Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Rewriting Bun in Rust

bun.com

Post reply on HN
Print view View original

231–240 of 560 posts

Re: Rewriting Bun in Rust

#231

Post by PeterHolzwarth »

duhhhhh1212 wrote: post #202
simonw wrote: post #180

Earlier quoted context omitted.

Have you seen the "rewrite by outsourcing to India" thing work?

What a weird thing to say. The phrase “outsourcing to India” being used as shorthand for “you don’t need top engineers.” The nationality stereotypes are mean and degrading.

And at a macro level, often found to be accurate due to how the businesses in India operate. Poll the west's engineers: you'll find that engineering from India is not currently viewed very favorably, in general.

There are excellent engineers in India, but the system they operate in unfortunately doesn't allow them to shine.

Re: Rewriting Bun in Rust

#232

Post by grandimam »

The rewrite itself is amazing, but I don't think folks realise the actual conditions that made it possible. It's not as simple as a company spending ~$160K on tokens.

This was done by someone who has essentially already rewritten Node once. Bun itself is a reimplementation of Node, so the author was walking in knowing exactly what the correct behavior is. And an exhaustive amount of test suite to verifiy the changes?. On top of that, there is a reference from Node and V8 to validate more throughly. So the $160K is simply the price of translating knowledge that already lived in one engineer's head in a newer syntax.

Re: Rewriting Bun in Rust

#233

Post by FridgeSeal »

comex wrote: post #222
kibwen wrote: post #137

Earlier quoted context omitted.

> The best way to speed it up appears to be organizing a codebase in many crates. A "crate" in Rust is the unit of compilation. In C, a file is the unit of compilation. Rust just lets you have a compilation unit that's composed of more than one file (without having to resort to C-style textual inclusion). But if you want, you can certainly have one-file-per-crate, just like you would in C. And what's nice about havin…

The forbidding of circular dependencies is exactly what makes it hard to achieve parallelism! It means you have to draw nice clean module boundaries and split your compilation units there. Clean boundaries sound nice, except… what if the module is getting large? Can you just take half the module, ctrl-x, ctrl-v into a new file, and get faster compilation times without having to do any massive refactors? In C, usually…

> Can you just take half the module, ctrl-x, ctrl-v into a new file, and get faster compilation times without having to do any massive refactors?…In Rust, almost always no, because of circular dependencies

This feels like a strange, overly-specific complaint. It reads a bit like “When I write entangled code, it’s hard to untangle”. Like, yeah, the only thing that’ll save you from that is…not writing entangled code? I’m not of the opinion that the argument of “yeah but C lets me do whacky stuff” is a particularly strong line.

FWIW, letting a module grow, and then splitting modules up by cut-and-pasting stuff out along natural domain lines generally _is_ how I write Rust. Largely due to how easy it makes it to construct modules and submodules.

Re: Rewriting Bun in Rust

#234

Post by minimaxir »

Zetaphor wrote: post #226
simonw wrote: post #178

Earlier quoted context omitted.

Claude Code is the main reason their revenue (ARR) grew from $9bn to ~$47bn in the first half of this year. That's a very big reason not to screw this up.

It's far less obvious how choosing Bun results in more revenue for Anthropic. Unlike Claude Code, Bun doesn't require you to pay for tokens to use it

Bun powers Claude Code. If the rewrite introduced catastrophic bugs, it would cause catastrophic bugs in Claude Code and therefore without exaggeration could cause $billions of lost revenue.

Re: Rewriting Bun in Rust

#235

Post by minimaxir »

galleywest200 wrote: post #136
sashank_1509 wrote: post #125

I think the important thing is this is much cheaper than hiring a software engineering team. They could have hired me for 200k and I could not do this in a year. I do not have the context, and I do not know Zig or Rust, perhaps I could pick it up in a month, but I would be extremely slow. Forgetting all the predictions about singularity etc, at the very least AI as it is now, is going to make it very hard to justify…

If you already employed the engineers the extra cost would have been $0.

https://en.wikipedia.org/wiki/Opportunity_cost

Re: Rewriting Bun in Rust

#236

Post by swiftcoder »

sitzkrieg wrote: post #181
didibus wrote: post #80

Article 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…

rust is still a non starter in some niche embedded applications (way too big). i still write c and assembly constantly.

> niche embedded applications

How niche are we talking? Rust is deployed on a bunch of popular microcontrollers at this point

Re: Rewriting Bun in Rust

#237

Post by simianwords »

rvz wrote: post #193
minimaxir wrote: post #184

Earlier quoted context omitted.

As steveklabnik noted above, Hacker News does not have a meme-y culture. Just because you made a joke doesn't mean it's inherently immune to criticism, especially when using the lowest-effort, most-overdone meme around agentic development adds nothing to the discussion. Get new material.

> As steveklabnik noted above, Hacker News does not have a meme-y culture. For this one, yes it does. Go search this one up yourself. [0] Literally everyone in the comments in [0] and even the author of this post acknowledges the joke except for you two. It. Is. A. Joke. Calm down. > Just because you made a joke doesn't mean it's inherently immune to criticism No one is arguing that. It's OK that you won't admit that…

Its not even that, its one of the most overdone jokes as your link suggests.

Re: Rewriting Bun in Rust

#238

Post by jatins »

Extremely thorough and well written.

I was hoping it’d end in a “so how much did this cost?” so that others team looking at similar migrations have an estimate on what they can expect

Re: Rewriting Bun in Rust

#239

Post by ozgrakkurt »

sashank_1509 wrote: post #125

I think the important thing is this is much cheaper than hiring a software engineering team. They could have hired me for 200k and I could not do this in a year. I do not have the context, and I do not know Zig or Rust, perhaps I could pick it up in a month, but I would be extremely slow. Forgetting all the predictions about singularity etc, at the very least AI as it is now, is going to make it very hard to justify…

It is highly debatable if a 200k cost engineer that is suitable for the job wouldn’t bring in more value.

Also it is debatable they got any value at all from this. Anyone who wrote unsafe rust and also wrote zig would know that unsafe rust is much much more unsafe in comparison

Re: Rewriting Bun in Rust

#240

Post by Rohansi »

vlovich123 wrote: post #220
leecommamichael wrote: post #113

Earlier quoted context omitted.

> As an aside, I don't know why anyone would not want to use a memory-safe (and possibly race-safe) language in 2026. The rust compiler is very slow. The best way to speed it up appears to be organizing a codebase in many crates. This is not preferable ergonomics to many. Beside that, for many problems, a garbage collector eliminates a large amount of defects (including the ones stated in the article) without any add…

For what it’s worth game devs often use C# or C++ engines which have even worse issues. Rust also has the early beginnings of hot reload which bevy adopted if I recall correctly [1]. I still think a higher level language is good for “business” logic to orchestrate how efficient low-level pieces connect, but Rust is holding its own even against those use cases IMHO. [1] https://docs.rs/hot-lib-reloader/latest/hot_lib_…

> For what it’s worth game devs often use C# or C++ engines which have even worse issues.

Such as? You can't be referring to hot reload alone because you can already do that in both C++ and C#.

Post reply on HN