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Hyeseong Kim

@hyeseong.kim
874 followers 434 following 239 posts

Integration engineer / Open source hitchhiker / DX enthusiast @rescript-lang.org committer

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Reposted by Hyeseong Kim
turbopuffer @turbopuffer.bsky.social · 02/10/2026
we implemented batched reads in the v3 full-text engine, leading to a ~9x performance improvement. postings are stored as columns, and we were reading them a row at a time sometimes optimization is not about being clever, but simply avoiding mistakes tpuf.link/v3/2026-10-02
tpuf.link
Batched reads speed up FTS by 9x
Follow along as we evolve turbopuffer's storage architecture and grind latency down til it's better than it ever was
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Reposted by Hyeseong Kim
Rob Palmer @robpalmer.bsky.social · 30/09/2026
ECMAScript excitement 😉 Congrats to @peet.bsky.social from TechAtBloomberg advancing JSON.parse Options to Stage 2.7 at @TC39 today 🎉 There are two independent opt-ins. 🔶 deep freezing the entire object 🔶 non-array objects get a null prototype Names may change ⚠️
JSON.parse(
    input: string, 
    reviverOrOptions?: Function | JsonParseOptions
): object
type JsonParseOptions = { 
    freeze?: boolean; 
    preferNullPrototype?: boolean 
}
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Reposted by Hyeseong Kim
Cloudflare @cloudflare.social · 30/09/2026
Cloudflare Containers now start 6x faster, let your agent choose each sandbox's image and instance type at runtime, and support filesystem snapshots in public beta, all controlled from a Durable Object. cfl.re/4z9xz6Q #BirthdayWeek
blog.cloudflare.com
Cloudflare Containers, rebuilt to scale agent sandboxes
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turbopuffer @turbopuffer.bsky.social · 30/09/2026
we're changing tpuf's storage architecture so we can keep pushing the search frontier the new engine (v3) now passes CI, but we have to make it fast before we ship it to prod we're grinding query plans in public until v3 wins on everything follow along: turbopuffer.com/v3
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Reposted by Hyeseong Kim
Rob Palmer @robpalmer.bsky.social · 30/09/2026
ECMAScript excitement 😉 Congrats to @ashley-c.bsky.social from TechAtBloomberg on advancing the Composites proposal to Stage 2 at @tc39.es today 🎉 Composites are objects that are compared by value instead of identity. They are an evolution of Record & Tuple proposal.
const pos1 = Composite({ x: 1, y: 4 });
const pos2 = Composite({ x: 1, y: 4 });
pos1 === pos2; // true

const positions = new Set(); // the standard ES Set
positions.add(pos1);
positions.has(pos2); // true
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Reposted by Hyeseong Kim
Jovi 🐨 @jovidecroock.com · 30/09/2026
Preact 11 is out 🎉 We’ve been hard at work at making our diffing use modern features like moveBefore , leveraging ESM for tree-shaking Preact Compat and ensuring you have a great experience with resumed hydration.
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James Snell @jasnell.me · 22/09/2026
Several nice additions here. util.debounce(fn, ...) util.throttle(fn, ...) SlidingWindowHistogram More FFI, net, and vfs goodness nodejs.org/en/blog/rele...
nodejs.org
Node.js — Node.js 26.10.0 (Current)
Node.js® is a free, open-source, cross-platform JavaScript runtime environment that lets developers create servers, web apps, command line tools and scripts.
