Just that?
I was expecting more from that rewrite. Maybe Rust is not so worth it after all.
ifwinterco 16 hours ago [-]
It was already written in a very performant language so no significant performance improvements should be expected.
The benefit of a rust rewrite is memory safety improvements, but currently they've just rewritten zig to unsafe rust so they don't have that either yet
voiper1 16 hours ago [-]
The blog claims rust chosen mainly to address memory issues, which rust is a better language for. So, success would simply be less new memory errors / easier to patch old ones.
marcindulak 13 hours ago [-]
Claude installer/updater had a high memory usage problem (Gigabytes of resident memory used during a fresh installation of Clade with it's native install.sh script, or during a claude update). This was reported as early as December 2025, see https://github.com/anthropics/claude-code/issues/12327#issue....
I don't think their motivation was primarily user-visible stuff. They backed themselves into a corner by forking Zig, and also were fed up with fixing memory errors.
You wouldn't notice either of those if you were a user, unless you happened to hit one of those bugs.
maverickaayush 16 hours ago [-]
I've been using Claude Code daily for a fairly large FastAPI project and didn't notice anything unusual around that timeframe. If this really was the Rust runtime underneath, "boring is good" seems like the right outcome.
larodi 9 hours ago [-]
Ok, so let me wrap this for everyone:
While everyone here in this forum kept arguing (and fighting and yelling at each other) whether tis moral/right/secure/cheap for ppl to rewrite and ship a major software package with LLMs/agents, one of the main drivers behind AI actually did it, without consulting your opinion, and most same everyone actually slurped this decision without paying a a notice.
Boring is good, but this boring is super massive major thing that happened, and precisely because security is still intact.
4 hours ago [-]
roundabout-host 12 hours ago [-]
I have a better idea: convert it to a prompt and commit the prompt to the repository. Then Mythos will be your compiler.
iririririr 11 hours ago [-]
the whole Ai skit is anthropomorphing the compiler as a coworker.
delegate 11 hours ago [-]
I'm looking at this situation strictly as 'What's possible today'. If a 1M lines code rewrite from one language to another goes into production in 1 month, that's a very strong signal that the models are now insanely capable.
My anxiety before merging a 2K lines PR is greatly reduced after 3 frontier models (Fable, 5.6 and kimi K3) finds no issues in it.
Just 6 months ago (Opus 4.6) this was not true, a big PR would have countless number of issues.
Aside from the human drama, the message to all of us is - these things are ready for whatever your imagination can throw at them.
I think that's exactly what Anthropic wanted to communicate.
rzmmm 11 hours ago [-]
It was not really a traditional rewrite. More like transpilation. Still impressive
dgellow 11 hours ago [-]
> Aside from the human drama, the message to all of us is - these things are ready for whatever your imagination can throw at them.
…if you have the compute and capital to run that whole agentic system
Rendered at 03:05:00 GMT+0000 (Coordinated Universal Time) with Vercel.
Humans and agents share one thing: they are both non-deterministic. He talks about the issue of tracking memory lifecycles manually in zig so it can be explicitly freed. As expected, this leads to a long list of bugs where people missed things.
Rust does this automatically. It removes an entire class of errors from his backlog. From an engineering management perspective, this looks like a pretty good trade.
The bonus here is that compiler errors are exactly the kind of deterministic guardrail you need to put around coding agents. Claude works really well if you give it a way to test for correctness and "make it compile" is a pretty good target.
There's a general version of this: the artifact you expose plus the test you run on it. Deterministic tests turn stochastic output into a hard guarantee. Wrote it up here if useful: https://michael.roth.rocks/blog/verification-surface/
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.
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.
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?
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.
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?
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.
Ownership is automatic. You don't have to explicitly drop things when they go out of scope. (although the responsibility for that is split between the compiler and the library code).
Lifetimes are not automatic, but also have no effect on memory allocation. They are purely a static analysis path and you can make a functioning rust compiler that completely ignores lifetimes.
