A developer used Anthropic's Claude Opus model to port Microsoft's TypeScript compiler from Go to Rust in two weeks, for about $24,047 in API costs, according to the project's GitHub README. The port, called ts-rust, targets TypeScript 7.1.0-dev.
An earlier attempt using OpenAI models cost more than $400,000 in tokens over several months and reached only about 84% compatibility with the original compiler, the README says. Switching to Claude Opus produced a working version in 10 hours, according to the project.
The finished port passes all 181,711 ported tests, with "100% compatibility in every real world project" the developer tested, the README says. The Rust version runs 1.61 times faster than the original Go compiler on real-world applications, according to the project.
The project's own documentation lists known gaps: monorepo source file handling differs from the original compiler in edge cases, memory use grows by about 20 megabytes per 1,000 edits in long sessions, and incremental builds can produce stale results in specific project-reference scenarios. The code is released under the MIT license, preserving the original Apache 2.0 and BSD-3-Clause notices from the TypeScript and Go projects it builds on, the README says.
A single developer spending less on Claude API calls than a junior engineer's monthly salary to get a passing-test rewrite of a compiler millions of developers depend on makes "LLMs can't do real engineering work" a harder argument, caveats about edge cases and all.