Type checking, or writing tests? Why not both!

Introduction to mypy

What is mypy, and how can I use it?

What is mypy?

Introduction to Python's type annotation syntax

Installing mypy on your machine, and in your code editor

Using mypy to type-check your code

Mypy errors, and how to debug them

We'll see what kind of errors mypy will throw at you, how to configure mypy to make the best use of it, and try to figure out what its errors mean.

Why doesn't mypy show an error here?

Mypy configuration

Simple type checking examples

Using reveal_type() to debug types

Mypy types, and the typing module

Modern Python has a LOT of type checking features baked into it. In this chapter we will see a glimpse of what the typing module has to offer.

Lists, Dictionaries, and other collections

Union and Optional types

Reading mypy error messages

Type checking your classes

Typing *args and **kwargs

The "Any" type

Diving deep into the typing module

The typing module also provides various functions and base classes, that create the basis of a lot of concepts of mypy's type system. In this chapter we will dive deep into these functionalities.

Static duck typing

Custom Generic types

The NamedTuple class

The TypedDict class

Function overloading with @overload

Some advanced type checking concepts

In this chapter we will learn some concepts, tips and tricks on how to properly type-check code using some of the more complicated Python concepts.

Type checking decorators

Type checking generators

The Type type

Conclusion

In this chapter, we will wrap up the series, and understand where type checking sits in the ecosystem of Python, and your software development process.

Type checking, or writing tests? Why not both!

Integrating mypy into your software development lifecycle