Even with the huge amount of "unsafe" rust currently in bun? https://news.ycombinator.com/item?id=48967630
Of course they’ll iterate and remove the unsafe bits which were necessary for the transition
All of this is just a (succesful) marketing stunt by Anthropic.
"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."
Personally my take on the entire affair is quite negative, whatever Jarred or Simonw says about it.
I think Bun owned by Anthropic and the entire rewrite with AI is not the real point (even if it's quite interesting, though).
My take is that Jarred, and Bun,didn't demonstrate a serious, adult approach, from "this is my branch, you are overreacting" message to just proceeding with a 1mil+ PR merged in less than month.
The communication is the issue, and it was handled very badly, in a way that impacted trust and divisions.
Was it so difficult to adopt the approach that the TS team adopted for 7.0?
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
Is there a huge need to run that typechecking on browsers?
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.
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.
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.
The fact that Anthropic felt the need to buy a runtime so they could make their TUI better speaks more to the quality of engineering than anything else IMO.
If rewrites are so easy, why not rewrite CC in a native language? Would’ve been a hell of a lot cheaper.
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.
Your counter argument would be valid for a 2000 or a 2020 business decision about some tech stack.
But the whole point of their product is that it supposedly nullifies such "business" concerns around the use of technology, by making it cheap and fast to build whatever you like automatically.
That they wont, or worse, couldn't, speaks against that.
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.
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.
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.
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.
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.
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.
they rewrite themselves, Bun team is under Antrophic umbrella
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.
The argument I responded to argued that cost might be the prohibiting factor. I'm saying that for them, the costs mentioned are negligible.
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.
Does anybody really believe that it only took 11 days, one engineer and $168k in tokens?
Jarred used many agents and they worked 24/7. It tracks for me.
So yes, I do believe it. What makes you skeptical?
There’s two arguments in competition:
1. LLMs make it cheap (in the time sense) and easy to build
2. Rewrites and/or writing something in a native app or program is harder and more time consuming
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.
I just don’t see how one can say that building things reliably good is easy now when the company providing these tools can’t even do it well.
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".
0 - https://finance.yahoo.com/news/anthropic-ceo-predicts-ai-mod...
Now whether they can do it -- that's a separate, and a much more interesting, discussion.
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).
In 2 years? A well-engineered TUI could be the difference between the Blackberry and the iPhone for all we know.
This can be true, while "nullifies such "business" concerns" can be false. Both are not dependent on each other.
Automation doesn't "nullify business concerns", it just changes them.
Eventually? I am sure they would agree. Currently it's you (and lots of people like you) who are doing the supposing, not Anthropic.
Any kind of scrolling back, copying text, using their menu system - basically anything that isn’t typing characters has had/still has unaddressed bugs.
OpenAI shipped a competitive model and I’m over in Codex now. I have yet to hit a bug.
If you’re holding the SOTA crown, people will put up with your buggy mess. As soon as that crown slips your pile of trash becomes a huge liability.
So weird that the same exact people telling you that programming careers are now obsolete are the same group who haven't been able to fix screen flickering bugs for like a year...
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.
It's like "why did you go all in on buying scamcoin 3.0 as your investment strategy?" -- "I 5xed my money! End of story! It was fine!"
Or those choices just don't matter, it's fundamentally just "tabs vs spaces".
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).
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.
But IMO the endless churning of code will slow down, if it has not already. Quantity does not equal quality as we know, it even erodes it. There are already consulting companies that are "vibe-code fixers".
I am also not sure it's about "elegant" code. What we might call elegant has multiple measurable axii f.ex. well-isolated effectful code layer so you can easily static-code-check it, domains and enforcement of boundaries between them, bespoke linting to enforce business processes and standing code discipline, and many others.
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.
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.
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.
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.
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 is just blatantly ignoring all of the glaring issues Claude Code has had over its lifespan.
Edit, the sonnet question shouldn't be taken as proof, it knows I'm a rust dev.
Nobody but a JS dev would choose react-on-terminal shenanigans over it
I could see CC getting a ratatui port eventually actually
the era in which the tech industry built software to last was over long before LLMs, especially VC-backed startups.
