Convert to Hex and back

to_hex.ex

defmodule ToHex do

  @hex_base 16

  def to_hex(0), do: 0

  def to_hex(num) when is_number(num) do
    div(num, @hex_base)
    |> IO.inspect
    |> then(& {to_hex(&1), rem(num, @hex_base)})
  end

  def reduce({a, b}, acc) when is_tuple(a) and is_number(b), do: reduce(a, [b | acc])

  def reduce({a, b}, acc) when is_number(a) and is_number(b), do: [a | [b | acc]]

  def to_decimal(<<digits::binary>> = hex_string), do: Integer.parse(digits, @hex_base) |> elem(0)
  
end