X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fcomponents%2Fng_kernel%2FnCicTypeChecker.ml;h=6f516b8db6eb010aaac1e3a6d449de901843f333;hb=67dd51c6c9ceb0186490033d77769d49404964ac;hp=f6d8d89025a84e9f9182ab7c601ed68ff5156132;hpb=0bc324c13d1eaaa0de54a4d37098dd669198e17e;p=helm.git

diff --git a/helm/software/components/ng_kernel/nCicTypeChecker.ml b/helm/software/components/ng_kernel/nCicTypeChecker.ml
index f6d8d8902..6f516b8db 100644
--- a/helm/software/components/ng_kernel/nCicTypeChecker.ml
+++ b/helm/software/components/ng_kernel/nCicTypeChecker.ml
@@ -22,12 +22,77 @@ let set_logger f = logger := f;;
 exception TypeCheckerFailure of string Lazy.t
 exception AssertFailure of string Lazy.t
 
-let shift_k e (c,rf,x,safes) =
-  e::c,List.map (fun (k,v) -> k+1,v) rf,x+1,List.map ((+)1) safes
+type recf_entry = 
+  | Evil of int (* rno *) 
+  | UnfFix of bool list (* fixed arguments *) 
+  | Safe
 ;;
 
-(* $Id: cicTypeChecker.ml 8213 2008-03-13 18:48:26Z sacerdot $ *)
+let is_dangerous i l = 
+  List.exists (function (j,Evil _) when j=i -> true | _ -> false) l
+;;
+
+let is_unfolded i l = 
+  List.exists (function (j,UnfFix _) when j=i -> true | _ -> false) l
+;;
+
+let is_safe i l =
+  List.exists (function (j,Safe) when j=i -> true | _ -> false) l
+;;
+
+let get_recno i l = 
+  try match List.assoc i l with Evil rno -> rno | _ -> assert false
+  with Not_found -> assert false
+;;
 
+let get_fixed_args i l = 
+  try match List.assoc i l with UnfFix fa -> fa | _ -> assert false
+  with Not_found -> assert false
+;;
+
+let shift_k e (c,rf,x) = e::c,List.map (fun (k,v) -> k+1,v) rf,x+1;;
+
+let string_of_recfuns ~subst ~metasenv ~context l = 
+  let pp = NCicPp.ppterm ~subst ~metasenv ~context in
+  let safe, rest = List.partition (function (_,Safe) -> true | _ -> false) l in
+  let dang, unf = List.partition (function (_,UnfFix _) -> false | _->true)rest in
+  "\n\tsafes: "^String.concat "," (List.map (fun (i,_)->pp (NCic.Rel i)) safe) ^
+  "\n\tfix  : "^String.concat "," 
+   (List.map 
+     (function (i,UnfFix l)-> pp(NCic.Rel i)^"/"^String.concat "," (List.map
+       string_of_bool l)
+     | _ ->assert false) unf) ^
+  "\n\trec  : "^String.concat "," 
+   (List.map 
+     (function (i,Evil rno)->pp(NCic.Rel i)^"/"^string_of_int rno
+     | _ -> assert false) dang)
+;;
+
+let fixed_args bos j n nn =
+ let rec aux k acc = function
+  | NCic.Appl (NCic.Rel i::args) when i-k > n && i-k <= nn ->
+     let rec combine l1 l2 =
+      match l1,l2 with
+         [],[] -> []
+       | he1::tl1, he2::tl2 -> (he1,he2)::combine tl1 tl2
+       | he::tl, [] -> (false,NCic.Rel ~-1)::combine tl [] (* dummy term *)
+       | [],_::_ -> assert false
+     in
+     let lefts, _ = HExtlib.split_nth (min j (List.length args)) args in
+      List.map (fun ((b,x),i) -> b && x = NCic.Rel (k-i)) 
+       (HExtlib.list_mapi (fun x i -> x,i) (combine acc lefts))
+  | t -> NCicUtils.fold (fun _ k -> k+1) k aux acc t    
+ in
+  List.fold_left (aux 0) 
+   (let rec f = function 0 -> [] | n -> true :: f (n-1) in f j) bos
+;;
+
+let rec list_iter_default2 f l1 def l2 = 
+  match l1,l2 with
+    | [], _ -> ()
+    | a::ta, b::tb -> f a b; list_iter_default2 f ta def tb 
+    | a::ta, [] -> f a def; list_iter_default2 f ta def [] 
+;;
 
