tyvars = tyConTyVars vect_tc
buildPReprType :: TyCon -> VM Type
-buildPReprType = mkPRepr . map dataConRepArgTys . tyConDataCons
+buildPReprType = liftM repr_type . mkTyConRepr
buildToPRepr :: Shape -> TyCon -> TyCon -> TyCon -> VM CoreExpr
buildToPRepr _ vect_tc prepr_tc _