struct X {
    id: Nat,
    x: Int,
    name: Option<String> = None,
}

// applying full-orderd-args
let x1 = X(0, 31, None);

// applying any-order
let x2 = X {
    name = Some("sample"),
    id = 1,
    x = -31,
};

// You can omit `name`, because it has default value.
let x3 = X {
    id = 2,
    x = 12345,
};

[
    x1,
    x2,
    x3,
]