Odd Lots · Monday, July 20, 2026
Boris Cherney discusses Claude Code's effectiveness in migrating legacy codebases, specifically mentioning COBOL. He highlights a case where a team used Claude Code to migrate an entire codebase from Zig to Rust in about eleven days, a task that would have previously taken engineers a year and significant resources. This capability is enabling banks to modernize their systems.
“There are actually a lot of banks that are using clod code for exactly this kind of migration.”
“As they said, Yeah, well, claud is really good at migrating code. This is one of the actually, the skills, like the core skills that's just been improving over time. One example, we just published a blog post about how Jared on the Bun team, and you know, Bun is the JavaScript engine that powers quad code, how he migrated the entire code base from one language to another language, from Zig to Rust and it took about eleven days wow, for one person and hughes quad code with dynamic wre clothes to do this.”
“In the past, this would have taken like a few engineers, like a year or something. And it's something we never would have done.”