Summary: Flow prioritizes the Facebook codebase’s need for more type safety and fast performance on very large codebases. Flow’s over-arching philosophy is evolving beyond just “JavaScript with types” and we will add new language features including new syntax that goes beyond type annotations to address internal users’ evolving needs. We are also making changes to how we engage with open source. Read on for more details.

Flow’s Latest Features

Since the last open source update a year ago, Flow has shipped many enhancements:

• A new architecture called Types First, which drastically improved performance
• More specific errors — both by adding error codes, and…