h <- connectTo "wettbewerb" (PortNumber 3333)
loop h z = do
     f <- hGetLine h
     putStrLn f
     case (zerlege_string f) of
       "HELO":_ -> helo h z
       "TURN":x:y:_ -> turn h z (read x) (read y)
       "THRW":x:_ -> thrw h z (read x)
       [...]
       _ -> error $ "loop: " ++ show f

helo h Vor_Auth = sende h Nach_Auth "AUTH utz"

turn h Nach_Auth x‘ z‘ = turn h (Ich_bin_dran 0 0 0)x‘z‘
turn h (Gegner x y z) x‘ z‘
  | z==x‘ && x==z‘ = turn h (Ich_bin_dran x‘x‘z‘)x‘z‘
  | otherwise = error $ "turn: gegner: " ++ show (x,y,z,x‘,z‘)
turn h (Ich_bin_dran x y z) x‘ z‘
  | x==x‘ && z==z‘ = turn_ h (Ich_bin_dran x y z)
  | otherwise = error $ "turn: ich: "          ++ show (x,y,z,x‘,z‘)