Removed the [env] parameter of [InsideRecVisit].

src/Unbound.ml

 type 'env mode =
-  | OutsideRec
-  | InsideRecDiscovery     (* updating [current] and doing nothing else; embedded subterms not visited *)
-  | InsideRecVisit of 'env (* [inner] component now known; embedded subterms visited *)
+  | OutsideRec          (* updating [current] and visiting [outer] subterms *)
+  | InsideRecDiscovery  (* updating [current] and doing nothing else; embedded subterms not visited *)
+  | InsideRecVisit      (* [current] not updated; [inner] is [current]; embedded subterms visited *)
   | Repeated
 
 type 'env penv = {
@@ -29,10 +29,8 @@ type ('p, 't) bind =
   (('p, 't outer) rebind) abstraction (* = 'p * 't *)
 
 (* [Abstraction] allowed only in an expression *)
-(* [Rebind], [Rec] forbidden under [Rec] *)
-(* [Outer], [Binder] allowed both outside and inside [Rec] *)
-(* [Inner] allowed only under [Rec]. *)
-(* [Repeated] allowed everywhere *)
+(* [Rebind], [Rec] forbidden under [Rec] and [Repeated] *)
+(* [Outer], [Inner], [Binder], [Repeated] allowed everywhere *)
 
 type 't inner =
   't
@@ -58,7 +56,7 @@ class virtual ['self] libmap = object (self : 'self)
   = fun visit_t penv t1 ->
       match penv.mode with
       | OutsideRec
-      | InsideRecVisit _
+      | InsideRecVisit
       | Repeated ->
           visit_t penv.outer t1
       | InsideRecDiscovery ->
@@ -77,15 +75,11 @@ class virtual ['self] libmap = object (self : 'self)
           let x2, env = self#extend x1 env in
           current := env;
           x2
-      | Repeated ->
-          let current = penv.current in
-          let env = !current in
-          self#lookup x1 env
-      | InsideRecVisit env ->
-          assert (env == !(penv.current)); (* TEMPORARY if always true, then we do not need to carry [env] *)
+      | Repeated
+      | InsideRecVisit ->
           (* The environment should not be extended when in visit mode.
              It has been extended already during the discovery phase. *)
-          self#lookup env x1
+          self#lookup x1 !(penv.current)
 
   method private visit_rebind: 'env 'p1 'p2 'q1 'q2 .
     ('env penv -> 'p1 -> 'p2) ->
@@ -101,7 +95,7 @@ class virtual ['self] libmap = object (self : 'self)
           let q2 = visit_q penv q1 in
           p2, q2
       | InsideRecDiscovery
-      | InsideRecVisit _
+      | InsideRecVisit
       | Repeated ->
           (* [rebind] forbidden under [rec] and [repeated] *)
           assert false
@@ -123,15 +117,11 @@ class virtual ['self] libmap = object (self : 'self)
     'env penv -> 't1 inner -> 't2 inner
   = fun visit_t penv t1 ->
       match penv.mode with
-      | OutsideRec ->
-          (* [inner] allowed only under [rec] *)
-          assert false
       | InsideRecDiscovery ->
           (* An [inner] subterm is NOT visited in discovery mode. *)
           Obj.magic ()
-      | InsideRecVisit env ->
-          assert (env == !(penv.current));
-          visit_t env t1
+      | OutsideRec
+      | InsideRecVisit
       | Repeated ->
           visit_t !(penv.current) t1
 
@@ -146,12 +136,12 @@ class virtual ['self] libmap = object (self : 'self)
           let penv = { penv with mode = InsideRecDiscovery } in
           let _ = visit_p penv p1 in
           (* [!current] becomes [inner] *)
-          let penv = { penv with mode = InsideRecVisit !(penv.current) } in
+          let penv = { penv with mode = InsideRecVisit } in
           visit_p penv p1
       | InsideRecDiscovery
-      | InsideRecVisit _
+      | InsideRecVisit
       | Repeated ->
-          (* [rec] not allowed under [rec] or [repeated] *)
+          (* [rec] forbidden under [rec] or [repeated] *)
           assert false
 
   method private visit_repeated: 'env 'p1 'p2 .