Simon Willison’s Weblog

Figma’s journey to TypeScript: Compiling away our custom programming language (via) I love a good migration story. Figma had their own custom language that compiled to JavaScript, called Skew. As WebAssembly support in browsers emerged and improved the need for Skew’s performance optimizations reduced, and TypeScript’s maturity and popularity convinced them to switch.

Rather than doing a stop-the-world rewrite they built a transpiler from Skew to TypeScript, enabling a multi-year migration without preventing their product teams from continuing to make progress on new features.