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_______________________________________________________________ *)
12 (* $Id: nCicReduction.ml 8250 2008-03-25 17:56:20Z tassi $ *)
14 (* web interface stuff *)
17 ref (function (`Start_type_checking _|`Type_checking_completed _) -> ())
20 let set_logger f = logger := f;;
22 exception TypeCheckerFailure of string Lazy.t
23 exception AssertFailure of string Lazy.t
25 let shift_k e (c,rf,x,safes) =
26 e::c,List.map (fun (k,v) -> k+1,v) rf,x+1,List.map ((+)1) safes
29 (* $Id: cicTypeChecker.ml 8213 2008-03-13 18:48:26Z sacerdot $ *)
32 exception CicEnvironmentError;;
34 (*CSC l'indice x dei tipi induttivi e' t.c. n < x <= nn *)
35 (*CSC questa funzione e' simile alla are_all_occurrences_positive, ma fa *)
36 (*CSC dei controlli leggermente diversi. Viene invocata solamente dalla *)
37 (*CSC strictly_positive *)
38 (*CSC definizione (giusta???) tratta dalla mail di Hugo ;-) *)
39 and weakly_positive context n nn uri te =
41 (*CSC: Che schifo! Bisogna capire meglio e trovare una soluzione ragionevole!*)
43 C.MutInd (HelmLibraryObjects.Datatypes.nat_URI,0,[])
45 (*CSC: mettere in cicSubstitution *)
46 let rec subst_inductive_type_with_dummy_mutind =
48 C.MutInd (uri',0,_) when UriManager.eq uri' uri ->
50 | C.Appl ((C.MutInd (uri',0,_))::tl) when UriManager.eq uri' uri ->
52 | C.Cast (te,ty) -> subst_inductive_type_with_dummy_mutind te
53 | C.Prod (name,so,ta) ->
54 C.Prod (name, subst_inductive_type_with_dummy_mutind so,
55 subst_inductive_type_with_dummy_mutind ta)
56 | C.Lambda (name,so,ta) ->
57 C.Lambda (name, subst_inductive_type_with_dummy_mutind so,
58 subst_inductive_type_with_dummy_mutind ta)
60 C.Appl (List.map subst_inductive_type_with_dummy_mutind tl)
61 | C.MutCase (uri,i,outtype,term,pl) ->
63 subst_inductive_type_with_dummy_mutind outtype,
64 subst_inductive_type_with_dummy_mutind term,
65 List.map subst_inductive_type_with_dummy_mutind pl)
67 C.Fix (i,List.map (fun (name,i,ty,bo) -> (name,i,
68 subst_inductive_type_with_dummy_mutind ty,
69 subst_inductive_type_with_dummy_mutind bo)) fl)
71 C.CoFix (i,List.map (fun (name,ty,bo) -> (name,
72 subst_inductive_type_with_dummy_mutind ty,
73 subst_inductive_type_with_dummy_mutind bo)) fl)
74 | C.Const (uri,exp_named_subst) ->
75 let exp_named_subst' =
77 (function (uri,t) -> (uri,subst_inductive_type_with_dummy_mutind t))
80 C.Const (uri,exp_named_subst')
81 | C.MutInd (uri,typeno,exp_named_subst) ->
82 let exp_named_subst' =
84 (function (uri,t) -> (uri,subst_inductive_type_with_dummy_mutind t))
87 C.MutInd (uri,typeno,exp_named_subst')
88 | C.MutConstruct (uri,typeno,consno,exp_named_subst) ->
89 let exp_named_subst' =
91 (function (uri,t) -> (uri,subst_inductive_type_with_dummy_mutind t))
94 C.MutConstruct (uri,typeno,consno,exp_named_subst')
97 match CicReduction.whd context te with
99 C.Appl ((C.MutInd (uri',0,_))::tl) when UriManager.eq uri' uri -> true
101 C.Appl ((C.MutInd (uri',_,_))::tl) when UriManager.eq uri' uri -> true
102 | C.MutInd (uri',0,_) when UriManager.eq uri' uri -> true
103 | C.Prod (C.Anonymous,source,dest) ->
104 strictly_positive context n nn
105 (subst_inductive_type_with_dummy_mutind source) &&
106 weakly_positive ((Some (C.Anonymous,(C.Decl source)))::context)
107 (n + 1) (nn + 1) uri dest
108 | C.Prod (name,source,dest) when
109 does_not_occur ((Some (name,(C.Decl source)))::context) 0 n dest ->
110 (* dummy abstraction, so we behave as in the anonimous case *)
111 strictly_positive context n nn
112 (subst_inductive_type_with_dummy_mutind source) &&
113 weakly_positive ((Some (name,(C.Decl source)))::context)
114 (n + 1) (nn + 1) uri dest
115 | C.Prod (name,source,dest) ->
116 does_not_occur context n nn
117 (subst_inductive_type_with_dummy_mutind source)&&
118 weakly_positive ((Some (name,(C.Decl source)))::context)
119 (n + 1) (nn + 1) uri dest
121 raise (TypeCheckerFailure (lazy "Malformed inductive constructor type"))
123 (* instantiate_parameters ps (x1:T1)...(xn:Tn)C *)
124 (* returns ((x_|ps|:T_|ps|)...(xn:Tn)C){ps_1 / x1 ; ... ; ps_|ps| / x_|ps|} *)
125 and instantiate_parameters params c =
126 let module C = Cic in
127 match (c,params) with
129 | (C.Prod (_,_,ta), he::tl) ->
130 instantiate_parameters tl
131 (CicSubstitution.subst he ta)
132 | (C.Cast (te,_), _) -> instantiate_parameters params te
133 | (t,l) -> raise (AssertFailure (lazy "1"))
135 and strictly_positive context n nn te =
136 let module C = Cic in
137 let module U = UriManager in
138 match CicReduction.whd context te with
139 | t when does_not_occur context n nn t -> true
142 (*CSC: bisogna controllare ty????*)
143 strictly_positive context n nn te
144 | C.Prod (name,so,ta) ->
145 does_not_occur context n nn so &&
146 strictly_positive ((Some (name,(C.Decl so)))::context) (n+1) (nn+1) ta
147 | C.Appl ((C.Rel m)::tl) when m > n && m <= nn ->
148 List.fold_right (fun x i -> i && does_not_occur context n nn x) tl true
149 | C.Appl ((C.MutInd (uri,i,exp_named_subst))::tl) ->
150 let (ok,paramsno,ity,cl,name) =
151 let o,_ = CicEnvironment.get_obj CicUniv.empty_ugraph uri in
153 C.InductiveDefinition (tl,_,paramsno,_) ->
154 let (name,_,ity,cl) = List.nth tl i in
155 (List.length tl = 1, paramsno, ity, cl, name)
156 (* (true, paramsno, ity, cl, name) *)
