Claude Code uses Bun written in Rust now

embedding-shape

> For me this outputs Bun v1.4.0 (macOS arm64). The most recent release of Bun on GitHub is currently v1.3.14 from May 12th, so that v1.4.0 version number in Claude supports them shipping a preview of a not-yet-released Bun version. And so, the FOSS project "Bun" silently dies in darkness and is now something completely else. I'm glad I still had "Investigate if Bun is worth it" on my TODO list and hadn't yet gotten to it. What is the governance structure for Bun by the way? Couldn't find any documents/explanations about how it's supposed to work. I'm guessing it's essentially just "Anthropic decides what gets done and accepted" today?

baq

Turns out it was just a build step after all.

kburman

Honestly, I initially thought rewriting an entire codebase with AI would be a huge mistake. After reading this, I'm starting to think I was wrong. If projects like Bun can be substantially rewritten and shipped to millions of users, it suggests we're entering a very different phase of software development. Today's AI-generated rewrites may not produce code that humans would consider high quality or maintainable. But I'm beginning to wonder whether that will even matter in a few months. If AI is the primary consumer, maintainer, and refactorer of code, human readability becomes far less important than correctness, performance, and the ability to iterate. This feels like a shift where software may no longer exist as a long-lived artifact in its current form. Instead of writing and maintaining applications for years, we may generate, adapt, and discard them continuously for each use case.

gabrieledarrigo

Bah. Personally my take on the entire affair is quite negative, whatever Jarred or Simonw says about it. I think Bun owned by Anthropic and the entire rewrite with AI is not the real point (even if it's quite interesting, though). My take is that Jarred, and Bun,didn't demonstrate a serious, adult approach, from "this is my branch, you are overreacting" message to just proceeding with a 1mil+ PR merged in less than month. The communication is the issue, and it was handled very badly, in a way that impacted trust and divisions. Was it so difficult to adopt the approach that the TS team adopted for 7.0?

bel8

Contrary to many, I have high hopes that Jarred and team will lapidate the ported codebase and it will continue to flourish as an open source project.

znpy

> Startup got 10% faster on Linux but otherwise, barely anyone noticed. Just that? I was expecting more from that rewrite. Maybe Rust is not so worth it after all.

ooofydoofy

bun upgrade --canary you are welcome

reddalo

Damn, I should have not migrated to Bun. Should I revert back to Npm?

IshKebab

This post is just "they didn't lie"...

thrance

Yeah, I noticed. I had Claude write a quick JS script for me a few days ago, it then tried to use Bun to run it. When it couldn't find it, it tried to install it with `sudo pacman`. I had to fucking tell it to use Node instead.

maverickaayush

I've been using Claude Code daily for a fairly large FastAPI project and didn't notice anything unusual around that timeframe. If this really was the Rust runtime underneath, "boring is good" seems like the right outcome.

rs_rs_rs_rs_rs

It is absolutely amazing to me that this ai rewrite work so well, maybe claude is not really that much of a complicated tool to stress the bun runtime but still...

feverzsj

It's a transpile. And not even a good one. The generated code is far from idiomatic rust. Some may consider it an abomination.

aureate

The port of Bun, which has >5000 open github issues, is used in Claude Code, which has >11000 open github issues. Do people use Bun in things that are expected to work reliably? Have any such projects tried the upgrade yet?

witx

What is the actual contribution and motivation of this post?

codethief

Incidentally, Claude Code has been very buggy for me lately (much more so than before). Lots of TUI rendering issues causing, e.g., the conversation history to be garbled etc.

tappaseater

Anthropic bought Bun, so they kinda, sorta had to make this work. I am sure the cost at $145,000 in Claude time will get some attention. I am curious how this will work going forward from FOSS perspective. Will humans be allowed to modify the generated code? Only the .md prompts for the agents? Or what?

lazzlazzlazz

Seeing all the people up in arms that there was an automated rewrite of Bun to Rust has been very revealing and disappointing. Very silly behavior and denial over the inevitable.

nottorp

So does that make Claude Code any better? Can you select text with shift + arrow keys now in the command line client? :)

softwaredoug

Whatever the headaches of the internals, I haven’t heard any substantive outcomes in hacker news that have been impacted by this change. Yes if we had a Zig->Rust transpiler maybe it would produce similar output. But I can’t find one. We’d have to use an agent to build one first :)