import Data.Set

data DFA = DFA {
   states :: Set String
 , sigma  :: Set String
 , tf     :: String -> String -> String
 , strt  :: String
 , final  :: Set String
}

instance Show DFA where
  show x = show states ++
           show sigma ++
           "tf" ++ strt ++
           show final

tf1 "q0" "1" = "q1"
tf1 "q1" "0" = "q0"

a = fromList [1,1,2,3]
dfa = DFA (fromList ["q0", "q1", "q2", "q3"])
          (fromList ["0", "1"])
          tf1
          "q0"
          (fromList ["q3"])