fn main(): Unit = {
    let nums = [1, 2, 3, 4, 5]
    let doubled = List.map(nums, fn(x: Int): Int => x * 2)
    let filtered = List.filter(doubled, fn(x: Int): Bool => x > 4)
    let reversed = List.reverse(filtered)
    let len = List.length(reversed)
    Console.print("done")
}