Type hinting: An overview

Before we start tackling the topic of APIs, let's take a look at Python's type hinting.

One of the reasons we chose FastAPI to create this project is that it is based on type hinting. Type hinting was introduced in Python 3.5, by PEP484 (https://www.python.org/dev/peps/pep-0484/). This PEP builds on top of another functionality, function annotations, that was introduced in Python 3.0 by PEP3107 (https://www.python.org/dev/peps/pep-3107/).

PEP484 was strongly inspired by Mypy (http://mypy-lang.org), an optional static type checker for Python.

Python is both a strongly typed and a dynamically typed language.

Strong typing means that variables have a type, and the type matters when we perform operations on variables. Let us explain this concept with an example in an imaginary language:

a = 7
b = "7"
a + b == 14
concatenate(a, b) == "77"

In this example, we imagine a language that is weakly typed...