diff --git a/bench/programs/bad-typing/alias1.mlw b/bench/programs/bad-typing/alias1.mlw
index 43e8927f9e5b34d85402dfcebed03d1645f578b0..8136381f6e9869c9320f75d2154e9b7c9222a285 100644
--- a/bench/programs/bad-typing/alias1.mlw
+++ b/bench/programs/bad-typing/alias1.mlw
@@ -1,6 +1,6 @@
 module M
 
-  use import module stdlib.Ref
+  use import module ref.Ref
 
   let foo (x : ref int) (y : ref int) = 
     x := 1;
diff --git a/bench/programs/bad-typing/alias2.mlw b/bench/programs/bad-typing/alias2.mlw
index fd1db78bd384c832f8433907c913bfda1e818508..da5880a3fd84a0f35575cb71d76aedb4bf9eba64 100644
--- a/bench/programs/bad-typing/alias2.mlw
+++ b/bench/programs/bad-typing/alias2.mlw
@@ -1,6 +1,6 @@
 module M
 
-  use import module stdlib.Ref
+  use import module ref.Ref
 
   let foo (x : ref int) (y : ref int) = 
     x := 1;
diff --git a/bench/programs/bad-typing/alias3.mlw b/bench/programs/bad-typing/alias3.mlw
index d66cacbf48c83228787ffe8f9397cc439f8c05d0..767998ac5cfb43ce4095153c070b63ae60b40d91 100644
--- a/bench/programs/bad-typing/alias3.mlw
+++ b/bench/programs/bad-typing/alias3.mlw
@@ -1,6 +1,6 @@
 module M
 
-  use import module stdlib.Ref
+  use import module ref.Ref
 
   let foo (x : ref int) (y : ref int) = 
     x := 1;
diff --git a/bench/programs/bad-typing/effect1.mlw b/bench/programs/bad-typing/effect1.mlw
index 624e2100d309b4f4384ed7dab1f39f236fe6066d..4f4eba3fa35f68c133334301e07f1d2fdaf78f52 100644
--- a/bench/programs/bad-typing/effect1.mlw
+++ b/bench/programs/bad-typing/effect1.mlw
@@ -1,7 +1,7 @@
 
 module M
 
-  use import module stdlib.Ref
+  use import module ref.Ref
 
   parameter f : x:int -> {} unit writes a.contents {}
 
diff --git a/bench/programs/bad-typing/effect2.mlw b/bench/programs/bad-typing/effect2.mlw
index 89610e5874829cc6979d71b2cf6fd5b958c72209..908da447efb23ab6f451c02297a9e6b093b44a23 100644
--- a/bench/programs/bad-typing/effect2.mlw
+++ b/bench/programs/bad-typing/effect2.mlw
@@ -1,7 +1,7 @@
 
 module M
 
-  use import module stdlib.Ref
+  use import module ref.Ref
 
   parameter f : x:int -> {} unit writes x.contents {}
 
diff --git a/bench/programs/bad-typing/effect3.mlw b/bench/programs/bad-typing/effect3.mlw
index 8a189a1520da66d3e1e1d4c5d8ebe8db7bea9f5c..79a4b873a886877024db2870b30e43f773f1fe4f 100644
--- a/bench/programs/bad-typing/effect3.mlw
+++ b/bench/programs/bad-typing/effect3.mlw
@@ -1,7 +1,7 @@
 
 module M
 
-  use import module stdlib.Ref
+  use import module ref.Ref
 
   parameter a : int
 
diff --git a/bench/programs/bad-typing/effect4.mlw b/bench/programs/bad-typing/effect4.mlw
index fde4c12250ce5042afd461f4fb035ffc1ba03023..c95456e24ba3fdd7ee453e7d7c210d3158065944 100644
--- a/bench/programs/bad-typing/effect4.mlw
+++ b/bench/programs/bad-typing/effect4.mlw
@@ -1,7 +1,7 @@
 
 module M
 
-  use import module stdlib.Ref
+  use import module ref.Ref
 
   parameter foo : int -> int
 
diff --git a/bench/programs/bad-typing/fresh1.mlw b/bench/programs/bad-typing/fresh1.mlw
index 9a0d23afc087d68e4b40c94ee444e27783d9f3ab..9e6955859455189906f982b63b690cf7664c4e1b 100644
--- a/bench/programs/bad-typing/fresh1.mlw
+++ b/bench/programs/bad-typing/fresh1.mlw
@@ -1,7 +1,7 @@
 module P
 
