2 ||M|| This file is part of HELM, an Hypertextual, Electronic
3 ||A|| Library of Mathematics, developed at the Computer Science
4 ||T|| Department, University of Bologna, Italy.
6 ||T|| HELM is free software; you can redistribute it and/or
7 ||A|| modify it under the terms of the GNU General Public License
8 \ / version 2 or (at your option) any later version.
9 \ / This software is distributed as is, NO WARRANTY.
10 V_______________________________________________________________ *)
14 exception MetaSubstFailure of string Lazy.t
15 exception Uncertain of string Lazy.t
18 (*** Functions to apply a substitution ***)
20 let apply_subst_gen ~appl_fun subst term =
23 let module S = CicSubstitution in
26 | C.Var (uri,exp_named_subst) ->
27 let exp_named_subst' =
28 List.map (fun (uri, t) -> (uri, um_aux t)) exp_named_subst
30 C.Var (uri, exp_named_subst')
33 let (_, t,_) = lookup_subst i subst in
34 um_aux (S.subst_meta l t)
35 with CicUtil.Subst_not_found _ ->
36 (* unconstrained variable, i.e. free in subst*)
38 List.map (function None -> None | Some t -> Some (um_aux t)) l
42 | C.Implicit _ as t -> t
43 | C.Cast (te,ty) -> C.Cast (um_aux te, um_aux ty)
44 | C.Prod (n,s,t) -> C.Prod (n, um_aux s, um_aux t)
45 | C.Lambda (n,s,t) -> C.Lambda (n, um_aux s, um_aux t)
46 | C.LetIn (n,s,ty,t) -> C.LetIn (n, um_aux s, um_aux ty, um_aux t)
47 | C.Appl (hd :: tl) -> appl_fun um_aux hd tl
48 | C.Appl _ -> assert false
49 | C.Const (uri,exp_named_subst) ->
50 let exp_named_subst' =
51 List.map (fun (uri, t) -> (uri, um_aux t)) exp_named_subst
53 C.Const (uri, exp_named_subst')
54 | C.MutInd (uri,typeno,exp_named_subst) ->
55 let exp_named_subst' =
56 List.map (fun (uri, t) -> (uri, um_aux t)) exp_named_subst
58 C.MutInd (uri,typeno,exp_named_subst')
59 | C.MutConstruct (uri,typeno,consno,exp_named_subst) ->
60 let exp_named_subst' =
61 List.map (fun (uri, t) -> (uri, um_aux t)) exp_named_subst
63 C.MutConstruct (uri,typeno,consno,exp_named_subst')
64 | C.MutCase (sp,i,outty,t,pl) ->
65 let pl' = List.map um_aux pl in
66 C.MutCase (sp, i, um_aux outty, um_aux t, pl')
69 List.map (fun (name, i, ty, bo) -> (name, i, um_aux ty, um_aux bo)) fl
74 List.map (fun (name, ty, bo) -> (name, um_aux ty, um_aux bo)) fl
82 let appl_fun um_aux he tl =
83 let tl' = List.map um_aux tl in
86 Cic.Appl l -> Cic.Appl (l@tl')
87 | he' -> Cic.Appl (he'::tl')
91 Cic.Meta (m,_) -> CicReduction.head_beta_reduce t'
96 (* incr apply_subst_counter; *)
99 | _ -> apply_subst_gen ~appl_fun subst t
102 let profiler = HExtlib.profile "U/CicMetaSubst.apply_subst"
103 let apply_subst s t =
104 profiler.HExtlib.profile (apply_subst s) t
107 let apply_subst_context subst context =
112 incr apply_subst_context_counter;
113 context_length := !context_length + List.length context;
118 | Some (n, Cic.Decl t) ->
119 let t' = apply_subst subst t in
120 Some (n, Cic.Decl t') :: context
121 | Some (n, Cic.Def (t, ty)) ->
122 let ty' = apply_subst subst ty in
123 let t' = apply_subst subst t in
124 Some (n, Cic.Def (t', ty')) :: context
125 | None -> None :: context)
128 let apply_subst_metasenv subst metasenv =
130 incr apply_subst_metasenv_counter;
131 metasenv_length := !metasenv_length + List.length metasenv;
137 (fun (n, context, ty) ->
138 (n, apply_subst_context subst context, apply_subst subst ty))
140 (fun (i, _, _) -> not (List.mem_assoc i subst))
