Stop Writing Python Without Type Hints — Here's How to Start

Type hints make Python code self-documenting, catch bugs before runtime, and supercharge your IDE. Here's a practical guide to adopting them incrementally. The Basics def greet ( name : str ) -> str : return f " Hello, { name } " def add ( a : int , b : int ) -> int : return a + b # Variables age : int = 25 names : list [ str ] = [ " Alice " , " Bob " ] config : dict [ str , int ] = { " timeout " : 30 , " retries " : 3 } Optional and Union Types from typing import Optional # Python 3.10+ def find_user ( user_id : int ) -> dict | None : if user_id in db : return db [ user_id ] return None # Pre-3.10 def find_user ( user_id : int ) -> Optional [ dict ]: ... Collections # Python 3.9+ — use built-in types def process ( items : list [ str ]) -> dict [ str , int ]: return { item : len ( item ) for item in items } # Tuples with specific types def get_coords () -> tuple [ float , float ]: return ( 40.7128 , - 74.0060 ) # Sets def unique_words ( text : str ) -> set [ str ]: return set ( text .