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It is a pity that you can't make an experimental commit on an experimental branch without igniting a fire of delirium through some people who -- if they were able to put their emotional response aside for a minute and could weigh this up on the basis of merit -- would probably agree with the motivations for researching this approach.

> if/how hard it’d be to get it to pass Bun’s test suite and be maintainable

Every month brings new opportunities to completely abstract the process of porting code with agents, all using linguistics. What an exciting time.

For those looking for a similarly interesting (and interestingly similar) example, see Cloudflare's port of Next.js[0], "vinext", from a couple of months ago. It had some teething problems at the start but I'm using it in a few production projects now with minimal issues.

[0] - https://github.com/cloudflare/vinext

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This is what it means to work on a popular project, unfortunately.
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I am a topic starter, and I had no emotional response, was just being curious. Never expected it will land at HN #1. I specifically posted the link to the first commit and not to the whole branch, because currently the prompt is the most interesting part.
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The title kinda set the tone for this post.
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The title is "Bun is being ported from Zig to Rust" The docs/PORTING.MD starts with "Zig → Rust porting guide"

I don't think the tone was the problem.

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Imaging title it "Bun is being ported from Zig to Rust in an experimental branch" though. Not enough drama with that
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That's not a very constructive, nor accurate, way of trying to dismiss all concerns around bun that has been raised.
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I think that was a very constructive comment about the unconstructive way people are shoe-horning other concerns about bun into this thread abut a specific aspect which itself turns out to be just an experiment that someone knee-jerk reacted to, despite several active threads already discussing those matters one of which only just fell off the front page.

While the concerns many have about Bun's potential future direction are valid IMO, of the posts on this thread the one you are criticising is one of the more constructive.

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I love your work on bun. How do you feel about all the constant concerns being raised about the quality of the project lately? I understand some of them might just be typical twitter hate but some of them are real. And I think people are right to question why you are adding image processing or web views inside a javascript runtime when there are bugs affecting production that sit unaddressed. For example on of our biggest blockers right now is https://github.com/oven-sh/bun/issues/6608 which was reported in 2023, still affecting us 3 years later.
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When you start getting hate, you’ve made it. Up until then you’re a hypothetical that people like. Maybe they’ve built a side project with you or read the docs. You only get hate when people have used your tool and butted up against limitations. We saw this with Deno too where they went from beloved potential savior to realistic, limited tool. Hate is good. It means people rely on you
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Do you know which project gets the most hate? Nodejs, so in that sense, Nodejs has made it and it is widely deployed but this hate was the reason that two seperate alternatives for Node have emerged as Deno and bun.

Recently Bun's latest version had memory leaks which crashed production code from my understanding and their attitude[0] of saying OSS will have no human contribution allowed, now doing these ports of zig to rust, going back for years what the decision making of using zig was and this code basically being vibed as there is no way that they are reviewing the code while being VC funded/bought by anthropic.

These are all genuine issues which cause hate. You can say people are hating because people rely on it but the true thing is that also seems like a bait and switch and that people switched from node.js to bun (maybe even being locked inside bun), only for them to do these highly questionable decisions which is the reason why people are starting to hate on bun.

Atleast that's my interpretation right now reading this whole thread.

[0]:https://x.com/jarredsumner/status/2048434628248359284: "I expect OSS to go the opposite direction: no human contribution allowed. Slop will be a nostalgic relic of 2025 & 2026."

- Jarred Sumner

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Why not offer a bounty to get this issue fixed? Are you otherwise paying any money to the bun team?
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This is getting stupid. Now one can’t even make a reasonable polite question with praise without being asked if they pay.

Bun raised millions of dollars and was acquired by a commercial entity which bragged in the same blog post of reaching $1B. They’re not a guy with an eyepatch and a tin can out on the street.

Open-source developers should be compensated, but they don’t have to be. You can’t reasonably offer your work for free then complain someone isn’t paying you. If you want to be paid, charge for it.

Signed: A long time open-source developer who has dedicated years of full-time work to useful projects without compensation or raising VC money or being acquired.

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Come on, whenever a project is discussed on hackernews, there is always one comment of "why are you working on X, when you should be fixing bug Y?!".

We are all software engineers on here (or at least many of us are), we all know how project management and prioritisation works right? We can't work on everything all at once.

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> Come on, whenever a project is discussed on hackernews, there is always one comment of "why are you working on X, when you should be fixing bug Y?!".

That is not what the question is about, which you’ll see if you engage with it properly in good faith. There is a single question in the comment (indicated, as one does in English, by a question mark):

> How do you feel about all the constant concerns being raised about the quality of the project lately?

