lazy_reduce.rb

gistfile1.rb

require 'fiber'

# lazy_reduce([1,2,3], 0) { |o,m| o + m } # => 6
def lazy_reduce(enumerable, memo, &block)
  generator = Fiber.new { enumerable.each { |o| Fiber.yield(o) } }

  loop do
    if generator.alive? 
      memo = block.call(generator.resume, memo)
    else
      return memo
    end
  end
end