anchor.diff:                    rebuild cfg env_arg stack t
                else let stack = App(env, t, aq, r)::stack in
                     norm cfg env_arg stack tm
  -        else begin match read_memo cfg m with
  +        else begin match !m with
             | None ->
               if cfg.steps.hnf && not (is_partial_primop_app cfg t)
               then let arg = closure_as_term cfg env_arg tm in
  
positive.code:                 let env0 = env in
                  let env = List.fold_left
                        (fun env (bv, t) -> (Some (S.mk_binder bv),
                                             Clos([], t, BU.mk_ref (Some (cfg, ([], t))), false))::env)
                        env s in
                  norm cfg env stack (guard_when_clause wopt b rest)
          in
  
negative.code:                    if not fix
                     || cfg.steps.zeta
                     || cfg.steps.zeta_full
                     then match !r with
                          | Some (env, t') ->
                              log cfg  (fun () -> BU.print2 "Lazy hit: %s cached to %s\n" (Print.term_to_string t) (Print.term_to_string t'));
                              if maybe_weakly_reduced t'
  