defmodule RnaTranscription do
  @doc """
  Transcribes a character list representing DNA nucleotides to RNA

  ## Examples

    iex> RnaTranscription.to_rna(~c"ACTG")
    ~c"UGAC"
  """
  @spec to_rna([char]) :: [char]
  def to_rna(?G), do: ?C
  def to_rna(?C), do: ?G
  def to_rna(?T), do: ?A
  def to_rna(?A), do: ?U
  def to_rna([char | rest]), do: [to_rna(char) | to_rna(rest)]
  def to_rna([]), do: []
end