gistfile1.hs

import Data.List
import qualified Data.Set as S
import Data.String.Utils

genEquivalentClass :: Ord a => [(a, a)] -> [[a]]
genEquivalentClass pairs =
  sort . map (sort . S.toList) $ foldr eqcs [] pairs
  where
    eqcs (n, m) cs = case (lookupClass n cs, lookupClass m cs) of
      (Nothing, Nothing) -> S.fromList [n, m] : cs
      (Nothing, Just mci) -> S.insert n (cs !! mci) : (cs !!~ [mci])
      (Just nci, Nothing) -> S.insert m (cs !! nci) : (cs !!~ [nci])
      (Just nci, Just mci)
        | nci == mci -> cs
        | otherwise -> S.union (cs !! nci) (cs !! mci) : (cs !!~ [nci, mci])
    lookupClass n cs = findIndex (n `S.member`) cs
    a !!~ is = snd . unzip . (filter $ (`notElem` is) . fst) . zip [0..] $ a

main = do
  str <- getContents
  let namePairs = map ((\[a, b] -> (a, b)) . (split "=") . rstrip) $ lines str
  putStr . unlines . map (intercalate "=") . genEquivalentClass $ namePairs