-  use import module stdlib.Ref
+  use import module ref.Ref
 
-  let f (a : ref int) = a
+  let f (a : ref int) = todo (* TODO *)
 
 end
diff --git a/modules/ref.mlw b/modules/ref.mlw
index 893ac111183053980f1269685714a8ce1dec216b..c74d39ac9a38cb67c242b8f2f4fbc01c5b2a0071 100644
--- a/modules/ref.mlw
+++ b/modules/ref.mlw
@@ -6,11 +6,14 @@ module Ref
 
   logic (!) (x: ref 'a) : 'a = x.contents
 
-  parameter ref : v:'a -> {} ref 'a { result = {| contents = v |} }
+  (* parameter ref : v:'a -> {} ref 'a { result = {| contents = v |} } *)
+  let ref (v: 'a) = {} {| contents = v |} { result = {| contents = v |} }
 
-  parameter (!) : r:ref 'a -> {} 'a reads r { result = !r }
+  (* parameter (!) : r:ref 'a -> {} 'a reads r { result = !r } *)
+  let (!) (r:ref 'a) = {} r.contents { result = !r }
 
-  parameter (:=) : r:ref 'a -> v:'a -> {} unit writes r { !r = v }
+  (* parameter (:=) : r:ref 'a -> v:'a -> {} unit writes r { !r = v } *)
+  let (:=) (r:ref 'a) (v:'a) = {} r.contents <- v { !r = v }
 
 end
 
@@ -24,3 +27,9 @@ module Refint
   parameter decr : r:ref int -> {} unit writes r { !r = old !r - 1 }
 
 end
+
+(*
+Local Variables:
+compile-command: "unset LANG; make -C .. modules/ref"
+End:
+*)
diff --git a/src/parser/parser.pre.mly b/src/parser/parser.pre.mly
index d53ed3dcadc7362e7c0fb322864dc93a3742bc3e..a4b4379c0eb9216b526f1c5101bc889fb735eeab 100644
--- a/src/parser/parser.pre.mly
+++ b/src/parser/parser.pre.mly
@@ -1030,11 +1030,11 @@ expr:
      mk_expr (mk_apply_id { id = "notb"; id_lab = []; id_loc = floc () } [t]) }
 | expr LARROW expr
     { match $1.expr_desc with
-        | Eapply (e11, e12) -> begin match e11.expr_desc with
-            | Eident x ->
-                mk_expr (Eassign (e12, x, $3))
+        | Eaccess (e1, x) -> 
+            mk_expr (Eassign (e1, x, $3))
+	| Eapply (e11, e12) -> begin match e11.expr_desc with
             | Eapply ({ expr_desc = Eident (Qident x) }, e11)
-              when x.id = mixfix "[]" ->
+      	      when x.id = mixfix "[]" ->
                 mk_mixfix3 "[]<-" e11 e12 $3
             | _ ->
                 raise Parsing.Parse_error
@@ -1132,7 +1132,7 @@ expr_dot:
 
 expr_sub:
 | expr_dot DOT lqualid_rich
-   { mk_expr (mk_apply (mk_expr_i 3 (Eident $3)) [$1]) }
+   { mk_expr (Eaccess ($1, $3)) }
 | LEFTPAR expr RIGHTPAR
     { $2 }
 | BEGIN expr END
diff --git a/src/parser/ptree.ml b/src/parser/ptree.ml
index dffb9dfcf1c28aa1d4d4475befab51814d804c0e..c64f9186c559fa7f9c779d837677efd305d3eed6 100644
--- a/src/parser/ptree.ml
+++ b/src/parser/ptree.ml
@@ -211,6 +211,7 @@ and expr_desc =
   | Eletrec of (ident * binder list * variant option * triple) list * expr
   | Etuple of expr list
   | Erecord of (qualid * expr) list
+  | Eaccess of expr * qualid
   | Eassign of expr * qualid * expr
   (* control *)
   | Esequence of expr * expr
diff --git a/src/programs/TODO b/src/programs/TODO
index 3e76cfab80aa18f0a8fee5d29db62392a7b98772..16143e45472b0a3c40b58cf8cf2480f8260bc187 100644
--- a/src/programs/TODO
+++ b/src/programs/TODO
@@ -1,12 +1,10 @@
 
