pykello

  result = init
  for value in values:
     result = func(result, value)
  return result

  result = []
  for (x1, h, x2) in bs:
     result = add_endpoints(result, (x1, h, x2))
  return result

  result = []
  for (x1, h, x2) in bs:
     result = result ++ [(x1, height x1), (x2, height x2)]
  return result

  skyline bs = (skyline (take n bs), 0) `merge` (skyline (drop n bs), 0)
                where n = (length bs) `div` 2

  first_half = first_n_elements(bs, length(bs) / 2)
  second_half = remove_first_n_elements(bs, length(bs) / 2)
  result = merge ((skyline(first_half), 0), (skyline(second_half), 0))

  merge ([], _) (ys, _) = ys
  merge (xs, _) ([], _) = xs

  merge ((x, xh):xs, xh_p) ((y, yh):ys, yh_p)
    | x > y = merge ((y, yh):ys, yh_p) ((x, xh):xs, xh_p)
    | x == y = (x, max xh yh) : merge (xs, xh) (ys, yh)
    | max xh_p yh_p /= max xh yh_p = (x, max xh yh_p) : merge (xs, xh) ((y, yh):ys, yh_p)
    | otherwise = merge (xs, xh) ((y, yh):ys, yh_p)