Nonempty List Types In Python

dependent.py

# pyright: standard

from typing import TypeIs, reveal_type, TypeVar, Generic, Sequence, cast

T1 = TypeVar('T1')
Numeric = TypeVar('Numeric', bound=float)

class NonemptyTuple(tuple, Generic[T1]):
    def __init__(self, *args, **kwargs):
        raise ValueError("Never construct me directly") # Idk
    pass

def has_items(items: tuple[T1, ...]) -> TypeIs[NonemptyTuple[T1]]:
    return len(items) > 0

class SafeMath(Generic[Numeric]):
    def __init__(self, items: NonemptyTuple[Numeric]):
        self.items = items

    def headSafe(self) -> Numeric:
        return self.items[0]

    def rest(self) -> tuple[Numeric]:
        rest: tuple[Numeric] = self.items[1:]
        return rest

    def max(self) -> Numeric:
        head = self.headSafe()
        rest = self.rest()
        if has_items(rest):
            return max(head, SafeMath(rest).max())
        else:
            return head

items = tuple([1,99,2,3,4])
if has_items(items):
    print(SafeMath(items).max())

# pretty cool that this is illegal!!
print(SafeMath(items).max())