I think we're finally getting to see a glimpse of the future. People and LLMs, working together. (And doing it really well.)
It's pretty exciting.
Rewriting Bun in Rust
141–150 of 560 posts
Re: Rewriting Bun in Rust
#142> In Bun v1.3.14, every build leaks about 3 MB, forever I'm sorry but that is insane, how was this never fixed before the rewrite?
I've been impacted by a couple of bugs in Bun.SQL and lo and behold these were only fixed for 1.4. Presumably Claude could have fixed those in the Zig version but the Bun team decided to not do that. Furthermore, there's no mention of an LTS plan for the Zig version. It seems that if a CVE is discovered in the future, Bun users will no have no option than to update to the Rust port. This is not how you run a project…
I'm a little puzzled: Why should you care? The language in which Bun is written isn't part of its API, if you will. You care that you have something that does various javascripty things according to a particular spec of what it's supposed to do. If a bug is fixed in 1.4.x it's fixed, why should it matter, really, if that's in Zig or Rust?
Re: Rewriting Bun in Rust
#143> This Rust rewrite would've taken a team of engineers with full-context on the codebase a year of work. With 1 engineer using Fable & closely monitoring Claude Code, we went from start to 100% of the test suite passing on all platforms in 11 days. This is impressive from a technological standpoint, but it does gloss over the fact that it would have cost $165k in tokens were Bun not part of Anthropic. The comparison…
$165k won't get you far on salaried engineers. There's every chance that 1 engineer, assuming Anthropic employs them, is on $500k or more. Assuming average of $336k in that pool of 50 engineers, then for 11 days for 50 engineers you've spent $710k[0]. Salary info: https://www.levels.fyi/companies/anthropic/salaries/software... [0]The maths I used (posting because I'm tired and prone to mistakes): $336,000 / 260 (work…
You don't need top engineers to port a program from one language to the other. Outsource it to India.
Of course, then you can also ask, could it have been done with a cheaper model. Probably yes. But then you wouldn't get free marketing.
Re: Rewriting Bun in Rust
#144Earlier quoted context omitted.
I've been impacted by a couple of bugs in Bun.SQL and lo and behold these were only fixed for 1.4. Presumably Claude could have fixed those in the Zig version but the Bun team decided to not do that. Furthermore, there's no mention of an LTS plan for the Zig version. It seems that if a CVE is discovered in the future, Bun users will no have no option than to update to the Rust port. This is not how you run a project…
I'm a little puzzled: Why should you care? The language in which Bun is written isn't part of its API, if you will. You care that you have something that does various javascripty things according to a particular spec of what it's supposed to do. If a bug is fixed in 1.4.x it's fixed, why should it matter, really, if that's in Zig or Rust?
Who in their right mind would immediately migrate their production apps into a complete re-write of a runtime?
It would be naive to think there aren't new bugs or changes in behavior introduced in 1.4.
Re: Rewriting Bun in Rust
#145> This Rust rewrite would've taken a team of engineers with full-context on the codebase a year of work. With 1 engineer using Fable & closely monitoring Claude Code, we went from start to 100% of the test suite passing on all platforms in 11 days. This is impressive from a technological standpoint, but it does gloss over the fact that it would have cost $165k in tokens were Bun not part of Anthropic. The comparison…
> I suspect Claude might be faster and therefore cheaper, but maybe not by a lot.
While Jarred used Mythos-class model, some open weights, if they were as capable (certainly, GLM 5.2 looks the part), would have been way, way cheaper than professionals.
Approx costs:
DeepSeek v4 Pro & Mimo v2.5 Pro $3,426 ($2,567 / $600 / $259)
Tencent HY3 $3,892 ($1,180 / $552 / $2,160)
GLM 5.2 $30,016 ($8,260 / $3,036 / $18,720)
Qwen 3.7 Max $37,925 ($14,750 / $5,175 / $18,000)
Claude Opus 4.8 & GPT 5.5 xhigh $82,750 ($29,500 / $17,250 / $36,000)
5.9 billion uncached input tokens, 690 million output tokens, 72 billion cached input token reads.Re: Rewriting Bun in Rust
#146It seems that Deno made the right decision by choosing Rust from the get-go.
Re: Rewriting Bun in Rust
#147Earlier quoted context omitted.
The article explicitly mentions the maintainability as a foremost concern.
People say a lot of things, especially when they have a vested interest in a positive outcome. Bun has been fully vibe coded into another language. There’s no way in hell it’s maintainable. Go read any analysis of the Claude Code leak for proof.
> There’s no way in hell it’s maintainable.
They rewrote the entire thing with extensive LLM use.
It is abundantly clear that their idea of maintainable and yours probably don't match up.
It's apparently out there, shipped in the real world, with people saying it's good. I think it's a pretty clear win for them.
Re: Rewriting Bun in Rust
#148Article did a decent job of showing discipline and care and human involvement to assert the automated rewrite was done diligently, as best as it can be when using AI for it. I does make me feel a bit more comfortable about it. As an aside, I don't know why anyone would not want to use a memory-safe (and possibly race-safe) language in 2026. Rust gives you that in a performant package, so if you are turned off by GCs…
I'll bite. The first language I could "just write" in was C. I had internalised the language and its standard lib and didn't need the internet to work with it.
Rust is pushed by many as the replacement to C, because of the memory safety guarantees. I'm sympathetic. I worked with Haskell for a time, so I get it. But Rust seems quite complex. There are so many language features that there's memes about it. There's also the friction and learning curve.
So, for fun, I choose zig because, like C, I can hold most of the language in my head and "just write." I choose zig because it does a great deal to help me write correct and highly performant code. I can use arena allocators and defer and cure my code of many memory issues. Then there's the various language rules around pointers (optionals, slices, etc) that help me write correct code. There's the built in testing and the test allocator. I love that comptime and the build system are not special cases, but rather are just garden variety zig. I love the simplicity and elegance of it all.
I also choose zig because I prefer the liberty it affords me. I am responsible for each and every allocation. It appeals to my libertarian sensiblities.
Re: Rewriting Bun in Rust
#149Without commenting on Bun itself as a project, or the nature of the rewrite, it can't be good for Zig that a naive rewrite away from it fixed memory leaks, improved stability, shrunk binary size by 20%, and improved performance by 5%.
zig has been developing too slowly. it still cannot reach a stable 1.0 (to the point that even vsc autocomplete gets its Hello World wrong), and then it ran headfirst into AI.
Re: Rewriting Bun in Rust
#150Without commenting on Bun itself as a project, or the nature of the rewrite, it can't be good for Zig that a naive rewrite away from it fixed memory leaks, improved stability, shrunk binary size by 20%, and improved performance by 5%.
The scary thing is the zig project prohibits LLM contributions - the world is going to move faster than them.