 
 (*
@@ -294,7 +359,7 @@ let rec split_prods ~subst context n te =
    | (_, _) -> raise (AssertFailure (lazy "split_prods"))
 ;;
 
-let debruijn ?(cb=fun _ _ -> ()) uri number_of_types = 
+let debruijn ?(cb=fun _ _ -> ()) uri number_of_types context = 
  let rec aux k t =
   let res =
    match t with
@@ -309,7 +374,7 @@ let debruijn ?(cb=fun _ _ -> ()) uri number_of_types =
   in
    cb t res; res
  in
-  aux 0
+  aux (List.length context)
 ;;
 
 let sort_of_prod ~metasenv ~subst context (name,s) (t1, t2) =
@@ -350,11 +415,12 @@ let eat_prods ~subst ~metasenv context he ty_he args_with_ty =
               (TypeCheckerFailure 
                 (lazy (Printf.sprintf
                   ("Appl: wrong application of %s: the parameter %s has type"^^
-                   "\n%s\nbut it should have type \n%s\n")
+                   "\n%s\nbut it should have type \n%s\nContext:\n%s\n")
                   (NCicPp.ppterm ~subst ~metasenv ~context he)
                   (NCicPp.ppterm ~subst ~metasenv ~context arg)
                   (NCicPp.ppterm ~subst ~metasenv ~context ty_arg)
-                  (NCicPp.ppterm ~subst ~metasenv ~context s))))
+                  (NCicPp.ppterm ~subst ~metasenv ~context s)
+                  (NCicPp.ppcontext ~subst ~metasenv context))))
        | _ ->
           raise 
             (TypeCheckerFailure
@@ -370,20 +436,44 @@ let eat_prods ~subst ~metasenv context he ty_he args_with_ty =
     aux ty_he args_with_ty
 ;;
 
-let fix_lefts_in_constrs ~subst uri paramsno tyl i =
-  let len = List.length tyl in
-  let _,_,arity,cl = List.nth tyl i in
-  let tys = List.map (fun (_,n,ty,_) -> n,C.Decl ty) tyl in
-  let cl' =
-   List.map
-    (fun (_,id,ty) ->
-      let debruijnedty = debruijn uri len ty in
-      id, snd (split_prods ~subst tys paramsno ty),
-       snd (split_prods ~subst tys paramsno debruijnedty))
-    cl 
+(* instantiate_parameters ps (x1:T1)...(xn:Tn)C                             *)
+(* returns ((x_|ps|:T_|ps|)...(xn:Tn)C){ps_1 / x1 ; ... ; ps_|ps| / x_|ps|} *)
+let rec instantiate_parameters params c =
+  match c, params with
+  | c,[] -> c
+  | C.Prod (_,_,ta), he::tl -> instantiate_parameters tl (S.subst he ta)
+  | t,l -> raise (AssertFailure (lazy "1"))
+;;
+
+let specialize_inductive_type ~subst context ty_term =
+  match R.whd ~subst context ty_term with
+  | C.Const (Ref.Ref (_,uri,Ref.Ind i) as ref)  
+  | C.Appl (C.Const (Ref.Ref (_,uri,Ref.Ind i) as ref) :: _ ) as ty ->
+      let args = match ty with C.Appl (_::tl) -> tl | _ -> [] in
+      let is_ind, leftno, itl, attrs, i = E.get_checked_indtys ref in
+      let left_args,_ = HExtlib.split_nth leftno args in
+      let itl =
+        List.map (fun (rel, name, arity, cl) ->
+          let arity = instantiate_parameters left_args arity in
+          let cl = 
+            List.map (fun (rel, name, ty) -> 
+              rel, name, instantiate_parameters left_args ty)
+              cl
+          in
+            rel, name, arity, cl)
+          itl
+      in
+        is_ind, leftno, itl, attrs, i
+  | _ -> assert false
+;;
+
+let fix_lefts_in_constrs ~subst r_uri r_len context ty_term =
+  let _,_,itl,_,i = specialize_inductive_type ~subst context ty_term in
+  let _,_,_,cl = List.nth itl i in  
+  let cl =
+    List.map (fun (_,id,ty) -> id, debruijn r_uri r_len context ty) cl 
   in
-  let lefts = fst (split_prods ~subst [] paramsno arity) in
-  lefts@tys, len, cl'
+  List.map (fun (_,name,arity,_) -> name, C.Decl arity) itl, cl
 ;;
 
