pyrightlangserver

pyrightlangserver is a language server implementation for Python that integrates the Pyright static type checker with the Language Server Protocol (LSP). It provides real-time type analysis and editor features, including diagnostics, autocompletion, go-to-definition, hover information, references, and signature help, enabling editors and IDEs to offer rich Python editing experiences driven by static typing.

The server is implemented in TypeScript for Node.js and is distributed as the npm package pyright-langserver. To use it, install Node.js and run npm install -g pyright-langserver (or add it to your project’s dev dependencies). Start the server with pyright-langserver --stdio and connect it to an LSP client within your editor.

Pyright-langserver relies on Pyright for analysis and reads configuration from a pyrightconfig.json file at the project root. It supports Pyright’s type checking modes (basic, strict, off) and respects Python interpreter settings such as version and path specified in the configuration. It can infer types across module boundaries to improve cross-file analysis.

Integration and ecosystem: It works with any editor or IDE that supports the Language Server Protocol, including Visual Studio Code, Neovim (with native LSP), Vim (via coc.nvim or other LSP clients), and Emacs lsp-mode. It is not a formatting tool; code formatting is typically handled by separate tools such as Black or isort.

History and scope: The Pyright project, maintained by Microsoft, includes the pyright-langserver as part of its tooling to provide fast, scalable Python type checking in an LSP-compatible server. The language server complements the Pyright command-line checker by delivering interactive feedback directly in editors.