YouTip

What are Type Hints?

Type hints (PEP 484) let you annotate variables and function parameters with expected types. They improve code readability and IDE support.

Basic Types

name: str = "Alice"
age: int = 25
height: float = 1.75

def greet(name: str) -> str:
    return f"Hello, {name}!"

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

Complex Types

from typing import List, Dict, Optional, Union

names: List = ["Alice", "Bob"]
scores: Dict[str, int] = {"Alice": 90}
email: Optional = None
id_val: Union[int, str] = "ABC123"

Python 3.10+ Syntax

names: list = ["Alice", "Bob"]
id_val: int | str = "ABC123"
email: str | None = None

Summary

• Type hints improve code documentation and IDE support
• Use typing module for complex types (List, Dict, Optional)
• Python 3.10+ supports list[], dict[], and | for unions
• Type hints are not enforced at runtime