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Pyre is a performant type checker for Python compliant withPEP 484. Pyre can analyze codebases with millions of lines of code incrementally – providing instantaneous feedback to developers as they write code. You can try it out on examples inthe Pyre Playground.

Pyre ships withPysa, a security focused static analysis tool we've built on top of Pyre that reasons about data flows in Python applications. Please refer to ourdocumentation to get started with our security analysis.

Pysa is also available on theGitHub Marketplace as a Github Action

To get started, you needPython 3.8 or later andwatchman working on your system. OnMacOS you can get everything withhomebrew:

$ brew install python3 watchman

OnUbuntu,Mint, orDebian; useapt-get andhomebrew:

$ sudo apt-get install python3 python3-pip python3-venv$ brew install watchman

We tested Pyre onUbuntu 18.04.5 LTS,CentOS 7, as well asOSX 10.11 and later.

We start by creating an empty project directory and setting up a virtual environment:

$ mkdir my_project&&cd my_project$ python3 -m venv~/.venvs/venv$source~/.venvs/venv/bin/activate(venv) $ pip install pyre-check

Next, we teach Pyre about our new project:

(venv) $ pyre init

This command will set up a configuration for Pyre (.pyre_configuration) as well as watchman (.watchmanconfig) in your project's directory. Accept the defaults for now – you can change them later if necessary.

We are now ready to run Pyre:

(venv) $echo"i: int = 'string'"> test.py(venv) $ pyre ƛ Found 1type error!test.py:1:0 Incompatible variabletype [9]: i is declared to havetype`int` but is used astype`str`.

This first invocation will start a daemon listening for filesystem changes – type checking your project incrementally as you make edits to the code. You will notice that subsequent invocations ofpyre will be faster than the first one.

For more detailed documentation, seehttps://pyre-check.org.

SeeCONTRIBUTING.md for how to help out.

Pyre is licensed under the MIT license.