Equivalent to python's zip_longest function for elixir.

zip.ex

defmodule Zip do
  @doc """
  Zips corresponding elements from a finite collection of enumerables into one list of tuples.

  The zipping finishes when the longest enumerable is finished. Default padding value is `nil`.
  
  Usage:

      iex> Bla.zip_longest([1, 2, 3], [1, 2])         
      [{1, 1}, {2, 2}, {3, nil}]

      iex> Bla.zip_longest([1, 2], [1, 2, 3])
      [{1, 1}, {2, 2}, {nil, 3}]
  """
  def zip_longest([h1 | next1], [h2 | next2]) do
    [{h1, h2} | zip_longest(next1, next2)]
  end

  def zip_longest([h1 | next1], []), do: [{h1, nil} | zip_longest(next1, [])]
  def zip_longest([], [h2 | next2]), do: [{nil, h2} | zip_longest([], next2)]
  def zip_longest([], []), do: []
end