What are the differences between type annotations and type checking in Python?

What are the differences between type annotations and type checking in Python?

Type annotations are hints you provide in your code to indicate the expected data types of variables, function parameters, and return values. Type checking, on the other hand, is the process of verifying that the types used in your code match the annotations you've provided.

Can you give me an example of type annotations in a function?

Sure! Here's a simple example:

def add_numbers(a: int, b: int) -> int:
    return a + b

In this function, a and b are annotated as integers, and the function is expected to return an integer.

How does type checking work in Python?

In Python, type checking can be done at runtime or using static type checkers like mypy. At runtime, Python checks the types as the code executes, while static type checkers analyze your code before it runs to catch type errors.

Are there any benefits to using type annotations?

Yes, type annotations improve code readability, help catch errors early, and enable better tooling support, such as autocompletion and refactoring.