-o pas de old dans les invariants
+o freshness analysis
 
-o e <- e
+o no `old' in loop invariants
 
 o {| e with x1 = e1; ...; xn = en |}
 
-o WP: update
-
 o syntactic sugar for postcondition:
   { pat | q } stands for { let pat = result in q }
 
@@ -36,4 +34,4 @@ o library
 
   - List
   - Map
-  - Set
\ No newline at end of file
+  - Set
diff --git a/src/programs/pgm_pretty.ml b/src/programs/pgm_pretty.ml
index 05faa84cbf9d778dc4c432b82f9377e32ed38211..e298757de696295f0ed6b3d9b9a552a6a51b8d22 100644
--- a/src/programs/pgm_pretty.ml
+++ b/src/programs/pgm_pretty.ml
@@ -76,7 +76,7 @@ let rec print_expr fmt e = match e.expr_desc with
       fprintf fmt "absurd"
 
 and print_pv fmt v =
-  fprintf fmt "<@[%a : %a@]>" print_vs v.pv_effect print_ty v.pv_pure.vs_ty
+  fprintf fmt "<@[%a@]>" print_vsty v.pv_effect
 
 and print_triple fmt (p, e, q) =
   fprintf fmt "@[<hv 0>%a@ %a@ %a@]" print_pre p print_expr e print_post q
diff --git a/src/programs/pgm_ttree.ml b/src/programs/pgm_ttree.ml
index 79c4631bb69f50e60a3db5c25ac205aa67625d7a..2a13d51e3292a47a4a66dd8368eccfe1356bd6c4 100644
--- a/src/programs/pgm_ttree.ml
+++ b/src/programs/pgm_ttree.ml
@@ -111,6 +111,8 @@ and dexpr_desc =
   | DEfun of dubinder list * dtriple
   | DElet of ident * dexpr * dexpr
   | DEletrec of drecfun list * dexpr
+  | DEaccess of dexpr * Term.lsymbol * int option
+  | DEassign of dexpr * Term.lsymbol * int * dexpr
 
   | DEsequence of dexpr * dexpr
   | DEif of dexpr * dexpr * dexpr
@@ -204,6 +206,7 @@ and iexpr_desc =
   | IEfun of ibinder list * itriple
   | IElet of ivsymbol * iexpr * iexpr
   | IEletrec of irecfun list * iexpr
+  | IEaccess of ivsymbol * Term.lsymbol * R.t option
 
   | IEif of iexpr * iexpr * iexpr
   | IEloop of loop_annotation * iexpr
diff --git a/src/programs/pgm_types.ml b/src/programs/pgm_types.ml
index 3dd9fb6dd51e7dbcc4426531ad74912376eed2bb..31ec732d96131ae0c314914ff25814003478a127 100644
--- a/src/programs/pgm_types.ml
+++ b/src/programs/pgm_types.ml
@@ -228,7 +228,6 @@ module rec T : sig
     | PSlogic
 
   type psymbol = {
-    (* ps_impure : lsymbol; *)
     ps_effect : lsymbol;
     ps_pure   : lsymbol;
     ps_kind   : psymbol_kind;
@@ -352,7 +351,6 @@ end = struct
     | PSlogic
 
   type psymbol = {
-    (* ps_impure : lsymbol; *)
     ps_effect : lsymbol;
     ps_pure   : lsymbol;
     ps_kind   : psymbol_kind;
diff --git a/src/programs/pgm_types.mli b/src/programs/pgm_types.mli
index ebaec01543193e40f9a6d90a488932c4f0ff9f03..3233ed51e2202e0be69b51465d7ab2d0707059c3 100644
--- a/src/programs/pgm_types.mli
+++ b/src/programs/pgm_types.mli
@@ -129,7 +129,6 @@ module rec T : sig
     | PSlogic
 