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Reposted by Hyeseong Kim
TypeScript @typescriptlang.org · 17/09/2026
A new documentary about @vscode.dev is out! 🎬🎞️🍿 Check out The Story of VS Code, the story of the editor that brought the TypeScript experience to everyone! www.youtube.com/watch?v=kHL3...
youtube.com
The Story of VS Code | Official Documentary
YouTube video by Visual Studio Code
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Reposted by Hyeseong Kim
Astro @astro.build · 17/09/2026
Ecosystem performance meets Astro. @florian-lefebvre.dev is here to explain how the @e18e.dev project is making your favorite framework smaller and faster ⚡️
youtube.com
e18e x Astro | Astro Together FRA 2026 × Seibert
One dependency at a time, we can make the JavaScript ecosystem faster and leaner. But what exactly is e18e, and why should you care? Florian Lefebvre explores e18e, Astro’s role in the movement, the…
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Reposted by Hyeseong Kim
Philipp Dunkel @pipobscure.com · 18/09/2026
Now I’m actually celebrating! @nodejs.org just merged github.com/nodejs/node/... Which means it will now be possible to bundle whole applications into ZIP archives and run them straight from the bundle.
github.com
vfs: add --vfs-mount and --vfs-load startup flags by pipobscure · Pull Request #65748 · nodejs/node
vfs: add --vfs-mount and --vfs-load startup flags Mounting a virtual file system requires calling vfs.mount() from inside the program, so a program cannot itself be served from one — something alre...
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Antoine du Hamel @aduh95.bsky.social · 16/09/2026
Node.js 26.9.0 is out, it enables by default node:ffi and adds support for Web Worker API (behind a flag). Full changelog and download links at nodejs.org/en/blog/rele...
nodejs.org
Node.js — Node.js 26.9.0 (Current)
Node.js® is a free, open-source, cross-platform JavaScript runtime environment that lets developers create servers, web apps, command line tools and scripts.
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Hyeseong Kim @hyeseong.kim · 17/09/2026
I've ported my unicode-segmenter JS library to Rust. It performs text segmentation 4–5x faster than existing libraries for the grapheme-specific path. Check it out: github.com/cometkim/fas...
github.com
GitHub - cometkim/fast-grapheme-segmenter: Fast, lightweight, forward-only Unicode extended grapheme cluster segmentation (UAX #29)
Fast, lightweight, forward-only Unicode extended grapheme cluster segmentation (UAX #29) - cometkim/fast-grapheme-segmenter
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Hyeseong Kim @hyeseong.kim · 14/09/2026
I thought I’d have some breathing room right after leaving my job, but my home setting is taking a huge amount of time. I'm not sure if I'll be able to finish everything in this month.
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Reposted by Hyeseong Kim
React @react.dev · 09/09/2026
React 19.3 is now available! This release makes View Transitions and Fragment Refs stable, and adds browser(), Trusted Types support, and Context in Server Components. react.dev/blog/2026/09...
react.dev
React 19.3 – React
The library for web and native user interfaces
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antirez @antirez.bsky.social · 10/09/2026
DwarfStar running DeepSeek v4.1 Flash on a 128GB M5 Max at steady 15 t/s. I didn't expect with SSD streaming it could be so fast. Recent SSD streaming changes to retain the right experts surely helped, but also maybe DS4.1 uses the same experts more. Will push online when ready QA > ASAP.
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Hyeseong Kim @hyeseong.kim · 20/08/2026
ulottie compiler is now SSR-ready, which means the compiler can extract the initial frame as a static markup. (even it includes dynamic bodymovin expressions) Your Lottie animation can be in the initial document, and the client side script only hydrates.
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Hyeseong Kim @hyeseong.kim · 19/08/2026
Insane price btw, but more insane is that it's still growing 😅
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Hyeseong Kim @hyeseong.kim · 19/08/2026
I'm Qwen-ready 😎
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Hyeseong Kim @hyeseong.kim · 19/08/2026
Who said that interface files are no longer needed? Writing interfaces yourself and delegating implementation is a great method to collaborate with your agent.
