rw.hs:14:47:
    Couldn't match expected type ‛a’ with actual type ‛Int’
      ‛a’ is a rigid type variable bound by
          the type signature for writeInt :: T a -> IORef a -> IO ()
          at rw.hs:12:12
    Relevant bindings include
      ref :: IORef a (bound at rw.hs:13:12)
      v :: T a (bound at rw.hs:13:10)
      writeInt :: T a -> IORef a -> IO () (bound at rw.hs:13:1)
    In the second argument of ‛writeIORef’, namely ‛(1 :: Int)’
    In the expression: writeIORef ref (1 :: Int)
    In a case alternative: ~(Li x) -> writeIORef ref (1 :: Int)

rw.hs:19:51:
    Couldn't match type ‛a’ with ‛Bool’
      ‛a’ is a rigid type variable bound by
          the type signature for readBool :: T a -> IORef a -> IO ()
          at rw.hs:16:12
    Expected type: a -> Bool
      Actual type: Bool -> Bool
    Relevant bindings include
      ref :: IORef a (bound at rw.hs:17:12)
      v :: T a (bound at rw.hs:17:10)
      readBool :: T a -> IORef a -> IO () (bound at rw.hs:17:1)
    In the second argument of ‛(.)’, namely ‛not’
    In the second argument of ‛(>>=)’, namely ‛(print . not)’