LLMs Port TypeScript Compiler to Rust: $420k Cost for High-Perf WASM Compatibility

ts-rust (aka tsc-rs)

I wanted to see if LLMs could port the TypeScript compiler, checker and lsp to Rust. Turns out they can.

It [cost over 420,000](#how-did-this-go) in tokens to do it, but you could probably have done it for ~20k (see below)

Motivations

• Test model capabilities
• Make a fast TypeScript type checker
• Make a ts checker that can work in WASM with high performance
• Memes

Warnings

This is an early release. It has 100% compatibility in every real world project we have tested. It should work as a drop in replacement for the vast majority of apps. See Known problems.

Also worth mentioning: I've never read a line of this code.

Install

Be warned, I have no idea if this will actually work.

npm install -D tsc-rs
npx tsc-rs -p tsconfig.json

How did this go?

I used a lot of OpenAI models to try and complete this port. In total I did over $400,000 in API priced tokens with GPT-5.6 Sol and GPT 6 Astra. They wrote over 1.3m lines of Rust over multiple months of /goal loops and never got past like 84% compat.

When I saw how little my Claude Code limits were burning, I figured it'd be fun to throw Opus 5.5 at this. It had a working v0 in 10 hours.

I assumed it kept using the code the Codex models wrote. I was wrong. Opus 5.5 started from scratch. It got further than Astra in 1/10th the time.

I let it keep going, and it definitely did. Total token spend was ~$24,047 of API spend over 2 weeks**. I was using my Claude accounts, and it worked out to somewhere between **925$200 plan weekly limits.

Expensive, for sure, but not that bad considering how much work has went into typescript-go.

"The Slop Line"

Everything below this was written by my LLMs, not me.

What actually is this?

ts-rust is a direct port of Microsoft's native TypeScript compiler, which is written in Go (microsoft/TypeScript, formerly typescript-go). It keeps Go's algorithms and behavior and has the same command line (tsc), language server and API.

Install

npm install -D tsc-rs
npx tsc-rs -p tsconfig.json

tsc-rs takes the same options as tsc. The npm package is tsc-rs so that it does not clash with the typescript package. Each release also has a standalone archive per platform: the tsc binary with the lib files next to it.

Platforms: Linux x64 (static, any distribution) and macOS arm64. Windows and Linux arm64 are not available yet.

To use it in VS Code, see the npm package README.

Effect diagnostics

tsc-rs has the Effect language service diagnostics built in (codes 377xxx), so an Effect project needs no second compiler. They come from the same check as the TypeScript diagnostics, and the language server shows them too. They run only when the tsconfig has the plugin, as with @effect/language-service:

{ "compilerOptions": { "plugins": [{ "name": "@effect/language-service" }] } }

The rules, options and @effect-diagnostics comments are a port of Effect-TS/tsgo 0.46.1. The editor features of the language service (quick fixes, refactors, hover, completions) are not ported.

Status

The port is pinned to one upstream revision, microsoft/TypeScript 673a5f17d713 (2026-09-29, TypeScript 7.1.0-dev; UPSTREAM.md), and compared with Go at that revision. To compare, use [email protected], not 7.0.x or @typescript/native-preview. A difference that this build also shows is upstream behavior, and it goes away when the port moves to a newer pin.

• Same results. TanStack Query core and Hono check with diagnostics identical to Go's. All 181,711 ported Go tests pass. The language server and API answers match Go on the oracle test sets.
• Faster. On 60 open-source projects, type checking takes about half of Go's time (geometric mean). The preview packages are built in CI without PGO and BOLT, so they are slower than that measured build.
• Real projects. On 120 open-source repos, the command-line output differs from Go's only in the problems below and where Go's own output changes from run to run.

（注：更多技术实现细节与完整 API 文档请查阅原项目 README）