Clojure

Other Clojure solutions.

;; Given a DNA strand, return its RNA complement (per RNA transcription) .

;; Both DNA and RNA strands are a sequence of nucleotides.

;; The four nucleotides found in DNA are adenine (A), cytosine (C), guanine (G) and thymine (T).
;; The four nucleotides found in RNA are adenine (A), cytosine (C), guanine (G) and uracil (U).
(ns rna-transcription)

(defn to-rna [dna]
  (let [dna-to-rna (fn [n] (condp = n
                             \G \C
                             \C \G
                             \T \A
                             \A \U
                             (assert false (format "%s is not a valid nucleotide" n))))]
    (apply str (map dna-to-rna dna))))

Elixir

Other Elixir solutions.

defmodule RnaTranscription do
  @transcription %{
    ?G => ?C,
    ?C => ?G,
    ?T => ?A,
    ?A => ?U
  }

  @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
    Enum.map(
      dna,
      fn c -> Map.fetch!(@transcription, c) end
    )
  end
end

Haskell

Other Haskell solutions.

module DNA (toRNA) where

import qualified Data.Map as M

translation :: M.Map Char Char
translation =
  M.fromList
    [ ('G', 'C'),
      ('C', 'G'),
      ('T', 'A'),
      ('A', 'U')
    ]

toRNA :: String -> Either Char String
toRNA =
  mapM translate
  where
    translate dna = case M.lookup dna translation of
      Just rna -> Right rna
      Nothing -> Left dna

Roc

Other Roc solutions.

module [toRna]

toRna : Str -> Str
toRna = \dna ->
    dna
    |> Str.toUtf8
    |> List.map nucleoTideComplement
    |> Str.fromUtf8
    |> Result.withDefault ""

nucleoTideComplement = \n ->
    when n is
        'G' -> 'C'
        'C' -> 'G'
        'T' -> 'A'
        'A' -> 'U'
        _ -> n