A simple bowling scorer that came to me in a dream.

bowling_scorer.rb

class BowlingScorer

  def initialize(rolls)
    @rolls = rolls
  end

  def score
    total = 0
    rolls_left = @rolls.dup
    10.times { total += score_frame(rolls_left) }
    total
  end

private

  def score_frame(rolls_left)
    roll1 = rolls_left.shift
    if roll1 == 10
      return 10 + rolls_left[0] + rolls_left[1]
    end

    roll2 = rolls_left.shift
    if roll1 + roll2 == 10
      return 10 + rolls_left[0]
    end

    roll1 + roll2
  end

end