# ty Extremely fast Python type checker and language server from [Astral](https://astral.sh). 10–60x faster than mypy and Pyright. ## Install ```bash uv tool install ty # or brew install ty ``` ## Commands ```bash ty check . # type-check current directory ty check src tests # check specific directories ty check file.py # check a single file ty check --watch # re-check on file changes ty server # start LSP language server ``` ## Key Flags | Flag | Purpose | |------|---------| | `--python-version 3.12` | Target Python version | | `--python-platform linux` | Target platform | | `--venv .venv` | Use specific virtual environment | | `--error RULE` | Treat rule as error | | `--warn RULE` | Treat rule as warning | | `--ignore RULE` | Disable a rule | | `--output-format concise` | Output: `full`, `concise`, `github`, `gitlab`, `junit` | | `--exit-zero` | Always return exit code 0 | | `--error-on-warning` | Warnings cause non-zero exit | ## Configuration Uses `ty.toml` or `[tool.ty]` in `pyproject.toml`: ```toml [tool.ty] python-version = "3.12" [tool.ty.rules] # override rule severities possibly-unbound-attribute = "warn" ``` CLI override: ```bash ty check --config "python-version='3.12'" . ``` --- See also: [[Ruff]], [[uv]]