Jarred Sumner
@jarredsumner
building @bunjavascript at @anthropicai. formerly: @stripe (twice) @thielfellowship. high school dropout. npm i -g bun
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8 days ago, while jogging, I asked Claude to solve the Riemann Hypothesis
It didn’t. 1.5 days later, it proved >= 67% of the zeros are on the line (prev: 41.6%)
Still not sure what that means, but some analytic number theorists seem excited
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In the next version of Bun
We fixed a GC retention cycle that made Next.js App Router SSR leak memory when a page called fetch()
In the next version of Bun
Several bugs involving backpressure propagation have been fixed
the spike in july: new fuzzer
overrides syscalls and diffs bun’s behavior against node on identical inputs. a /loop in claude code drives it and sends bugs to robobun to fix
i think _some_ visual indicator that it's stderr and not stdout is a good idea. it's always been weird to me that the terminal doesn't say you're looking at an error.
but i've been kind of annoyed by the red styling in bun for awhile now
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the red console.error ansi styling in bun - should we get rid of it?
this also makes FFI a lot more reliable
ratio improving
That engineer: @cirospaciari 🙌
1 engineer + Claude Code got more of Node.js’s test suite passing over the last month than the entire Bun team (me included) did in the 9 months from 1.2 → 1.3
Bun v1.4 will be our biggest jump in Node.js compatibility since Bun v1.0
now do Jarred.sleep()
In the next version of Bun
Improved timer accuracy on Windows makes `Bun.sleep` faster
If you have Claude Code installed you're running software that uses the new (unreleased) version of Bun that's been rewritten in Rust - here are two commands you can run to see that for yourself
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In the next version of Bun
Idle CPU usage drops by 5x
The Bun rewrite was dirt cheap even at Fable pricing. For comparison, it took 3-5 engineers (about half the core team) about ~14 months to rewrite @Turborepo in Rust between 2023 and 2024. When you consider the opportunity cost on top of eng salaries, it actually cost several millions of dollars.
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hopefully the blog post was good enough to justify the wait
we’re merging some more node.js compatibility improvements and then will release bun v1.4
Rewriting Bun in Rust
rust rewrite blog post Monday
Bun v1.4 hopefully Tuesday (video still editing)
In the next version of Bun
Web Streams get faster, use less memory, and pass 100% of relevant Web Platform Tests
You can also use Claude Tag to make charts.
Claude Tag is the next evolution of agents.
It's a proactive, multiplayer agent with memory and identity, built on top of Claude Code.
Learn more about how Claude Tag works and best practices for using it in this deep dive.
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Bun v1.4 ships July 7th
