$24,000 AI experiment ports TypeScript compiler to Rust

Microsoft's Go rewrite gets some competition, with a developer claiming his port runs twice as fast

With some extra tokens to burn, developer and popular YouTuber Theo Browne used AI agents to port Microsoft's TypeScript compiler to Rust, just to see if it could be done. Not only did he produce a working implementation, but the resulting code could also pave the way for more memory-efficient environments for AI agents.

Browne claims his Rust port runs twice as fast as Microsoft's official Go-based TypeScript rewrite (v7) released earlier this year and 12.5 times as fast as the previous version of TypeScript (v6) – not bad work considering he says he hasn’t even inspected the code.  

TS_Rust is a project that would have been impractical even earlier this year, Browne noted in a video presentation. But models are developing so quickly that heretofore unimaginable tasks are now possible. 

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The resulting Rust-based TypeScript also opens the possibility of using Google’s V8 engine as a less-memory-intensive alternative for running agentic workloads written in TypeScript, an approach that would be unfeasible using Microsoft’s Go implementation of TypeScript, Browne argued. 

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A job that shouldn’t be possible

Browne’s original idea was to burn his excess tokens by tackling a project so large that it couldn’t possibly be finished, just to see how far the latest models could get. The agentic rewrite involved porting the TypeScript compiler, type checker, and language server, which provides features such as error checking and code completion in editors.

He burned more than $400,000 worth of API-equivalent tokens using OpenAI's GPT-5.6 Sol and GPT-6 Astra, which reached roughly 84 percent compatibility before the models struggled to complete the remaining work.

When Anthropic released Claude Opus 5.5 last month, he revisited the idea. To his surprise, the new model produced a working implementation, consuming about $24,000 worth of API-equivalent tokens through Browne's Claude subscriptions. The resulting implementation passed the TypeScript conformance tests with nearly 100 percent accuracy. 

Perhaps this unexpected success was due to Claude 5.5 being a more muscular model, Browne reasoned. But Claude was also clever enough to change its strategy to get a head start. Rather than attempting a direct translation from JavaScript to Rust, the model ported Microsoft's Go implementation of TypeScript to Rust, copying a few bugs from the original along the way.

Browne only learned that Claude did this after someone else pointed it out.

“Writing all of TypeScript from JS to Rust would not have been viable,” he said in the video. “The Microsoft team went through every line of code in TypeScript, ported it to Go, and then started refining it to make it better and faster in Go. My agents did the same thing from the Go version to Rust."

TS_Rust is one of several recent projects that used LLMs to rewrite some software in Rust. Microsoft itself recently rewrote the Copilot runtime in Rust. That project cost the 'softies about $120,000 in AI coins. Google, with the release of its Gemini 4 Argon model, is also using AI agents to port several major C/C++ codebases (RE2, libgav1, and parts of Fuchsia's Zircon kernel) to Rust.

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V8-powered agents

Beyond the novelty factor, Browne’s own version of TypeScript may ultimately provide a practical benefit by eliminating the need for agents to deploy relatively heavy agentic workspaces such as virtual machines and Docker containers. It’s a job even Microsoft’s own official Go implementation couldn’t do as effectively, he argued.

This work, should someone see it through, would be timely. Browne argued that with more powerful models on the horizon, inference costs are plummeting exponentially, so much so that the underlying compute costs needed to support developer environments will soon be the most expensive part of the job.   

With a Rust-based TypeScript compiler, some agentic workloads could potentially run within Google's V8 engine, instead of requiring a full container or VM. Cloudflare, for instance, already isolates multiple user environments using the Google V8 JavaScript runtime, thereby saving hundreds of megabytes per customer environment.

TypeScript itself, stripped of its type annotations, runs cleanly within V8, but Microsoft’s Go-based TypeScript compiler is not a good fit because Go's garbage collector must be bundled into the runtime using WebAssembly – no easy task. 

But Rust doesn’t need a garbage collector, so it compiles more efficiently with WebAssembly. A lightweight agentic environment could, in theory, run within V8 using TS_Rust and an in-memory shell environment such as Vercel's Just Bash, potentially reducing costs compared with running the same workloads in a VM.

As for Browne, he remains bullish on AI and software engineering.

“These types of YOLO projects should not be viable at all. Like [it] shouldn't even be able to pass the tests, much less actually work as a drop-in replacement for TypeScript,” he said. ®