# Title: Functions that call themselves
# About: Recursion: Fibonacci numbers, factorials, and a staircase of stars.

# Each Fibonacci number is the two before it added together.
fn fib(n) {
  if n < 2 {
    return n
  }
  return fib(n - 1) + fib(n - 2)
}

let numbers = []
for i in range(10) {
  push(numbers, fib(i))
}
say("The first 10 Fibonacci numbers:", numbers)

# 5 factorial means 5 * 4 * 3 * 2 * 1.
fn factorial(n) {
  if n <= 1 {
    return 1
  }
  return n * factorial(n - 1)
}
say("5 factorial is", factorial(5))

# Draw a staircase by calling stairs() with a smaller number each time.
fn stairs(n) {
  if n == 0 {
    return
  }
  stairs(n - 1)
  say("*" * n)
}
stairs(4)