numbers2.rb

# rubocop:disable all

require "ruby_badge_numbers/version"

module RubyBadgeNumbers
  # Your code goes here...
  class PositiveNumber
    attr_reader :pred
    def initialize(zero, pred)
      @zero = zero
      @pred = pred
    end

    def succ
      @succ ||= PositiveNumber.new(@zero, self)
    end

    def +(number)
      current = @zero
      sum = self
      until current == number
        current = current.succ
        sum = sum.succ
      end
      sum
    end

    def -(number)
      # does not take into account negative numbers
      current = number
      sum = self
      until current == @zero
        current = current.pred
        sum = sum.pred
      end
      sum
    end
  end

  class Zero
    def succ
              # PostiveNumber.new(zero, pred)
      @succ ||= PositiveNumber.new(self, self)
    end
  end
end