Converting a large codebase to Hack
Facebook recently open-sourced Hack, a programming language for HHVM. Hack uses gradual typing and is fully compatible with PHP. Over the last year, Facebook has migrated a large part of its PHP codebase to Hack, thanks to both organic adoption and a number of homegrown refactoring tools. In this talk, I will give a high-level overview of the language and share some of the lessons learned during the migration process.