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 (* the boolean h means already protected *)
243 (* args is the list of arguments the type of the constructor that may be *)
244 (* found in head position must be applied to. *)
245 and guarded_by_constructors ~subst context n nn h te args coInductiveTypeURI =
246 let module C = Cic in
247 (*CSC: There is a lot of code replication between the cases X and *)
248 (*CSC: (C.Appl X tl). Maybe it will be better to define a function *)
249 (*CSC: that maps X into (C.Appl X []) when X is not already a C.Appl *)
250 match CicReduction.whd ~subst context te with
251 C.Rel m when m > n && m <= nn -> h
259 (* the term has just been type-checked *)
260 raise (AssertFailure (lazy "17"))
261 | C.Lambda (name,so,de) ->
262 does_not_occur ~subst context n nn so &&
263 guarded_by_constructors ~subst ((Some (name,(C.Decl so)))::context)
264 (n + 1) (nn + 1) h de args coInductiveTypeURI
265 | C.Appl ((C.Rel m)::tl) when m > n && m <= nn ->
267 List.fold_right (fun x i -> i && does_not_occur ~subst context n nn x) tl true
268 | C.Appl ((C.MutConstruct (uri,i,j,exp_named_subst))::tl) ->
272 CicEnvironment.get_cooked_obj ~trust:false CicUniv.empty_ugraph uri
273 with Not_found -> assert false
276 C.InductiveDefinition (itl,_,_,_) ->
277 let (_,_,_,cl) = List.nth itl i in
278 let (_,cons) = List.nth cl (j - 1) in
279 CicSubstitution.subst_vars exp_named_subst cons
281 raise (TypeCheckerFailure
282 (lazy ("Unknown mutual inductive definition:" ^ UriManager.string_of_uri uri)))
284 let rec analyse_branch context ty te =
285 match CicReduction.whd ~subst context ty with
286 C.Meta _ -> raise (AssertFailure (lazy "34"))
290 does_not_occur ~subst context n nn te
293 raise (AssertFailure (lazy "24"))(* due to type-checking *)
294 | C.Prod (name,so,de) ->
295 analyse_branch ((Some (name,(C.Decl so)))::context) de te
298 raise (AssertFailure (lazy "25"))(* due to type-checking *)
299 | C.Appl ((C.MutInd (uri,_,_))::_) when uri == coInductiveTypeURI ->
300 guarded_by_constructors ~subst context n nn true te []
302 | C.Appl ((C.MutInd (uri,_,_))::_) ->
303 guarded_by_constructors ~subst context n nn true te tl
306 does_not_occur ~subst context n nn te
307 | C.Const _ -> raise (AssertFailure (lazy "26"))
308 | C.MutInd (uri,_,_) when uri == coInductiveTypeURI ->
309 guarded_by_constructors ~subst context n nn true te []
312 does_not_occur ~subst context n nn te
313 | C.MutConstruct _ -> raise (AssertFailure (lazy "27"))
314 (*CSC: we do not consider backbones with a MutCase, Fix, Cofix *)
315 (*CSC: in head position. *)
319 raise (AssertFailure (lazy "28"))(* due to type-checking *)
321 let rec analyse_instantiated_type context ty l =
322 match CicReduction.whd ~subst context ty with
328 | C.Cast _ -> raise (AssertFailure (lazy "29"))(* due to type-checking *)
329 | C.Prod (name,so,de) ->
334 analyse_branch context so he &&
335 analyse_instantiated_type
336 ((Some (name,(C.Decl so)))::context) de tl
340 raise (AssertFailure (lazy "30"))(* due to type-checking *)
343 (fun i x -> i && does_not_occur ~subst context n nn x) true l
344 | C.Const _ -> raise (AssertFailure (lazy "31"))
347 (fun i x -> i && does_not_occur ~subst context n nn x) true l
348 | C.MutConstruct _ -> raise (AssertFailure (lazy "32"))
349 (*CSC: we do not consider backbones with a MutCase, Fix, Cofix *)
350 (*CSC: in head position. *)
354 raise (AssertFailure (lazy "33"))(* due to type-checking *)
356 let rec instantiate_type args consty =
360 let consty' = CicReduction.whd ~subst context consty in
366 let instantiated_de = CicSubstitution.subst he de in
367 (*CSC: siamo sicuri che non sia troppo forte? *)
368 does_not_occur ~subst context n nn tlhe &
369 instantiate_type tl instantiated_de tltl
371 (*CSC:We do not consider backbones with a MutCase, a *)
372 (*CSC:FixPoint, a CoFixPoint and so on in head position.*)
373 raise (AssertFailure (lazy "23"))
375 | [] -> analyse_instantiated_type context consty' l