 exception DoesOccur;;
@@ -444,14 +534,6 @@ let rec weakly_positive ~subst context n nn uri te =
    | _ ->
      raise (TypeCheckerFailure (lazy "Malformed inductive constructor type"))
 
-(* instantiate_parameters ps (x1:T1)...(xn:Tn)C                             *)
-(* returns ((x_|ps|:T_|ps|)...(xn:Tn)C){ps_1 / x1 ; ... ; ps_|ps| / x_|ps|} *)
-and instantiate_parameters params c =
-  match c, params with
-  | c,[] -> c
-  | C.Prod (_,_,ta), he::tl -> instantiate_parameters tl (S.subst he ta)
-  | t,l -> raise (AssertFailure (lazy "1"))
-
 and strictly_positive ~subst context n nn te =
   match R.whd context te with
    | t when does_not_occur ~subst context n nn t -> true
@@ -528,7 +610,7 @@ exception NotGuarded of string Lazy.t;;
 
 let rec typeof ~subst ~metasenv context term =
   let rec typeof_aux context = 
-    fun t -> (*prerr_endline (NCicPp.ppterm ~context t); *)
+    fun t -> (*prerr_endline (NCicPp.ppterm ~metasenv ~subst ~context t);*)
     match t with
     | C.Rel n ->
        (try
@@ -863,7 +945,7 @@ and check_mutual_inductive_defs uri ~metasenv ~subst is_ind leftno tyl =
     (fun (_,_,_,cl) i ->
        List.iter
          (fun (_,name,te) -> 
-           let debruijnedte = debruijn uri len te in
+           let debruijnedte = debruijn uri len [] te in
            ignore (typeof ~subst ~metasenv tys debruijnedte);
            (* let's check also the positivity conditions *)
            if 
@@ -884,61 +966,118 @@ and eat_lambdas ~subst ~metasenv context n te =
   | (n, C.Lambda (name,so,ta)) when n > 0 ->
       eat_lambdas ~subst ~metasenv ((name,(C.Decl so))::context) (n - 1) ta
    | (n, te) ->
-      raise (AssertFailure (lazy (Printf.sprintf "9 (%d, %s)" n 
+      raise (AssertFailure (lazy (Printf.sprintf "eat_lambdas (%d, %s)" n 
         (NCicPp.ppterm ~subst ~metasenv ~context te))))
 
