possible AOC #1 solution in Elixir

aoc_1.exs

defmodule Increases do

  def count_increases(string) when is_binary(string) do
    string
    |> String.split("\n")
    |> Enum.map(fn x -> Integer.parse(x) end)
    |> Increases.count_increases
  end

  def count_increases(list) when is_list(list), do: count_increases(list, 0)

  def count_increases([a, b | tail], acc) when b > a, do: count_increases([b | tail], acc + 1)

  def count_increases([_a, b | tail], acc), do: count_increases([b | tail], acc)

  def count_increases(_, acc), do: acc

  def count_from_file(filename) when is_binary(filename), do: count_increases(File.read!(filename))

end

# run the inline suite with "elixir #{__ENV__.file} test"
case hd(System.argv) do
  "test" ->
    ExUnit.start

    defmodule IncrementCountTest do
      use ExUnit.Case, async: true

      test "sanity check" do
        test_data = [1, 5, 4, 6, 2, 199, 202, 50, 45, 90]
        assert Increases.count_increases(test_data) == 5
      end

      test "binary input" do
        test_data = "1\n5\n4\n6\n2\n199\n202\n50\n45\n90"
        assert Increases.count_increases(test_data) == 5
      end

    end

  filename ->
    IO.puts(Increases.count_from_file(filename))

end