376 (* These are all the other cases *)
378 instantiate_type args consty tl
379 | C.Appl ((C.CoFix (_,fl))::tl) ->
380 List.fold_left (fun i x -> i && does_not_occur ~subst context n nn x) true tl &&
381 let len = List.length fl in
382 let n_plus_len = n + len
383 and nn_plus_len = nn + len
384 (*CSC: Is a Decl of the ty ok or should I use Def of a Fix? *)
387 (fun (types,len) (n,ty,_) ->
388 (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types,
394 i && does_not_occur ~subst context n nn ty &&
395 guarded_by_constructors ~subst (tys@context) n_plus_len nn_plus_len
396 h bo args coInductiveTypeURI
398 | C.Appl ((C.MutCase (_,_,out,te,pl))::tl) ->
399 List.fold_left (fun i x -> i && does_not_occur ~subst context n nn x) true tl &&
400 does_not_occur ~subst context n nn out &&
401 does_not_occur ~subst context n nn te &&
405 guarded_by_constructors ~subst context n nn h x args
409 List.fold_right (fun x i -> i && does_not_occur ~subst context n nn x) l true
410 | C.Var (_,exp_named_subst)
411 | C.Const (_,exp_named_subst) ->
413 (fun (_,x) i -> i && does_not_occur ~subst context n nn x) exp_named_subst true
414 | C.MutInd _ -> assert false
415 | C.MutConstruct (_,_,_,exp_named_subst) ->
417 (fun (_,x) i -> i && does_not_occur ~subst context n nn x) exp_named_subst true
418 | C.MutCase (_,_,out,te,pl) ->
419 does_not_occur ~subst context n nn out &&
420 does_not_occur ~subst context n nn te &&
424 guarded_by_constructors ~subst context n nn h x args
428 let len = List.length fl in
429 let n_plus_len = n + len
430 and nn_plus_len = nn + len
431 (*CSC: Is a Decl of the ty ok or should I use Def of a Fix? *)
434 (fun (types,len) (n,_,ty,_) ->
435 (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types,
440 (fun (_,_,ty,bo) i ->
441 i && does_not_occur ~subst context n nn ty &&
442 does_not_occur ~subst (tys@context) n_plus_len nn_plus_len bo
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
461 args coInductiveTypeURI
465 type_of_aux ~logger context t ugraph
469 (** wrappers which instantiate fresh loggers *)
471 (* check_allowed_sort_elimination uri i s1 s2
472 This function is used outside the kernel to determine in advance whether
473 a MutCase will be allowed or not.
474 [uri,i] is the type of the term to match
475 [s1] is the sort of the term to eliminate (i.e. the head of the arity
476 of the inductive type [uri,i])
477 [s2] is the sort of the goal (i.e. the head of the type of the outtype
479 let check_allowed_sort_elimination uri i s1 s2 =
480 fst (check_allowed_sort_elimination ~subst:[] ~metasenv:[]
481 ~logger:(new CicLogger.logger) [] uri i true
482 (Cic.Implicit None) (* never used *) (Cic.Sort s1) (Cic.Sort s2)
483 CicUniv.empty_ugraph)
486 Deannotate.type_of_aux' := fun context t -> fst (type_of_aux' [] context t CicUniv.oblivion_ugraph);;
491 module R = NCicReduction
492 module Ref = NReference
493 module S = NCicSubstitution
495 module E = NCicEnvironment
497 let rec split_prods ~subst context n te =
498 match (n, R.whd ~subst context te) with
499 | (0, _) -> context,te
500 | (n, C.Prod (name,so,ta)) when n > 0 ->
501 split_prods ~subst ((name,(C.Decl so))::context) (n - 1) ta
502 | (_, _) -> raise (AssertFailure (lazy "split_prods"))
505 let debruijn ?(cb=fun _ _ -> ()) uri number_of_types =
509 | C.Meta (i,(s,C.Ctx l)) ->
510 let l1 = NCicUtils.sharing_map (aux (k-s)) l in
511 if l1 == l then t else C.Meta (i,(s,C.Ctx l1))
513 | C.Const (Ref.Ref (_,uri1,(Ref.Fix (no,_) | Ref.CoFix no)))
514 | C.Const (Ref.Ref (_,uri1,Ref.Ind no)) when NUri.eq uri uri1 ->
515 C.Rel (k + number_of_types - no)
516 | t -> NCicUtils.map (fun _ k -> k+1) k aux t
523 let sort_of_prod ~metasenv ~subst context (name,s) (t1, t2) =
524 let t1 = R.whd ~subst context t1 in
525 let t2 = R.whd ~subst ((name,C.Decl s)::context) t2 in
527 | C.Sort s1, C.Sort C.Prop -> t2
528 | C.Sort (C.Type u1), C.Sort (C.Type u2) -> C.Sort (C.Type (max u1 u2))
529 | C.Sort _,C.Sort (C.Type _) -> t2