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Reposted by Hyeseong Kim
Sung Kim @sungkim.bsky.social · 14/08/2026
Z AI's GLM-5.3: Built to Code. Ready for Cyber Defense. (open-weight soon) - Top-tier coding and agentic capabilities, achieved through post-training on the 743B base model - A major leap in cybersecurity, setting a new standard among open models z.ai/blog/glm-5.3
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Andy Bell @bell.bz · 13/08/2026
I'm p confident a lot of people will resonate with this brettcodes.com/im-done-usin... We need more perspectives from people with lots of experience as developers!
brettcodes.com
I'm done using AI
Why I'm stopping using AI for coding (and anything else) after using it earnestly for a year and coming to understand the harms it causes on personal, societal, and environmental levels.
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Reposted by Hyeseong Kim
AT Protocol Developers @atproto.com · 13/08/2026
Today we’re launching Bluesky Protocol Services, a new brand and website for the infrastructure Bluesky operates. And Jetstream v2, the best way for developers to use atproto at scale, now with network replay. atproto.com/blog/introdu...
atproto.com
Introducing Bluesky Protocol Services
A new home for the infrastructure Bluesky runs on the open network — including Jetstream v2 with network replay, a new Jetstream SDK, and a lex-based TypeScript SDK
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Hyeseong Kim @hyeseong.kim · 13/08/2026
Previously, when I thought I needed a simple Kotlin library for this, I was overwhelmed by the amount of configuration and had to give up on publishing, but the world has become so much more convenient now. github.com/cometkim/kourl
github.com
GitHub - cometkim/kourl: Custom kotlinx.serialization format for URL payloads; a handy adapter between your URL parser and Kotlin data classes
Custom kotlinx.serialization format for URL payloads; a handy adapter between your URL parser and Kotlin data classes - cometkim/kourl
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Hyeseong Kim @hyeseong.kim · 12/08/2026
Umm, it seems Claude doesn't really like the AOT approach. It keeps resisting it, calling it an overcomplication, and arguing that runtime dispatch is a simpler solution. Of course, that is true... but it wasn't what I wanted.
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Reposted by Hyeseong Kim
Mateusz Burzyński @andarist.bsky.social · 11/08/2026
Changesets v3 is here! 🦋 After months of chipping away at issues alongside @bluwy.me, @haglund.dev, and many other contributors, we’re excited to finally share it. changesets.dev/blog/announc...
changesets.dev
Announcing Changesets v3 | Changesets
A tool to manage versioning and changelogs with a focus on monorepos
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Reposted by Hyeseong Kim
Astro @astro.build · 06/08/2026
Astro 7.2 is out now! Experimental incremental static builds are here: only re-render the pages that actually changed and watch your build times drop. Plus opt-out session support, background astro preview, and relative logger entrypoints. astro.build/blog/astro-7...
astro.build
Astro 7.2 | Astro
Astro 7.2 adds experimental incremental static builds, an option to opt out of session support, background mode for astro preview, and relative logger entrypoints.
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Hyeseong Kim @hyeseong.kim · 10/08/2026
It is important to note that while it is not included in heap use, the code text itself allocates memory. The same applies to JIT compilation. Codegen and eval() are popular optimization tricks, but if misused, they spam gigabytes of duplicate text on the host and never release.
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Hyeseong Kim @hyeseong.kim · 10/08/2026
When claiming that your library is faster than alternatives, it is important to show how much memory space was sacrificed as a result. Mine is: github.com/cometkim/uni...
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Hyeseong Kim @hyeseong.kim · 10/08/2026
We all need to care about memory usage for sure. Especially JS libs. If you focus too much on CPU-centric microbenchmarks, there is a very high chance that you will accidentally over-allocate and retain objects/buffers.
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James @43081j.com · 10/08/2026
had another good chat about @e18e.dev and what the community has been up to. check it out! 🎉 big thanks to @josh.bressers.name for having me along and for the good conversation 🙏
opensourcesecurity.io
Cleanup, Speedup, Levelup open source at e18e
Josh chats with James from e18e. This is a project that is working on improving Javascript packages by cleaning up, speeding up, and leveling up the dependencies. The way the e18e project handles this...
