Python Types

Python has support for type hints (also called type annotations).
- Type hints are useful when coding in IDEs.
FastAPI is all based on these type hints, they give it many advantages and benefits.
To declare type hints we use :. For example, first_name: str.

Simple Types

Simple types in Python are:
- int
- float
- bool
- bytes

Generic Types

There are some data structures that can contain other values like dict, list, set and tuple. And the internal values can have their own type too → these types that have internal types are called generic types.
You should use the typing standard Python module for these generic types.
- Note → In newer versions of Python, you don’t need to import them from typing.

Example: Python 3.8+

from typing import List

def process_items(items: List[str]):
    for item in items:
        print(item)
 
       
from typing import Set, Tuple

def process_items(items_t: Tuple[int, int, str], items_s: Set[bytes]):
    return items_t, items_s
    
    
from typing import Dict

def process_items(prices: Dict[str, float]):
    for item_name, item_price in prices.items():
        print(item_name)
        print(item_price)

Example: Python 3.9+

def process_items(items: list[str]):
    for item in items:
        print(item)

        
def process_items(items_t: tuple[int, int, str], items_s: set[bytes]):
    return items_t, items_s
 
   
def process_items(prices: dict[str, float]):
    for item_name, item_price in prices.items():
        print(item_name)
        print(item_price)

Note → Those internal types in the square brackets are called "type parameters".