143 let tempi_type_of_aux_subst = ref 0.0;;
144 let tempi_subst = ref 0.0;;
145 let tempi_type_of_aux = ref 0.0;;
149 let maxmeta = ref 0 in
150 fun () -> incr maxmeta; !maxmeta
153 exception NotInTheList;;
155 let position n (shift, lc) =
157 | NCic.Irl len when n <= shift || n > shift + len -> raise NotInTheList
158 | NCic.Irl _ -> n - shift
160 let rec aux k = function
161 | [] -> raise NotInTheList
162 | (NCic.Rel m)::_ when m + shift = n -> k
163 | _::tl -> aux (k+1) tl
169 let rec are_contiguous k = function
171 | (NCic.Rel j) :: tl when j = k+1 -> are_contiguous j tl
175 | _, NCic.Ctx [] -> 0, NCic.Irl 0
176 | shift, NCic.Ctx (NCic.Rel k::tl as l) when are_contiguous k tl ->
177 shift+k-1, NCic.Irl (List.length l)
183 let mk_perforated_irl shift len restrictions =
185 if n = 0 then [] else
186 if List.mem (n+shift) restrictions then aux (n-1)
187 else (NCic.Rel n) :: aux (n-1)
189 pack_lc (shift, NCic.Ctx (List.rev (aux len)))
194 let rec force_does_not_occur metasenv subst restrictions t =
195 let rec aux k ms = function
196 | NCic.Rel r when List.mem (r - k) restrictions -> raise Occur
197 | NCic.Rel r as orig ->
199 List.length (List.filter (fun x -> x < r - k) restrictions)
201 if amount > 0 then ms, NCic.Rel (r - amount) else ms, orig
202 | NCic.Meta (n, (shift,lc as l)) as orig ->
203 (* we ignore the subst since restrict will take care of already
204 * instantiated/restricted metavariabels *)
205 let (metasenv,subst as ms), restrictions_for_n, l' =
206 let l = NCicUtils.expand_local_context lc in
207 let ms, _, restrictions_for_n, l =
209 (fun t (ms, i, restrictions_for_n, l) ->
211 let ms, t = aux (k-shift) ms t in
212 ms, i-1, restrictions_for_n, t::l
214 ms, i-1, i::restrictions_for_n, l)
215 l (ms, List.length l, [], [])
217 ms, restrictions_for_n, pack_lc (shift, NCic.Ctx l)
219 if restrictions_for_n = [] then
220 ms, if l = l' then orig else NCic.Meta (n, l')
222 let metasenv, subst, newmeta =
223 restrict metasenv subst n restrictions_for_n
225 (metasenv, subst), NCic.Meta (newmeta, l')
226 | t -> NCicUntrusted.map_term_fold_a (fun _ k -> k+1) k aux ms t
228 aux 0 (metasenv,subst) t
230 and force_does_not_occur_in_context metasenv subst restrictions = function
231 | name, NCic.Decl t as orig ->
232 let (metasenv, subst), t' =
233 force_does_not_occur metasenv subst restrictions t in
234 metasenv, subst, (if t == t' then orig else (name,NCic.Decl t'))
235 | name, NCic.Def (bo, ty) as orig ->
236 let (metasenv, subst), bo' =
237 force_does_not_occur metasenv subst restrictions bo in
238 let (metasenv, subst), ty' =
239 force_does_not_occur metasenv subst restrictions ty in
241 (if bo == bo' && ty == ty' then orig else (name, NCic.Def (bo', ty')))
243 and erase_in_context metasenv subst pos restrictions = function
244 | [] -> metasenv, subst, restrictions, []
246 let metasenv, subst, restricted, tl' =
247 erase_in_context metasenv subst (pos+1) restrictions tl in
248 if List.mem pos restricted then
249 metasenv, subst, restricted, tl'
252 let metasenv, subst, hd' =
253 let delifted_restricted =
254 List.map ((+) ~-pos) (List.filter ((<=) pos) restricted) in
255 force_does_not_occur_in_context
256 metasenv subst delifted_restricted hd
258 metasenv, subst, restricted,
259 (if hd' == hd && tl' == tl then orig else (hd' :: tl'))