-and guarded_by_destructors ~subst ~metasenv context recfuns t = 
+and eat_or_subst_lambdas 
+ ~subst ~metasenv app_all_args n te to_be_subst args (context, recfuns, x as k) 
+=
+  match n, R.whd ~subst context te, to_be_subst, args with
+  | (0, _,_,_) when args = [] || not app_all_args -> te, k
+  | (0, _,_,_::_) -> C.Appl (te::args), k
+  | (n, C.Lambda (name,so,ta),true::to_be_subst,arg::args) when n > 0 ->
+      eat_or_subst_lambdas ~subst ~metasenv app_all_args
+       (n - 1) (S.subst arg ta) to_be_subst args k
+  | (n, C.Lambda (name,so,ta),false::to_be_subst,arg::args) when n > 0 ->
+      eat_or_subst_lambdas ~subst ~metasenv app_all_args
+       (n - 1) ta to_be_subst args (shift_k (name,(C.Decl so)) k)
+  | (n, te, _, _) when args = [] || not app_all_args -> te, k
+  | (n, te, _, _::_) -> C.Appl (te::args), k
+  | (_,_,_,[]) -> assert false (* caml thinks is missing *)
+
+and guarded_by_destructors r_uri r_len ~subst ~metasenv context recfuns t = 
  let recursor f k t = NCicUtils.fold shift_k k (fun k () -> f k) () t in
- let rec aux (context, recfuns, x, safes as k) t = 
-  match R.whd ~subst context t with (* TODO: use ~delta:false as mush as poss*)
-  | C.Rel m as t when List.mem_assoc m recfuns -> 
+ let rec aux (context, recfuns, x as k) t = 
+  let t = R.whd ~delta:max_int ~subst context t in
+(*
+   prerr_endline ("GB:\n" ^ 
+     NCicPp.ppcontext ~subst ~metasenv context^
+     NCicPp.ppterm ~metasenv ~subst ~context t^
+       string_of_recfuns ~subst ~metasenv ~context recfuns);
+*)
+  try
+  match t with
+  | C.Rel m as t when is_dangerous m recfuns -> 
       raise (NotGuarded (lazy 
-        (NCicPp.ppterm ~subst ~metasenv ~context t ^ " passed around")))
-  | C.Rel m ->
-     (match List.nth context (m-1) with 
-     | _,C.Decl _ -> ()
-     | _,C.Def (bo,_) -> aux (context, recfuns, x, safes) (S.lift m bo))
-  | C.Meta _ -> ()
-  | C.Appl ((C.Rel m)::tl) as t when List.mem_assoc m recfuns ->
-     let rec_no = List.assoc m recfuns in
+        (NCicPp.ppterm ~subst ~metasenv ~context t ^ 
+         " is a partial application of a fix")))
+  | C.Appl ((C.Rel m)::tl) as t when is_dangerous m recfuns ->
+     let rec_no = get_recno m recfuns in
      if not (List.length tl > rec_no) then 
        raise (NotGuarded (lazy 
          (NCicPp.ppterm ~context ~subst ~metasenv t ^ 
          " is a partial application of a fix")))
      else
        let rec_arg = List.nth tl rec_no in
-       if not (is_really_smaller ~subst ~metasenv k rec_arg) then 
-         raise (NotGuarded (lazy 
-           (NCicPp.ppterm ~context ~subst ~metasenv rec_arg ^ " not smaller")));
+       if not (is_really_smaller r_uri r_len ~subst ~metasenv k rec_arg) then 
+         raise (NotGuarded (lazy (Printf.sprintf ("Recursive call %s, %s is not"
+          ^^ " smaller.\ncontext:\n%s") (NCicPp.ppterm ~context ~subst ~metasenv
+          t) (NCicPp.ppterm ~context ~subst ~metasenv rec_arg)
+          (NCicPp.ppcontext ~subst ~metasenv context))));
        List.iter (aux k) tl
-       (*
-  | C.Appl (C.Const ((Ref.Ref (_,_,Ref.Fix (i,j))) as r)::args) ->
-      List.iter (aux k) args;
-      let fixes,_,_ = E.get_checked_fixes r in
-      let _,_,_,_,bo = List.nth fixes i in
-      let bo_wout_lam, context = eat_lambdas ~subst ~metasenv context j in
-      (* debruijna body..... *) assert false