530 | C.Sort (C.Type _) , C.Sort C.CProp -> t1
531 | C.Sort _, C.Sort C.CProp -> t2
534 | C.Sort _, C.Meta _ when U.is_closed t2 -> t2
536 raise (TypeCheckerFailure (lazy (Printf.sprintf
537 "Prod: expected two sorts, found = %s, %s"
538 (NCicPp.ppterm ~subst ~metasenv ~context t1)
539 (NCicPp.ppterm ~subst ~metasenv ~context t2))))
542 let eat_prods ~subst ~metasenv context he ty_he args_with_ty =
543 let rec aux ty_he = function
545 | (arg, ty_arg)::tl ->
546 match R.whd ~subst context ty_he with
549 prerr_endline (NCicPp.ppterm ~subst ~metasenv ~context s ^ " - Vs - "
550 ^ NCicPp.ppterm ~subst ~metasenv
552 prerr_endline (NCicPp.ppterm ~subst ~metasenv ~context (S.subst ~avoid_beta_redexes:true arg t));
554 if R.are_convertible ~subst ~metasenv context ty_arg s then
555 aux (S.subst ~avoid_beta_redexes:true arg t) tl
559 (lazy (Printf.sprintf
560 ("Appl: wrong parameter-type, expected\n%s\nfound\n%s")
561 (NCicPp.ppterm ~subst ~metasenv ~context s)
562 (NCicPp.ppterm ~subst ~metasenv ~context ty_arg))))
566 (lazy (Printf.sprintf
567 "Appl: %s is not a function, it cannot be applied"
568 (NCicPp.ppterm ~subst ~metasenv ~context
569 (let res = List.length tl in
570 let eaten = List.length args_with_ty - res in
573 (fst (HExtlib.split_nth eaten args_with_ty)))))))))
575 aux ty_he args_with_ty
578 let fix_lefts_in_constrs ~subst uri paramsno tyl i =
579 let len = List.length tyl in
580 let _,_,arity,cl = List.nth tyl i in
581 let tys = List.map (fun (_,n,ty,_) -> n,C.Decl ty) tyl in
585 let debruijnedty = debruijn uri len ty in
586 id, snd (split_prods ~subst tys paramsno ty),
587 snd (split_prods ~subst tys paramsno debruijnedty))
590 let lefts = fst (split_prods ~subst [] paramsno arity) in
594 exception DoesOccur;;
596 let does_not_occur ~subst context n nn t =
597 let rec aux (context,n,nn as k) _ = function
598 | C.Rel m when m > n && m <= nn -> raise DoesOccur
600 (try (match List.nth context (m-1) with
601 | _,C.Def (bo,_) -> aux k () (S.lift m bo)
603 with Failure _ -> assert false)
604 | C.Meta (_,(_,(C.Irl 0 | C.Ctx []))) -> (* closed meta *) ()
605 | C.Meta (mno,(s,l)) ->
607 let _,_,term,_ = U.lookup_subst mno subst in
608 aux (context,n+s,nn+s) () (S.subst_meta (0,l) term)
609 with CicUtil.Subst_not_found _ -> match l with
610 | C.Irl len -> if not (n >= s+len || s > nn) then raise DoesOccur
611 | C.Ctx lc -> List.iter (aux (context,n+s,nn+s) ()) lc)
612 | t -> U.fold (fun e (ctx,n,nn) -> (e::ctx,n+1,nn+1)) k aux () t
614 try aux (context,n,nn) () t; true
615 with DoesOccur -> false
618 exception NotGuarded of string Lazy.t;;
620 let rec typeof ~subst ~metasenv context term =
621 let rec typeof_aux context =
622 fun t -> (*prerr_endline (NCicPp.ppterm ~context t); *)
626 match List.nth context (n - 1) with
627 | (_,C.Decl ty) -> S.lift n ty
628 | (_,C.Def (_,ty)) -> S.lift n ty
629 with Failure _ -> raise (TypeCheckerFailure (lazy "unbound variable")))
630 | C.Sort (C.Type i) -> C.Sort (C.Type (i+1))
631 | C.Sort s -> C.Sort (C.Type 0)
632 | C.Implicit _ -> raise (AssertFailure (lazy "Implicit found"))
633 | C.Meta (n,l) as t ->
634 let canonical_ctx,ty =
636 let _,c,_,ty = U.lookup_subst n subst in c,ty
637 with U.Subst_not_found _ -> try
638 let _,_,c,ty = U.lookup_meta n metasenv in c,ty
639 with U.Meta_not_found _ ->
640 raise (AssertFailure (lazy (Printf.sprintf
641 "%s not found" (NCicPp.ppterm ~subst ~metasenv ~context t))))
643 check_metasenv_consistency t ~subst ~metasenv context canonical_ctx l;
645 | C.Const ref -> type_of_constant ref
646 | C.Prod (name,s,t) ->
647 let sort1 = typeof_aux context s in
648 let sort2 = typeof_aux ((name,(C.Decl s))::context) t in
649 sort_of_prod ~metasenv ~subst context (name,s) (sort1,sort2)
650 | C.Lambda (n,s,t) ->
651 let sort = typeof_aux context s in
652 (match R.whd ~subst context sort with
653 | C.Meta _ | C.Sort _ -> ()
656 (TypeCheckerFailure (lazy (Printf.sprintf
657 ("Not well-typed lambda-abstraction: " ^^