261 metasenv, subst, (pos :: restricted), tl'
263 and restrict metasenv subst i restrictions =
264 assert (restrictions <> []);
266 let name, ctx, bo, ty = NCicUtils.lookup_subst i subst in
268 let metasenv, subst, restrictions, newctx =
269 erase_in_context metasenv subst 1 restrictions ctx in
270 let (metasenv, subst), newty =
271 force_does_not_occur metasenv subst restrictions ty in
272 let (metasenv, subst), newbo =
273 force_does_not_occur metasenv subst restrictions bo in
274 let j = newmeta () in
275 let subst_entry_j = j, (name, newctx, newbo, newty) in
276 let reloc_irl = mk_perforated_irl 0 (List.length ctx) restrictions in
277 let subst_entry_i = i, (name, ctx, NCic.Meta (j, reloc_irl), ty) in
279 subst_entry_j :: List.map
280 (fun (n,_) as orig -> if i = n then subst_entry_i else orig) subst
283 prerr_endline ("restringo nella subst: " ^string_of_int i ^ " -> " ^
284 string_of_int j ^ "\n" ^
285 NCicPp.ppsubst ~metasenv [subst_entry_j] ^ "\n\n" ^
286 NCicPp.ppsubst ~metasenv [subst_entry_i] ^ "\n" ^
287 NCicPp.ppterm ~metasenv ~subst ~context:ctx bo ^ " ---- " ^
288 NCicPp.ppterm ~metasenv ~subst ~context:newctx newbo
291 metasenv, new_subst, j
292 with Occur -> raise (MetaSubstFailure (lazy (Printf.sprintf
293 ("Cannot restrict the context of the metavariable ?%d over "^^
294 "the hypotheses %s since ?%d is already instantiated "^^
295 "with %s and at least one of the hypotheses occurs in "^^
296 "the substituted term") i (String.concat ", "
297 (List.map (fun x -> fst (List.nth ctx (x-1))) restrictions)) i
298 (NCicPp.ppterm ~metasenv ~subst ~context:ctx bo))))
299 with NCicUtils.Subst_not_found _ ->
301 let name, ctx, ty = NCicUtils.lookup_meta i metasenv in
303 let metasenv, subst, restrictions, newctx =
304 erase_in_context metasenv subst 1 restrictions ctx in
305 let (metasenv, subst), newty =
306 force_does_not_occur metasenv subst restrictions ty in
307 let j = newmeta () in
308 let metasenv_entry = j, (name, newctx, newty) in
310 mk_perforated_irl 0 (List.length ctx) restrictions in
311 let subst_entry = i, (name, ctx, NCic.Meta (j, reloc_irl), ty) in
313 (fun (n,_) as orig -> if i = n then metasenv_entry else orig)
315 subst_entry :: subst, j
316 with Occur -> raise (MetaSubstFailure (lazy (Printf.sprintf
317 ("Cannot restrict the context of the metavariable ?%d "^^
318 "over the hypotheses %s since metavariable's type depends "^^
319 "on at least one of them") i (String.concat ", "
320 (List.map (fun x -> fst (List.nth ctx (x-1))) restrictions)))))
322 | NCicUtils.Meta_not_found _ -> assert false
325 (* INVARIANT: we suppose that t is not another occurrence of Meta(n,_),
326 otherwise the occur check does not make sense in case of unification
328 let delift metasenv subst context n l t =
329 let rec aux k (metasenv, subst as ms) = function
330 | NCic.Rel n as t when n <= k -> ms, t
333 match List.nth context (n-k-1) with
334 | _,NCic.Def (bo,_) ->
335 (try ms, NCic.Rel ((position (n-k) l) + k)
337 (* CSC: This bit of reduction hurts performances since it is
338 * possible to have an exponential explosion of the size of the
339 * proof. required for nat/nth_prime.ma *)
340 aux k ms (NCicSubstitution.lift n bo))
341 | _,NCic.Decl _ -> ms, NCic.Rel ((position (n-k) l) + k)
342 with Failure _ -> assert false) (*Unbound variable found in delift*)
