declare struct Vec2(x: int, y: int)
[
    (x: int, y: int): (x, y) as default
    (s: int): (s, s) as square
]
[[
    ZERO: square(0)
]]
{
    pub fn len(self: this): int {
        return x * x + y * y;
    }
}

fn frame(): void {
    let zero = Vec2.ZERO;
    let zz = zero.len();
}