Local Type Inference for Flow

Over the course of 2021 and 2022, we have built LTI (Local Type Inference), a rewrite of Flow’s type inference algorithm. This change makes Flow’s inference behavior more reliable and predictable. It replaces a global inference scheme that Flow has relied on since its…

Announcing Partial & Required Flow utility types + catch annotations

Flow can now detect unused Promises

As of v0.201.0, Flow can now lint against unused/floating Promises. Unused promises can be dangerous, because errors are potentially unhandled, and the code may not execute in the intended order. They are usually mistakes that Flow is perfectly positioned to warn you…

Announcing 5 new Flow tuple type features

Labeled tuple elements, read-only tuples, optional tuple elements, tuple spread, and more.

Tuples are a lighter weight alternative to objects when you want to group data…