Project Rosalind - Locating Restriction Sites 2

LocatingRestrictionSites2.hs

import           Bioinformatics.DNANucleotide (DNANucleotide (..),
                                               charToDNANucleotide)
import           Bioinformatics.Utilities     (getLines, reverseComplement)
import           Data.List                    (sort)

type PotentialSite = (Int, Int)

slice :: PotentialSite -> [a] -> [a]
slice (b, l) xs = take l $ drop b xs

buildIndices :: [a] -> [PotentialSite]
buildIndices xs = sort [(b, l) | l <- [4,6..12], b <- [0..length xs - l]]

isRevPalindrome :: [DNANucleotide] -> Bool
isRevPalindrome xs =
  xs == reverseComplement xs

buildSites :: [DNANucleotide] -> [PotentialSite]
buildSites xs =
  let possibleIndices = buildIndices xs
  in filter (\ps -> isRevPalindrome $ slice ps xs) possibleIndices

main :: IO ()
main = do
  dnaString <- getLines ""
  let dna = map charToDNANucleotide $ init dnaString
      sites = buildSites dna
      resWords = map (\(b,l) -> unwords [show (b+1), show l]) sites
      resLines = unlines resWords
  putStr resLines