.iex.exs

defmodule RnaTranscription do
  @doc """
  Transcribes a character list representing DNA nucleotides to RNA
  ## Examples
  RnaTranscription.to_rna('ACTG')
  'UGAC'
  """
  @rna_map %{?A => 'U', ?T => 'A', ?G => 'C', ?C => 'G'}

  def lookup(k) do
    @rna_map[k]
  end

  @spec to_rna([char]) :: [char]
  def to_rna(dna) do
    dna
    |> Enum.map(&lookup(&1))
    |> Enum.reduce(&(&2 ++ &1))
  end
end