X-Git-Url: http://matita.cs.unibo.it/gitweb/?p=helm.git;a=blobdiff_plain;f=components%2Fng_kernel%2FnCicTypeChecker.ml;fp=components%2Fng_kernel%2FnCicTypeChecker.ml;h=e96169e3e905d36d3f08057825b7971e67f2e0dc;hp=0000000000000000000000000000000000000000;hb=f61af501fb4608cc4fb062a0864c774e677f0d76;hpb=58ae1809c352e71e7b5530dc41e2bfc834e1aef1 diff --git a/components/ng_kernel/nCicTypeChecker.ml b/components/ng_kernel/nCicTypeChecker.ml new file mode 100644 index 000000000..e96169e3e --- /dev/null +++ b/components/ng_kernel/nCicTypeChecker.ml @@ -0,0 +1,1149 @@ +(* + ||M|| This file is part of HELM, an Hypertextual, Electronic + ||A|| Library of Mathematics, developed at the Computer Science + ||T|| Department, University of Bologna, Italy. + ||I|| + ||T|| HELM is free software; you can redistribute it and/or + ||A|| modify it under the terms of the GNU General Public License + \ / version 2 or (at your option) any later version. + \ / This software is distributed as is, NO WARRANTY. + V_______________________________________________________________ *) + +(* $Id: nCicReduction.ml 8250 2008-03-25 17:56:20Z tassi $ *) + +(* web interface stuff *) + +let logger = + ref (function (`Start_type_checking _|`Type_checking_completed _) -> ()) +;; + +let set_logger f = logger := f;; + +exception TypeCheckerFailure of string Lazy.t +exception AssertFailure of string Lazy.t + +let shift_k e (c,rf,x,safes) = + e::c,List.map (fun (k,v) -> k+1,v) rf,x+1,List.map ((+)1) safes +;; + +(* $Id: cicTypeChecker.ml 8213 2008-03-13 18:48:26Z sacerdot $ *) + + + +(* +(* the boolean h means already protected *) +(* args is the list of arguments the type of the constructor that may be *) +(* found in head position must be applied to. *) +and guarded_by_constructors ~subst context n nn h te args coInductiveTypeURI = + let module C = Cic in + (*CSC: There is a lot of code replication between the cases X and *) + (*CSC: (C.Appl X tl). Maybe it will be better to define a function *) + (*CSC: that maps X into (C.Appl X []) when X is not already a C.Appl *) + match CicReduction.whd ~subst context te with + C.Rel m when m > n && m <= nn -> h + | C.Rel _ -> true + | C.Meta _ + | C.Sort _ + | C.Implicit _ + | C.Cast _ + | C.Prod _ + | C.LetIn _ -> + (* the term has just been type-checked *) + raise (AssertFailure (lazy "17")) + | C.Lambda (name,so,de) -> + does_not_occur ~subst context n nn so && + guarded_by_constructors ~subst ((Some (name,(C.Decl so)))::context) + (n + 1) (nn + 1) h de args coInductiveTypeURI + | C.Appl ((C.Rel m)::tl) when m > n && m <= nn -> + h && + List.fold_right (fun x i -> i && does_not_occur ~subst context n nn x) tl true + | C.Appl ((C.MutConstruct (uri,i,j,exp_named_subst))::tl) -> + let consty = + let obj,_ = + try + CicEnvironment.get_cooked_obj ~trust:false CicUniv.empty_ugraph uri + with Not_found -> assert false + in + match obj with + C.InductiveDefinition (itl,_,_,_) -> + let (_,_,_,cl) = List.nth itl i in + let (_,cons) = List.nth cl (j - 1) in + CicSubstitution.subst_vars exp_named_subst cons + | _ -> + raise (TypeCheckerFailure + (lazy ("Unknown mutual inductive definition:" ^ UriManager.string_of_uri uri))) + in + let rec analyse_branch context ty te = + match CicReduction.whd ~subst context ty with + C.Meta _ -> raise (AssertFailure (lazy "34")) + | C.Rel _ + | C.Var _ + | C.Sort _ -> + does_not_occur ~subst context n nn te + | C.Implicit _ + | C.Cast _ -> + raise (AssertFailure (lazy "24"))(* due to type-checking *) + | C.Prod (name,so,de) -> + analyse_branch ((Some (name,(C.Decl so)))::context) de te + | C.Lambda _ + | C.LetIn _ -> + raise (AssertFailure (lazy "25"))(* due to type-checking *) + | C.Appl ((C.MutInd (uri,_,_))::_) when uri == coInductiveTypeURI -> + guarded_by_constructors ~subst context n nn true te [] + coInductiveTypeURI + | C.Appl ((C.MutInd (uri,_,_))::_) -> + guarded_by_constructors ~subst context n nn true te tl + coInductiveTypeURI + | C.Appl _ -> + does_not_occur ~subst context n nn te + | C.Const _ -> raise (AssertFailure (lazy "26")) + | C.MutInd (uri,_,_) when uri == coInductiveTypeURI -> + guarded_by_constructors ~subst context n nn true te [] + coInductiveTypeURI + | C.MutInd _ -> + does_not_occur ~subst context n nn te + | C.MutConstruct _ -> raise (AssertFailure (lazy "27")) + (*CSC: we do not consider backbones with a MutCase, Fix, Cofix *) + (*CSC: in head position. *) + | C.MutCase _ + | C.Fix _ + | C.CoFix _ -> + raise (AssertFailure (lazy "28"))(* due to type-checking *) + in + let rec analyse_instantiated_type context ty l = + match CicReduction.whd ~subst context ty with + C.Rel _ + | C.Var _ + | C.Meta _ + | C.Sort _ + | C.Implicit _ + | C.Cast _ -> raise (AssertFailure (lazy "29"))(* due to type-checking *) + | C.Prod (name,so,de) -> + begin + match l with + [] -> true + | he::tl -> + analyse_branch context so he && + analyse_instantiated_type + ((Some (name,(C.Decl so)))::context) de tl + end + | C.Lambda _ + | C.LetIn _ -> + raise (AssertFailure (lazy "30"))(* due to type-checking *) + | C.Appl _ -> + List.fold_left + (fun i x -> i && does_not_occur ~subst context n nn x) true l + | C.Const _ -> raise (AssertFailure (lazy "31")) + | C.MutInd _ -> + List.fold_left + (fun i x -> i && does_not_occur ~subst context n nn x) true l + | C.MutConstruct _ -> raise (AssertFailure (lazy "32")) + (*CSC: we do not consider backbones with a MutCase, Fix, Cofix *) + (*CSC: in head position. *) + | C.MutCase _ + | C.Fix _ + | C.CoFix _ -> + raise (AssertFailure (lazy "33"))(* due to type-checking *) + in + let rec instantiate_type args consty = + function + [] -> true + | tlhe::tltl as l -> + let consty' = CicReduction.whd ~subst context consty in + match args with + he::tl -> + begin + match consty' with + C.Prod (_,_,de) -> + let instantiated_de = CicSubstitution.subst he de in + (*CSC: siamo sicuri che non sia troppo forte? *) + does_not_occur ~subst context n nn tlhe & + instantiate_type tl instantiated_de tltl + | _ -> + (*CSC:We do not consider backbones with a MutCase, a *) + (*CSC:FixPoint, a CoFixPoint and so on in head position.*) + raise (AssertFailure (lazy "23")) + end + | [] -> analyse_instantiated_type context consty' l + (* These are all the other cases *) + in + instantiate_type args consty tl + | C.Appl ((C.CoFix (_,fl))::tl) -> + List.fold_left (fun i x -> i && does_not_occur ~subst context n nn x) true tl && + let len = List.length fl in + let n_plus_len = n + len + and nn_plus_len = nn + len + (*CSC: Is a Decl of the ty ok or should I use Def of a Fix? *) + and tys,_ = + List.fold_left + (fun (types,len) (n,ty,_) -> + (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types, + len+1) + ) ([],0) fl + in + List.fold_right + (fun (_,ty,bo) i -> + i && does_not_occur ~subst context n nn ty && + guarded_by_constructors ~subst (tys@context) n_plus_len nn_plus_len + h bo args coInductiveTypeURI + ) fl true + | C.Appl ((C.MutCase (_,_,out,te,pl))::tl) -> + List.fold_left (fun i x -> i && does_not_occur ~subst context n nn x) true tl && + does_not_occur ~subst context n nn out && + does_not_occur ~subst context n nn te && + List.fold_right + (fun x i -> + i && + guarded_by_constructors ~subst context n nn h x args + coInductiveTypeURI + ) pl true + | C.Appl l -> + List.fold_right (fun x i -> i && does_not_occur ~subst context n nn x) l true + | C.Var (_,exp_named_subst) + | C.Const (_,exp_named_subst) -> + List.fold_right + (fun (_,x) i -> i && does_not_occur ~subst context n nn x) exp_named_subst true + | C.MutInd _ -> assert false + | C.MutConstruct (_,_,_,exp_named_subst) -> + List.fold_right + (fun (_,x) i -> i && does_not_occur ~subst context n nn x) exp_named_subst true + | C.MutCase (_,_,out,te,pl) -> + does_not_occur ~subst context n nn out && + does_not_occur ~subst context n nn te && + List.fold_right + (fun x i -> + i && + guarded_by_constructors ~subst context n nn h x args + coInductiveTypeURI + ) pl true + | C.Fix (_,fl) -> + let len = List.length fl in + let n_plus_len = n + len + and nn_plus_len = nn + len + (*CSC: Is a Decl of the ty ok or should I use Def of a Fix? *) + and tys,_ = + List.fold_left + (fun (types,len) (n,_,ty,_) -> + (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types, + len+1) + ) ([],0) fl + in + List.fold_right + (fun (_,_,ty,bo) i -> + i && does_not_occur ~subst context n nn ty && + does_not_occur ~subst (tys@context) n_plus_len nn_plus_len bo + ) fl true + | C.CoFix (_,fl) -> + let len = List.length fl in + let n_plus_len = n + len + and nn_plus_len = nn + len + (*CSC: Is a Decl of the ty ok or should I use Def of a Fix? *) + and tys,_ = + List.fold_left + (fun (types,len) (n,ty,_) -> + (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types, + len+1) + ) ([],0) fl + in + List.fold_right + (fun (_,ty,bo) i -> + i && does_not_occur ~subst context n nn ty && + guarded_by_constructors ~subst (tys@context) n_plus_len nn_plus_len + h bo + args coInductiveTypeURI + ) fl true + + in + type_of_aux ~logger context t ugraph + +;; + +(** wrappers which instantiate fresh loggers *) + +(* check_allowed_sort_elimination uri i s1 s2 + This function is used outside the kernel to determine in advance whether + a MutCase will be allowed or not. + [uri,i] is the type of the term to match + [s1] is the sort of the term to eliminate (i.e. the head of the arity + of the inductive type [uri,i]) + [s2] is the sort of the goal (i.e. the head of the type of the outtype + of the MutCase) *) +let check_allowed_sort_elimination uri i s1 s2 = + fst (check_allowed_sort_elimination ~subst:[] ~metasenv:[] + ~logger:(new CicLogger.logger) [] uri i true + (Cic.Implicit None) (* never used *) (Cic.Sort s1) (Cic.Sort s2) + CicUniv.empty_ugraph) +;; + +Deannotate.type_of_aux' := fun context t -> fst (type_of_aux' [] context t CicUniv.oblivion_ugraph);; + +*) + +module C = NCic +module R = NCicReduction +module Ref = NReference +module S = NCicSubstitution +module U = NCicUtils +module E = NCicEnvironment + +let rec split_prods ~subst context n te = + match (n, R.whd ~subst context te) with + | (0, _) -> context,te + | (n, C.Prod (name,so,ta)) when n > 0 -> + split_prods ~subst ((name,(C.Decl so))::context) (n - 1) ta + | (_, _) -> raise (AssertFailure (lazy "split_prods")) +;; + +let debruijn ?(cb=fun _ _ -> ()) uri number_of_types = + let rec aux k t = + let res = + match t with + | C.Meta (i,(s,C.Ctx l)) -> + let l1 = NCicUtils.sharing_map (aux (k-s)) l in + if l1 == l then t else C.Meta (i,(s,C.Ctx l1)) + | C.Meta _ -> t + | C.Const (Ref.Ref (_,uri1,(Ref.Fix (no,_) | Ref.CoFix no))) + | C.Const (Ref.Ref (_,uri1,Ref.Ind no)) when NUri.eq uri uri1 -> + C.Rel (k + number_of_types - no) + | t -> NCicUtils.map (fun _ k -> k+1) k aux t + in + cb t res; res + in + aux 0 +;; + +let sort_of_prod ~metasenv ~subst context (name,s) (t1, t2) = + let t1 = R.whd ~subst context t1 in + let t2 = R.whd ~subst ((name,C.Decl s)::context) t2 in + match t1, t2 with + | C.Sort s1, C.Sort C.Prop -> t2 + | C.Sort (C.Type u1), C.Sort (C.Type u2) -> C.Sort (C.Type (max u1 u2)) + | C.Sort _,C.Sort (C.Type _) -> t2 + | C.Sort (C.Type _) , C.Sort C.CProp -> t1 + | C.Sort _, C.Sort C.CProp -> t2 + | C.Meta _, C.Sort _ + | C.Meta _, C.Meta _ + | C.Sort _, C.Meta _ when U.is_closed t2 -> t2 + | _ -> + raise (TypeCheckerFailure (lazy (Printf.sprintf + "Prod: expected two sorts, found = %s, %s" + (NCicPp.ppterm ~subst ~metasenv ~context t1) + (NCicPp.ppterm ~subst ~metasenv ~context t2)))) +;; + +let eat_prods ~subst ~metasenv context he ty_he args_with_ty = + let rec aux ty_he = function + | [] -> ty_he + | (arg, ty_arg)::tl -> + match R.whd ~subst context ty_he with + | C.Prod (n,s,t) -> +(* + prerr_endline (NCicPp.ppterm ~subst ~metasenv ~context s ^ " - Vs - " + ^ NCicPp.ppterm ~subst ~metasenv + ~context ty_arg); + prerr_endline (NCicPp.ppterm ~subst ~metasenv ~context (S.subst ~avoid_beta_redexes:true arg t)); +*) + if R.are_convertible ~subst ~metasenv context ty_arg s then + aux (S.subst ~avoid_beta_redexes:true arg t) tl + else + raise + (TypeCheckerFailure + (lazy (Printf.sprintf + ("Appl: wrong application of %s: the parameter %s has type"^^ + "\n%s\nbut it should have type \n%s\nContext:\n%s\n") + (NCicPp.ppterm ~subst ~metasenv ~context he) + (NCicPp.ppterm ~subst ~metasenv ~context arg) + (NCicPp.ppterm ~subst ~metasenv ~context ty_arg) + (NCicPp.ppterm ~subst ~metasenv ~context s) + (NCicPp.ppcontext ~subst ~metasenv context)))) + | _ -> + raise + (TypeCheckerFailure + (lazy (Printf.sprintf + "Appl: %s is not a function, it cannot be applied" + (NCicPp.ppterm ~subst ~metasenv ~context + (let res = List.length tl in + let eaten = List.length args_with_ty - res in + (NCic.Appl + (he::List.map fst + (fst (HExtlib.split_nth eaten args_with_ty))))))))) + in + aux ty_he args_with_ty +;; + +let fix_lefts_in_constrs ~subst uri paramsno tyl i = + let len = List.length tyl in + let _,_,arity,cl = List.nth tyl i in + let tys = List.map (fun (_,n,ty,_) -> n,C.Decl ty) tyl in + let cl' = + List.map + (fun (_,id,ty) -> + let debruijnedty = debruijn uri len ty in + id, snd (split_prods ~subst tys paramsno ty), + snd (split_prods ~subst tys paramsno debruijnedty)) + cl + in + let lefts = fst (split_prods ~subst [] paramsno arity) in + lefts@tys, len, cl' +;; + +exception DoesOccur;; + +let does_not_occur ~subst context n nn t = + let rec aux (context,n,nn as k) _ = function + | C.Rel m when m > n && m <= nn -> raise DoesOccur + | C.Rel m -> + (try (match List.nth context (m-1) with + | _,C.Def (bo,_) -> aux k () (S.lift m bo) + | _ -> ()) + with Failure _ -> assert false) + | C.Meta (_,(_,(C.Irl 0 | C.Ctx []))) -> (* closed meta *) () + | C.Meta (mno,(s,l)) -> + (try + let _,_,term,_ = U.lookup_subst mno subst in + aux (context,n+s,nn+s) () (S.subst_meta (0,l) term) + with CicUtil.Subst_not_found _ -> match l with + | C.Irl len -> if not (n >= s+len || s > nn) then raise DoesOccur + | C.Ctx lc -> List.iter (aux (context,n+s,nn+s) ()) lc) + | t -> U.fold (fun e (ctx,n,nn) -> (e::ctx,n+1,nn+1)) k aux () t + in + try aux (context,n,nn) () t; true + with DoesOccur -> false +;; + +(*CSC l'indice x dei tipi induttivi e' t.c. n < x <= nn *) +(*CSC questa funzione e' simile alla are_all_occurrences_positive, ma fa *) +(*CSC dei controlli leggermente diversi. Viene invocata solamente dalla *) +(*CSC strictly_positive *) +(*CSC definizione (giusta???) tratta dalla mail di Hugo ;-) *) +let rec weakly_positive ~subst context n nn uri te = +(*CSC: Che schifo! Bisogna capire meglio e trovare una soluzione ragionevole!