I'm pretty sure "built to last" was only ever more true in specific contexts, and wasn't particularly more true than today.
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.
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.
The engineer is suggesting that it could be done cheaper and maybe with better outcome. Ironically, this is a classic business case.
If you have unlimited access to the magical development tool, then why would you not?
But they haven't.
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.
A ringing endorsement!
Much less fragmented compared to "write the app 3 times in 3 different languages".
I'd argue these tech companies got popular because they have good models, nothing else.
Even OpenAI took two years to fix basic chat scrolling.
The point is that if you were starting a new TUI LLM harness today, you would basically use CC's architectural decisions as a guide for what not to do.
But the "coding is mostly solved" narrative kinda doesn't match right? If good, correct, high-performance software is like, free now? Wouldn't you want it to be slick as hell, really reliable, all that? Even a little breakage costs a lot of money at that scale and pricing, it would be better than a wash if you put the magic code thing on the case.
"Claude. Do all employee work. Make no mistake. Notify in slack when revenue is double."
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.
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.
> 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.
> 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.
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.
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.
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.
— Henry Petroski
Casey Muratori addressed this years ago with the windows terminal drama, https://github.com/cmuratori/refterm
Put up the code and prove it. We already know exactly how fast golang is in comparison to nodejs on basic numeric computations, it's roughly 40 to 50% faster.
Bad coding is just bad coding.
It's also all cpu bound work. The majority of the stuff on your screen is being rendered by the gpu.
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.
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.
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.
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.
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...
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...
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.
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.
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
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.
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.
Proves LLMs don’t help with taste.
My question is moreso “why was it ever JS in the first place”
& the cost of a native rewrite would be cheaper than acquiring Bun no matter how you shake it
I hear some version of this anecdote constantly
yet despite using all these prompting tools since 2019 I have never once heard a lab or professional say “x model can do anything”
Can you provide me whatever specific source you heard for this?
Yeah, they "merely" say that they're about to break the singularity in a couple of years, that it's too capable to be safe to release, that it's going to take 50% (or all, depening on the day and audience) of programmers out of work, that it's smarter than Nobel prize winners, that their programmers don't write anything themselves anymore, and things to that effect.
Again… provide me a quote from someone doing this every day that says: “they're about to break the singularity in a couple of years”
The only people saying this stuff are random Internet commenters, breathless reporters and reactionaries.
The only person on record for a statement like this was Geoff Hinton about radiologists and he has since walked back his statement
Dario Amodei said in January that he expected software engineers to be replaced [0], so I suppose the quote should be extended to “can do anything… a software engineer can do”
And I think we can all agree that SWE is on the more complex end of all white collar jobs. So, my thinking is that if SWE can hypothetically be replaced, so can many other jobs. Hence, the claim the models can “do anything” intending to capture the majority of white collar work.
This, of course, is if you take their claim at face value - which I certainly do not.
[0] https://www.entrepreneur.com/business-news/ai-ceo-says-softw...
So then its misleading in the extreme to say “I’ve been told AI can do anything”
It amplifies hype when people make claims like this by including hyperbolic statements as though they are reflective of the state of the discussion.
That said, with respect what I clarified, I’m curious your thoughts.
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.
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.
To me it comes back to the premise I hear a lot from AI hype men (of which I do not subscribe but it’s worth clarifying that I find great value in using it for code) that the code doesn’t matter anymore. I just don’t know how to square that claim with the idea that we’re limited still by JS/TS being easier to use or approachable despite inferior TUI toolsets.
Unless you use an ancient teletype, you don't have to redraw everything. That would make any interactive applications way too slow/flickery.
You can move the cursor arbitrarily in the terminal and start overwriting characters from there. So you need to track state to know what is "dirty" and needs refreshing. Occasionally you issue a full redraw to catch missed artifacts left behind or when the terminal is resized (SIGWINCH).
This is close to the same "why Spotify is a chromium embed?" question. Because it works, and users are ok with it.