-*)
+  | C.Appl ((C.Rel m)::tl) when is_unfolded m recfuns ->
+       let fixed_args = get_fixed_args m recfuns in
+       list_iter_default2 (fun x b -> if not b then aux k x) tl false fixed_args
+  | C.Rel m ->
+     (match List.nth context (m-1) with 
+     | _,C.Decl _ -> ()
+     | _,C.Def (bo,_) -> aux k (S.lift m bo))
+  | C.Meta _ -> ()
+  | C.Appl (C.Const ((Ref.Ref (_,uri,Ref.Fix (i,_))) as r)::args) ->
+      if List.exists (fun t -> try aux k t;false with NotGuarded _ -> true) args
+      then
+      let fl,_,_ = E.get_checked_fixes r in
+      let ctx_tys, bos = 
+        List.split (List.map (fun (_,name,_,ty,bo) -> (name, C.Decl ty), bo) fl)
+      in
+      let fl_len = List.length fl in
+      let bos = List.map (debruijn uri fl_len context) bos in
+      let j = List.fold_left min max_int (List.map (fun (_,_,i,_,_)->i) fl) in
+      let ctx_len = List.length context in
+        (* we may look for fixed params not only up to j ... *)
+      let fa = fixed_args bos j ctx_len (ctx_len + fl_len) in
+      list_iter_default2 (fun x b -> if not b then aux k x) args false fa; 
+      let context = context@ctx_tys in
+      let ctx_len = List.length context in
+      let extra_recfuns = 
+        HExtlib.list_mapi (fun _ i -> ctx_len - i, UnfFix fa) ctx_tys
+      in
+      let k = context, extra_recfuns@recfuns, x in
+      let bos_and_ks = 
+        HExtlib.list_mapi (fun bo fno ->
+          (* potrebbe anche aggiungere un arg di cui fa push alle safe *)
+          eat_or_subst_lambdas ~subst ~metasenv (fno=i) j bo fa args k) bos
+      in
+       List.iter (fun (bo,k) -> aux k bo) bos_and_ks
   | C.Match (Ref.Ref (_,uri,_) as ref,outtype,term,pl) as t ->
      (match R.whd ~subst context term with
-     | C.Rel m | C.Appl (C.Rel m :: _ ) as t when List.mem m safes || m = x ->
-        let isinductive, paramsno, tl, _, i = E.get_checked_indtys ref in
+     | C.Rel m | C.Appl (C.Rel m :: _ ) as t when is_safe m recfuns || m = x ->
+        (* TODO: add CoInd to references so that this call is useless *)
+        let isinductive, _, _, _, _ = E.get_checked_indtys ref in
         if not isinductive then recursor aux k t
         else
-         let c_ctx,len,cl = fix_lefts_in_constrs ~subst uri paramsno tl i in
+         let ty = typeof ~subst ~metasenv context term in
+         let itl_ctx,dcl = fix_lefts_in_constrs ~subst r_uri r_len context ty in
          let args = match t with C.Appl (_::tl) -> tl | _ -> [] in
+         let dc_ctx = context @ itl_ctx in
+         let start, stop = List.length context, List.length context + r_len in
          aux k outtype; 
          List.iter (aux k) args; 
          List.iter2
-           (fun p (_,_,bruijnedc) ->
-             let rl = recursive_args ~subst ~metasenv c_ctx 0 len bruijnedc in
+           (fun p (_,dc) ->
+             let rl = recursive_args ~subst ~metasenv dc_ctx start stop dc in
              let p, k = get_new_safes ~subst k p rl in
              aux k p) 
-           pl cl
+           pl dcl
      | _ -> recursor aux k t)
   | t -> recursor aux k t
+  with
+   NotGuarded _ as exc ->
+    let t' = R.whd ~delta:0 ~subst context t in
+    if t = t' then raise exc
+    else aux k t'
  in
-  try aux (context, recfuns, 1, []) t
+  try aux (context, recfuns, 1) t
   with NotGuarded s -> raise (TypeCheckerFailure s)
 
