# calculate fibonacci numbers with a loop

fn range(from: int, to: int) -> (fn() -> (int, bool)) {
    i := from - 1

    fn() -> (int, bool) {
        (i = i+1, i+1 < to)
    }
}

(a, b) := (0, 1)
for _ in range(0, 100) {
    (a, b) = (a + b, a)
    println(a)
}