It's hell to maintain for not much gain (for a use case like this at least). As much as it's become a meme, JS and web tech in general has become extremely portable and stable.
I also don't think Anthropic bought bun to make their TUI better. They could have forked it, they bought bun because it incidentally was excellent for the way agents prefer to work and they wanted to capture that audience.
Their new flagship product (earning them billions of dollars in revenue per month) was dependent on a platform maintained by a tiny startup.
Buying Bun was a very rational way to reduce that risk, epically since it also got them some top tier engineering talent.
Thinking about that further, I wonder if that was part of the rationale for switching from Zig to Rust that they haven't talked about?
Zig is a much riskier bet for your multi-billion dollar cash cow than Rust is.
But saying that out loud would be rude - they took steps to NOT openly criticize Zig, even after Zig's founder did not show them the same courtesy.
It's like asking "why does everything run on Windows?" Because everything runs on Windows.
No, you are not crazy. They do crazy things with unlimited budget, and still their chat app flickers when using.
They should just port pi-tui from pi coding agent, since they have no clue.
I have been trying to keep away in the last couple weeks and it was all win for me. I still come down here sometimes when I am stressed with real work since it is a strong addiction to see “how terrible the plebs are doing”.
This is especially useful when you're trying to evaluate behaviors while changing state surgically.
And so, the FOSS project "Bun" silently dies in darkness and is now something completely else. I'm glad I still had "Investigate if Bun is worth it" on my TODO list and hadn't yet gotten to it.
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?
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.
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.
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.
And for most part I don't think it was communicated well apart from the last blog post.
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?
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/
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?
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.
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.
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?
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.
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...
Issues on GitHub was mass closed claiming zig is no longer relevant without fixing the real issues.
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".
> 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.
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
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.
You don't create PRs like this when you're working "completely in the open"
https://web.archive.org/web/20260509235415/https://github.co...I don't consider the following comment to be good, honest, and open communication:
https://news.ycombinator.com/item?id=48016880#48019226
> 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.
> Inevitable collapse
According to who? You? The well ackshually guy?
> Low in trust before acquisition
Cite your sources.
> Unreleased version
v140 is the canary version which has been available for a long time.
https://github.com/oven-sh/bun/releases/tag/canary
> Not open source anymore
Who died and made you the dictator of open source?
Your post is just a bunch of opinions and lies and speculation wrapped as facts.
What is actually going on with that tag? It has files uploaded in Jul 29, 2024 and files uploaded "6 hours ago" (some hours after Simon first published his blog post). Do they not do proper releases with immutable tags and instead use one tag kind of like a git branch that mutates and changes over time?
I don't like that, personally. I think the project would be easier to reason about if they shipped alpha versions instead.
“bun the JavaScript runtime ” is not dead though.
Can't help laughing at this point.
Any review would get to the simple conclusion that this should not be released before all the obvious bads are sorted out.
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?
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.
Known unsound code should not be merged, let alone released to production. If you have good enough tests and run them under MIRI or ASAN, maybe you can get away with it for a time, but most Rust experts would not sign-off on such a project.
If somebody put a gun to my head and told me to make the best of such a codebase, I would try to figure out how to turn off the LLVM optimizations that assume the Rust references don't alias. With these optimizations this codebase is scarier than most C or C++ code.
> 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.
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).
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.
I personally know 3 categories of newly introduced issues spanning the code base with 200+ occurrences, that leads to undefined behavior and memory issues. Not doing any contributions to the code is my conscious decision, which includes not pointing to the specific problems in public.
It's nice to hear that people are doing the same.
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.
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.
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.
> 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.
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....
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?
Barthes aside, C's changed a lot in the years since they left.
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.
I don't think it proves anything other than the wanted to work on something else.
> 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.
However, people also report that the canary version doesn’t identify itself as version 1.4.
Doesn’t sound like responsible software deployment
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?
> For me this outputs Bun v1.4.0 (macOS arm64). 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.
Which is still true as I write this comment.