 (*
@@ -985,7 +1124,7 @@ and guarded_by_constructors ~subst ~metasenv _ _ _ _ _ _ _ = true
 
 and recursive_args ~subst ~metasenv context n nn te =
   match R.whd context te with
-  | C.Rel _ | C.Appl _ -> []
+  | C.Rel _ | C.Appl _ | C.Const _ -> []
   | C.Prod (name,so,de) ->
      (not (does_not_occur ~subst context n nn so)) ::
       (recursive_args ~subst ~metasenv 
@@ -994,12 +1133,12 @@ and recursive_args ~subst ~metasenv context n nn te =
      raise (AssertFailure (lazy ("recursive_args:" ^ NCicPp.ppterm ~subst
      ~metasenv ~context:[] t)))
 
-and get_new_safes ~subst (context, recfuns, x, safes as k) p rl =
+and get_new_safes ~subst (context, recfuns, x as k) p rl =
   match R.whd ~subst context p, rl with
   | C.Lambda (name,so,ta), b::tl ->
-      let safes = (if b then [0] else []) @ safes in
+      let recfuns = (if b then [0,Safe] else []) @ recfuns in
       get_new_safes ~subst 
-        (shift_k (name,(C.Decl so)) (context, recfuns, x, safes)) ta tl
+        (shift_k (name,(C.Decl so)) (context, recfuns, x)) ta tl
   | C.Meta _ as e, _ | e, [] -> e, k
   | _ -> raise (AssertFailure (lazy "Ill formed pattern"))
 
@@ -1010,13 +1149,15 @@ and split_prods ~subst context n te =
        split_prods ~subst ((name,(C.Decl so))::context) (n - 1) ta
   | _ -> raise (AssertFailure (lazy "split_prods"))
 
-and is_really_smaller ~subst ~metasenv (context, recfuns, x, safes as k) te =
+and is_really_smaller 
+  r_uri r_len ~subst ~metasenv (context, recfuns, x as k) te 
+=
  match R.whd ~subst context te with
- | C.Rel m when List.mem m safes -> true
+ | C.Rel m when is_safe m recfuns -> true
  | C.Lambda (name, s, t) ->
-     is_really_smaller ~subst ~metasenv (shift_k (name, C.Decl s) k) t
+    is_really_smaller r_uri r_len ~subst ~metasenv (shift_k (name,C.Decl s) k) t
  | C.Appl (he::_) ->
-     is_really_smaller ~subst ~metasenv k he
+    is_really_smaller r_uri r_len ~subst ~metasenv k he
  | C.Appl _
  | C.Rel _ 
  | C.Const (Ref.Ref (_,_,Ref.Con _)) -> false
@@ -1042,19 +1183,23 @@ and is_really_smaller ~subst ~metasenv (context, recfuns, x, safes as k) te =
  | C.Meta _ -> true 
  | C.Match (Ref.Ref (_,uri,_) as ref,outtype,term,pl) ->
     (match term with
-    | C.Rel m | C.Appl (C.Rel m :: _ ) when List.mem m safes || m = x ->
-        let isinductive, paramsno, tl, _, i = E.get_checked_indtys ref in
+    | C.Rel m | C.Appl (C.Rel m :: _ ) when is_safe m recfuns || m = x ->
+        (* TODO: add CoInd to references so that this call is useless *)
+        let isinductive, _, _, _, _ = E.get_checked_indtys ref in
         if not isinductive then
-          List.for_all (is_really_smaller ~subst ~metasenv k) pl
+          List.for_all (is_really_smaller r_uri r_len ~subst ~metasenv k) pl
         else
-          let c_ctx,len,cl = fix_lefts_in_constrs ~subst uri paramsno tl i in
+          let ty = typeof ~subst ~metasenv context term in
+          let itl_ctx,dcl= fix_lefts_in_constrs ~subst r_uri r_len context ty in
+          let start, stop = List.length context, List.length context + r_len in
+          let dc_ctx = context @ itl_ctx in
           List.for_all2
-           (fun p (_,_,debruijnedte) -> 
-             let rl'=recursive_args ~subst ~metasenv c_ctx 0 len debruijnedte in
-             let e, k = get_new_safes ~subst k p rl' in
-             is_really_smaller ~subst ~metasenv k e)
-           pl cl
-    | _ -> List.for_all (is_really_smaller ~subst ~metasenv k) pl)
+           (fun p (_,dc) -> 
+             let rl = recursive_args ~subst ~metasenv dc_ctx start stop dc in
+             let e, k = get_new_safes ~subst k p rl in
+             is_really_smaller r_uri r_len ~subst ~metasenv k e)
+           pl dcl
+    | _ -> List.for_all (is_really_smaller r_uri r_len ~subst ~metasenv k) pl)
  | _ -> assert false
 
