T5334.hs:7:5: Warning:
    Fields of ‘T’ not initialised: b
    In the expression: T {..}
    In an equation for ‘t’:
        t = T {..}
          where
              a = 1

T5334.hs:14:5: Warning:
    Fields of ‘S’ not initialised: y
    In the expression: S {x = 1}
    In an equation for ‘s’: s = S {x = 1}