What motive could he have for secretly maintaining a private fork of Bun that's shipped with Claude Code while simultaneously working on the open source repairs every day?
i am a clankersceptic as much as the next guy and i hate "anthropic" for participating in the murder of innocent people (maven "smart" system, offers them as a provider to the pedo criminal unitedstatistan government)
but this whole "unreleased" framing is just manufacturing drama / lack of knowledge
I don't see what it would buy Anthropic to have some sort of secret internal fork with special private code in it.
It's not about making the dev experience better than node, that use-case is now secondary.
Stay your pitchforks.
I think it’s valid to object to. If 1.4 is good enough to be used by Claude, why not us?
That might even be the reason why they switched to rust.
Don't worry too much.
…but they have? Claude users are public, no? If they were dogfooding internally I’d agree with you.
You just can't win.
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 believe you've just made your opponent's point for them.
But more to your point: Do you believe in "guilty until proven innocent"? Do you believe that they're doing bad things with the bun code, and you can't be convinced otherwise in your judgment of them until they release the code?
> Do you believe in "guilty until proven innocent"? Do you believe that they're doing bad things with the bun code, and you can't be convinced otherwise in your judgment of them until they release the code?
Hell yes, and anyone who trusts one of the AI labs for anything important is insane.
Whether it's their initial mass piracy and then lying about it, dealmaking with the US government, or continually shifting opt-out lines on what they are and aren't training on, they haven't earned the trust to skip the "but verify" step.
Their economic incentives are too transparently aligned with ends at any costs.
At this point, charging is the least of your issues.
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.
from strings:
This build does have a different way of identifying itself than earlier builds so it's possible this string isn't correct.(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.
> 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.
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.
What?
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?
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.
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.
https://news.ycombinator.com/item?id=48837877
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).
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.
Now it is a Deno clone, both without anything enticing over node.js.
Theres thousands of PRs from claude agents or whatever.
Yeah really feels like a worthwhile place to contribute lol.
FOSS as in FOSS - Free and Open Source Software. Has nothing to do with if it's community driven or not, I'm strictly talking about FOSS.
I don't care about meh Zig being rewritten to bad Rust if it does the same thing, but taking what is presented as" look at this funny experiment I did" and then taking that into production with barely any announcement is what kills off the interest to me.
Bun has been a great ad for whatever LLM they were using but the cool factor is gone now, and that's really what set it apart from basic NodeJS in my mind.
Did Bun v1.4.0 release weeks ago and I missed it? I would call a formal release the point that it goes "into production", and I think dogfooding it via Claude Code is yet another form of testing Bun-in-Rust before the latter goes to casual users.
The normal process would be "hey, this experiment is going well, we've made this plan, come help us shake out the new codebase for the switchover in X time." None of that happened. There wasn't even an announcement, just a silent commit that trashed hard work from hundreds of community members.
All those PRs can be fed thru Claude and converted to rust and then manual polish can be added.
Bun has bugs? yes. Do they affect vast majority of users? Not really. Been using bun for about 3 years; never had an issue with it.
"Because the discussion was interesting" is why I care.
It's cool that the Zig project exists, but I'm unlikely to ever use Zig so that’s sort of orthogonal to my interests.
I'm concerned that the complete rewrite in an entirely different language is not a sound technical decision and instead is a ploy to shed copyright claims from past contributors.
Now, based on comments from this thread, the formerly FLOSS project is somehow granting special access to a corporation that apparently is invested in going way out of their way to push implementations that consume the complete rewrite before the world has access to it.
I for one won't be touching Bun. This doesn't pass the smell test. It feels like a bait-and-switch in progress.
Even if this was a terrible technical decision, it is a good, maybe even unavoidable, business decision. And I don’t think moving to Rust was a bad technical decision at all, given Zig is unstable and constantly changing, and that it’s not memory safe, which is a big problem for something like a JS runtime!
The reason it’s a necessary business decision is that Bun is owned by an AI company and Zig has a policy to not accept AI assisted contributions, making it impossible for Anthropic to contribute to a language that is still evolving rapidly, not to mention the bad marketing of using a language that basically is hostile to your product.