343 | NCic.Meta (_,(_,(NCic.Irl 0| NCic.Ctx []))) as orig -> ms, orig
344 | NCic.Meta (i,l1) as orig ->
346 let _,_,t,_ = NCicUtils.lookup_subst i subst in
347 aux k ms (NCicSubstitution.subst_meta l1 t)
348 with NCicUtils.Subst_not_found _ ->
349 (* see the top level invariant *)
351 raise (MetaSubstFailure (lazy (Printf.sprintf (
352 "Cannot unify the metavariable ?%d with a term that has "^^
353 "as subterm %s in which the same metavariable "^^
354 "occurs (occur check)") i
355 (NCicPp.ppterm ~context ~metasenv ~subst t))))
357 let shift1,lc1 = l1 in
359 let shift = shift + k in
361 | NCic.Irl len, NCic.Irl len1
362 when shift1 + len1 < shift || shift1 > shift + len ->
363 let restrictions = HExtlib.list_seq 1 (len1 + 1) in
364 let metasenv, subst, newmeta =
365 restrict metasenv subst i restrictions
368 NCic.Meta (newmeta, (0,NCic.Irl (max 0 (k-shift1))))
369 | NCic.Irl len, NCic.Irl len1
370 when shift1 < shift || len1 + shift1 > len + shift ->
371 (* C. Hoare. Premature optimization is the root of all evil*)
372 let stop = shift + len in
373 let stop1 = shift1 + len1 in
374 let low_gap = max 0 (shift - shift1) in
375 let high_gap = max 0 (stop1 - stop) in
377 HExtlib.list_seq (k+1-shift1) (low_gap + 1) @
378 HExtlib.list_seq (len1 - high_gap + 1) (len1 + 1)
380 let metasenv, subst, newmeta =
381 restrict metasenv subst i restrictions
384 prerr_endline ("RESTRICTIONS FOR: " ^
385 NCicPp.ppterm ~metasenv ~subst ~context:[]
386 (NCic.Meta (i,l1))^" that was part of a term unified with "
387 ^ NCicPp.ppterm ~metasenv ~subst ~context:[] (NCic.Meta
388 (n,l)) ^ " ====> " ^ String.concat "," (List.map
389 string_of_int restrictions) ^ "\nMENV:\n" ^
390 NCicPp.ppmetasenv ~subst metasenv ^ "\nSUBST:\n" ^
391 NCicPp.ppsubst subst ~metasenv);
394 len1 - low_gap - high_gap + max 0 (k - shift1) in
395 assert (if shift1 > k then
396 shift1 + low_gap - shift = 0 else true);
398 NCic.Meta(newmeta,(shift1 + low_gap - shift,
401 let _, cctx, _ = NCicUtils.lookup_meta newmeta metasenv in
402 assert (List.length cctx = newlc_len);
403 (metasenv, subst), meta
405 | NCic.Irl _, NCic.Irl _ when shift = 0 -> ms, orig
406 | NCic.Irl _, NCic.Irl _ ->
407 ms, NCic.Meta (i, (max 0 (shift1 - shift), lc1))
409 let lc1 = NCicUtils.expand_local_context lc1 in
410 let lc1 = List.map (NCicSubstitution.lift shift1) lc1 in
411 let rec deliftl tbr j ms = function
414 let ms, tbr, tl = deliftl tbr (j+1) ms tl in
416 let ms, t = aux k ms t in
419 | NotInTheList | MetaSubstFailure _ -> ms, j::tbr, tl
421 let (metasenv, subst), to_be_r, lc1' = deliftl [] 1 ms lc1 in
423 prerr_endline ("TO BE RESTRICTED: " ^
424 (String.concat "," (List.map string_of_int to_be_r)));
426 let l1 = pack_lc (0, NCic.Ctx lc1') in
428 prerr_endline ("newmeta:" ^ NCicPp.ppterm
429 ~metasenv ~subst ~context (NCic.Meta (999,l1)));
433 (if lc1' = lc1 then orig else NCic.Meta (i,l1))
435 let metasenv, subst, newmeta =
436 restrict metasenv subst i to_be_r in
437 (metasenv, subst), NCic.Meta(newmeta,l1))
439 | t -> NCicUntrusted.map_term_fold_a (fun _ k -> k+1) k aux ms t
441 try aux 0 (metasenv,subst) t
443 (* This is the case where we fail even first order unification. *)
444 (* The reason is that our delift function is weaker than first *)
445 (* order (in the sense of alpha-conversion). See comment above *)
446 (* related to the delift function. *)
447 let msg = (lazy (Printf.sprintf