658 "the source %s should be a type; instead it is a term " ^^
659 "of type %s") (NCicPp.ppterm ~subst ~metasenv ~context s)
660 (NCicPp.ppterm ~subst ~metasenv ~context sort)))));
661 let ty = typeof_aux ((n,(C.Decl s))::context) t in
663 | C.LetIn (n,ty,t,bo) ->
664 let ty_t = typeof_aux context t in
665 let _ = typeof_aux context ty in
666 if not (R.are_convertible ~subst ~metasenv context ty ty_t) then
669 (lazy (Printf.sprintf
670 "The type of %s is %s but it is expected to be %s"
671 (NCicPp.ppterm ~subst ~metasenv ~context t)
672 (NCicPp.ppterm ~subst ~metasenv ~context ty_t)
673 (NCicPp.ppterm ~subst ~metasenv ~context ty))))
675 let ty_bo = typeof_aux ((n,C.Def (t,ty))::context) bo in
676 S.subst ~avoid_beta_redexes:true t ty_bo
677 | C.Appl (he::(_::_ as args)) ->
678 let ty_he = typeof_aux context he in
679 let args_with_ty = List.map (fun t -> t, typeof_aux context t) args in
681 prerr_endline ("HEAD: " ^ NCicPp.ppterm ~context ty_he);
682 prerr_endline ("TARGS: " ^ String.concat " | " (List.map (NCicPp.ppterm
683 ~context) (List.map snd args_with_ty)));
684 prerr_endline ("ARGS: " ^ String.concat " | " (List.map (NCicPp.ppterm
685 ~context) (List.map fst args_with_ty)));
687 eat_prods ~subst ~metasenv context he ty_he args_with_ty
688 | C.Appl _ -> raise (AssertFailure (lazy "Appl of length < 2"))
689 | C.Match (Ref.Ref (_,_,Ref.Ind tyno) as r,outtype,term,pl) ->
690 let outsort = typeof_aux context outtype in
691 let leftno = E.get_indty_leftno r in
692 let parameters, arguments =
693 let ty = R.whd ~subst context (typeof_aux context term) in
696 C.Const (Ref.Ref (_,_,Ref.Ind _) as r') -> r',[]
697 | C.Appl (C.Const (Ref.Ref (_,_,Ref.Ind _) as r') :: tl) -> r',tl
700 (TypeCheckerFailure (lazy (Printf.sprintf
701 "Case analysis: analysed term %s is not an inductive one"
702 (NCicPp.ppterm ~subst ~metasenv ~context term)))) in
703 if not (Ref.eq r r') then
705 (TypeCheckerFailure (lazy (Printf.sprintf
706 ("Case analysys: analysed term type is %s, but is expected " ^^
707 "to be (an application of) %s")
708 (NCicPp.ppterm ~subst ~metasenv ~context ty)
709 (NCicPp.ppterm ~subst ~metasenv ~context (C.Const r')))))
711 try HExtlib.split_nth leftno tl
714 raise (TypeCheckerFailure (lazy (Printf.sprintf
715 "%s is partially applied"
716 (NCicPp.ppterm ~subst ~metasenv ~context ty)))) in
717 (* let's control if the sort elimination is allowed: [(I q1 ... qr)|B] *)
718 let sort_of_ind_type =
719 if parameters = [] then C.Const r
720 else C.Appl ((C.Const r)::parameters) in
721 let type_of_sort_of_ind_ty = typeof_aux context sort_of_ind_type in
722 if not (check_allowed_sort_elimination ~subst ~metasenv r context
723 sort_of_ind_type type_of_sort_of_ind_ty outsort)
724 then raise (TypeCheckerFailure (lazy ("Sort elimination not allowed")));
725 (* let's check if the type of branches are right *)
726 let leftno,constructorsno =
727 let inductive,leftno,itl,_,i = E.get_checked_indtys r in
728 let _,name,ty,cl = List.nth itl i in
729 let cl_len = List.length cl in
732 if List.length pl <> constructorsno then
733 raise (TypeCheckerFailure (lazy ("Wrong number of cases in a match")));
734 let j,branches_ok,p_ty, exp_p_ty =
736 (fun (j,b,old_p_ty,old_exp_p_ty) p ->
739 let cons = Ref.mk_constructor j r in
740 if parameters = [] then C.Const cons
741 else C.Appl (C.Const cons::parameters)
743 let ty_p = typeof_aux context p in
744 let ty_cons = typeof_aux context cons in
746 type_of_branch ~subst context leftno outtype cons ty_cons 0
748 j+1, R.are_convertible ~subst ~metasenv context ty_p ty_branch,
751 j,false,old_p_ty,old_exp_p_ty
752 ) (1,true,C.Sort C.Prop,C.Sort C.Prop) pl
754 if not branches_ok then
757 (lazy (Printf.sprintf ("Branch for constructor %s :=\n%s\n"^^
758 "has type %s\nnot convertible with %s")
759 (NCicPp.ppterm ~subst ~metasenv ~context
760 (C.Const (Ref.mk_constructor (j-1) r)))
761 (NCicPp.ppterm ~metasenv ~subst ~context (List.nth pl (j-2)))
762 (NCicPp.ppterm ~metasenv ~subst ~context p_ty)
