RNA Transcription Exercise - Elixir

rna_transcription.ex

defmodule RNATranscription do
  @guanine "G"
  @adenine "A"
  @cystosine "C"
  @uracil "U"
  @thymine "T"

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

  ## Examples

  iex> RNATranscription.to_rna('ACTG')
  'UGAC'
  """
  @spec to_rna([char]) :: [char]
  def to_rna(dna) do
    rna_strand =
      Enum.map(String.graphemes(to_string(dna)), fn dna_char ->
        case dna_char do
          @guanine -> @cystosine
          @cystosine -> @guanine
          @thymine -> @adenine
          @adenine -> @uracil
          _ -> "Error"
        end
      end)

    rna_strand
    |> to_string
    |> to_charlist
  end
end