fibonacci sequence in Ruby

fibonacci.rb

# without memoizing
def fibonacci n
  n < 2 ? n : fibonacci(n - 2) + fibonacci(n - 1)
end

10.times { |i| p fibonacci(i) }

# memoize
module Fibonacci
  @@memo = [0, 1]
  
  class << self
    def [] n
      @@memo[n] = self[n - 2] + self[n - 1] unless @@memo[n]
      return @@memo[n]
    end
  end
end

10.times { |i| p Fibonacci[i] }