Pyright is typically 5x or more faster than mypy and other type checkers that are written in Python. It is meant for large Python source bases. It can run in a “watch” mode and performs fast incremental updates when files are modified.
Pyright is written in TypeScript and runs within node. It does not require a Python environment or imported third-party packages to be installed. This is especially useful when used with the VS Code editor, which uses node as its extension runtime.
Pyright supports flexible configuration that provides granular control over settings. Different “execution environments” can be specified for different subsets of a source base. Each environment can specify different PYTHON_PATH settings, python language version, and platform target.
* Type inference for function return values, instance variables, class variables, and globals
* Smart conditional type exclusions
### Built-in Type Stubs
Pyright includes a recent copy of the stdlib type stubs from [Typeshed](https://github.com/python/typeshed). It can be configured to use another (perhaps more recent or modified) copy of the Typeshed type stubs. Of course, it also works with custom type stub files that are part of your project.
### Command-line or Language Service
Pyright includes both a command-line tool and a [Language Server Protocol](https://microsoft.github.io/language-server-protocol/) plugin for VS Code.
### Language Service Features
Pyright offers the following language service features:
Pyright currently provides support for Python 3.0 and newer. There is currently no plan to support older versions.
## FAQ
Q: What is the difference between pyright and the [Microsoft Python VS Code plugin](https://github.com/Microsoft/vscode-python)?
A: The Python VS Code plugin is the official Python support extension for VS Code. It is officially supported by a team of engineers at Microsoft. It supports a diverse array of features including debugging, linter plugins, type checking plugins, and much more. Pyright is focused entirely on type checking. It is a side project with no dedicated team.
Q: What is the difference between pyright and the [Microsoft Python Language Server](https://github.com/Microsoft/python-language-server)?
A: The Microsoft Python Language Server is a [language server protocol (LSP)](https://microsoft.github.io/language-server-protocol/) implementation that works with the Microsoft Python VS Code plugin. It also provides type checking capabilities. Pyright's provides overlapping functionality but provides some unique features such as more configurabilty, command-line execution, and better performance.
* client/src/extension.ts: Language Server Protocol (LSP) client entry point for VS Code extension.
* client/typeshed-fallback/: Recent copy of Typeshed type stub files for Python stdlib
* server/src/pyright.ts: Main entry point for command-line tool
* server/src/server.ts: Main entry point for LSP server
* server/src/analyzer: Modules that perform analysis passes over Python parse tree
* server/src/common: Modules that are common to the parser and analyzer
* server/src/parser: Modules that perform tokenization and parsing of Python source
* server/src/tests: Tests for the parser and analyzer
## TODO
Pyright is a work in progress. The following functionality is not yet finished. If you would like to contribute to any of these areas, contact the maintainers of the repo.
