closest kata

closest-kata.ex

defmodule Closest do

  def closest(""), do: [{}, {}]
  def closest(s) do
    s
    |> String.split
    |> Enum.map(&String.to_integer/1)
    |> Enum.with_index
    |> Enum.map(&weight/1)
    |> Enum.sort(&sort/2)
    |> Enum.chunk(2, 1)
    |> Enum.min_by(&min/1)
  end
  
  defp weight({x, i}), do: {x |> Integer.digits |> Enum.sum, i, x}
  defp sort({d1, _, _}, {d2, _, _}), do: d1 <= d2
  defp min([{d1, _, _}, {d2, _, _}]), do: d2 - d1
end