How Meta is translating its Java codebase to Kotlin

This post details Meta's ongoing effort to translate its substantial Android codebase from Java to Kotlin. It highlights the scale of the migration (tens of millions of lines of code), the development of open-sourced tools for manipulating Kotlin Abstract Syntax Trees (ASTs), and the challenges encountered, such as avoiding nullability issues and generating idiomatic code for internal frameworks. The post also references a podcast episode for deeper technical discussion.