What is the difference between type annotations and type checking in Python?

What is the difference 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 are consistent with these annotations, often done by tools like mypy.

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.

What tools can I use for type checking in Python?

You can use tools like mypy, Pyright, or the built-in type checker in IDEs like PyCharm. These tools analyze your code and check for type consistency based on your annotations.

Are type annotations mandatory in Python?

No, type annotations are optional in Python. You can write Python code without them, but using them can help improve code readability and catch type-related errors early.