   type psymbol = {
-    (* ps_impure : lsymbol; *)
     ps_effect : lsymbol;
     ps_pure   : lsymbol;
     ps_kind   : psymbol_kind;
diff --git a/src/programs/pgm_typing.ml b/src/programs/pgm_typing.ml
index 6c65b3ac857dff23dbcaad3d351147f2d5c32210..0980fcb7bd1fb7f94216f33786a61058599ba93c 100644
--- a/src/programs/pgm_typing.ml
+++ b/src/programs/pgm_typing.ml
@@ -59,6 +59,25 @@ let () = Exn_printer.register (fun fmt e -> match e with
 
 let id_result = "result"
 
+(* Table of record mutable fields ******************************************)
+
+let mutable_fields = Hts.create 17 (* ts -> field:int -> region:int *)
+
+let declare_mutable_field ts i j =
+  Pgm_wp.declare_mutable_field ts i j;
+  let h =
+    try
+      Hts.find mutable_fields ts
+    with Not_found ->
+      let h = Hashtbl.create 17 in Hts.add mutable_fields ts h; h
+  in
+  Hashtbl.add h i j
+
+let mutable_field ts i =
+  Hashtbl.find (Hts.find mutable_fields ts) i
+let is_mutable_field ts i =
+  Hashtbl.mem (Hts.find mutable_fields ts) i
+
 (* phase 1: typing programs (using destructive type inference) **************)
 
 let dty_app (ts, tyl) = assert (ts.ts_def = None); tyapp (ts, tyl)
@@ -135,6 +154,9 @@ let check_region_vars () =
   List.iter (fun h -> Htv.clear values; Htv.iter check h) !region_vars;
   region_vars := []
 
+let is_fresh_region r =
+  r.R.r_tv.tv_name.id_string = "fresh"
+
 let rec specialize_ty ?(policy=Region_var) ~loc htv ty = match ty.ty_node with
   | Ty.Tyvar _ ->
       Denv.specialize_ty ~loc htv ty
@@ -142,7 +164,7 @@ let rec specialize_ty ?(policy=Region_var) ~loc htv ty = match ty.ty_node with
       let n = (get_mtsymbol ts).mt_regions in
       let mk_region ty = match ty.ty_node with
         | Ty.Tyvar _ when policy = Region_ret ->
-            tyvar (Typing.create_user_type_var "rho")
+            tyvar (Typing.create_user_type_var "fresh")
         | Ty.Tyvar tv when policy = Region_var ->
             let v = Denv.find_type_var ~loc htv tv in
             push_region_var tv (v, loc);
@@ -473,9 +495,56 @@ and dexpr_desc ~ghost env loc = function
       in
       let d = List.fold_left2 constructor d fl tyl in
       d.dexpr_desc, ty
-  | Ptree.Eassign _ ->
-      assert false (*TODO*)
-
+  | Ptree.Eaccess (e1, q) ->
+      let e1 = dexpr ~ghost env e1 in
+      let x = Typing.string_list_of_qualid [] q in
+      let ls =
+	try ns_find_ls (get_namespace (impure_uc env.uc)) x
+	with Not_found -> errorm ~loc "unbound record field %a" print_qualid q
+      in
+      new_regions_vars ();
+      let ty2 = match specialize_lsymbol ~loc (Htv.create 17) ls with
+	| [ty1], Some ty2 -> expected_type e1 ty1; ty2
+	| _ -> assert false
+      in
+      begin match Typing.is_projection (impure_uc env.uc) ls with
+	| Some (ts, _, i)  ->
+	    let mt = get_mtsymbol ts in
+	    let j = 
+	      try Some (mutable_field mt.mt_effect i) with Not_found -> None
+	    in
+	    DEaccess (e1, ls, j), ty2
+	| _ ->
+	    errorm ~loc "unbound record field %a" print_qualid q
+      end
+  | Ptree.Eassign (e1, q, e2) ->
+      let e1 = dexpr ~ghost env e1 in
+      let e2 = dexpr ~ghost env e2 in
+      let x = Typing.string_list_of_qualid [] q in
+      let ls =
+	try ns_find_ls (get_namespace (impure_uc env.uc)) x
+	with Not_found -> errorm ~loc "unbound record field %a" print_qualid q
+      in
+      new_regions_vars ();
+      begin match specialize_lsymbol ~loc (Htv.create 17) ls with
+	| [ty1], Some ty2 ->
+	    expected_type e1 ty1;
+	    expected_type e2 ty2
+	| _ ->
+	    assert false
+      end;
+      begin match Typing.is_projection (impure_uc env.uc) ls with
+	| Some (ts, _, i)  ->
+	    let mt = get_mtsymbol ts in
+	    let j = 
+	      try mutable_field mt.mt_effect i 
+	      with Not_found -> errorm ~loc "not a mutable field"
+	    in
+	    DEassign (e1, ls, j, e2), dty_unit env.uc
+	| None ->
+	    errorm ~loc "unbound record field %a" print_qualid q
+      end
+ 
   | Ptree.Esequence (e1, e2) ->
       let e1 = dexpr ~ghost env e1 in
       expected_type e1 (dty_unit env.uc);
@@ -623,21 +692,6 @@ let region_type ts i =
   (* eprintf "%a@." print_mt_symbol mt; *)
   Hashtbl.find (Hts.find region_types ts) i
 