160 (lazy ("Unknown inductive type:" ^ U.string_of_uri uri)))
162 let (params,arguments) = split tl paramsno in
163 let lifted_params = List.map (CicSubstitution.lift 1) params in
167 instantiate_parameters lifted_params
168 (CicSubstitution.subst_vars exp_named_subst te)
173 (fun x i -> i && does_not_occur context n nn x)
175 (*CSC: MEGAPATCH3 (sara' quella giusta?)*)
180 ((Some (C.Name name,(Cic.Decl ity)))::context) (n+1) (nn+1) uri
185 (* the inductive type indexes are s.t. n < x <= nn *)
186 and are_all_occurrences_positive context uri indparamsno i n nn te =
187 let module C = Cic in
188 match CicReduction.whd context te with
189 C.Appl ((C.Rel m)::tl) when m = i ->
190 (*CSC: riscrivere fermandosi a 0 *)
191 (* let's check if the inductive type is applied at least to *)
192 (* indparamsno parameters *)
198 match CicReduction.whd context x with
199 C.Rel m when m = n - (indparamsno - k) -> k - 1
201 raise (TypeCheckerFailure
203 ("Non-positive occurence in mutual inductive definition(s) [1]" ^
204 UriManager.string_of_uri uri)))
208 List.fold_right (fun x i -> i && does_not_occur context n nn x) tl true
210 raise (TypeCheckerFailure
211 (lazy ("Non-positive occurence in mutual inductive definition(s) [2]"^
212 UriManager.string_of_uri uri)))
213 | C.Rel m when m = i ->
214 if indparamsno = 0 then
217 raise (TypeCheckerFailure
218 (lazy ("Non-positive occurence in mutual inductive definition(s) [3]"^
219 UriManager.string_of_uri uri)))
220 | C.Prod (C.Anonymous,source,dest) ->
221 let b = strictly_positive context n nn source in
223 are_all_occurrences_positive
224 ((Some (C.Anonymous,(C.Decl source)))::context) uri indparamsno
225 (i+1) (n + 1) (nn + 1) dest
226 | C.Prod (name,source,dest) when
227 does_not_occur ((Some (name,(C.Decl source)))::context) 0 n dest ->
228 (* dummy abstraction, so we behave as in the anonimous case *)
229 strictly_positive context n nn source &&
230 are_all_occurrences_positive
231 ((Some (name,(C.Decl source)))::context) uri indparamsno
232 (i+1) (n + 1) (nn + 1) dest
233 | C.Prod (name,source,dest) ->
234 does_not_occur context n nn source &&
235 are_all_occurrences_positive ((Some (name,(C.Decl source)))::context)
236 uri indparamsno (i+1) (n + 1) (nn + 1) dest
239 (TypeCheckerFailure (lazy ("Malformed inductive constructor type " ^
240 (UriManager.string_of_uri uri))))
242 (* Main function to checks the correctness of a mutual *)
243 (* inductive block definition. This is the function *)
244 (* exported to the proof-engine. *)
245 and typecheck_mutual_inductive_defs ~logger uri (itl,_,indparamsno) ugraph =
246 let module U = UriManager in
247 (* let's check if the arity of the inductive types are well *)
249 let ugrap1 = List.fold_left
250 (fun ugraph (_,_,x,_) -> let _,ugraph' =
251 type_of ~logger x ugraph in ugraph')
254 (* let's check if the types of the inductive constructors *)
255 (* are well formed. *)
256 (* In order not to use type_of_aux we put the types of the *)
257 (* mutual inductive types at the head of the types of the *)
258 (* constructors using Prods *)
259 let len = List.length itl in
261 List.map (fun (n,_,ty,_) -> Some (Cic.Name n,(Cic.Decl ty))) itl in
264 (fun (_,_,_,cl) (i,ugraph) ->
267 (fun ugraph (name,te) ->
268 let debruijnedte = debruijn uri len te in
271 (fun (name,_,ty,_) i -> Cic.Prod (Cic.Name name, ty, i))
274 let _,ugraph' = type_of ~logger augmented_term ugraph in
275 (* let's check also the positivity conditions *)
278 (are_all_occurrences_positive tys uri indparamsno i 0 len
282 prerr_endline (UriManager.string_of_uri uri);
283 prerr_endline (string_of_int (List.length tys));
286 (lazy ("Non positive occurence in " ^ U.string_of_uri uri))) end
295 (* Main function to checks the correctness of a mutual *)
296 (* inductive block definition. *)
297 and check_mutual_inductive_defs uri obj ugraph =
299 Cic.InductiveDefinition (itl, params, indparamsno, _) ->
300 typecheck_mutual_inductive_defs uri (itl,params,indparamsno) ugraph
302 raise (TypeCheckerFailure (
303 lazy ("Unknown mutual inductive definition:" ^
304 UriManager.string_of_uri uri)))
306 (* the boolean h means already protected *)
307 (* args is the list of arguments the type of the constructor that may be *)
308 (* found in head position must be applied to. *)
309 and guarded_by_constructors ~subst context n nn h te args coInductiveTypeURI =
310 let module C = Cic in
311 (*CSC: There is a lot of code replication between the cases X and *)
312 (*CSC: (C.Appl X tl). Maybe it will be better to define a function *)
313 (*CSC: that maps X into (C.Appl X []) when X is not already a C.Appl *)
314 match CicReduction.whd ~subst context te with
315 C.Rel m when m > n && m <= nn -> h
323 (* the term has just been type-checked *)
324 raise (AssertFailure (lazy "17"))
325 | C.Lambda (name,so,de) ->
326 does_not_occur ~subst context n nn so &&
327 guarded_by_constructors ~subst ((Some (name,(C.Decl so)))::context)
328 (n + 1) (nn + 1) h de args coInductiveTypeURI
329 | C.Appl ((C.Rel m)::tl) when m > n && m <= nn ->
331 List.fold_right (fun x i -> i && does_not_occur ~subst context n nn x) tl true
332 | C.Appl ((C.MutConstruct (uri,i,j,exp_named_subst))::tl) ->
336 CicEnvironment.get_cooked_obj ~trust:false CicUniv.empty_ugraph uri
337 with Not_found -> assert false
