Union Types in Python

🔀 Union Types

Union types are used when a variable or function can accept more than one specific type.

Union comes from the typing module.

from typing import Union

age: Union[int, str]

This means age can be either an integer or a string.

age = 23
age = "23"

Both are valid according to the type hint.

from typing import Union

def display(value: Union[int, str]) -> None:
    print(value)

Now the function can accept:

display(100)
display("Hello")

In modern Python, you can use | instead of Union:

def display(value: int | str) -> None:
    print(value)

This is equivalent to:

Union[int, str]

Union Type = A type hint that allows multiple possible types.

Optional is actually a special case of Union:

Optional[str]

means:

str | None