763 (NCicPp.ppterm ~metasenv ~subst ~context exp_p_ty))));
764 let res = outtype::arguments@[term] in
765 R.head_beta_reduce (C.Appl res)
766 | C.Match _ -> assert false
768 and type_of_branch ~subst context leftno outty cons tycons liftno =
769 match R.whd ~subst context tycons with
770 | C.Const (Ref.Ref (_,_,Ref.Ind _)) -> C.Appl [S.lift liftno outty ; cons]
771 | C.Appl (C.Const (Ref.Ref (_,_,Ref.Ind _))::tl) ->
772 let _,arguments = HExtlib.split_nth leftno tl in
773 C.Appl (S.lift liftno outty::arguments@[cons])
774 | C.Prod (name,so,de) ->
776 match S.lift 1 cons with
777 | C.Appl l -> C.Appl (l@[C.Rel 1])
778 | t -> C.Appl [t ; C.Rel 1]
781 type_of_branch ~subst ((name,(C.Decl so))::context)
782 leftno outty cons de (liftno+1))
783 | _ -> raise (AssertFailure (lazy "type_of_branch"))
785 (* check_metasenv_consistency checks that the "canonical" context of a
786 metavariable is consitent - up to relocation via the relocation list l -
787 with the actual context *)
788 and check_metasenv_consistency
789 ~subst ~metasenv term context canonical_context l
792 | shift, NCic.Irl n ->
793 let context = snd (HExtlib.split_nth shift context) in
794 let rec compare = function
798 raise (AssertFailure (lazy (Printf.sprintf
799 "Local and canonical context %s have different lengths"
800 (NCicPp.ppterm ~subst ~context ~metasenv term))))
802 raise (TypeCheckerFailure (lazy (Printf.sprintf
803 "Unbound variable -%d in %s" m
804 (NCicPp.ppterm ~subst ~metasenv ~context term))))
807 (_,C.Decl t1), (_,C.Decl t2)
808 | (_,C.Def (t1,_)), (_,C.Def (t2,_))
809 | (_,C.Def (_,t1)), (_,C.Decl t2) ->
810 if not (R.are_convertible ~subst ~metasenv tl t1 t2) then
813 (lazy (Printf.sprintf
814 ("Not well typed metavariable local context for %s: " ^^
815 "%s expected, which is not convertible with %s")
816 (NCicPp.ppterm ~subst ~metasenv ~context term)
817 (NCicPp.ppterm ~subst ~metasenv ~context t2)
818 (NCicPp.ppterm ~subst ~metasenv ~context t1))))
821 (TypeCheckerFailure (lazy (Printf.sprintf
822 ("Not well typed metavariable local context for %s: " ^^
823 "a definition expected, but a declaration found")
824 (NCicPp.ppterm ~subst ~metasenv ~context term)))));
825 compare (m - 1,tl,ctl)
827 compare (n,context,canonical_context)
829 (* we avoid useless lifting by shortening the context*)
830 let l,context = (0,lc_kind), snd (HExtlib.split_nth shift context) in
831 let lifted_canonical_context =
832 let rec lift_metas i = function
834 | (n,C.Decl t)::tl ->
835 (n,C.Decl (S.subst_meta l (S.lift i t)))::(lift_metas (i+1) tl)
836 | (n,C.Def (t,ty))::tl ->
837 (n,C.Def ((S.subst_meta l (S.lift i t)),
838 S.subst_meta l (S.lift i ty)))::(lift_metas (i+1) tl)
840 lift_metas 1 canonical_context in
841 let l = U.expand_local_context lc_kind in
846 | t, (_,C.Def (ct,_)) ->
847 (*CSC: the following optimization is to avoid a possibly expensive
848 reduction that can be easily avoided and that is quite
849 frequent. However, this is better handled using levels to
855 match List.nth context (n - 1) with
856 | (_,C.Def (te,_)) -> S.lift n te
861 if not (R.are_convertible ~subst ~metasenv context optimized_t ct)
865 (lazy (Printf.sprintf
866 ("Not well typed metavariable local context: " ^^
867 "expected a term convertible with %s, found %s")
868 (NCicPp.ppterm ~subst ~metasenv ~context ct)
869 (NCicPp.ppterm ~subst ~metasenv ~context t))))
870 | t, (_,C.Decl ct) ->
871 let type_t = typeof_aux context t in
872 if not (R.are_convertible ~subst ~metasenv context type_t ct) then
873 raise (TypeCheckerFailure
874 (lazy (Printf.sprintf
875 ("Not well typed metavariable local context: "^^
876 "expected a term of type %s, found %s of type %s")
877 (NCicPp.ppterm ~subst ~metasenv ~context ct)
878 (NCicPp.ppterm ~subst ~metasenv ~context t)
879 (NCicPp.ppterm ~subst ~metasenv ~context type_t))))
880 ) l lifted_canonical_context
882 Invalid_argument _ ->
883 raise (AssertFailure (lazy (Printf.sprintf
