T11347.hs:6:41: error: [GHC-10283]
    • Couldn't match representation of type ‘a’ with that of ‘b’
        arising from the coercion of the method ‘unsafe’
          from type ‘Id1 a -> Discern (Id1 a) b’
            to type ‘Id2 a -> Discern (Id2 a) b’
      ‘a’ is a rigid type variable bound by
        the deriving clause for ‘UnsafeCast b (Id2 a)’
        at T11347.hs:6:41-52
      ‘b’ is a rigid type variable bound by
        the deriving clause for ‘UnsafeCast b (Id2 a)’
        at T11347.hs:6:41-52
    • When deriving the instance for (UnsafeCast b (Id2 a))