def refTest {a} (x: a) (y: a) : IO () :=
  do let w := newIORef ()
     writeIORef w x
     let w1 := readIORef w
     print (show w1)
     writeIORef w y
     let w2 := readIORef w
     print (show w2)
     flush ()

def main (args: [String]) : IO () := refTest 1 2