884 "Local and canonical context %s have different lengths"
885 (NCicPp.ppterm ~subst ~metasenv ~context term))))
887 and is_non_informative context paramsno c =
888 let rec aux context c =
889 match R.whd context c with
890 | C.Prod (n,so,de) ->
891 let s = typeof_aux context so in
892 s = C.Sort C.Prop && aux ((n,(C.Decl so))::context) de
894 let context',dx = split_prods ~subst:[] context paramsno c in
897 and check_allowed_sort_elimination ~subst ~metasenv r =
900 | C.Appl l -> C.Appl (l @ [arg])
901 | t -> C.Appl [t;arg] in
902 let rec aux context ind arity1 arity2 =
903 let arity1 = R.whd ~subst context arity1 in
904 let arity2 = R.whd ~subst context arity2 in
905 match arity1,arity2 with
906 | C.Prod (name,so1,de1), C.Prod (_,so2,de2) ->
907 R.are_convertible ~subst ~metasenv context so1 so2 &&
908 aux ((name, C.Decl so1)::context)
909 (mkapp (S.lift 1 ind) (C.Rel 1)) de1 de2
910 | C.Sort _, C.Prod (name,so,ta) ->
911 (R.are_convertible ~subst ~metasenv context so ind &&
913 | (C.Sort (C.CProp | C.Type _), C.Sort _)
914 | (C.Sort C.Prop, C.Sort C.Prop) -> true
915 | (C.Sort C.Prop, C.Sort (C.CProp | C.Type _)) ->
916 let inductive,leftno,itl,_,i = E.get_checked_indtys r in
917 let itl_len = List.length itl in
918 let _,name,ty,cl = List.nth itl i in
919 let cl_len = List.length cl in
920 (* is it a singleton or empty non recursive and non informative
923 (itl_len = 1 && cl_len = 1 &&
924 is_non_informative [name,C.Decl ty] leftno
925 (let _,_,x = List.nth cl 0 in x))
932 typeof_aux context term
934 and check_mutual_inductive_defs uri ~metasenv ~subst is_ind leftno tyl =
935 (* let's check if the arity of the inductive types are well formed *)
936 List.iter (fun (_,_,x,_) -> ignore (typeof ~subst ~metasenv [] x)) tyl;
937 (* let's check if the types of the inductive constructors are well formed. *)
938 let len = List.length tyl in
939 let tys = List.map (fun (_,n,ty,_) -> (n,(C.Decl ty))) tyl in
945 let debruijnedte = debruijn uri len te in
946 ignore (typeof ~subst ~metasenv tys debruijnedte);
947 (* let's check also the positivity conditions *)
950 (are_all_occurrences_positive tys uri indparamsno i 0 len
955 (lazy ("Non positive occurence in "^NUri.string_of_uri uri))))
960 and eat_lambdas ~subst ~metasenv context n te =
961 match (n, R.whd ~subst context te) with
962 | (0, _) -> (te, context)
963 | (n, C.Lambda (name,so,ta)) when n > 0 ->
964 eat_lambdas ~subst ~metasenv ((name,(C.Decl so))::context) (n - 1) ta
966 raise (AssertFailure (lazy (Printf.sprintf "9 (%d, %s)" n
967 (NCicPp.ppterm ~subst ~metasenv ~context te))))
969 and guarded_by_destructors ~subst ~metasenv context recfuns t =
970 let recursor f k t = NCicUtils.fold shift_k k (fun k () -> f k) () t in
971 let rec aux (context, recfuns, x, safes as k) = function
972 | C.Rel m as t when List.mem_assoc m recfuns ->
973 raise (NotGuarded (lazy
974 (NCicPp.ppterm ~subst ~metasenv ~context t ^ " passed around")))
976 (match List.nth context (m-1) with
978 | _,C.Def (bo,_) -> aux (context, recfuns, x, safes) (S.lift m bo))
980 | C.Appl ((C.Rel m)::tl) as t when List.mem_assoc m recfuns ->
981 let rec_no = List.assoc m recfuns in
982 if not (List.length tl > rec_no) then
983 raise (NotGuarded (lazy
984 (NCicPp.ppterm ~context ~subst ~metasenv t ^
985 " is a partial application of a fix")))
987 let rec_arg = List.nth tl rec_no in
988 if not (is_really_smaller ~subst ~metasenv k rec_arg) then
989 raise (NotGuarded (lazy
990 (NCicPp.ppterm ~context ~subst ~metasenv rec_arg ^ " not smaller")));
992 | C.Match (Ref.Ref (_,uri,_) as ref,outtype,term,pl) as t ->
993 (match R.whd ~subst context term with
994 | C.Rel m | C.Appl (C.Rel m :: _ ) as t when List.mem m safes || m = x ->
995 let isinductive, paramsno, tl, _, i = E.get_checked_indtys ref in
996 if not isinductive then recursor aux k t
998 let c_ctx,len,cl = fix_lefts_in_constrs ~subst uri paramsno tl i in
999 let args = match t with C.Appl (_::tl) -> tl | _ -> [] in
1001 List.iter (aux k) args;
