Comment by tasuki

Because in the software world, especially before 2022, ownership and stability have been valued. People like using things that do not randomly start breaking more often after every new release, and if things break, there is a human who knows exactly why it broke and what's the best way to fix it. Businesses would not want their losses to be attributed to an AI rewriting an entire codebase. AI owns nothing, not even the bugs which it produces. I would not want my SaaS to have downtime because a JavaScript runtime it depends on decided that they had to market their LLM by rewriting years of code recklessly.

People are not betrayed by a rewrite. They are betrayed by an LLM rewriting with minimal supervision fasttracked to a merge within 9 days of commencement.

To the contrary I do not understand how we have become so insensitive towards stability since the LLM era. Why is unbreakable code no longer the goal but a truckload of generated code is.

The unhappiness is primarily stemming from Bun’s ownership by Anthropic - HN sees this as Anthropic using an OSS project for reckless marketing stunts.

For the record I don’t believe it’s a stunt, it’s ridiculous to me - everyone’s just seeing what they want to see out of sheer hate for anything Anthropic does.

In any case if the rewrite is really as reckless as many in this thread claim, we will see Bun collapse in on itself with a 1M LOC codebase the core team doesn’t understand, or rollback to Zig. So we don’t need to have a flamewar over it, time will answer the question.

Vibe coding a Rust rewrite of a widely used tool is basically catnip for the HN crowd.

My read is it's less the rewrite and more the messaging around the rewrite. Nine days between "you're over-reacting" and merge is surprising, to say the least. Sure will be interesting to see that blog post!

The context nobody is mentioning is this came shortly after Bun forked Zig in the name of optimization, but then a Zig maintainer came out and basically said they (Bun) don't know what they're doing, or else they would have known that wasn't an effective optimization.

It outwardly seemed like they forked Zig for a flashy headline, were called out, then immediately started moving to Rust. This, combined with being bought by Anthropic, and plugging vibe coding the whole way, just gives the impression of random and chaotic technical decisions, which is not what people want in software their business depends on.

https://ziggit.dev/t/bun-s-zig-fork-got-4x-faster-compilatio...

My read. If the code has a comprehensive feature test suite, a performance test suite (how long a function takes), and a linter with readability guidelines (e.g. cyclomatic complexity; no code duplication), and the LLM rewrite passes all three, then it should be fine. But I think that in the real world only the first one (functional tests) exists.

My read is that it just seems a bit reckless doing a full rewrite so quickly.

posting my read (since it differs so much from the others')- there's a 'holy war' being waged by people that think LLMs shouldn't do full rewrites of software. There are various reasons people think this (think LLMs are parrots that make slop and are incapable of writing good code, have environmental concerns, or are angry that software licenses can be circumvented). I call it a 'holy war' because I think most see our current trajectory as a bit inevitable and have a strong urge to proselytize their views and chide maintainers that use LLMs in ways they don't like.

Very similar angry comments happened with the discussions of the Chardet rewrite, next.js/vinext, and JSONata/gnata if you want to look at this in context.

Yes sure it's ok to change your mind. But don't you think the people Jarred accused of "overreacting" in retrospect didn't?

It's a high profile open source project. While Bun/Jarred don't owe anything to anyone, nobody should be surprised when decisions like these result in strong backlash.

Imagine if Guido or Linus said a couple of days ago that they're just experimenting and then submitted and merged complete machine-assisted rewrite of CPython or Linux in Rust.

This actually happened to me a couple months ago. Started a Rust rewrite of a project as an experiment, then a few weeks later it was presented to the team and promoted to mainline.

Although in that case the language change was almost incidental — the rewrite was very much not a straight 1:1 port, but more of a substantive architectural overhaul and longstanding tech debt cleanup; Rust was just one of many tools and design decisions that helped get the best possible end result. There were also various reasons it made sense to attempt a rewrite within that particular window of time.

The upshot is we've ended up with a substantially stronger QA posture, a much higher-quality and more maintainable codebase, and an extremely positive audit report by a group that was brought in to review the project. There were some early kinks to work out, but the longer we've lived in this version of code the more it's proven itself to be a stronger foundation than its predecessor.

Of course, Bun is its own thing and all circumstances are unique. I have no idea how that rewrite was approached, whether it was the right decision, or how it will ultimately prove itself. Just saying the shift from "experiment" to "official new direction" is normal and credible, and that I'd give it some time to see how it handles contact with reality before passing judgement. If it's truly a disaster, nothing's stopping them from reversing course and backporting any new changes to the old Zig codebase.