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Reposted by Hyeseong Kim
Sam Rose @samwho.dev · 07/08/2026
I found a real bug in Kubernetes through webernetes, my port of Kubernetes to TypeScript. github.com/kubernetes/k... I found it by using webernetes to visualise how liveness probes work and noticed they didn’t work as I expected. Thought it was a webernetes bug but it was a Kubernetes bug!
github.com
Liveness probe failure container restart leads to container starting up with started=true and liveness probes starting before startup probes have run · Issue #141155 · kubernetes/kubernetes
What happened? The full details of the repro can be seen in the Bash script below, but roughly: Start a container with startup and liveness probe. Wait for both to succeed. All normal so far. Flip ...
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Reposted by Hyeseong Kim
Ben Schwarz @benschwarz.bsky.social · 05/08/2026
An enormous amount of the world’s CI and automation runs headless Chrome, all of it on x86—until last week. Chrome now ships official arm64 Linux builds. AWS says Graviton uses up to 60% less energy for the same performance. Chrome for Testing coming soon 🥳 calibreapp.com/blog/chrome-...
calibreapp.com
Chrome lands on arm64 | Calibre
Google has shipped official arm64 Linux builds of Chrome. Here’s where to get them, and why it’s good news for anyone running browser automation.
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Cloudflare @cloudflare.social · 05/08/2026
Cloudflare OS is an open-source platform that lets everyone in your company build apps, automate work, and safely access internal systems, shaped around what your organization knows and how it operates. cfl.re/4fGBl0w
blog.cloudflare.com
Cloudflare OS: an open platform for agents, apps, and work
Cloudflare OS gives every person an agent and workspace built around their company: how it works, what it knows, and the systems it relies on.
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Alexander Lichter @thealexlichter.com · 05/08/2026
And we are live now with @honk.foo youtube.com/live/L8Edgas...
youtube.com
e18e & friends E004 - Oliver Medhurst
What if you could compile JavaScript to Native but ahead of time? W...
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Dominik 🔮 @tkdodo.eu · 03/08/2026
Don't be a meat proxy gruhn.me/blog/2026-08...
gruhn.me
Don't be a meat proxy
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Cloudflare @cloudflare.social · 03/08/2026
gRPC support is now available in Cloudflare Workers. You can now route, transform, and serve gRPC services natively at the edge without maintaining dedicated proxy infrastructure or translation layers. Read the launch post: cfl.re/4fMsitT
blog.cloudflare.com
Cloudflare Workers and Containers now support inbound TCP connections and gRPC
Cloudflare Workers now support inbound TCP connections via Spectrum, allowing direct socket forwarding to Durable Objects and Containers. Developers can run full-duplex gRPC applications or leverage a...
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Hyeseong Kim @hyeseong.kim · 30/07/2026
One major milestone is to fully extract the initial frame markup and embedded image data. This allows the compiled animation module to be mounted even in static environments such as SSR and enables optimized resource loading for web-friendliness.
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Hyeseong Kim @hyeseong.kim · 30/07/2026
Most animations, excluding embedded image data, are shipped at an average size 20x smaller. Compilers can fold static frames to compress them into much smaller data. And any part of the runtime that isn't used by the animation will be completely eliminated!
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Hyeseong Kim @hyeseong.kim · 30/07/2026
The runtime architecture has been fully rebuilt to better leverage the compiler's capabilities. No more JSON. It evaluates the initial frame, pretty compact keyframe data, and statically bounded operations. Animations are powered by optimized loops over a linear data stream.
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Hyeseong Kim @hyeseong.kim · 30/07/2026
I think it's worth sharing the progress of my lottie compiler here: github.com/cometkim/ulo... You can test it on the demo page, which now has a live output preview in the breakdown section.