1003 (fun p (_,_,bruijnedc) ->
1004 let rl = recursive_args ~subst ~metasenv c_ctx 0 len bruijnedc in
1005 let p, k = get_new_safes ~subst k p rl in
1008 | _ -> recursor aux k t)
1009 | t -> recursor aux k t
1011 try aux (context, recfuns, 1, []) t
1012 with NotGuarded s -> raise (TypeCheckerFailure s)
1016 let len = List.length fl in
1017 let n_plus_len = n + len
1018 and nn_plus_len = nn + len
1019 and x_plus_len = x + len
1022 (fun (types,len) (n,_,ty,_) ->
1023 (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types,
1026 and safes' = List.map (fun x -> x + len) safes in
1028 (fun (_,_,ty,bo) i ->
1029 i && guarded_by_destructors ~subst context n nn kl x_plus_len safes' ty &&
1030 guarded_by_destructors ~subst (tys@context) n_plus_len nn_plus_len kl
1031 x_plus_len safes' bo
1033 | C.CoFix (_, fl) ->
1034 let len = List.length fl in
1035 let n_plus_len = n + len
1036 and nn_plus_len = nn + len
1037 and x_plus_len = x + len
1040 (fun (types,len) (n,ty,_) ->
1041 (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types,
1044 and safes' = List.map (fun x -> x + len) safes in
1048 guarded_by_destructors ~subst context n nn kl x_plus_len safes' ty &&
1049 guarded_by_destructors ~subst (tys@context) n_plus_len nn_plus_len kl
1050 x_plus_len safes' bo
1054 and guarded_by_constructors ~subst _ _ _ _ _ _ _ = assert false
1056 and recursive_args ~subst ~metasenv context n nn te =
1057 match R.whd context te with
1058 | C.Rel _ | C.Appl _ -> []
1059 | C.Prod (name,so,de) ->
1060 (not (does_not_occur ~subst context n nn so)) ::
1061 (recursive_args ~subst ~metasenv
1062 ((name,(C.Decl so))::context) (n+1) (nn + 1) de)
1064 raise (AssertFailure (lazy ("recursive_args:" ^ NCicPp.ppterm ~subst
1065 ~metasenv ~context:[] t)))
1067 and get_new_safes ~subst (context, recfuns, x, safes as k) p rl =
1068 match R.whd ~subst context p, rl with
1069 | C.Lambda (name,so,ta), b::tl ->
1070 let safes = (if b then [0] else []) @ safes in
1071 get_new_safes ~subst
1072 (shift_k (name,(C.Decl so)) (context, recfuns, x, safes)) ta tl
1073 | C.Meta _ as e, _ | e, [] -> e, k
1074 | _ -> raise (AssertFailure (lazy "Ill formed pattern"))
1076 and split_prods ~subst context n te =
1077 match n, R.whd ~subst context te with
1078 | 0, _ -> context,te
1079 | n, C.Prod (name,so,ta) when n > 0 ->
1080 split_prods ~subst ((name,(C.Decl so))::context) (n - 1) ta
1081 | _ -> raise (AssertFailure (lazy "split_prods"))
1083 and is_really_smaller ~subst ~metasenv (context, recfuns, x, safes as k) te =
1084 match R.whd ~subst context te with
1085 | C.Rel m when List.mem m safes -> true
1087 | C.LetIn _ -> raise (AssertFailure (lazy "letin after whd"))
1088 | C.Sort _ | C.Implicit _ | C.Prod _ | C.Lambda _
1089 | C.Const (Ref.Ref (_,_,(Ref.Decl | Ref.Def | Ref.Ind _ | Ref.CoFix _))) ->
1090 raise (AssertFailure (lazy "not a constructor"))
1091 | C.Appl ([]|[_]) -> raise (AssertFailure (lazy "empty/unary appl"))
1093 (*CSC: sulla coda ci vogliono dei controlli? secondo noi no, ma *)
1094 (*CSC: solo perche' non abbiamo trovato controesempi *)
1095 (*TASSI: da capire soprattutto se he รจ un altro fix che non ha ridotto...*)
1096 is_really_smaller ~subst ~metasenv k he
1097 | C.Const (Ref.Ref (_,_,Ref.Con _)) -> false
1098 | C.Const (Ref.Ref (_,_,Ref.Fix _)) -> assert false
1099 (*| C.Fix (_, fl) ->
1100 let len = List.length fl in
1101 let n_plus_len = n + len
1102 and nn_plus_len = nn + len
1103 and x_plus_len = x + len
1106 (fun (types,len) (n,_,ty,_) ->
1107 (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types,
1110 and safes' = List.map (fun x -> x + len) safes in
1112 (fun (_,_,ty,bo) i ->
1114 is_really_smaller ~subst (tys@context) n_plus_len nn_plus_len kl
1115 x_plus_len safes' bo
1118 true (* XXX if this check is repeated when the user completes the
1120 | C.Match (Ref.Ref (_,uri,_) as ref,outtype,term,pl) ->
1122 | C.Rel m | C.Appl (C.Rel m :: _ ) when List.mem m safes || m = x ->
1123 let isinductive, paramsno, tl, _, i = E.get_checked_indtys ref in
