Mypy Primer
Installing mypy on your machine, and in your code editor

Before we move ahead with the rest of the course, I want to explain how you can install mypy on your machine and code editor.

Installing mypy locally

To run mypy locally, you need to have Python installed.

  • If you're running Windows 10, you can open Command Prompt, and type python, which should either start Python, or open up Windows Store, where you can install it.
  • On a Mac or linux machine, you probably already have Python installed, under the name python3. Simply open a terminal and type python3 to confirm.

Now to install mypy, you need to run pip, a package manager which comes with Python:

$ python -m pip install mypy
Collecting mypy
Successfully installed mypy-1.x typing-extensions-4.x

Now you should have access to the mypy command:

$ mypy
usage: mypy [-h] [-v] [-V] [more options; see below]
            [-m MODULE] [-p PACKAGE] [-c PROGRAM_TEXT] [files ...]
mypy: error: Missing target module, package, files, or command.

To test it, pass it the name of any Python file:

$ mypy
Success: no issues found in 1 source file

Editor integration

While mypy and the other type checkers can be used directly through the command line, it is a bit more convenient for IDE users if the type checking errors integrate directly with their editor. There are two popular editors for Python users which can do this, Visual Studio Code and PyCharm. Let’s take a look at them.

Visual Studio Code

VSCode has a Python extension that comes with an official language server called “Pylance”, which provides type information out of the box.

You can however, enable mypy support in VSCode as well, by adding the following to your settings.json file:

  'python.linting.mypyEnabled': true,
  'python.linting.mypyArgs': [

You should then be able to see type checking issues directly in your code:

If you don’t, restart your editor and that should resolve any issues.


PyCharm has created its own type inference and refactoring system that works quite well and provides things like attribute auto-completion in the IDE by default. If you want to integrate mypy however, a Plugin called “Mypy” made by Roberto Leinardi exists in the JetBrains Marketplace. Simply installing it should enable mypy checks for you:

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