CalculatingProteinMass.hs

import qualified Bioinformatics.Protein as P
import qualified Data.Map as M
import Control.Applicative

calculateProteinMass :: String -> Maybe Double
calculateProteinMass aas = sum <$> (sequence $ map (flip M.lookup P.monoisotopicMasses . P.charToAminoAcid) aas)

main = do
  aas <- getLine
  -- putStrLn . show . calculateProteinMass $ map P.charToAminoAcid aas
  putStrLn . show $ calculateProteinMass aas