-- NB: A newtype always has a vanilla DataCon; no existentials etc
-- res_tys will simply be the dataConUnivTyVars
sel_body | isNewTyCon tycon = unwrapNewTypeBody tycon res_tys (Var data_id)
- | otherwise = Case (Var data_id) data_id field_tau (default_alt ++ the_alts)
+ | otherwise = Case (Var data_id) data_id field_ty (default_alt ++ the_alts)
mk_result poly_result = mkVarApps (mkVarApps poly_result field_tyvars) field_dict_ids
-- We pull the field lambdas to the top, so we need to