*) + let dummy = C.Sort (C.Type ~-1) in + (*CSC: mettere in cicSubstitution *) + let rec subst_inductive_type_with_dummy _ = function + | C.Const (Ref.Ref (_,uri',Ref.Ind 0)) when NUri.eq uri' uri -> dummy + | C.Appl ((C.Const (Ref.Ref (_,uri',Ref.Ind 0)))::tl) + when NUri.eq uri' uri -> dummy + | t -> U.map (fun _ x->x) () subst_inductive_type_with_dummy t + in + match R.whd context te with + | C.Const (Ref.Ref (_,uri',Ref.Ind _)) + | C.Appl ((C.Const (Ref.Ref (_,uri',Ref.Ind _)))::_) + when NUri.eq uri' uri -> true + | C.Prod (name,source,dest) when + does_not_occur ~subst ((name,C.Decl source)::context) 0 1 dest -> + (* dummy abstraction, so we behave as in the anonimous case *) + strictly_positive ~subst context n nn + (subst_inductive_type_with_dummy () source) && + weakly_positive ~subst ((name,C.Decl source)::context) + (n + 1) (nn + 1) uri dest + | C.Prod (name,source,dest) -> + does_not_occur ~subst context n nn + (subst_inductive_type_with_dummy () source)&& + weakly_positive ~subst ((name,C.Decl source)::context) + (n + 1) (nn + 1) uri dest + | _ -> + raise (TypeCheckerFailure (lazy "Malformed inductive constructor type")) + +(* instantiate_parameters ps (x1:T1)...(xn:Tn)C *) +(* returns ((x_|ps|:T_|ps|)...(xn:Tn)C){ps_1 / x1 ; ... ; ps_|ps| / x_|ps|} *) +and instantiate_parameters params c = + match c, params with + | c,[] -> c + | C.Prod (_,_,ta), he::tl -> instantiate_parameters tl (S.subst he ta) + | t,l -> raise (AssertFailure (lazy "1")) + +and strictly_positive ~subst context n nn te = + match R.whd context te with + | t when does_not_occur ~subst context n nn t -> true + | C.Rel _ -> true + | C.Prod (name,so,ta) -> + does_not_occur ~subst context n nn so && + strictly_positive ~subst ((name,C.Decl so)::context) (n+1) (nn+1) ta + | C.Appl ((C.Rel m)::tl) when m > n && m <= nn -> + List.for_all (does_not_occur ~subst context n nn) tl + | C.Appl (C.Const (Ref.Ref (_,uri,Ref.Ind i) as r)::tl) -> + let _,paramsno,tyl,_,i = E.get_checked_indtys r in + let _,name,ity,cl = List.nth tyl i in + let ok = List.length tyl = 1 in + let params, arguments = HExtlib.split_nth paramsno tl in + let lifted_params = List.map (S.lift 1) params in + let cl = + List.map (fun (_,_,te) -> instantiate_parameters lifted_params te) cl + in + ok && + List.for_all (does_not_occur ~subst context n nn) arguments && + List.for_all + (weakly_positive ~subst ((name,C.Decl ity)::context) (n+1) (nn+1) uri) cl + | _ -> false + +(* the inductive type indexes are s.t. n < x <= nn *) +and are_all_occurrences_positive ~subst context uri indparamsno i n nn te = + match R.whd context te with + | C.Appl ((C.Rel m)::tl) as reduct when m = i -> + let last = + List.fold_left + (fun k x -> + if k = 0 then 0 + else + match R.whd context x with + | C.Rel m when m = n - (indparamsno - k) -> k - 1 + | y -> raise (TypeCheckerFailure (lazy + ("Argument "^string_of_int (indparamsno - k + 1) ^ " (of " ^ + string_of_int indparamsno ^ " fixed) is not homogeneous in "^ + "appl:\n"^ NCicPp.ppterm ~context ~subst ~metasenv:[] reduct)))) + indparamsno tl + in + if last = 0 then + List.for_all (does_not_occur ~subst context n nn) tl + else + raise (TypeCheckerFailure + (lazy ("Non-positive occurence in mutual inductive definition(s) [2]"^ + NUri.string_of_uri uri))) + | C.Rel m when m = i -> + if indparamsno = 0 then + true + else + raise (TypeCheckerFailure + (lazy ("Non-positive occurence in mutual inductive definition(s) [3]"^ + NUri.string_of_uri uri))) + | C.Prod (name,source,dest) when + does_not_occur ~subst ((name,C.Decl source)::context) 0 1 dest -> + strictly_positive ~subst context n nn source && + are_all_occurrences_positive ~subst + ((name,C.Decl source)::context) uri indparamsno + (i+1) (n + 1) (nn + 1) dest + | C.Prod (name,source,dest) -> + if not (does_not_occur ~subst context n nn source) then + raise (TypeCheckerFailure (lazy ("Non-positive