 and returns_a_coinductive ~subst context ty =
@@ -1108,40 +1253,57 @@ and check_obj_well_typed (uri,height,metasenv,subst,kind) =
    | C.Inductive (is_ind, leftno, tyl, _) -> 
        check_mutual_inductive_defs uri ~metasenv ~subst is_ind leftno tyl
    | C.Fixpoint (inductive,fl,_) ->
-      let types,kl,len =
+      let types, kl, len =
         List.fold_left
          (fun (types,kl,len) (_,name,k,ty,_) ->
            let _ = typeof ~subst ~metasenv [] ty in
             ((name,(C.Decl (S.lift len ty)))::types, k::kl,len+1)
          ) ([],[],0) fl
       in
-        List.iter (fun (_,name,x,ty,bo) ->
-         let bo = debruijn uri len bo in
-         let ty_bo = typeof ~subst ~metasenv types bo in
-         if not (R.are_convertible ~subst ~metasenv types ty_bo (S.lift len ty))
-         then raise (TypeCheckerFailure (lazy ("(Co)Fix: ill-typed bodies")))
-         else
-          if inductive then begin
-            let m, context = eat_lambdas ~subst ~metasenv types (x + 1) bo in
-            (* guarded by destructors conditions D{f,k,x,M} *)
-            let rec enum_from k = 
-              function [] -> [] | v::tl -> (k,v)::enum_from (k+1) tl 
+      let dfl, kl =   
+        List.split (List.map2 
+          (fun (_,_,_,_,bo) rno -> 
+             let dbo = debruijn uri len [] bo in
+             dbo, Evil rno)
+          fl kl)
+      in
+      List.iter2 (fun (_,name,x,ty,_) bo ->
+       let ty_bo = typeof ~subst ~metasenv types bo in
+       if not (R.are_convertible ~subst ~metasenv types ty_bo (S.lift len ty))
+       then raise (TypeCheckerFailure (lazy ("(Co)Fix: ill-typed bodies")))
+       else
+        if inductive then begin
+          let m, context = eat_lambdas ~subst ~metasenv types (x + 1) bo in
+          let r_uri, r_len =
+            let he =
+             match List.hd context with _,C.Decl t -> t | _ -> assert false
             in
-            guarded_by_destructors 
-             ~subst ~metasenv context (enum_from (x+2) kl) m
-          end else
-           match returns_a_coinductive ~subst [] ty with
-            | None ->
+            match R.whd ~subst (List.tl context) he with
+            | C.Const (Ref.Ref (_,uri,Ref.Ind _) as ref)
+            | C.Appl (C.Const (Ref.Ref (_,uri,Ref.Ind _) as ref) :: _) ->
+                let _,_,itl,_,_ = E.get_checked_indtys ref in
+                  uri, List.length itl
+            | _ -> assert false
+          in
+          (* guarded by destructors conditions D{f,k,x,M} *)
+          let rec enum_from k = 
+            function [] -> [] | v::tl -> (k,v)::enum_from (k+1) tl 
+          in
+          guarded_by_destructors r_uri r_len 
+           ~subst ~metasenv context (enum_from (x+2) kl) m
+        end else
+         match returns_a_coinductive ~subst [] ty with
+          | None ->
+              raise (TypeCheckerFailure
+                (lazy "CoFix: does not return a coinductive type"))
+          | Some uri ->
+              (* guarded by constructors conditions C{f,M} *)
+              if not (guarded_by_constructors ~subst ~metasenv
+                  types 0 len false bo [] uri)
+              then
                 raise (TypeCheckerFailure
-                  (lazy "CoFix: does not return a coinductive type"))
-            | Some uri ->
-                (* guarded by constructors conditions C{f,M} *)
-                if not (guarded_by_constructors ~subst ~metasenv
-                    types 0 len false bo [] uri)
-                then
-                  raise (TypeCheckerFailure
-                   (lazy "CoFix: not guarded by constructors"))
-          ) fl
+                 (lazy "CoFix: not guarded by constructors"))
+        ) fl dfl
 
 let typecheck_obj = check_obj_well_typed;;