lazy edition of Enumerable.product

lazy_product.rb

class LazyProduct
  include Enumerable

  def initialize(array)
    @array = array
  end

  def self.from(array)
    new(array)
  end

  def each(&block)
    inner_each(rest_array_of_array: @array, &block)
    nil
  end

  private def inner_each(args: [], rest_array_of_array:, &block)
    if rest_array_of_array.nil? || rest_array_of_array.empty?
      yield args
      return
    end

    rest_array_of_array[0].each do |arg|
      inner_each(args: args + [arg], rest_array_of_array: rest_array_of_array[1..-1], &block)
    end
  end
end