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).
Given a DNA strand, its transcribed RNA strand is formed by replacing each nucleotide with its complement:
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
module Test.Main where import Prelude import Effect (Effect) import Data.Maybe (Maybe(..)) import Test.Unit (TestSuite, suite, test) import Test.Unit.Assert as Assert import Test.Unit.Main (runTest) import RNATranscription (toRNA) main :: Effect Unit main = runTest suites suites :: TestSuite suites = suite "RNATranscription.toRNA" do test "RNA complement of cytosine is guanine" $ Assert.equal (Just "G") (toRNA "C") test "RNA complement of guanine is cytosine" $ Assert.equal (Just "C") (toRNA "G") test "RNA complement of thymine is adenine" $ Assert.equal (Just "A") (toRNA "T") test "RNA complement of adenine is uracil" $ Assert.equal (Just "U") (toRNA "A") test "RNA complement" $ Assert.equal (Just "UGCACCAGAAUU") (toRNA "ACGTGGTCTTAA") test "correctly handles invalid input (RNA instead of DNA)" $ Assert.equal Nothing (toRNA "U") test "correctly handles completely invalid DNA input" $ Assert.equal Nothing (toRNA "XXX") test "correctly handles partially invalid DNA input" $ Assert.equal Nothing (toRNA "ACGTXXXCTTAA")
module RNATranscription ( toRNA, transcribe ) where import Prelude import Data.Foldable (any) import Data.Maybe (Maybe(..), isNothing, fromMaybe) import Data.String.CodeUnits (fromCharArray, toCharArray) transcribe :: Char -> Maybe Char transcribe 'G' = Just 'C' transcribe 'C' = Just 'G' transcribe 'T' = Just 'A' transcribe 'A' = Just 'U' transcribe _ = Nothing justChar :: Maybe Char -> Char justChar = fromMaybe 'a' isValid :: Array Char -> Maybe String isValid chars | any isNothing $ map transcribe chars = Nothing | otherwise = Just $ fromCharArray $ map justChar $ map transcribe chars toRNA :: String -> Maybe String toRNA "" = Nothing toRNA dna = isValid sequence' where sequence' = toCharArray dna
A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.
Here are some questions to help you reflect on this solution and learn the most from it.