1124 if not isinductive then
1125 List.for_all (is_really_smaller ~subst ~metasenv k) pl
1127 let c_ctx,len,cl = fix_lefts_in_constrs ~subst uri paramsno tl i in
1129 (fun p (_,_,debruijnedte) ->
1130 let rl'=recursive_args ~subst ~metasenv c_ctx 0 len debruijnedte in
1131 let e, k = get_new_safes ~subst k p rl' in
1132 is_really_smaller ~subst ~metasenv k e)
1134 | _ -> List.for_all (is_really_smaller ~subst ~metasenv k) pl)
1136 and returns_a_coinductive ~subst context ty =
1137 match R.whd ~subst context ty with
1138 | C.Const (Ref.Ref (_,uri,Ref.Ind _) as ref)
1139 | C.Appl (C.Const (Ref.Ref (_,uri,Ref.Ind _) as ref)::_) ->
1140 let isinductive, _, _, _, _ = E.get_checked_indtys ref in
1141 if isinductive then None else (Some uri)
1142 | C.Prod (n,so,de) ->
1143 returns_a_coinductive ~subst ((n,C.Decl so)::context) de
1146 and type_of_constant ((Ref.Ref (_,uri,_)) as ref) =
1148 match E.get_obj uri with
1149 | true, cobj -> cobj
1151 !logger (`Start_type_checking uri);
1152 check_obj_well_typed uobj;
1154 !logger (`Type_checking_completed uri);
1155 if not (fst (E.get_obj uri)) then
1156 raise (AssertFailure (lazy "environment error"));
1159 match cobj, ref with
1160 | (_,_,_,_,C.Inductive (_,_,tl,_)), Ref.Ref (_,_,Ref.Ind i) ->
1161 let _,_,arity,_ = List.nth tl i in arity
1162 | (_,_,_,_,C.Inductive (_,_,tl,_)), Ref.Ref (_,_,Ref.Con (i,j)) ->
1163 let _,_,_,cl = List.nth tl i in
1164 let _,_,arity = List.nth cl (j-1) in
1166 | (_,_,_,_,C.Fixpoint (_,fl,_)), Ref.Ref (_,_,(Ref.Fix (i,_)|Ref.CoFix i)) ->
1167 let _,_,_,arity,_ = List.nth fl i in
1169 | (_,_,_,_,C.Constant (_,_,_,ty,_)), Ref.Ref (_,_,(Ref.Def |Ref.Decl)) -> ty
1170 | _ -> raise (AssertFailure (lazy "type_of_constant: environment/reference"))
1172 and check_obj_well_typed (uri,height,metasenv,subst,kind) =
1173 (* CSC: here we should typecheck the metasenv and the subst *)
1174 assert (metasenv = [] && subst = []);
1176 | C.Constant (_,_,Some te,ty,_) ->
1178 prerr_endline ("TY: " ^ NCicPp.ppterm ~subst ~metasenv ~context:[] ty);
1179 prerr_endline ("BO: " ^ NCicPp.ppterm ~subst ~metasenv ~context:[] te);
1181 let _ = typeof ~subst ~metasenv [] ty in
1182 let ty_te = typeof ~subst ~metasenv [] te in
1183 (* prerr_endline "XXXX"; *)
1184 if not (R.are_convertible ~subst ~metasenv [] ty_te ty) then
1185 raise (TypeCheckerFailure (lazy (Printf.sprintf
1186 "the type of the body is not the one expected:\n%s\nvs\n%s"
1187 (NCicPp.ppterm ~subst ~metasenv ~context:[] ty_te)
1188 (NCicPp.ppterm ~subst ~metasenv ~context:[] ty))))
1189 | C.Constant (_,_,None,ty,_) -> ignore (typeof ~subst ~metasenv [] ty)
1190 | C.Inductive (is_ind, leftno, tyl, _) ->
1191 check_mutual_inductive_defs uri ~metasenv ~subst is_ind leftno tyl
1192 | C.Fixpoint (inductive,fl,_) ->
1195 (fun (types,kl,len) (_,name,k,ty,_) ->
1196 let _ = typeof ~subst ~metasenv [] ty in
1197 ((name,(C.Decl (S.lift len ty)))::types, k::kl,len+1)
1200 List.iter (fun (_,name,x,ty,bo) ->
1201 let bo = debruijn uri len bo in
1202 let ty_bo = typeof ~subst ~metasenv types bo in
1203 if not (R.are_convertible ~subst ~metasenv types ty_bo (S.lift len ty))
1204 then raise (TypeCheckerFailure (lazy ("(Co)Fix: ill-typed bodies")))
1206 if inductive then begin
1207 let m, context = eat_lambdas ~subst ~metasenv types (x + 1) bo in
1208 (* guarded by destructors conditions D{f,k,x,M} *)
1209 let rec enum_from k =
1210 function [] -> [] | v::tl -> (k,v)::enum_from (k+1) tl
1212 guarded_by_destructors
1213 ~subst ~metasenv context (enum_from (x+2) kl) m
1215 match returns_a_coinductive ~subst [] ty with
1217 raise (TypeCheckerFailure
1218 (lazy "CoFix: does not return a coinductive type"))
1220 (* guarded by constructors conditions C{f,M} *)
1221 if not (guarded_by_constructors ~subst ~metasenv
1222 types 0 len false bo [] uri)
1224 raise (TypeCheckerFailure
1225 (lazy "CoFix: not guarded by constructors"))
1228 let typecheck_obj = check_obj_well_typed;;