340 C.InductiveDefinition (itl,_,_,_) ->
341 let (_,_,_,cl) = List.nth itl i in
342 let (_,cons) = List.nth cl (j - 1) in
343 CicSubstitution.subst_vars exp_named_subst cons
345 raise (TypeCheckerFailure
346 (lazy ("Unknown mutual inductive definition:" ^ UriManager.string_of_uri uri)))
348 let rec analyse_branch context ty te =
349 match CicReduction.whd ~subst context ty with
350 C.Meta _ -> raise (AssertFailure (lazy "34"))
354 does_not_occur ~subst context n nn te
357 raise (AssertFailure (lazy "24"))(* due to type-checking *)
358 | C.Prod (name,so,de) ->
359 analyse_branch ((Some (name,(C.Decl so)))::context) de te
362 raise (AssertFailure (lazy "25"))(* due to type-checking *)
363 | C.Appl ((C.MutInd (uri,_,_))::_) when uri == coInductiveTypeURI ->
364 guarded_by_constructors ~subst context n nn true te []
366 | C.Appl ((C.MutInd (uri,_,_))::_) ->
367 guarded_by_constructors ~subst context n nn true te tl
370 does_not_occur ~subst context n nn te
371 | C.Const _ -> raise (AssertFailure (lazy "26"))
372 | C.MutInd (uri,_,_) when uri == coInductiveTypeURI ->
373 guarded_by_constructors ~subst context n nn true te []
376 does_not_occur ~subst context n nn te
377 | C.MutConstruct _ -> raise (AssertFailure (lazy "27"))
378 (*CSC: we do not consider backbones with a MutCase, Fix, Cofix *)
379 (*CSC: in head position. *)
383 raise (AssertFailure (lazy "28"))(* due to type-checking *)
385 let rec analyse_instantiated_type context ty l =
386 match CicReduction.whd ~subst context ty with
392 | C.Cast _ -> raise (AssertFailure (lazy "29"))(* due to type-checking *)
393 | C.Prod (name,so,de) ->
398 analyse_branch context so he &&
399 analyse_instantiated_type
400 ((Some (name,(C.Decl so)))::context) de tl
404 raise (AssertFailure (lazy "30"))(* due to type-checking *)
407 (fun i x -> i && does_not_occur ~subst context n nn x) true l
408 | C.Const _ -> raise (AssertFailure (lazy "31"))
411 (fun i x -> i && does_not_occur ~subst context n nn x) true l
412 | C.MutConstruct _ -> raise (AssertFailure (lazy "32"))
413 (*CSC: we do not consider backbones with a MutCase, Fix, Cofix *)
414 (*CSC: in head position. *)
418 raise (AssertFailure (lazy "33"))(* due to type-checking *)
420 let rec instantiate_type args consty =
424 let consty' = CicReduction.whd ~subst context consty in
430 let instantiated_de = CicSubstitution.subst he de in
431 (*CSC: siamo sicuri che non sia troppo forte? *)
432 does_not_occur ~subst context n nn tlhe &
433 instantiate_type tl instantiated_de tltl
435 (*CSC:We do not consider backbones with a MutCase, a *)
436 (*CSC:FixPoint, a CoFixPoint and so on in head position.*)
437 raise (AssertFailure (lazy "23"))
439 | [] -> analyse_instantiated_type context consty' l
440 (* These are all the other cases *)
442 instantiate_type args consty tl
443 | C.Appl ((C.CoFix (_,fl))::tl) ->
444 List.fold_left (fun i x -> i && does_not_occur ~subst context n nn x) true tl &&
445 let len = List.length fl in
446 let n_plus_len = n + len
447 and nn_plus_len = nn + len
448 (*CSC: Is a Decl of the ty ok or should I use Def of a Fix? *)
451 (fun (types,len) (n,ty,_) ->
452 (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types,
458 i && does_not_occur ~subst context n nn ty &&
459 guarded_by_constructors ~subst (tys@context) n_plus_len nn_plus_len
460 h bo args coInductiveTypeURI
462 | C.Appl ((C.MutCase (_,_,out,te,pl))::tl) ->
463 List.fold_left (fun i x -> i && does_not_occur ~subst context n nn x) true tl &&
464 does_not_occur ~subst context n nn out &&
465 does_not_occur ~subst context n nn te &&
469 guarded_by_constructors ~subst context n nn h x args
473 List.fold_right (fun x i -> i && does_not_occur ~subst context n nn x) l true
474 | C.Var (_,exp_named_subst)
475 | C.Const (_,exp_named_subst) ->
477 (fun (_,x) i -> i && does_not_occur ~subst context n nn x) exp_named_subst true
478 | C.MutInd _ -> assert false
479 | C.MutConstruct (_,_,_,exp_named_subst) ->
481 (fun (_,x) i -> i && does_not_occur ~subst context n nn x) exp_named_subst true
482 | C.MutCase (_,_,out,te,pl) ->
483 does_not_occur ~subst context n nn out &&
484 does_not_occur ~subst context n nn te &&
488 guarded_by_constructors ~subst context n nn h x args
492 let len = List.length fl in
493 let n_plus_len = n + len
494 and nn_plus_len = nn + len
495 (*CSC: Is a Decl of the ty ok or should I use Def of a Fix? *)
498 (fun (types,len) (n,_,ty,_) ->
499 (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types,
504 (fun (_,_,ty,bo) i ->
505 i && does_not_occur ~subst context n nn ty &&
506 does_not_occur ~subst (tys@context) n_plus_len nn_plus_len bo
509 let len = List.length fl in
510 let n_plus_len = n + len
511 and nn_plus_len = nn + len
512 (*CSC: Is a Decl of the ty ok or should I use Def of a Fix? *)
515 (fun (types,len) (n,ty,_) ->
516 (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types,
522 i && does_not_occur ~subst context n nn ty &&
523 guarded_by_constructors ~subst (tys@context) n_plus_len nn_plus_len
525 args coInductiveTypeURI
529 type_of_aux ~logger context t ugraph
533 (** wrappers which instantiate fresh loggers *)
535 (* check_allowed_sort_elimination uri i s1 s2
536 This function is used outside the kernel to determine in advance whether
537 a MutCase will be allowed or not.
