Dark

let greet (name: String) : String =
  if name == ""
  then "Hello, World!"
  else "Hello, " ++ name ++ "!"

let factorial (n: Int) : Int =
  if n <= 1
  then 1
  else n * (factorial (n - 1))

let fizzbuzz (n: Int) : String =
  if Int.remainder n 15 == Ok 0
  then "FizzBuzz"
  else if Int.remainder n 3 == Ok 0
  then "Fizz"
  else if Int.remainder n 5 == Ok 0
  then "Buzz"
  else Int.toString n

let main =
  let message = greet "Dark"
  let fact5 = factorial 5
  let results = List.map (List.range 1 21) (fun n -> fizzbuzz n)
  (message, fact5, results)