Structural pattern matching for list of unknown length in Python 3.10

Let’s assume I have the following function:

def sum_ints(my_list: list[int]) -> int:
    return sum(my_list)

Before I start adding the elements in my_list, I want to check the type of all elements using the new match statement.

If my_list has a length of 2 for example, I can do:

def sum_ints(my_list: list[int]) -> int:
    match my_list:
        case [int(), int()]:
            return sum(my_list)
        case _:
            raise Exception("...")

How can I match the case for a list with n elements?

>Solution :

I think in your case you only need all built-in function.

if all(isinstance(i, int) for i in my_list):
    # Do Something
else:
    # raise Exception("...")

But if you really really want to try this logic via match statement you can use match guard but it’s kind of a complicated/unreadable solution in this case.

a = [1, 2]
match a:
    case [*elements] if all(isinstance(i, int) for i in elements):
        print("All Int")
    case _:
        raise Exception("test")