Pyrefly is not the first Python type-checking tool from Meta. Previously, the company delivered Pyre, written in OCaml. Pyre ...

Python’s new template strings, or t-strings, ... Pyrefly and Ty: Two new Rust-powered Python type-checking tools compared. Jun 25, 2025 5 mins. how-to. Get started with Python type hints.

Similarly, the Python "string" type functions as a collection type to an extent, allowing index referencing and manipulation. But, as strings have their own internal quirks, ...