538 [uri,i] is the type of the term to match
539 [s1] is the sort of the term to eliminate (i.e. the head of the arity
540 of the inductive type [uri,i])
541 [s2] is the sort of the goal (i.e. the head of the type of the outtype
543 let check_allowed_sort_elimination uri i s1 s2 =
544 fst (check_allowed_sort_elimination ~subst:[] ~metasenv:[]
545 ~logger:(new CicLogger.logger) [] uri i true
546 (Cic.Implicit None) (* never used *) (Cic.Sort s1) (Cic.Sort s2)
547 CicUniv.empty_ugraph)
550 Deannotate.type_of_aux' := fun context t -> fst (type_of_aux' [] context t CicUniv.oblivion_ugraph);;
555 module R = NCicReduction
556 module Ref = NReference
557 module S = NCicSubstitution
559 module E = NCicEnvironment
561 let rec split_prods ~subst context n te =
562 match (n, R.whd ~subst context te) with
563 | (0, _) -> context,te
564 | (n, C.Prod (name,so,ta)) when n > 0 ->
565 split_prods ~subst ((name,(C.Decl so))::context) (n - 1) ta
566 | (_, _) -> raise (AssertFailure (lazy "split_prods"))
569 let debruijn ?(cb=fun _ _ -> ()) uri number_of_types =
573 | C.Meta (i,(s,C.Ctx l)) ->
574 let l1 = NCicUtils.sharing_map (aux (k-s)) l in
575 if l1 == l then t else C.Meta (i,(s,C.Ctx l1))
577 | C.Const (Ref.Ref (_,uri1,(Ref.Fix (no,_) | Ref.CoFix no)))
578 | C.Const (Ref.Ref (_,uri1,Ref.Ind no)) when NUri.eq uri uri1 ->
579 C.Rel (k + number_of_types - no)
580 | t -> NCicUtils.map (fun _ k -> k+1) k aux t
587 let sort_of_prod ~metasenv ~subst context (name,s) (t1, t2) =
588 let t1 = R.whd ~subst context t1 in
589 let t2 = R.whd ~subst ((name,C.Decl s)::context) t2 in
591 | C.Sort s1, C.Sort C.Prop -> t2
592 | C.Sort (C.Type u1), C.Sort (C.Type u2) -> C.Sort (C.Type (max u1 u2))
593 | C.Sort _,C.Sort (C.Type _) -> t2
594 | C.Sort (C.Type _) , C.Sort C.CProp -> t1
595 | C.Sort _, C.Sort C.CProp -> t2
598 | C.Sort _, C.Meta _ when U.is_closed t2 -> t2
600 raise (TypeCheckerFailure (lazy (Printf.sprintf
601 "Prod: expected two sorts, found = %s, %s"
602 (NCicPp.ppterm ~subst ~metasenv ~context t1)
603 (NCicPp.ppterm ~subst ~metasenv ~context t2))))
606 let eat_prods ~subst ~metasenv context ty_he args_with_ty =
607 let rec aux ty_he = function
609 | (arg, ty_arg)::tl ->
610 (match R.whd ~subst context ty_he with
613 prerr_endline (NCicPp.ppterm ~context s ^ " - Vs - " ^ NCicPp.ppterm
615 prerr_endline (NCicPp.ppterm ~context (S.subst ~avoid_beta_redexes:true arg t));
617 if R.are_convertible ~subst ~metasenv context ty_arg s then
618 aux (S.subst ~avoid_beta_redexes:true arg t) tl
622 (lazy (Printf.sprintf
623 ("Appl: wrong parameter-type, expected %s, found %s")
624 (NCicPp.ppterm ~subst ~metasenv ~context ty_arg)
625 (NCicPp.ppterm ~subst ~metasenv ~context s))))
629 (lazy "Appl: this is not a function, it cannot be applied")))
631 aux ty_he args_with_ty
634 let fix_lefts_in_constrs ~subst uri paramsno tyl i =
635 let len = List.length tyl in
636 let _,_,arity,cl = List.nth tyl i in
637 let tys = List.map (fun (_,n,ty,_) -> n,C.Decl ty) tyl in
641 let debruijnedty = debruijn uri len ty in
642 id, snd (split_prods ~subst tys paramsno ty),
643 snd (split_prods ~subst tys paramsno debruijnedty))
646 let lefts = fst (split_prods ~subst [] paramsno arity) in
650 exception DoesOccur;;
652 let does_not_occur ~subst context n nn t =
653 let rec aux (context,n,nn as k) _ = function
654 | C.Rel m when m > n && m <= nn -> raise DoesOccur
656 (try (match List.nth context (m-1) with
657 | _,C.Def (bo,_) -> aux k () (S.lift m bo)
659 with Failure _ -> assert false)
660 | C.Meta (_,(_,(C.Irl 0 | C.Ctx []))) -> (* closed meta *) ()
661 | C.Meta (mno,(s,l)) ->
663 let _,_,term,_ = U.lookup_subst mno subst in
664 aux (context,n+s,nn+s) () (S.subst_meta (0,l) term)
665 with CicUtil.Subst_not_found _ -> match l with
666 | C.Irl len -> if not (n >= s+len || s > nn) then raise DoesOccur
667 | C.Ctx lc -> List.iter (aux (context,n+s,nn+s) ()) lc)
668 | t -> U.fold (fun e (ctx,n,nn) -> (e::ctx,n+1,nn+1)) k aux () t
670 try aux (context,n,nn) () t; true
671 with DoesOccur -> false
674 exception NotGuarded of string Lazy.t;;
676 let rec typeof ~subst ~metasenv context term =
677 let rec typeof_aux context =
678 fun t -> (*prerr_endline (NCicPp.ppterm ~context t); *)
682 match List.nth context (n - 1) with
683 | (_,C.Decl ty) -> S.lift n ty
684 | (_,C.Def (_,ty)) -> S.lift n ty
685 with Failure _ -> raise (TypeCheckerFailure (lazy "unbound variable")))
686 | C.Sort (C.Type i) -> C.Sort (C.Type (i+1))
687 | C.Sort s -> C.Sort (C.Type 0)
688 | C.Implicit _ -> raise (AssertFailure (lazy "Implicit found"))
689 | C.Meta (n,l) as t ->
690 let canonical_ctx,ty =
692 let _,c,_,ty = U.lookup_subst n subst in c,ty
693 with U.Subst_not_found _ -> try
694 let _,_,c,ty = U.lookup_meta n metasenv in c,ty
695 with U.Meta_not_found _ ->
696 raise (AssertFailure (lazy (Printf.sprintf
697 "%s not found" (NCicPp.ppterm ~subst ~metasenv ~context t))))
