Claude Code uses Bun written in Rust now

Post by uecker » Sun, Jul 19, 2026, 3:49 PM UTC

Matl wrote: post #93

stymaar wrote: post #40

Earlier quoted context omitted.

Rust as a language is irrelevant to this discussion, the problem is that bun was vibe coded by a single dude without any open source community involvement. “bun the open source project” is basically dead at that point: don't expect any of the zig enthusiasts who had their code being forcibly rewritten in a language they don't like to follow Jared. “bun the JavaScript runtime ” is not dead though.

I agree, it's unfortunate the headlines seem to have become 'rewritten in Rust' (not a bad thing) and not 'vibecoded in a week without review' (a bad thing).

Post by galangalalgol » Sun, Jul 19, 2026, 3:50 PM UTC

switz wrote: post #236

weakfish wrote: post #212

Maybe I’m taking crazy pills, but I’m still stuck on “why the hell does a TUI need to run in terminal React by way of JavaScript” The fact that Anthropic felt the need to buy a runtime so they could make their TUI better speaks more to the quality of engineering than anything else IMO. If rewrites are so easy, why not rewrite CC in a native language? Would’ve been a hell of a lot cheaper.

It largely works and it's a massive business success. This is the classic engineer asking the 'why this technology?' to what amounts to a business question. They chose it early on, it works, and it makes obscene amounts of revenue. End of story. That doesn't mean it was the "greatest" choice, or has a perfect technical architecture. Rewrites are never easy, even the bun rewrite. But a non-UI developer tool with a rig…

Post by tln » Sun, Jul 19, 2026, 3:52 PM UTC

pygy_ wrote: post #118

thevinter wrote: post #107

Earlier quoted context omitted.

> Update: The Rust version has been released as Bun canary - running bun upgrade --canary will install this release.)

Does `bun upgrade` provide the source code?

    https://github.com/oven-sh/bun/issues

    https://github.com/oven-sh/bun/compare/f161e0311...98f664962

Post by weakfish » Sun, Jul 19, 2026, 3:53 PM UTC

galangalalgol wrote: post #244

switz wrote: post #236

Earlier quoted context omitted.

It largely works and it's a massive business success. This is the classic engineer asking the 'why this technology?' to what amounts to a business question. They chose it early on, it works, and it makes obscene amounts of revenue. End of story. That doesn't mean it was the "greatest" choice, or has a perfect technical architecture. Rewrites are never easy, even the bun rewrite. But a non-UI developer tool with a rig…

The criticism didn't appear to me to be that the solution didn't work, just that many of the working solutions we are selecting are dangerously overcomplicated due to shortsighted decisionmaking. The benefits of throwing redundant stacks of abstraction atop each other in terms of time to market are questionable, and obviously absent in every other metric.

Post by agrippanux » Sun, Jul 19, 2026, 3:54 PM UTC

senderista wrote: post #243

ljm wrote: post #223

Earlier quoted context omitted.

I never knew that running an interactive program in my terminal would absolutely rinse my CPU and battery but that's what Claude, OpenCode and Ghostty have colluded to achieve. Even when the laptop is asleep overnight it's practically melting. I'm sure there was some logical reason for shoehorning web technology into this stack given that we have a good 40 years or so of experience with interactive terminal programs…

Why are you implicating ghostty? Have you compared its CPU usage to any other terminal?