mylist.ex

defmodule Mylist do
  def filter([], func, f_array), do: f_array

  def filter([head|tail], func, f_array // []) do
    if func.(head) do
      filter(tail, func, List.concat(f_array , [head]))
    else
      filter(tail, func, List.concat(f_array , []))
    end
  end
end