699 check_metasenv_consistency t ~subst ~metasenv context canonical_ctx l;
701 | C.Const ref -> type_of_constant ref
702 | C.Prod (name,s,t) ->
703 let sort1 = typeof_aux context s in
704 let sort2 = typeof_aux ((name,(C.Decl s))::context) t in
705 sort_of_prod ~metasenv ~subst context (name,s) (sort1,sort2)
706 | C.Lambda (n,s,t) ->
707 let sort = typeof_aux context s in
708 (match R.whd ~subst context sort with
709 | C.Meta _ | C.Sort _ -> ()
712 (TypeCheckerFailure (lazy (Printf.sprintf
713 ("Not well-typed lambda-abstraction: " ^^
714 "the source %s should be a type; instead it is a term " ^^
715 "of type %s") (NCicPp.ppterm ~subst ~metasenv ~context s)
716 (NCicPp.ppterm ~subst ~metasenv ~context sort)))));
717 let ty = typeof_aux ((n,(C.Decl s))::context) t in
719 | C.LetIn (n,ty,t,bo) ->
720 let ty_t = typeof_aux context t in
721 if not (R.are_convertible ~subst ~metasenv context ty ty_t) then
724 (lazy (Printf.sprintf
725 "The type of %s is %s but it is expected to be %s"
726 (NCicPp.ppterm ~subst ~metasenv ~context t)
727 (NCicPp.ppterm ~subst ~metasenv ~context ty_t)
728 (NCicPp.ppterm ~subst ~metasenv ~context ty))))
730 let ty_bo = typeof_aux ((n,C.Def (t,ty))::context) bo in
731 S.subst ~avoid_beta_redexes:true t ty_bo
732 | C.Appl (he::(_::_ as args)) ->
733 let ty_he = typeof_aux context he in
734 let args_with_ty = List.map (fun t -> t, typeof_aux context t) args in
736 prerr_endline ("HEAD: " ^ NCicPp.ppterm ~context ty_he);
737 prerr_endline ("TARGS: " ^ String.concat " | " (List.map (NCicPp.ppterm
738 ~context) (List.map snd args_with_ty)));
739 prerr_endline ("ARGS: " ^ String.concat " | " (List.map (NCicPp.ppterm
740 ~context) (List.map fst args_with_ty)));
742 eat_prods ~subst ~metasenv context ty_he args_with_ty
743 | C.Appl _ -> raise (AssertFailure (lazy "Appl of length < 2"))
744 | C.Match (Ref.Ref (_,_,Ref.Ind tyno) as r,outtype,term,pl) ->
745 let outsort = typeof_aux context outtype in
746 let leftno = E.get_indty_leftno r in
747 let parameters, arguments =
748 let ty = R.whd ~subst context (typeof_aux context term) in
751 C.Const (Ref.Ref (_,_,Ref.Ind _) as r') -> r',[]
752 | C.Appl (C.Const (Ref.Ref (_,_,Ref.Ind _) as r') :: tl) -> r',tl
755 (TypeCheckerFailure (lazy (Printf.sprintf
756 "Case analysis: analysed term %s is not an inductive one"
757 (NCicPp.ppterm ~subst ~metasenv ~context term)))) in
758 if not (Ref.eq r r') then
760 (TypeCheckerFailure (lazy (Printf.sprintf
761 ("Case analysys: analysed term type is %s, but is expected " ^^
762 "to be (an application of) %s")
763 (NCicPp.ppterm ~subst ~metasenv ~context ty)
764 (NCicPp.ppterm ~subst ~metasenv ~context (C.Const r')))))
766 try HExtlib.split_nth leftno tl
769 raise (TypeCheckerFailure (lazy (Printf.sprintf
770 "%s is partially applied"
771 (NCicPp.ppterm ~subst ~metasenv ~context ty)))) in
772 (* let's control if the sort elimination is allowed: [(I q1 ... qr)|B] *)
773 let sort_of_ind_type =
774 if parameters = [] then C.Const r
775 else C.Appl ((C.Const r)::parameters) in
776 let type_of_sort_of_ind_ty = typeof_aux context sort_of_ind_type in
777 if not (check_allowed_sort_elimination ~subst ~metasenv r context
778 sort_of_ind_type type_of_sort_of_ind_ty outsort)
779 then raise (TypeCheckerFailure (lazy ("Sort elimination not allowed")));
780 (* let's check if the type of branches are right *)
781 let leftno,constructorsno =
782 let inductive,leftno,itl,_,i = E.get_checked_indtys r in
783 let _,name,ty,cl = List.nth itl i in
784 let cl_len = List.length cl in
787 if List.length pl <> constructorsno then
788 raise (TypeCheckerFailure (lazy ("Wrong number of cases in a match")));
789 let j,branches_ok,p_ty, exp_p_ty =
791 (fun (j,b,old_p_ty,old_exp_p_ty) p ->
794 let cons = Ref.mk_constructor j r in
795 if parameters = [] then C.Const cons
796 else C.Appl (C.Const cons::parameters)
798 let ty_p = typeof_aux context p in
799 let ty_cons = typeof_aux context cons in
801 type_of_branch ~subst context leftno outtype cons ty_cons 0
803 j+1, R.are_convertible ~subst ~metasenv context ty_p ty_branch,
806 j,false,old_p_ty,old_exp_p_ty
807 ) (1,true,C.Sort C.Prop,C.Sort C.Prop) pl
809 if not branches_ok then
812 (lazy (Printf.sprintf ("Branch for constructor %s :=\n%s\n"^^
813 "has type %s\nnot convertible with %s")
814 (NCicPp.ppterm ~subst ~metasenv ~context
815 (C.Const (Ref.mk_constructor j r)))
816 (NCicPp.ppterm ~metasenv ~subst ~context (List.nth pl (j-1)))
817 (NCicPp.ppterm ~metasenv ~subst ~context p_ty)
818 (NCicPp.ppterm ~metasenv ~subst ~context exp_p_ty))));
819 let res = outtype::arguments@[term] in
820 R.head_beta_reduce (C.Appl res)
821 | C.Match _ -> assert false
823 and type_of_branch ~subst context leftno outty cons tycons liftno =
824 match R.whd ~subst context tycons with
825 | C.Const (Ref.Ref (_,_,Ref.Ind _)) -> C.Appl [S.lift liftno outty ; cons]