448 ("Error trying to abstract %s over [%s]: the algorithm only tried to "^^
449 "abstract over bound variables") (NCicPp.ppterm ~metasenv ~subst
450 ~context t) (String.concat "; " (List.map (NCicPp.ppterm ~metasenv
451 ~subst ~context) (let shift, lc = l in List.map (NCicSubstitution.lift
452 shift) (NCicUtils.expand_local_context lc))))))
455 let lc = NCicUtils.expand_local_context lc in
456 let l = List.map (NCicSubstitution.lift shift) lc in
459 (fun t -> NCicUntrusted.metas_of_term subst context t = [])
462 raise (Uncertain msg)
464 raise (MetaSubstFailure msg)
468 (* delifts a term t of n levels strating from k, that is changes (Rel m)
469 * to (Rel (m - n)) when m > (k + n). if k <= m < k + n delift fails
471 let delift_rels_from subst metasenv k n =
472 let rec liftaux subst metasenv k =
473 let module C = Cic in
478 else if m < k + n then
479 raise DeliftingARelWouldCaptureAFreeVariable
481 C.Rel (m - n), subst, metasenv
482 | C.Var (uri,exp_named_subst) ->
483 let exp_named_subst',subst,metasenv =
485 (fun (uri,t) (l,subst,metasenv) ->
486 let t',subst,metasenv = liftaux subst metasenv k t in
487 (uri,t')::l,subst,metasenv) exp_named_subst ([],subst,metasenv)
489 C.Var (uri,exp_named_subst'),subst,metasenv
492 let (_, t,_) = lookup_subst i subst in
493 liftaux subst metasenv k (CicSubstitution.subst_meta l t)
494 with CicUtil.Subst_not_found _ ->
495 let l',to_be_restricted,subst,metasenv =
496 let rec aux con l subst metasenv =
498 [] -> [],[],subst,metasenv
500 let tl',to_be_restricted,subst,metasenv =
501 aux (con + 1) tl subst metasenv in
502 let he',more_to_be_restricted,subst,metasenv =
504 None -> None,[],subst,metasenv
507 let t',subst,metasenv = liftaux subst metasenv k t in
508 Some t',[],subst,metasenv
510 DeliftingARelWouldCaptureAFreeVariable ->
511 None,[i,con],subst,metasenv
513 he'::tl',more_to_be_restricted@to_be_restricted,subst,metasenv
515 aux 1 l subst metasenv in
516 let metasenv,subst = restrict subst to_be_restricted metasenv in
517 C.Meta(i,l'),subst,metasenv)
518 | C.Sort _ as t -> t,subst,metasenv
519 | C.Implicit _ as t -> t,subst,metasenv
521 let te',subst,metasenv = liftaux subst metasenv k te in
522 let ty',subst,metasenv = liftaux subst metasenv k ty in
523 C.Cast (te',ty'),subst,metasenv
525 let s',subst,metasenv = liftaux subst metasenv k s in
526 let t',subst,metasenv = liftaux subst metasenv (k+1) t in
527 C.Prod (n,s',t'),subst,metasenv
528 | C.Lambda (n,s,t) ->
529 let s',subst,metasenv = liftaux subst metasenv k s in
530 let t',subst,metasenv = liftaux subst metasenv (k+1) t in
531 C.Lambda (n,s',t'),subst,metasenv
532 | C.LetIn (n,s,ty,t) ->
533 let s',subst,metasenv = liftaux subst metasenv k s in
534 let ty',subst,metasenv = liftaux subst metasenv k ty in
535 let t',subst,metasenv = liftaux subst metasenv (k+1) t in
536 C.LetIn (n,s',ty',t'),subst,metasenv
538 let l',subst,metasenv =
540 (fun t (l,subst,metasenv) ->
541 let t',subst,metasenv = liftaux subst metasenv k t in
542 t'::l,subst,metasenv) l ([],subst,metasenv) in
543 C.Appl l',subst,metasenv
544 | C.Const (uri,exp_named_subst) ->
545 let exp_named_subst',subst,metasenv =
547 (fun (uri,t) (l,subst,metasenv) ->
548 let t',subst,metasenv = liftaux subst metasenv k t in
549 (uri,t')::l,subst,metasenv) exp_named_subst ([],subst,metasenv)
