fn apply(f: fn(Int): Int, x: Int): Int = f(x)

fn compose(f: fn(Int): Int, g: fn(Int): Int): fn(Int): Int = fn(x: Int): Int => f(g(x))

fn square(n: Int): Int = n * n

fn cube(n: Int): Int = n * n * n

fn makeAdder(n: Int): fn(Int): Int = fn(x: Int): Int => x + n

fn main(): Unit with {Console} = {
    Console.print("Square of 5: " + toString(apply(square, 5)))
    Console.print("Cube of 3: " + toString(apply(cube, 3)))
    let add10 = makeAdder(10)
    Console.print("Add 10 to 5: " + toString(add10(5)))
    Console.print("Add 10 to 20: " + toString(add10(20)))
    let squareThenCube = compose(cube, square)
    Console.print("Composed: " + toString(squareThenCube(5)))
}

let output = run main() with {}