fn sma(period int) fn (f64) f64 {
    mut i := 0
    mut sum := 0.0
    mut storage := []f64{len: 0, cap: period}

    return fn [mut storage, mut sum, mut i, period] (input f64) f64 {
        if storage.len < period {
            sum += input
            storage << input
        }

        sum += input - storage[i]
        storage[i], i = input, (i + 1) % period
        return sum / f64(storage.len)
    }
}

fn test_assign_literal_with_closure() {
    sma3 := sma(3)
    sma5 := sma(5)
    println('x       sma3   sma5')
    for x in [f64(1), 2, 3, 4, 5, 5, 4, 3, 2, 1] {
        println('${x:5.3f}  ${sma3(x):5.3f}  ${sma5(x):5.3f}')
    }
    assert true
}