monad based floyd cycle detection

gistfile1.txt

require_relative 'linked_list_node'

Maybe = Struct.new(:value) do
  def and_then(&block)
    if value.nil?
      Maybe.new(nil)
    else
      block.call(value)
    end 
  end 

  def method_missing(*args, &block)
    and_then do |value|
      Maybe.new(value.public_send(*args, &block))
    end 
  end 
end

def is_infinite?(list_node)
  return false unless list_node
  tortoise = Maybe.new(list_node)
  hare = tortoise.next_node

  floyd(tortoise, hare)
end

def floyd(tortoise, hare)
  return false if tortoise.value.nil? || hare.value.nil?
  return true if tortoise == hare
  return floyd(tortoise.next_node, hare.next_node.next_node)
end