Freecodecamp Inventory Update in Elixir

inventory.exs

defmodule FCCL.Algos.Inventory do
  @doc """
    ## Examples

      iex> current = [[21, "Bowling Ball"], [2, "Dirty Sock"], [1, "Hair Pin"], [5, "Microphone"]]
      iex> new     = [[2, "Hair Pin"], [3, "Half-Eaten Apple"], [67, "Bowling Ball"], [7, "Toothpaste"]]
      iex> FCCL.Algos.Inventory.update(current, new)
      [[88, "Bowling Ball"], [2, "Dirty Sock"], [3, "Hair Pin"], [3, "Half-Eaten Apple"], [5, "Microphone"], [7, "Toothpaste"]]
  """
  def update(current, new) do
    Enum.reduce(new, current, fn [qty, name] = item, acc ->
      c = Enum.find(current, fn [_, item_name] -> item_name == name end)

      if c == nil do
        [item | acc]
      else
        [c_qty, c_name] = c
        acc = Enum.reject(acc, fn [_, acc_name] -> acc_name == c_name end)
        [[c_qty + qty, c_name] | acc]
      end
    end)
    |> Enum.sort(fn [_, a], [_, b] -> a < b end)
  end
end