occurrence in "^ + NCicPp.ppterm ~context ~metasenv:[] ~subst te))); + are_all_occurrences_positive ~subst ((name,C.Decl source)::context) + uri indparamsno (i+1) (n + 1) (nn + 1) dest + | _ -> + raise + (TypeCheckerFailure (lazy ("Malformed inductive constructor type " ^ + (NUri.string_of_uri uri)))) +;; + +exception NotGuarded of string Lazy.t;; + +let rec typeof ~subst ~metasenv context term = + let rec typeof_aux context = + fun t -> (*prerr_endline (NCicPp.ppterm ~context t); *) + match t with + | C.Rel n -> + (try + match List.nth context (n - 1) with + | (_,C.Decl ty) -> S.lift n ty + | (_,C.Def (_,ty)) -> S.lift n ty + with Failure _ -> raise (TypeCheckerFailure (lazy "unbound variable"))) + | C.Sort (C.Type i) -> C.Sort (C.Type (i+1)) + | C.Sort s -> C.Sort (C.Type 0) + | C.Implicit _ -> raise (AssertFailure (lazy "Implicit found")) + | C.Meta (n,l) as t -> + let canonical_ctx,ty = + try + let _,c,_,ty = U.lookup_subst n subst in c,ty + with U.Subst_not_found _ -> try + let _,_,c,ty = U.lookup_meta n metasenv in c,ty + with U.Meta_not_found _ -> + raise (AssertFailure (lazy (Printf.sprintf + "%s not found" (NCicPp.ppterm ~subst ~metasenv ~context t)))) + in + check_metasenv_consistency t ~subst ~metasenv context canonical_ctx l; + S.subst_meta l ty + | C.Const ref -> type_of_constant ref + | C.Prod (name,s,t) -> + let sort1 = typeof_aux context s in + let sort2 = typeof_aux ((name,(C.Decl s))::context) t in + sort_of_prod ~metasenv ~subst context (name,s) (sort1,sort2) + | C.Lambda (n,s,t) -> + let sort = typeof_aux context s in + (match R.whd ~subst context sort with + | C.Meta _ | C.Sort _ -> () + | _ -> + raise + (TypeCheckerFailure (lazy (Printf.sprintf + ("Not well-typed lambda-abstraction: " ^^ + "the source %s should be a type; instead it is a term " ^^ + "of type %s") (NCicPp.ppterm ~subst ~metasenv ~context s) + (NCicPp.ppterm ~subst ~metasenv ~context sort))))); + let ty = typeof_aux ((n,(C.Decl s))::context) t in + C.Prod (n,s,ty) + | C.LetIn (n,ty,t,bo) -> + let ty_t = typeof_aux context t in + let _ = typeof_aux context ty in + if not (R.are_convertible ~subst ~metasenv context ty ty_t) then + raise + (TypeCheckerFailure + (lazy (Printf.sprintf + "The type of %s is %s but it is expected to be %s" + (NCicPp.ppterm ~subst ~metasenv ~context t) + (NCicPp.ppterm ~subst ~metasenv ~context ty_t) + (NCicPp.ppterm ~subst ~metasenv ~context ty)))) + else + let ty_bo = typeof_aux ((n,C.Def (t,ty))::context) bo in + S.subst ~avoid_beta_redexes:true t ty_bo + | C.Appl (he::(_::_ as args)) -> + let ty_he = typeof_aux context he in + let args_with_ty = List.map (fun t -> t, typeof_aux context t) args in +(* + prerr_endline ("HEAD: " ^ NCicPp.ppterm ~subst ~metasenv ~context ty_he); + prerr_endline ("TARGS: " ^ String.concat " | " (List.map (NCicPp.ppterm + ~subst ~metasenv ~context) (List.map snd args_with_ty))); + prerr_endline ("ARGS: " ^ String.concat " | " (List.map (NCicPp.ppterm + ~subst ~metasenv ~context) (List.map fst args_with_ty))); +*) + eat_prods ~subst ~metasenv context he ty_he args_with_ty + | C.Appl _ -> raise (AssertFailure (lazy "Appl of length < 2")) + | C.Match (Ref.Ref (_,_,Ref.Ind tyno) as r,outtype,term,pl) -> + let outsort = typeof_aux context outtype in + let inductive,leftno,itl,_,_ = E.get_checked_indtys r in + let constructorsno = + let _,_,_,cl = List.nth itl tyno in List.length cl + in + let parameters, arguments = + let ty = R.whd ~subst context (typeof_aux context term) in + let r',tl = + match ty with + C.Const (Ref.Ref (_,_,Ref.Ind _) as r') -> r',[] + | C.Appl (C.Const (Ref.Ref (_,_,Ref.Ind _) as r') :: tl) -> r',tl + | _ -> + raise + (TypeCheckerFailure (lazy (Printf.sprintf + "Case analysis: analysed term %s is not an inductive one" + (NCicPp.ppterm ~subst ~metasenv ~context term)))) in + if not (Ref.eq r r') then + raise + (TypeCheckerFailure (lazy (Printf.sprintf + ("Case analysys: analysed term type is %s, but is expected " ^^ + "to be (an application of) %s") + (NCicPp.ppterm ~subst ~metasenv ~context ty) + (NCicPp.ppterm ~subst ~metasenv ~context (C.Const r'))))) + else + try HExtlib.split_nth leftno tl + with + Failure _ -> + raise (TypeCheckerFailure (lazy (Printf.sprintf + "%s is partially applied" + (NCicPp.ppterm ~subst ~metasenv ~context ty)))) in + (* let's control if the sort elimination is allowed: [(I q1 ... qr)|B] *) + let sort_of_ind_type = + if parameters = [] then C.Const r + else C.Appl ((C.Const r)::parameters) in + let type_of_sort_of_ind_ty = typeof_aux context sort_of_ind_type in + check_allowed_sort_elimination ~subst ~metasenv r context + sort_of_ind_type type_of_sort_of_ind_ty outsort; + (* let's check if the type of branches are right *) + if List.length pl <> constructorsno then + raise (TypeCheckerFailure (lazy ("Wrong number of cases in a match"))); + let j,branches_ok,p_ty, exp_p_ty = + List.fold_left + (fun (j,b,old_p_ty,old_exp_p_ty) p -> + if b then + let cons = + let cons = Ref.mk_constructor j r in + if parameters = [] then C.Const cons + else C.Appl (C.Const cons::parameters) + in + let ty_p = typeof_aux context p in + let ty_cons = typeof_aux context cons in + let ty_branch = + type_of_branch ~subst context leftno outtype cons ty_cons 0 + in + j+1, R.are_convertible ~subst ~metasenv context ty_p ty_branch, + ty_p, ty_branch + else + j,false,old_p_ty,old_exp_p_ty + ) (1,true,C.Sort C.Prop,C.Sort C.Prop) pl + in + if not branches_ok then + raise + (TypeCheckerFailure + (lazy (Printf.sprintf ("Branch for constructor %s :=\n%s\n"^^ + "has type %s\nnot convertible with %s") + (NCicPp.ppterm ~subst ~metasenv ~context + (C.Const (Ref.mk_constructor (j-1) r))) + (NCicPp.ppterm ~metasenv ~subst ~context (List.nth pl (j-2))) + (NCicPp.ppterm ~metasenv ~subst ~context p_ty) + (NCicPp.ppterm ~metasenv ~subst ~context exp_p_ty)))); + let res = outtype::arguments@[term] in + R.head_beta_reduce (C.Appl res) + | C.Match _ -> assert false + + and type_of_branch ~subst context leftno outty cons tycons liftno = + match R.whd ~subst context tycons with + | C.Const (Ref.Ref (_,_,Ref.Ind _)) -> C.Appl [S.lift liftno outty ; cons] + | C.Appl (C.Const (Ref.Ref (_,_,Ref.Ind _))::tl) -> + let _,arguments = HExtlib.split_nth leftno tl in + C.Appl (S.lift liftno outty::arguments@[cons]) + | C.Prod (name,so,de) -> + let cons = + match S.lift 1 cons with + | C.Appl l -> C.Appl (l@[C.Rel 1]) + | t -> C.Appl [t ; C.Rel 1] + in + C.Prod (name,so, + type_of_branch ~subst ((name,(C.Decl so))::context) + leftno outty cons de (liftno+1)) + | _ -> raise (AssertFailure (lazy "type_of_branch")) + + (* check_metasenv_consistency checks that the "canonical" context of a + metavariable is consitent - up to relocation via the relocation list l - + with the actual context *) + and check_metasenv_consistency + ~subst ~metasenv term context canonical_context l + = + match l with + | shift, NCic.Irl n -> + let context = snd (HExtlib.split_nth shift context) in + let rec compare = function + | 0,_,[] -> () + | 0,_,_::_ + | _,_,[] -> + raise (AssertFailure (lazy (Printf.sprintf + "Local and canonical context %s have different lengths" + (NCicPp.ppterm ~subst ~context ~metasenv term)))) + | m,[],_::_ -> + raise (TypeCheckerFailure (lazy (Printf.sprintf + "Unbound variable -%d in %s" m + (NCicPp.ppterm ~subst ~metasenv ~context term)))) + | m,t::tl,ct::ctl -> + (match t,ct with + (_,C.Decl