cursed_ruby.rb

def score(rolls) = score_helper(0, 1, rolls.reverse)
def score_helper(sum, frame, remaining)
  case remaining
  in 10, 10, x       if frame == 10 && x <= 10                then sum + 20 + x
  in 10, x, y        if frame == 10 && x + y <= 10            then sum + 10 + x + y
  in x, y, z         if frame == 10 && x + y == 10 && z <= 10 then sum + x + y + z
  in x, y            if frame == 10 && x + y < 10             then sum + x + y
  in 10, x, y, *rest                                          then score_helper(sum + 10 + x + y, frame + 1, [x, y, *rest])
  in x, y, z, *rest  if x + y == 10 && z <= 10                then score_helper(sum + 10 + z, frame + 1, [z, *rest])
  in x, y, *rest     if x + y <= 10                           then score_helper(sum + x + y, frame + 1, rest)
  else
    raise BowlingError
  end
end