Everything is in the open: PR #30412
Ok, go ask those people what they think then, I feel no outrage over a project switching language or merging whatever. But when once-semi-transparent projects become more opaque after an acquisition, I'm starting to readjust anything to the project I had in mind.
If you can't find an update at that place in the codebase saying 1.4.0 you can ask where it is. It seems after doing that and not receiving an answer would be the appropriate time to start making the claims that people are throwing around.
This seems like a candidate
https://github.com/oven-sh/bun/commit/b18bf6d1d0a92238f240bf...
I'm talking about the 1.4.0 release:
> Claude supports them shipping a preview of a not-yet-released Bun version
Maybe Bun/Anthropic fixed this after Simon's initial release of the blog post, but seemingly when we both looked, it wasn't public.
~$ bun upgrade [2.42s] Upgraded.
Welcome to Bun's latest canary build!
Report any bugs:
Changelog: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.
Nevertheless, the principles of open source never demanded more than providing the source upon request.
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
Where? Is see no CHANGELOG in the root. I do see LATEST, last modified 2 months ago, and it says 1.3.14
> Upgraded the bundled Bun runtime to 1.4
(Though that doesn't clarify that this is the Rust rewrite)
Couldn't they have rewritten Claude Code in Rust directly? No more need for a JS runtime, better performance, etc... If their agents can do Zig to Rust, why not JS to Rust?
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.
I think a JS runtime is fine because the ecosystem of tools is very large and plugins are easy.
The answer is because you still need at least one human to develop and test any tool, integration, feature.
If it run as good as before or even better, then that's kinda impressive.
I'm a developer so I really don't like it when AI might took my job, but if everyone on this planet could create a software for themselves exactly as how they wanted with just a few simple demands, that will change the world for the better.
Think of it as a democratization of technology. You don't want Microsoft stealing your data? Just ask a AI to write an OS for you. You don't want Google to listen to what you're saying? Just ask a AI to design a phone for you. If one day the AI ended up doing that, it will be the ultimate technology self-sufficient. In front of that, your job security is insignificant.
It is also why keeping the tech open source is that much important. Otherwise, it's still the same old shit again and again, and, you lose your job too.
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
The secret is individual humans are already largely irrelevant to our society. That's how we got here. The trend will only continue.
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
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!
When this happens, a link shows up to report the issue. It’s not clickable (likely due to the segfault), and perhaps more important: it’s encoded, so you can’t see what you would be sending in your report.
Hope it gets better.
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)
If nothing prints "Segmentation fault", this just sounds like a hang
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.
And I can believe you because I’ve seen JavaScript-heavy Safari tabs crash.
In Chrome or Firefox, a segfault is usually automatic CVE and in most cases a bounty of thousands of dollars…
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.
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.
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.
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.
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"
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.
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.
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.
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.
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.
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.
Is all you need to know to consider how much of an abomination it is
ChatGPT written script for counting here: https://gist.github.com/simonw/b1015bcadcedd1a781cedb7af9cbb...
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?
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.
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!)
A dirty secret of AI data centers are that they’re only getting 40-60% efficiency out of their GPU clusters and because the moneygun go brrrrr they just buy more.
You wonder why they’re so afraid of the Chinese competition… they can’t afford to be as wasteful
> Maybe I’m taking crazy pills, but I’m still stuck on “why the hell does a TUI need to run in terminal React by way of JavaScript”
> The fact that Anthropic felt the need to buy a runtime so they could make their TUI better speaks more to the quality of engineering than anything else IMO.
> If rewrites are so easy, why not rewrite CC in a native language? Would’ve been a hell of a lot cheaper.
It turns out, there's some similar sentiments in the last year ish:
https://news.ycombinator.com/item?id=47043325
https://news.ycombinator.com/item?id=47105720
https://news.ycombinator.com/item?id=48001113
https://news.ycombinator.com/item?id=46134570
https://news.ycombinator.com/item?id=46124596
I'm not a fan of any of the technologies, companies, or people related to this. I just couldn't shake the feeling that I've seen similar comments.