-let mutable_fields = Hts.create 17 (* ts -> field:int -> region:int *)
-
-let declare_mutable_field ts i j =
-  Pgm_wp.declare_mutable_field ts i j;
-  let h =
-    try
-      Hts.find mutable_fields ts
-    with Not_found ->
-      let h = Hashtbl.create 17 in Hts.add mutable_fields ts h; h
-  in
-  Hashtbl.add h i j
-
-let mutable_field ts i =
-  Hashtbl.find (Hts.find mutable_fields ts) i
-
 let regions_tyapp ts nregions tyl =
   let tymatch s tv ty = Ty.ty_match s (ty_var tv) ty in
   let s = List.fold_left2 tymatch Mtv.empty ts.ts_args tyl in
@@ -1043,6 +1097,49 @@ and iexpr_desc gl env loc ty = function
       let env, dl = iletrec gl env dl in
       let e1 = iexpr gl env e1 in
       IEletrec (dl, e1)
+  | DEaccess (e1, ls, j) ->
+      let e1 = iexpr gl env e1 in
+      let x1 = create_ivsymbol (id_fresh "x") e1.iexpr_type in
+      let r = match e1.iexpr_type.ty_node, j with
+	| Ty.Tyapp (ts, tyl), Some j -> 
+	    let mt = get_mtsymbol ts in
+            let r = regions_tyapp mt.mt_effect mt.mt_regions tyl in
+            Some (List.nth r j)
+	| Ty.Tyapp _, None ->
+	    None
+	| Ty.Tyvar _, _ -> 
+	    assert false
+      in
+      IElet (x1, e1, mk_iexpr loc ty (
+      IEaccess (x1, ls, r)))
+  | DEassign (e1, ls, j, e2) ->
+      (* e1.f <- e2 is syntactic sugar for 
+         let x1 = e1 in let x2 = e2 in any {} writes f { x1.f = x2 } *)
+      let e1 = iexpr gl env e1 in
+      let e2 = iexpr gl env e2 in
+      let x1 = create_ivsymbol (id_fresh "x") e1.iexpr_type in
+      let x2 = create_ivsymbol (id_fresh "x") e2.iexpr_type in
+      let r = match e1.iexpr_type.ty_node with
+	| Ty.Tyapp (ts, tyl) -> 
+	    let mt = get_mtsymbol ts in
+            let r = regions_tyapp mt.mt_effect mt.mt_regions tyl in
+            List.nth r j
+	| Ty.Tyvar _ -> 
+	    assert false
+      in
+      let ef = { ie_reads = []; ie_writes = [r]; ie_raises = [] } in
+      let q = 
+	let ls = (get_psymbol ls).ps_pure in
+	t_equ (fs_app ls [t_var x1.i_pure] x2.i_pure.vs_ty) (t_var x2.i_pure)
+      in
+      let q = (create_vsymbol (id_fresh "result") ty, q), [] in
+      let c = { 
+	ic_result_type = ITpure ty; ic_effect = ef;
+	ic_pre = t_true; ic_post = q }
+      in
+      IElet (x1, e1, mk_iexpr loc ty (
+      IElet (x2, e2, mk_iexpr loc ty (
+      IEany c))))
 
