Type Hints (Type annotations)

• Python is dynamically typed (contrary to C++, Java, etc that are statically typed). With python you can provide type hints to assist on the development
• Type Hints or Annotations are a special syntax that allow declaring the type of a variable
• Type hints are not validated at runtime! That means that even if you provide wrong types it will compile normally

Python will remain a dynamically typed language, and the authors have no desire to ever make type hints mandatory, even by convention.

type SetOfIntegers = set[int]

a: SetOfIntegers = {1, 2, 3}
b: set[int] = {1, 2, 3}

Classes as types

class Person:
    def __init__(self, name: str):
        self.name = name


person: Person = Person("Henry")

• Types are usually represented in form of classes

Generic Types

• Types that take parameters. Example: dict[str, int]