python-typing-patterns

# Python Typing Patterns Modern type hints for safe, documented Python code. ## Basic Annotations ```python # Variables name: str = "Alice" count: int = 42 items: list[str] = ["a", "b"] mapping: dict[str, int] = {"key": 1} # Function signatures def greet(name: str, times: int = 1) -> str: return f"Hello, {name}!" * times # None handling def find(id: int) -> str | None: return db.get(id) # May return None ``` ## Collections ```python from collections.abc import Sequence, Mapping, Iterable # Use collection ABCs for flexibility def process(items: Sequence[str]) -> list[str]: """Accepts list, tuple, or any sequence.""" return [item.upper() for item in items] def lookup(data: Mapping[str, int], key: str) -> int: """Accepts dict or any mapping.""" return data.get(key, 0) # Nested types Matrix = list[list[float]] Config = dict[str, str | int | bool] ``` ## Optional and Union ```python # Modern syntax (3.10+) def find(id: int) -> User | None: pass def parse(value: str | int | float) -> str: pass # With default None def fetch(url: str, timeout: float | None = None) -> bytes: pass ``` ## TypedDict ```python from typing import TypedDict, Required, NotRequired class UserDict(TypedDict): id: int name: str email: str | None class ConfigDict(TypedDict, total=False): # All optional debug: bool log_level: str class APIResponse(TypedDict): data: Required[list[dict]] error: NotRequired[str] def process_user(us...