Cleaner way to add a fresh variable for patterns, but can't keep it until the

	execution yet

compile/compile.ml

@@ -182,11 +182,11 @@ and compile_branches env (brs : Typed.branches) =
  * p_i / t_i is used here to add elements to env.gamma *)
 and compile_branch env br =
   (* We add a fresh variable "pat<nb>:x" for each pattern *)
-  let t, _, d = br.Typed.br_pat.Patterns.descr in
+  let t, fv, d = br.Typed.br_pat.Patterns.descr in
   let fv, d = incr Patterns.counter;
     let freshname = "pat" ^ (string_of_int !Patterns.counter) ^ ":x" in
-    let fv = (Patterns.fv br.Typed.br_pat) @ [!Patterns.counter, freshname] in
-    fv, Patterns.Cap((Types.any, fv, Patterns.Capture(!Patterns.counter, freshname)), (t, [], d))
+    let newfv = fv @ [!Patterns.counter, freshname] in
+    newfv, Patterns.Cap((Types.any, newfv, Patterns.Capture(!Patterns.counter, freshname)), (t, fv, d))
   in
   let pat = { br.Typed.br_pat with Patterns.descr=(t,fv,d); Patterns.fv=fv } in
   let env = List.fold_left enter_local env fv in

types/patterns.ml

@@ -336,7 +336,7 @@ and filter_node t p : Types.Positive.v id_map =
     let res = IdMap.map_from_slist (fun _ -> Types.Positive.forward ()) fv in
     memo_filter := MemoFilter.add (t,p) res !memo_filter;
     let r = filter_descr t (descr p) in
-    IdMap.collide Types.Positive.define res r; (* Had to comment this to add fresh variables for patterns *)
+    IdMap.collide Types.Positive.define res r;
     r
 
 let filter t p =
@@ -370,10 +370,14 @@ x=(1,2)
       | Cup ((a1,_,_) as p1,p2) ->
 	  approx_var seen p2 (Types.diff t a1)
 	    (approx_var seen p1 (Types.cap t a1) xs) 
-      | Cap ((_,fv1,_) as p1,((_,fv2,_) as p2)) ->
-	  IdSet.cup
+      | Cap ((_,fv1,d1) as p1,((_,fv2,d2) as p2)) ->
+	(* TODO: In case we have a fresh variable, we must keep it somewhere *)
+	(match d1 with
+	  | Capture(_, name) when Str.string_match (Str.regexp "pat[0-9]+:") name 0 ->
+	    (match d2 with | Constr _ -> xs | _ -> approx_var seen p2 t xs)
+	  | _ -> IdSet.cup
 	    (approx_var seen p1 t (IdSet.cap fv1 xs))
-	    (approx_var seen p2 t (IdSet.cap fv2 xs))
+	    (approx_var seen p2 t (IdSet.cap fv2 xs)))
       | Capture _ ->
 	  xs
       | Constant (_,c) -> 
@@ -389,7 +393,6 @@ x=(1,2)
 	    (approx_var_node seen q1 (pi1 ~kind:`XML t) xs)
 	    (approx_var_node seen q2 (pi2 ~kind:`XML t) xs)
       | Record _ -> IdSet.empty
-(*      | Constr _ -> xs (* Needed to add fresh variables to patterns *)*)
       | _ -> assert false
 	  
   and approx_var_node seen q t xs =