826 | C.Appl (C.Const (Ref.Ref (_,_,Ref.Ind _))::tl) ->
827 let _,arguments = HExtlib.split_nth leftno tl in
828 C.Appl (S.lift liftno outty::arguments@[cons])
829 | C.Prod (name,so,de) ->
831 match S.lift 1 cons with
832 | C.Appl l -> C.Appl (l@[C.Rel 1])
833 | t -> C.Appl [t ; C.Rel 1]
836 type_of_branch ~subst ((name,(C.Decl so))::context)
837 leftno outty cons de (liftno+1))
838 | _ -> raise (AssertFailure (lazy "type_of_branch"))
840 (* check_metasenv_consistency checks that the "canonical" context of a
841 metavariable is consitent - up to relocation via the relocation list l -
842 with the actual context *)
843 and check_metasenv_consistency
844 ~subst ~metasenv term context canonical_context l
847 | shift, NCic.Irl n ->
848 let context = snd (HExtlib.split_nth shift context) in
849 let rec compare = function
853 raise (AssertFailure (lazy (Printf.sprintf
854 "Local and canonical context %s have different lengths"
855 (NCicPp.ppterm ~subst ~context ~metasenv term))))
857 raise (TypeCheckerFailure (lazy (Printf.sprintf
858 "Unbound variable -%d in %s" m
859 (NCicPp.ppterm ~subst ~metasenv ~context term))))
862 (_,C.Decl t1), (_,C.Decl t2)
863 | (_,C.Def (t1,_)), (_,C.Def (t2,_))
864 | (_,C.Def (_,t1)), (_,C.Decl t2) ->
865 if not (R.are_convertible ~subst ~metasenv tl t1 t2) then
868 (lazy (Printf.sprintf
869 ("Not well typed metavariable local context for %s: " ^^
870 "%s expected, which is not convertible with %s")
871 (NCicPp.ppterm ~subst ~metasenv ~context term)
872 (NCicPp.ppterm ~subst ~metasenv ~context t2)
873 (NCicPp.ppterm ~subst ~metasenv ~context t1))))
876 (TypeCheckerFailure (lazy (Printf.sprintf
877 ("Not well typed metavariable local context for %s: " ^^
878 "a definition expected, but a declaration found")
879 (NCicPp.ppterm ~subst ~metasenv ~context term)))));
880 compare (m - 1,tl,ctl)
882 compare (n,context,canonical_context)
884 (* we avoid useless lifting by shortening the context*)
885 let l,context = (0,lc_kind), snd (HExtlib.split_nth shift context) in
886 let lifted_canonical_context =
887 let rec lift_metas i = function
889 | (n,C.Decl t)::tl ->
890 (n,C.Decl (S.subst_meta l (S.lift i t)))::(lift_metas (i+1) tl)
891 | (n,C.Def (t,ty))::tl ->
892 (n,C.Def ((S.subst_meta l (S.lift i t)),
893 S.subst_meta l (S.lift i ty)))::(lift_metas (i+1) tl)
895 lift_metas 1 canonical_context in
896 let l = U.expand_local_context lc_kind in
901 | t, (_,C.Def (ct,_)) ->
902 (*CSC: the following optimization is to avoid a possibly expensive
903 reduction that can be easily avoided and that is quite
904 frequent. However, this is better handled using levels to
910 match List.nth context (n - 1) with
911 | (_,C.Def (te,_)) -> S.lift n te
916 if not (R.are_convertible ~subst ~metasenv context optimized_t ct)
920 (lazy (Printf.sprintf
921 ("Not well typed metavariable local context: " ^^
922 "expected a term convertible with %s, found %s")
923 (NCicPp.ppterm ~subst ~metasenv ~context ct)
924 (NCicPp.ppterm ~subst ~metasenv ~context t))))
925 | t, (_,C.Decl ct) ->
926 let type_t = typeof_aux context t in
927 if not (R.are_convertible ~subst ~metasenv context type_t ct) then
928 raise (TypeCheckerFailure
929 (lazy (Printf.sprintf
930 ("Not well typed metavariable local context: "^^
931 "expected a term of type %s, found %s of type %s")
932 (NCicPp.ppterm ~subst ~metasenv ~context ct)
933 (NCicPp.ppterm ~subst ~metasenv ~context t)
934 (NCicPp.ppterm ~subst ~metasenv ~context type_t))))
935 ) l lifted_canonical_context
937 Invalid_argument _ ->
938 raise (AssertFailure (lazy (Printf.sprintf
939 "Local and canonical context %s have different lengths"
940 (NCicPp.ppterm ~subst ~metasenv ~context term))))
942 and is_non_informative context paramsno c =
943 let rec aux context c =
944 match R.whd context c with
945 | C.Prod (n,so,de) ->
946 let s = typeof_aux context so in
947 s = C.Sort C.Prop && aux ((n,(C.Decl so))::context) de
949 let context',dx = split_prods ~subst:[] context paramsno c in
952 and check_allowed_sort_elimination ~subst ~metasenv r =
955 | C.Appl l -> C.Appl (l @ [arg])
956 | t -> C.Appl [t;arg] in
957 let rec aux context ind arity1 arity2 =
958 let arity1 = R.whd ~subst context arity1 in
959 let arity2 = R.whd ~subst context arity2 in
960 match arity1,arity2 with
961 | C.Prod (name,so1,de1), C.Prod (_,so2,de2) ->
962 R.are_convertible ~subst ~metasenv context so1 so2 &&
963 aux ((name, C.Decl so1)::context)
964 (mkapp (S.lift 1 ind) (C.Rel 1)) de1 de2
965 | C.Sort _, C.Prod (name,so,ta) ->
966 (R.are_convertible ~subst ~metasenv context so ind &&
968 | (C.Sort (C.CProp | C.Type _), C.Sort _)
969 | (C.Sort C.Prop, C.Sort C.Prop) -> true
970 | (C.Sort C.Prop, C.Sort (C.CProp | C.Type _)) ->
971 let inductive,leftno,itl,_,i = E.get_checked_indtys r in
972 let itl_len = List.length itl in
973 let _,name,ty,cl = List.nth itl i in
974 let cl_len = List.length cl in
