sasa1977

# http://adventofcode.com/2017/day/1

defmodule Day1 do
  def sum1(digits), do:
    digits
    |> Stream.concat(Enum.take(digits, 1))
    |> Stream.chunk_every(2, 1, :discard)
    |> Stream.filter(&match?([el, el], &1))
    |> Stream.map(&hd(&1))
    |> Enum.sum()