551 C.Const (uri,exp_named_subst'),subst,metasenv
552 | C.MutInd (uri,tyno,exp_named_subst) ->
553 let exp_named_subst',subst,metasenv =
555 (fun (uri,t) (l,subst,metasenv) ->
556 let t',subst,metasenv = liftaux subst metasenv k t in
557 (uri,t')::l,subst,metasenv) exp_named_subst ([],subst,metasenv)
559 C.MutInd (uri,tyno,exp_named_subst'),subst,metasenv
560 | C.MutConstruct (uri,tyno,consno,exp_named_subst) ->
561 let exp_named_subst',subst,metasenv =
563 (fun (uri,t) (l,subst,metasenv) ->
564 let t',subst,metasenv = liftaux subst metasenv k t in
565 (uri,t')::l,subst,metasenv) exp_named_subst ([],subst,metasenv)
567 C.MutConstruct (uri,tyno,consno,exp_named_subst'),subst,metasenv
568 | C.MutCase (sp,i,outty,t,pl) ->
569 let outty',subst,metasenv = liftaux subst metasenv k outty in
570 let t',subst,metasenv = liftaux subst metasenv k t in
571 let pl',subst,metasenv =
573 (fun t (l,subst,metasenv) ->
574 let t',subst,metasenv = liftaux subst metasenv k t in
575 t'::l,subst,metasenv) pl ([],subst,metasenv)
577 C.MutCase (sp,i,outty',t',pl'),subst,metasenv
579 let len = List.length fl in
580 let liftedfl,subst,metasenv =
582 (fun (name, i, ty, bo) (l,subst,metasenv) ->
583 let ty',subst,metasenv = liftaux subst metasenv k ty in
584 let bo',subst,metasenv = liftaux subst metasenv (k+len) bo in
585 (name,i,ty',bo')::l,subst,metasenv
586 ) fl ([],subst,metasenv)
588 C.Fix (i, liftedfl),subst,metasenv
590 let len = List.length fl in
591 let liftedfl,subst,metasenv =
593 (fun (name, ty, bo) (l,subst,metasenv) ->
594 let ty',subst,metasenv = liftaux subst metasenv k ty in
595 let bo',subst,metasenv = liftaux subst metasenv (k+len) bo in
596 (name,ty',bo')::l,subst,metasenv
597 ) fl ([],subst,metasenv)
599 C.CoFix (i, liftedfl),subst,metasenv
601 liftaux subst metasenv k
603 let delift_rels subst metasenv n t =
604 delift_rels_from subst metasenv 1 n t
607 let mk_meta ?name metasenv context ty =
610 let n = newmeta () in
611 let ty = NCic.Implicit (`Typeof n) in
612 let menv_entry = (n, (name, context, ty)) in
613 menv_entry :: metasenv,NCic.Meta (n, (0,NCic.Irl (List.length context))), ty
616 let context_for_ty = if ty = `Type then [] else context in
617 let n = newmeta () in
618 let ty_menv_entry = (n, (name,context_for_ty, NCic.Implicit (`Typeof n))) in
619 let m = newmeta () in
620 let ty = NCic.Meta (n, (0,NCic.Irl (List.length context_for_ty))) in
621 let menv_entry = (m, (name, context, ty)) in
622 menv_entry :: ty_menv_entry :: metasenv,
623 NCic.Meta (m, (0,NCic.Irl (List.length context))), ty
625 let n = newmeta () in
626 let len = List.length context in
627 let menv_entry = (n, (name, context, ty)) in
628 menv_entry :: metasenv, NCic.Meta (n, (0,NCic.Irl len)), ty
631 let saturate ?(delta=0) metasenv context ty goal_arity =
632 assert (goal_arity >= 0);
633 let rec aux metasenv = function
634 | NCic.Prod (name,s,t) ->
635 let metasenv1, arg,_ =
636 mk_meta ~name:name metasenv context (`WithType s) in
637 let t, metasenv1, args, pno =
638 aux metasenv1 (NCicSubstitution.subst arg t)
640 if pno + 1 = goal_arity then
641 ty, metasenv, [], goal_arity+1
643 t, metasenv1, arg::args, pno+1
645 match NCicReduction.whd context ty ~delta with
646 | NCic.Prod _ as ty -> aux metasenv ty
647 | ty -> ty, metasenv, [], 0
649 let res, newmetasenv, arguments, _ = aux metasenv ty in
650 res, newmetasenv, arguments