975 (* is it a singleton or empty non recursive and non informative
978 (itl_len = 1 && cl_len = 1 &&
979 is_non_informative [name,C.Decl ty] leftno
980 (let _,_,x = List.nth cl 0 in x))
987 typeof_aux context term
989 and check_mutual_inductive_defs _ = ()
991 and eat_lambdas ~subst ~metasenv context n te =
992 match (n, R.whd ~subst context te) with
993 | (0, _) -> (te, context)
994 | (n, C.Lambda (name,so,ta)) when n > 0 ->
995 eat_lambdas ~subst ~metasenv ((name,(C.Decl so))::context) (n - 1) ta
997 raise (AssertFailure (lazy (Printf.sprintf "9 (%d, %s)" n
998 (NCicPp.ppterm ~subst ~metasenv ~context te))))
1000 and guarded_by_destructors ~subst ~metasenv context recfuns t =
1001 let recursor f k t = NCicUtils.fold shift_k k (fun k () -> f k) () t in
1002 let rec aux (context, recfuns, x, safes as k) = function
1003 | C.Rel m as t when List.mem_assoc m recfuns ->
1004 raise (NotGuarded (lazy
1005 (NCicPp.ppterm ~subst ~metasenv ~context t ^ " passed around")))
1007 (match List.nth context (m-1) with
1009 | _,C.Def (bo,_) -> aux (context, recfuns, x, safes) (S.lift m bo))
1011 | C.Appl ((C.Rel m)::tl) as t when List.mem_assoc m recfuns ->
1012 let rec_no = List.assoc m recfuns in
1013 if not (List.length tl > rec_no) then
1014 raise (NotGuarded (lazy
1015 (NCicPp.ppterm ~context ~subst ~metasenv t ^
1016 " is a partial application of a fix")))
1018 let rec_arg = List.nth tl rec_no in
1019 if not (is_really_smaller ~subst k rec_arg) then
1020 raise (NotGuarded (lazy
1021 (NCicPp.ppterm ~context ~subst ~metasenv rec_arg ^ " not smaller")));
1022 List.iter (aux k) tl
1023 | C.Match (Ref.Ref (_,uri,_) as ref,outtype,term,pl) as t ->
1024 (match R.whd ~subst context term with
1025 | C.Rel m | C.Appl (C.Rel m :: _ ) as t when List.mem m safes || m = x ->
1026 let isinductive, paramsno, tl, _, i = E.get_checked_indtys ref in
1027 if not isinductive then recursor aux k t
1029 let c_ctx,len,cl = fix_lefts_in_constrs ~subst uri paramsno tl i in
1030 let args = match t with C.Appl (_::tl) -> tl | _ -> [] in
1032 List.iter (aux k) args;
1034 (fun p (_,_,bruijnedc) ->
1035 let rl = recursive_args ~subst c_ctx 0 len bruijnedc in
1036 let p, k = get_new_safes ~subst k p rl in
1039 | _ -> recursor aux k t)
1040 | t -> recursor aux k t
1042 try aux (context, recfuns, 1, []) t
1043 with NotGuarded s -> raise (TypeCheckerFailure s)
1047 let len = List.length fl in
1048 let n_plus_len = n + len
1049 and nn_plus_len = nn + len
1050 and x_plus_len = x + len
1053 (fun (types,len) (n,_,ty,_) ->
1054 (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types,
1057 and safes' = List.map (fun x -> x + len) safes in
1059 (fun (_,_,ty,bo) i ->
1060 i && guarded_by_destructors ~subst context n nn kl x_plus_len safes' ty &&
1061 guarded_by_destructors ~subst (tys@context) n_plus_len nn_plus_len kl
1062 x_plus_len safes' bo
1064 | C.CoFix (_, fl) ->
1065 let len = List.length fl in
1066 let n_plus_len = n + len
1067 and nn_plus_len = nn + len
1068 and x_plus_len = x + len
1071 (fun (types,len) (n,ty,_) ->
1072 (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types,
1075 and safes' = List.map (fun x -> x + len) safes in
1079 guarded_by_destructors ~subst context n nn kl x_plus_len safes' ty &&
1080 guarded_by_destructors ~subst (tys@context) n_plus_len nn_plus_len kl
1081 x_plus_len safes' bo
1085 and guarded_by_constructors ~subst _ _ _ _ _ _ _ = assert false
1087 and recursive_args ~subst context n nn te =
1088 match R.whd context te with
1090 | C.Prod (name,so,de) ->
1091 (not (does_not_occur ~subst context n nn so)) ::
1092 (recursive_args ~subst ((name,(C.Decl so))::context) (n+1) (nn + 1) de)
1093 | _ -> raise (AssertFailure (lazy ("recursive_args")))
1095 and get_new_safes ~subst (context, recfuns, x, safes as k) p rl =
1096 match R.whd ~subst context p, rl with
1097 | C.Lambda (name,so,ta), b::tl ->
1098 let safes = (if b then [0] else []) @ safes in
1099 get_new_safes ~subst
1100 (shift_k (name,(C.Decl so)) (context, recfuns, x, safes)) ta tl
1101 | C.Meta _ as e, _ | e, [] -> e, k
1102 | _ -> raise (AssertFailure (lazy "Ill formed pattern"))
1104 and split_prods ~subst context n te =
1105 match n, R.whd ~subst context te with
1106 | 0, _ -> context,te
1107 | n, C.Prod (name,so,ta) when n > 0 ->
1108 split_prods ~subst ((name,(C.Decl so))::context) (n - 1) ta
1109 | _ -> raise (AssertFailure (lazy "split_prods"))
1111 and is_really_smaller ~subst (context, recfuns, x, safes as k) te =
1112 match R.whd ~subst context te with
1113 | C.Rel m when List.mem m safes -> true
1115 | C.LetIn _ -> raise (AssertFailure (lazy "letin after whd"))
1116 | C.Sort _ | C.Implicit _ | C.Prod _ | C.Lambda _
1117 | C.Const (Ref.Ref (_,_,(Ref.Decl | Ref.Def | Ref.Ind _ | Ref.CoFix _))) ->
1118 raise (AssertFailure (lazy "not a constructor"))
1119 | C.Appl ([]|[_]) -> raise (AssertFailure (lazy "empty/unary appl"))