Everything else is context and opinion to explain the question.

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given the alleged context, X being something "reported in 2023, still affecting us 3 years later", is this not a reasonable PM / priority decision to question?
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I think the question still deserves a proper answer.
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No it doesn't. No opensource dev need to answer anything, if you dont like it, fork it and do the work yourself.
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Maybe it can be better phrased as "I think this question doesn't deserve that answer"
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No, open-source maintainers don't owe you anything if you don't pay for it
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I have similar problems with product I do pay for, and I still get told I have no say. FO/OSS distinction is a red herring.

At some point it need to be made clear; it's not a legal obligation, but a reputational challenge.

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Please observe a policy of extreme wisdom: https://github.com/Fody/Home/blob/master/pages/licensing-pat...
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Are you being ironic or serious? I can see both pros (encourage people to see themselves as customers) and cons (less initial adoption) to the licensing, although I'd maybe leave bug issues open for everybody.

What aspect do you think dominates?

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The answer is because YOU haven’t fixed it yet. Chop chop, we’re all waiting on you.
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What's the main motivation for considering Rust?

For what it's worth, in my last experience with Bun[0] I ran into a couple of bugs where it seemed Rust could have helped, e.g. using Bun.write

[0]: https://mastrojs.github.io/blog/2025-10-29-what-struggled-wi...)

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With AI agents and how good they are in doing "language translation" tasks against an identical target with a comprehensive test suite, you end up doing these things out of curiosity. The AI agent has the originals to test it's assumptions with too.

I've had surprisingly good results from getting AI agents to take a script in shell, python or typescript and have it translate it into those other programming languages, including rust versions. Or swapping from one build system to another.

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Thank you, Jarred, for your work. It’s unfortunate to see so much backlash toward legitimate research. Bun is often seen by some as “the flagship project for zig” - especially among those frustrated with rust who want zig to "win over rust" for whatever reasons. At the end of the day, you should do what makes the most sense for your project and your circumstances, regardless of the language or tools involved.

Personally, I find this experiment interesting and I’m curious to see how it develops. Writing idiomatic rust requires a shift in mindset, so it’ll be worth watching how well LLMs adapt to that over time.

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Calm and curious about your results.

I hope you get the code elegant and not only maintainable but future friendly and performant.

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I'm very curious what Zig vs Rust code looks like for the same project! What are your thoughts so far?
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Thank you for the clarification!

While you are here, can you elaborate on the method chosen? For example, why not write a conversion script for phase A? I mean, same Anthropic model will produce it in no time, prompting it is at the same cognitive load level, but you would have a deterministic result.

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> We haven’t committed to rewriting. There’s a very high chance all this code gets thrown out completely.

Props for the effort man, but people have already picked up on Zig-to-Rust transition.

Poor Zig folks ...

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Hoping that an AI rewrite is thrown out.

You may even be an OK programmer, but IF YOU AREN'T ABLE TO DO THE WORK I DON'T WANT TO USE IT.

Not worth your time? Not worth my time.

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Most of Bun’s code is already written by LLMs. If you feel that way, it’s already been too late for a while. Furthermore, we’re talking about a million line port done in a couple of days. The question of whether it’s worth the time looks extremely different if done by hand. It would take a year.
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The "too late" argument isn't gonna fly with someone like me who has both the time and energy to own a Javascript runtime. Heck, I'm quickly becoming the most prolific author of the ES spec too.
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Cool. Fork it and maintain your own runtime, then. Why are you complaining about what the bun team does with their project?
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Cause I'm sick of this amateur hour shit
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From what I'm reading, it's too late for Bun. I hear the whole dev stream is slop now. It was nice while it lasted, but that's not a foundation to build rock-solid stuff on top of. Not for me, not for them, not for anyone.
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I think the criticism is still a valid to an extent because I don't see how this would give you a good way to evaluate Zig vs. Rust. Maybe a better approach is to migrate a particularly problematic space and bench that on its own?
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It's not like OP asked for any criticism to start with, right? This whole thread is pretty good example of why saying "Fools and children should never see half-finished work" exists. ¯\_(ツ)_/¯
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Since when was HN ever about asked for criticism?
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Not HN, but from my experience of over a decade, it's certainly US culture to criticise without expertise.
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I can say from expertise that vibing a full move of any project from one language to another is probably not a great way to evaluate if the decision is a good one. I got downvoted, maybe I said it too authoritatively. But hey, that is just like, my experienced opinion, man.
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