simplify (TyConApp tc ts) = SimpleType (tyConName tc)
                                       (mapMaybe simplify_maybe ts)
simplify (TyConApp tc ts) = SimpleType (tyConName tc)
                                       (mapMaybe simplify_maybe ts)
simplify (TyConApp tc ts) = SimpleType (tyConName tc)
                                       (mapMaybe simplify_maybe ts)