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Bun's experimental Rust rewrite hits 99.8% test compatibility on Linux x64 glibc(twitter.com)
32 points by heldrida 9 hours ago | 32 comments
aurareturn 8 hours ago | parent | next [-]

6 days of work to do this. Even if it doesn't end up becoming meaningful, it shows just how tokens and work done will be linked now and in the future.

It's going to be hard to compete with someone or a company that has more compute. They will just be able to do things you can't.

nbf_1995 an hour ago | parent | next [-]

I can't help but wonder what this cost in USD assuming you paid standard rates from Anthropic. Can someone even ballpark the price?

twoodfin 4 hours ago | parent | prev | next [-]

You could have said the same thing about steam power or electricity. And it’s not just an analogy: The magic of these things is in being universal information engines. You spend capital to build them, using well-understood, scalable techniques, plug them into electricity, and out comes value.

My point is, there’s no chance of a “haves and have nots” emerging, any more than electricity turned out that way in the modern world.

pjmlp 5 hours ago | parent | prev [-]

With less employees....

aurareturn 5 hours ago | parent [-]

Isn’t just one guy?

Defletter 5 hours ago | parent [-]

Exactly

rvz an hour ago | parent [-]

This is exactly how Anthropic will market this rewrite towards companies thinking about doing more layoffs.

1 person did a rust rewrite that took 6 days that would have taken hundreds of engineers more than a year to do.

spicyusername 6 hours ago | parent | prev | next [-]

What a time to be alive.

So much of the fundamental dynamics of the industry and the job have changed in so little time. Basically over night.

Some days I am so excited at how much I can do now. You can build anything you want, in basically no time! 100% of my software dreams can be a reality.

Some days I am terrified at what's going to happen to the job market.

Suddenly you can get so much with so little. The world only needs so much software.

Is every company that sells software as their core business model going to go out of business?

What will happen if only certain companies or governments get access to the best models?

ksec 4 hours ago | parent | prev | next [-]

I think a lot of people taking this at face value , a lot of this was possible because of the beyond standard extensive and comprehensive test suit previously built.

anilgulecha 6 hours ago | parent | prev | next [-]

I think the industry is moving to English as the programming language, and specifications-context-tdd as the framework for building software.

Many find it distasteful, and many finding liberating. I think it's broadly correlates with how they feel about expressing themselves in english vs say C++.

As a side question, is there anyone who's using LLMs primarily in non-english mode to program? I suspect there's quite a few people using mandarin, but can someone share first-hand account.

SwiftyBug 6 hours ago | parent | next [-]

I wonder how well Mandarin works for LLM-based programming. On one hand, it's very token efficient as Mandarin script is very dense in meaning. On the other, I suppose this can increase ambiguity.

pyonpyon 5 hours ago | parent | prev | next [-]

I'm using it 50% English (personal projects)/50% Polish (workplace; reasons being agents.md / team is not that english proficient) and honestly I haven't seen much difference in the output/ambiguity.

Polish prompts tend to be shorter due to the language having a lot of verb forms/conjugations, the only "bad" thing for me is that when it's saying "it broke" it tends to use uncanny / blunt words that make me sometimes laugh.

thedevilslawyer 5 hours ago | parent [-]

Interesting. Some questions: Would you say polish is more dense or less dense than english? It's interesting to hear that code quality is not suffering but the response text is sillier or blunter. Any other descrepenacies compared to English?

pyonpyon 5 hours ago | parent [-]

I would say it certainly can be more dense but even if it's more dense, the tokenizers count it as more. Last time I checked in OpenAI tokenizer for my agents.md it ate 30/40%~ more tokens than the English version at roughly 1:1 meaning.

pjmlp 5 hours ago | parent | prev | next [-]

I agree, and those are still too focused on code generation for specific languages are fighting the last war.

It is the revenge of UML modeling.

Eventually it will get good enough that what comes out of agent work, is a matter of formal specification.

Assuming that code is actually needed and cannot be achieved as pure agent orchestration workflows.

_woland 4 hours ago | parent | prev [-]

I'm using it in english / albanian. Not much difference really. Impressive.

pulsartwin 5 hours ago | parent | prev | next [-]

At the very least, it's interesting to be a bystander observering as efforts like this progress. The first thing it makes me wonder is how comprehensive/high quality the test suite is to begin with. Not to cast aspersions, but even at 100% on all platforms I wonder how confident the Bun team would be in migrating.

akagusu 3 hours ago | parent | prev | next [-]

What does this mean for Zig?

Few big popular projects use Zig, if they start to move away from it, what Zig's future will look like?

rererereferred 3 hours ago | parent | prev | next [-]

The branch in question: https://github.com/oven-sh/bun/compare/main...claude/phase-a...

lousken 6 hours ago | parent | prev | next [-]

Good enough for a side project, not good enough for transferring banking system from cobol

pjmlp 5 hours ago | parent | next [-]

That is actually what companies like IBM and Unisys are already doing today, LLM assisted porting.

https://research.ibm.com/publications/enterprise-scale-cobol...

jaytaph 5 hours ago | parent | prev [-]

Why not? I think we are perfectly capable on generating a test and validation environment that we can use for correctness. Most likely llms could do this better than engineers with zero to none domain and language knowledge can do these days. From that point on, rewrites would become feasable (not easy, feasable).

m4rtink 5 hours ago | parent | prev | next [-]

What license is this ? Let me guess, its is no GPL...

scared_together 4 hours ago | parent [-]

Unlike the GNU coreutils rewrite in Rust, the Bun rewrite in Rust is being undertaken by the owners of the project.

That said, yes, you’re correct that Bun isn’t GPL: https://github.com/oven-sh/bun?tab=License-1-ov-file

0-bad-sectors 4 hours ago | parent | prev | next [-]

Interesting! I wonder how the performance is compared to the Zig version

heldrida 9 hours ago | parent | prev | next [-]

An update on Bun’s experimental migration from Zig to Rust:

The Rust rewrite now passes 99.8% of Bun’s pre-existing Linux x64 glibc test suite.

black_13 7 hours ago | parent | prev | next [-]

[dead]

rvz 8 hours ago | parent | prev [-]

[flagged]

vintagedave 8 hours ago | parent | next [-]

> absolute position of hating something such as AI and progress

Most takes I've seen are far more nuanced.

Key is that 'progress' has a positive connotation. It is different from change. Mere change - such as new inventions - may not necessarily be aligned with progress in a field, society, etc.

Change may be inevitable, but it's up to us humans to sculpt it into progress.

rvz 7 hours ago | parent [-]

But I am talking about Zig and others who have the same stance. Zig has a very strict No LLM / AI contribution policy and it likely got in the way of the Bun maintainers at Anthropic. From [0]

>> No LLMs for issues.

>> No LLMs for patches / pull requests.

>> No LLMs for comments on the bug tracker, including translation.

[0] https://codeberg.org/ziglang/zig#strict-no-llm-no-ai-policy

vintagedave 6 hours ago | parent [-]

They don't hate it. There's no antagonism that I know of there. I believe they want it to be fully human-authored and want low-hanging fruit items to be good onboarding for developers, not targeted by AI contributions. Simon Willison wrote a good blog post on it: https://simonwillison.net/2026/Apr/30/zig-anti-ai/

The Bun pull request was refused for additional reasons: 'AI is entirely beside the point here...': https://ziggit.dev/t/bun-s-zig-fork-got-4x-faster-compilatio...

None of this is, in the original comment's text, "hating... AI".

heldrida 7 hours ago | parent | prev [-]

Thats true, but the author might have decided on its own. Not everything is a marketing plan.