1121 (*CSC: sulla coda ci vogliono dei controlli? secondo noi no, ma *)
1122 (*CSC: solo perche' non abbiamo trovato controesempi *)
1123 (*TASSI: da capire soprattutto se he รจ un altro fix che non ha ridotto...*)
1124 is_really_smaller ~subst k he
1125 | C.Const (Ref.Ref (_,_,Ref.Con _)) -> false
1126 | C.Const (Ref.Ref (_,_,Ref.Fix _)) -> assert false
1127 (*| C.Fix (_, fl) ->
1128 let len = List.length fl in
1129 let n_plus_len = n + len
1130 and nn_plus_len = nn + len
1131 and x_plus_len = x + len
1134 (fun (types,len) (n,_,ty,_) ->
1135 (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types,
1138 and safes' = List.map (fun x -> x + len) safes in
1140 (fun (_,_,ty,bo) i ->
1142 is_really_smaller ~subst (tys@context) n_plus_len nn_plus_len kl
1143 x_plus_len safes' bo
1146 true (* XXX if this check is repeated when the user completes the
1148 | C.Match (Ref.Ref (_,uri,_) as ref,outtype,term,pl) ->
1150 | C.Rel m | C.Appl (C.Rel m :: _ ) when List.mem m safes || m = x ->
1151 let isinductive, paramsno, tl, _, i = E.get_checked_indtys ref in
1152 if not isinductive then
1153 List.for_all (is_really_smaller ~subst k) pl
1155 let c_ctx,len,cl = fix_lefts_in_constrs ~subst uri paramsno tl i in
1157 (fun p (_,_,debruijnedte) ->
1158 let rl' = recursive_args ~subst c_ctx 0 len debruijnedte in
1159 let e, k = get_new_safes ~subst k p rl' in
1160 is_really_smaller ~subst k e)
1162 | _ -> List.for_all (is_really_smaller ~subst k) pl)
1164 and returns_a_coinductive ~subst context ty =
1165 match R.whd ~subst context ty with
1166 | C.Const (Ref.Ref (_,uri,Ref.Ind _) as ref)
1167 | C.Appl (C.Const (Ref.Ref (_,uri,Ref.Ind _) as ref)::_) ->
1168 let isinductive, _, _, _, _ = E.get_checked_indtys ref in
1169 if isinductive then None else (Some uri)
1170 | C.Prod (n,so,de) ->
1171 returns_a_coinductive ~subst ((n,C.Decl so)::context) de
1174 and type_of_constant ((Ref.Ref (_,uri,_)) as ref) =
1176 match E.get_obj uri with
1177 | true, cobj -> cobj
1179 !logger (`Start_type_checking uri);
1180 check_obj_well_typed uobj;
1182 !logger (`Type_checking_completed uri);
1183 if not (fst (E.get_obj uri)) then
1184 raise (AssertFailure (lazy "environment error"));
1187 match cobj, ref with
1188 | (_,_,_,_,C.Inductive (_,_,tl,_)), Ref.Ref (_,_,Ref.Ind i) ->
1189 let _,_,arity,_ = List.nth tl i in arity
1190 | (_,_,_,_,C.Inductive (_,_,tl,_)), Ref.Ref (_,_,Ref.Con (i,j)) ->
1191 let _,_,_,cl = List.nth tl i in
1192 let _,_,arity = List.nth cl (j-1) in
1194 | (_,_,_,_,C.Fixpoint (_,fl,_)), Ref.Ref (_,_,(Ref.Fix (i,_)|Ref.CoFix i)) ->
1195 let _,_,_,arity,_ = List.nth fl i in
1197 | (_,_,_,_,C.Constant (_,_,_,ty,_)), Ref.Ref (_,_,(Ref.Def |Ref.Decl)) -> ty
1198 | _ -> raise (AssertFailure (lazy "type_of_constant: environment/reference"))
1200 and check_obj_well_typed (uri,height,metasenv,subst,kind) =
1201 (* CSC: here we should typecheck the metasenv and the subst *)
1202 assert (metasenv = [] && subst = []);
1204 | C.Constant (_,_,Some te,ty,_) ->
1205 prerr_endline ("TY: " ^ NCicPp.ppterm ~subst ~metasenv ~context:[] ty);
1206 prerr_endline ("BO: " ^ NCicPp.ppterm ~subst ~metasenv ~context:[] te);
1207 let _ = typeof ~subst ~metasenv [] ty in
1208 let ty_te = typeof ~subst ~metasenv [] te in
1209 prerr_endline "XXXX";
1210 if not (R.are_convertible ~subst ~metasenv [] ty_te ty) then
1211 raise (TypeCheckerFailure (lazy (Printf.sprintf
1212 "the type of the body is not the one expected:\n%s\nvs\n%s"
1213 (NCicPp.ppterm ~subst ~metasenv ~context:[] ty_te)
1214 (NCicPp.ppterm ~subst ~metasenv ~context:[] ty))))
1215 | C.Constant (_,_,None,ty,_) -> ignore (typeof ~subst ~metasenv [] ty)
1216 | C.Inductive _ as obj -> check_mutual_inductive_defs obj
1217 | C.Fixpoint (inductive,fl,_) ->
1220 (fun (types,kl,len) (_,name,k,ty,_) ->
1221 let _ = typeof ~subst ~metasenv [] ty in
1222 ((name,(C.Decl (S.lift len ty)))::types, k::kl,len+1)
1225 List.iter (fun (_,name,x,ty,bo) ->
1226 let bo = debruijn uri len bo in
1227 let ty_bo = typeof ~subst ~metasenv types bo in
1228 if not (R.are_convertible ~subst ~metasenv types ty_bo (S.lift len ty))
1229 then raise (TypeCheckerFailure (lazy ("(Co)Fix: ill-typed bodies")))
1231 if inductive then begin
1232 let m, context = eat_lambdas ~subst ~metasenv types (x + 1) bo in
1233 (* guarded by destructors conditions D{f,k,x,M} *)
1234 let rec enum_from k =
1235 function [] -> [] | v::tl -> (k,v)::enum_from (k+1) tl
1237 guarded_by_destructors
1238 ~subst ~metasenv context (enum_from (x+2) kl) m
1240 match returns_a_coinductive ~subst [] ty with
1242 raise (TypeCheckerFailure
1243 (lazy "CoFix: does not return a coinductive type"))
1245 (* guarded by constructors conditions C{f,M} *)
1246 if not (guarded_by_constructors ~subst ~metasenv
1247 types 0 len false bo [] uri)
1249 raise (TypeCheckerFailure
1250 (lazy "CoFix: not guarded by constructors"))
1253 let typecheck_obj = check_obj_well_typed;;