Microsoft Distinguished Eng: Why And How To Port Your Entire Codebase to Rust | Stephen Toub

Stephen Toub is a Distinguished Engineer at Microsoft who single-handledly rewrote the GitHub Copilot runtime (400,000-line codebase) in Rust. We talked about why/how he did it, how Rust compared with other languages, and everything he learned in the process.

• My ergonomic keyboard project I mentioned, you can follow along here: https://read.compose.llc/
• The Kickstarter page for it: https://www.kickstarter.com/projects/ryanlpeterman/compose-simple-ergonomics-beautifully-done

Podcast links:

• YouTube: https://www.youtube.com/watch?v=PLMOVlZC4eU
• Apple: https://podcasts.apple.com/us/podcast/the-peterman-pod/id1777363835
• Transcript: https://www.developing.dev/p/e073-stephen-toub

Thank you to this episode's sponsor for supporting my work:

• WorkOS: makes your app Enterprise Ready with easy to use APIs to add SSO, SCIM, RBAC, and more in just a few lines of code, check them out at https://workos.com/

Timestamps:

(00:00) Intro
(01:06) Why the Copilot runtime needed a Rust port
(05:38) Why he chose Rust
(11:28) Discussing rollout strategies
(21:57) How he caught regressions
(32:08) Guiding the agents
(42:11) Catching regressions before prod
(45:16) Which models he used
(50:03) The end benefit and costs
(01:03:24) When to do a full rewrite
(01:06:40) Career learnings on the way to Distinguished
(01:16:00) Top technical book recommendation
(01:17:49) Advice for young engineers
(01:21:00) Outro

Where to find Stephen:

• GitHub: https://github.com/stephentoub
• X: https://twitter.com/stephentoub
• LinkedIn: https://www.linkedin.com/in/stephen-toub-75979745/

Where to find Ryan:

• Newsletter: https://www.developing.dev/
• X/Twitter: https://x.com/ryanlpeterman
• LinkedIn: https://www.linkedin.com/in/ryanlpeterman/
• Threads: https://www.threads.com/@ryanlpeterman
• Instagram: https://www.instagram.com/ryanlpeterman
• TikTok: https://www.tiktok.com/@ryanlpeterman

Referenced in this episode:

• Stephen Toub’s post on porting the GitHub Copilot runtime to Rust: https://github.blog/ai-and-ml/generative-ai/migrating-the-github-copilot-runtime-to-rust-using-copilot/
• Jarred Sumner’s post on porting Bun to Rust: https://bun.com/blog/bun-in-rust
• Code: The Hidden Language of Computer Hardware and Software: https://www.charlespetzold.com/code/index.html