From fbd70fb84e347b45db79eb24cc2c53e447a04147 Mon Sep 17 00:00:00 2001
From: Maggie Moss <maggiebmoss@gmail.com>
Date: Wed, 5 Nov 2025 19:35:34 +0000
Subject: [PATCH] Update typing docs to reference pyrefly  (#166883)

Replacing mypy codumentation in the CONTRIBUTING.MD file with pyrefly references. I have made initial changes to https://github.com/pytorch/pytorch/wiki/Guide-for-adding-type-annotations-to-PyTorch documentation, and will replace the script at the bottom with one tailored to the pyrefly tool as a follow-up.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/166883
Approved by: https://github.com/malfet
---
 CONTRIBUTING.md | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 9df55ca6acd..bc0b0fc9bb0 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -18,7 +18,7 @@ aspects of contributing to PyTorch.
   - [Python Unit Testing](#python-unit-testing)
   - [Better local unit tests with `pytest`](#better-local-unit-tests-with-pytest)
   - [Local linting](#local-linting)
-    - [Running `mypy`](#running-mypy)
+    - [Running `pyrefly`](#running-pyrefly)
   - [C++ Unit Testing](#c-unit-testing)
   - [Run Specific CI Jobs](#run-specific-ci-jobs)
 - [Merging your Change](#merging-your-change)
@@ -281,7 +281,7 @@ dependencies as well as the nightly binaries into the repo directory.
 **Prerequisites**:
 The following packages should be installed with `pip`:
 - `expecttest` and `hypothesis` - required to run tests
-- `mypy` - recommended for linting
+- `pyrefly` - recommended for type checking. [Pyrefly](https://pyrefly.org/)
 - `pytest` - recommended to run tests more selectively
 Running
 ```
@@ -350,15 +350,32 @@ make lint
 
 Learn more about the linter on the [lintrunner wiki page](https://github.com/pytorch/pytorch/wiki/lintrunner)
 
-#### Running `mypy`
+#### Running `pyrefly`
 
-`mypy` is an optional static type checker for Python. We have multiple `mypy`
-configs for the PyTorch codebase that are automatically validated against whenever the linter is run.
+[Pyrefly](https://pyrefly.org/) is a high-performance static type checker for Python. It provides fast type checking along with IDE features like autocomplete and instant error feedback.
+
+PyTorch uses Pyrefly for type checking across the codebase. The configuration is managed in `pyrefly.toml` at the root of the repository.
+
+**Getting Started with Pyrefly:**
+
+To run type checking on the PyTorch codebase:
+```bash
+pyrefly check
+```
+
+For more detailed error information with summaries:
+```bash
+pyrefly check --summarize-errors
+```
+
+**Learn More:**
+- [Pyrefly Configuration](https://pyrefly.org/en/docs/configuration/) - Detailed configuration options
+- [Pyrefly IDE Features](https://pyrefly.org/en/docs/IDE-features/) - Set up Pyrefly in your editor for real-time type checking
+- [Python Typing Tutorial](https://pyrefly.org/en/docs/typing-for-python-developers/) - Learn about Python type annotations
 
 See [Guide for adding type annotations to
 PyTorch](https://github.com/pytorch/pytorch/wiki/Guide-for-adding-type-annotations-to-PyTorch)
-for more information on how to set up `mypy` and tackle type annotation
-tasks.
+for PyTorch-specific guidance on how to set up `pyrefly` and tackle type annotation tasks in this codebase.
 
 ### C++ Unit Testing