Type Hints In Python

1. Basic Type Hints

• What and Why https://peps.python.org/pep-3107/ https://peps.python.org/pep-0484/

• Life without types

• Type Hints: Mypy, pycharm, VS Code

• Type Hints are available in runtime (inspect.get_annotations)

2. Generic Types

• Generic lists

  • list[int], list[str], list[int|str|bool]

• Generic Dictionaries

  • dict[str, int], dict[Any, int]

• TypedDict

  • use only specific keys in dict
  • Literal
  • NotRequired

3. Types & Functions

• Simple input/output type hints def x(a: str, b: int) -> list[int]: pass

• Typing *args

• Typing **kwargs

• Default args

• Generator Functions

• Warning: Type Hints and Built-in functions

4. Types And Object Oriented Programming

• Every class is a type

• Protocols

• Type Hints for Recursive Structures

class Node: value: int left: Node right: Node

def dfs(): pass

n = Node(10) n.right = Node(12) n.right.right = Node(15) n.right.left = Node(9) n.dfs()

5. Type Vars

• Unsolved Identity Problem

• Hello TypeVar

• Hello ParamSpec

• Types for Decorators

6. User Defined Type Guards

• Built-in Type Guards

• Creating Your Own Type Guard

• casting

7. NewType and Type Aliases

• Creating type aliases

• Defining new types with NewType