September and all.
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.
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.
If you're crashing every 5 minutes, either you have a cursed build, or you need to do a memtest.
And your "it's just ANSI escape codes" is the weirdest take on any kind of software.
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.
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.
If they could migrate an entire runtime to Rust why can’t they migrate CC? It’s not as if React is the only way to do declarative UI.
As it is now, your post is meaningless to me.
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.
Anthropic seems to be all in on 100% AI code.
Yes if we had a Zig->Rust transpiler maybe it would produce similar output. But I can’t find one. We’d have to use an agent to build one first :)
If anyone else did that on HN, they would be accused of slop with their domain blacklisted.
(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
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.
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.
Knowing Simon - he’s very much both :)
(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.)
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.
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-...
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!)
Project-wise, nothing has changed.
Bun was always great because of the fantastic dx - it was just really easy to use , with stuff like out of the box typescript (unreal that it took so long for node, and it's behind a super long flag, wtf...). And it didnt have the weirdness of deno, it maintained backwards compatability with node api, and it just worked.
But it was never stable. You'd have to be fool to believe that a single project could stably do everything bun covers. It's always been an insane project. It was built on top of zig, a langauge that hasn't reached 1.0, and is constantly changing, and throw in how he was rewriting his own custom zig stuff. Like c'mon, let's apply some common sense here.
For me, little has changed. I am still going to use bun as a nice dev tool, and use node for production.
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
I am curious how this will work going forward from FOSS perspective. Will humans be allowed to modify the generated code? Only the .md prompts for the agents? Or what?
AI is pretty good at rewrites and ports. Quite good infact.
I have a long running side project I migrated to bun, and I'm starting to regret it. I don't want to build on top of this much churn.
Can you select text with shift + arrow keys now in the command line client? :)
Claude Code is closed source, doesn't let me extend it beyond hooks, and these I write in bash anyways.
That all said, why should I bother about this change? Feels like a nothing burger to me, as an end user. This should matter more for those that are internal to Claude Code and Bun developing it.
And the crowd is cheering.
you are welcome
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.
Today's AI-generated rewrites may not produce code that humans would consider high quality or maintainable. But I'm beginning to wonder whether that will even matter in a few months. If AI is the primary consumer, maintainer, and refactorer of code, human readability becomes far less important than correctness, performance, and the ability to iterate.
This feels like a shift where software may no longer exist as a long-lived artifact in its current form. Instead of writing and maintaining applications for years, we may generate, adapt, and discard them continuously for each use case.
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.
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.
[1] https://news.ycombinator.com/item?id=48967630
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.
https://doi.org/10.1007/s11869-026-01918-5
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.
> 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.
Just that?
I was expecting more from that rewrite. Maybe Rust is not so worth it after all.
The benefit of a rust rewrite is memory safety improvements, but currently they've just rewritten zig to unsafe rust so they don't have that either yet
The latest Claude installer (2.1.215) possibly does not have it anymore https://github.com/anthropics/claude-code/issues/4953#issuec..., but more tries on various machines are needed to confirm that.
You wouldn't notice either of those if you were a user, unless you happened to hit one of those bugs.
While everyone here in this forum kept arguing (and fighting and yelling at each other) whether tis moral/right/secure/cheap for ppl to rewrite and ship a major software package with LLMs/agents, one of the main drivers behind AI actually did it, without consulting your opinion, and most same everyone actually slurped this decision without paying a a notice.
Boring is good, but this boring is super massive major thing that happened, and precisely because security is still intact.
My anxiety before merging a 2K lines PR is greatly reduced after 3 frontier models (Fable, 5.6 and kimi K3) finds no issues in it.
Just 6 months ago (Opus 4.6) this was not true, a big PR would have countless number of issues.
Aside from the human drama, the message to all of us is - these things are ready for whatever your imagination can throw at them.
I think that's exactly what Anthropic wanted to communicate.
…if you have the compute and capital to run that whole agentic system