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Hyeseong Kim @hyeseong.kim · 24/07/2026
github.com/cometkim/rky... allows Rust's rkyv from/to JS applications. You can (zero-copy) deserialize wire messages sent from JS in Rust, or vice versa! Would be useful for JS-Rust interop projects, e.g., a Rust CLI with Cloudflare Workers, a web app with a Rust backend, etc.
github.com
GitHub - cometkim/rkyv-js: An unofficial library to use rkyv (Zero-copy deserialization framework for Rust) in JavaScript/TypeScript projects.
An unofficial library to use rkyv (Zero-copy deserialization framework for Rust) in JavaScript/TypeScript projects. - cometkim/rkyv-js
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Hyeseong Kim @hyeseong.kim · 23/07/2026
github.com/cometkim/uni... unicode-segmenter `countGrapheme` speedup by avoiding unnecessary allocation and iterator overhead. If you are using `Intl.Segmenter` simply to count numbers, you could consider this. It is almost 15-30x faster (varying depending on the input corpus).
github.com
Release unicode-segmenter@0.17.1 · cometkim/unicode-segmenter
Patch Changes e94d203: Add collectGraphemes(input) API that collects grapheme clusters into an array directly. This is a fast version of [...splitGraphemes(input)], which is acually the most used...
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Hyeseong Kim @hyeseong.kim · 09/07/2026
After much effort, it seems I have approached the lower threshold of the library's bundle size. When I make the code smaller, its compressed size actually becomes larger.
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TypeScript @typescriptlang.org · 08/07/2026
📣 The moment is here. 📣 TypeScript 7 is officially released! 7️⃣ devblogs.microsoft.com/typescript/a...
devblogs.microsoft.com
Announcing TypeScript 7.0 - TypeScript
Today we are proud to announce the availability of TypeScript 7, a 10x faster native port of TypeScript! Since its early days, TypeScript has promised to
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Jiahan Chen @chenjiahan.bsky.social · 08/07/2026
OMG, @jddalton.bsky.social has a wild proposal for Rspack's native binding: - size: 38.4 MiB -> 13.8 MiB (-64%) - first load: 853ms -> 615ms (-28%)
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Cloudflare @cloudflare.social · 08/07/2026
Cloudflare Research is building a global consensus service called Meerkat that uses a new consensus algorithm called QuePaxa. We plan to use Meerkat to build a strongly consistent, fault-tolerant key-value store, and other applications. cfl.re/3SKpK7L
blog.cloudflare.com
Introducing Meerkat: an experiment in global consensus
Meerkat is an experimental consensus service that is still in development. It’s being designed initially to manage small pieces of control plane state (e.g., leadership for replicated databases) and so it will be kept internal-only for the immediate future.
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Hyeseong Kim @hyeseong.kim · 07/07/2026
unicode-segmenter/grapheme is now only 2.5 KiB mingzipped. Faster than ever. github.com/cometkim/uni... Last dance with Claude Fable 5
github.com
perf: rewrite grapheme segmenter with flat tables and pair-rule dispatch by cometkim · Pull Request #133 · cometkim/unicode-segmenter
Summary Rewrites unicode-segmenter/grapheme for the three axes that matter for a core dependency — bundle size, runtime speed, and memory footprint — and, as a byproduct of making the rule state ma...
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Zach Leatherman @zachleat.com · 16/06/2026
uhh… TIL: <marquee direction="down" behavior="alternate"> <marquee behavior="alternate">This text will bounce</marquee> </marquee> developer.mozilla.org/en-US/docs/W...
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Hyeseong Kim @hyeseong.kim · 16/06/2026
Of course, the Rust ecosystem has many good resources and reusable components. We can easily reuse already completed components like ungrammar, salsa, oxc_minifier, etc. But then, what differentiates us from other vibe-coded compilers released today?
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Hyeseong Kim @hyeseong.kim · 16/06/2026
In terms of host support as well, js_of_ocaml is a good friend. We can easily port the compiler to the web, and their WASM support is in a much better state than Rust wasm_bindgen.
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