Clojure-inspired fibonacci streams with Fibers

fibers.rb

require 'fiber'

class Fiber

  def map &block
    Fiber.new { loop { Fiber.yield block.call(resume) } }
  end

  def to_a
    [].tap{|xs| xs << resume while alive?}
  end

  def take n
    Fiber.new do
      (n-1).times { Fiber.yield resume }
      resume
    end
  end

  def self.iterate x,&block
    Fiber.new do
      loop do
        Fiber.yield x
        x = block.call(x)
      end
    end
  end
end

fibs = Fiber.iterate([1,0]){|(a,b)|[b,a+b]}.map(&:last)

p fibs.take(10).to_a