   | DEsequence (e1, e2) ->
       let vs = create_ivsymbol (id_fresh "_") (ty_app (ts_tuple 0) []) in
@@ -1432,14 +1529,21 @@ and expr_desc gl env loc ty = function
       let env, v = add_local env v e1.expr_type_v in
       let e2 = expr gl env e2 in
       let ef = E.union e1.expr_effect e2.expr_effect in
-      if Sreg.exists (fun r -> occur_type_v r e2.expr_type_v) v.pv_regions then
+      let s = Sreg.filter is_fresh_region v.pv_regions in
+      if Sreg.exists (fun r -> occur_type_v r e2.expr_type_v) s then
         errorm ~loc "local reference would escape its scope";
-      let ef = E.remove v.pv_regions ef in
+      let ef = E.remove s ef in
       Elet (v, e1, e2), e2.expr_type_v, ef
   | IEletrec (dl, e1) ->
       let env, dl = letrec gl env dl in
       let e1 = expr gl env e1 in
       Eletrec (dl, e1), e1.expr_type_v, e1.expr_effect
+  | IEaccess (i, ls, r) ->
+      let ef = option_apply E.empty (fun r -> E.add_read r E.empty) r in
+      let ls = (get_psymbol ls).ps_pure in
+      let v = Mvs.find i.i_impure env in
+      let t = fs_app ls [t_var v.pv_pure] (purify ty) in
+      Elogic t, tpure ty, ef
 
   | IEif (e1, e2, e3) ->
       let e1 = expr gl env e1 in
@@ -1698,7 +1802,7 @@ let type_expr gl e =
   let e = iexpr gl ienv e in
   let e = expr gl Mvs.empty e in
   check_region_vars ();
-  fresh_expr gl ~term:true Spv.empty e;
+  (* fresh_expr gl ~term:true Spv.empty e; *)
   e
 
 let type_type uc ty =
@@ -2082,6 +2186,9 @@ let rec decl ~wp env penv ltm lmod uc = function
       let tyv = iutype_v uc (create_ienv denv) tyv in
       let tyv = type_v Mvs.empty tyv in
       if cannot_be_generalized tyv then errorm ~loc "cannot be generalized";
+      if Debug.test_flag debug then
+        eprintf "@[--parameter %s-----@\n  %a@]@."
+          id.id print_type_v tyv;
       let ps, uc = match tyv with
         | Tarrow _ ->
             let ps, uc = add_global_fun loc id.id tyv uc in
diff --git a/tests/test-pgm-jcf.mlw b/tests/test-pgm-jcf.mlw
index 3cf1f6af249293682452cae3c3491c98f02bfed4..0b56318677763d45b3bb66becefd59cf038f453d 100644
--- a/tests/test-pgm-jcf.mlw
+++ b/tests/test-pgm-jcf.mlw
@@ -1,12 +1,18 @@
+
 module M
 
-  use import int.Int
-  use import module array.Array
+  use import module ref.Ref
+
+  let test (x: ref int) =
+    { !x = 0 }
+    !x
+    { result = 0 }
 
-  let foo (a: array int) =
-    { 1 <= a.length }
-    a[0] <- 1
-    { a[0] = 1 }
+  (* BUG *)
+  (* 
+  let foo (a: ref int) = let x = a in fun () -> {} x := 0 { !x = 0 }
+  let test () = let x = ref 0 in begin foo x (); assert { !x = 0 } end 
+  *)  
 
 end