t1), (_,C.Decl t2) + | (_,C.Def (t1,_)), (_,C.Def (t2,_)) + | (_,C.Def (_,t1)), (_,C.Decl t2) -> + if not (R.are_convertible ~subst ~metasenv tl t1 t2) then + raise + (TypeCheckerFailure + (lazy (Printf.sprintf + ("Not well typed metavariable local context for %s: " ^^ + "%s expected, which is not convertible with %s") + (NCicPp.ppterm ~subst ~metasenv ~context term) + (NCicPp.ppterm ~subst ~metasenv ~context t2) + (NCicPp.ppterm ~subst ~metasenv ~context t1)))) + | _,_ -> + raise + (TypeCheckerFailure (lazy (Printf.sprintf + ("Not well typed metavariable local context for %s: " ^^ + "a definition expected, but a declaration found") + (NCicPp.ppterm ~subst ~metasenv ~context term))))); + compare (m - 1,tl,ctl) + in + compare (n,context,canonical_context) + | shift, lc_kind -> + (* we avoid useless lifting by shortening the context*) + let l,context = (0,lc_kind), snd (HExtlib.split_nth shift context) in + let lifted_canonical_context = + let rec lift_metas i = function + | [] -> [] + | (n,C.Decl t)::tl -> + (n,C.Decl (S.subst_meta l (S.lift i t)))::(lift_metas (i+1) tl) + | (n,C.Def (t,ty))::tl -> + (n,C.Def ((S.subst_meta l (S.lift i t)), + S.subst_meta l (S.lift i ty)))::(lift_metas (i+1) tl) + in + lift_metas 1 canonical_context in + let l = U.expand_local_context lc_kind in + try + List.iter2 + (fun t ct -> + match (t,ct) with + | t, (_,C.Def (ct,_)) -> + (*CSC: the following optimization is to avoid a possibly expensive + reduction that can be easily avoided and that is quite + frequent. However, this is better handled using levels to + control reduction *) + let optimized_t = + match t with + | C.Rel n -> + (try + match List.nth context (n - 1) with + | (_,C.Def (te,_)) -> S.lift n te + | _ -> t + with Failure _ -> t) + | _ -> t + in + if not (R.are_convertible ~subst ~metasenv context optimized_t ct) + then + raise + (TypeCheckerFailure + (lazy (Printf.sprintf + ("Not well typed metavariable local context: " ^^ + "expected a term convertible with %s, found %s") + (NCicPp.ppterm ~subst ~metasenv ~context ct) + (NCicPp.ppterm ~subst ~metasenv ~context t)))) + | t, (_,C.Decl ct) -> + let type_t = typeof_aux context t in + if not (R.are_convertible ~subst ~metasenv context type_t ct) then + raise (TypeCheckerFailure + (lazy (Printf.sprintf + ("Not well typed metavariable local context: "^^ + "expected a term of type %s, found %s of type %s") + (NCicPp.ppterm ~subst ~metasenv ~context ct) + (NCicPp.ppterm ~subst ~metasenv ~context t) + (NCicPp.ppterm ~subst ~metasenv ~context type_t)))) + ) l lifted_canonical_context + with + Invalid_argument _ -> + raise (AssertFailure (lazy (Printf.sprintf + "Local and canonical context %s have different lengths" + (NCicPp.ppterm ~subst ~metasenv ~context term)))) + + and is_non_informative context paramsno c = + let rec aux context c = + match R.whd context c with + | C.Prod (n,so,de) -> + let s = typeof_aux context so in + s = C.Sort C.Prop && aux ((n,(C.Decl so))::context) de + | _ -> true in + let context',dx = split_prods ~subst:[] context paramsno c in + aux context' dx + + and check_allowed_sort_elimination ~subst ~metasenv r = + let mkapp he arg = + match he with + | C.Appl l -> C.Appl (l @ [arg]) + | t -> C.Appl [t;arg] in + let rec aux context ind arity1 arity2 = + let arity1 = R.whd ~subst context arity1 in + let arity2 = R.whd ~subst context arity2 in + match arity1,arity2 with + | C.Prod (name,so1,de1), C.Prod (_,so2,de2) -> + if not (R.are_convertible ~subst ~metasenv context so1 so2) then + raise (TypeCheckerFailure (lazy (Printf.sprintf + "In outtype: expected %s, found %s" + (NCicPp.ppterm ~subst ~metasenv ~context so1) + (NCicPp.ppterm ~subst ~metasenv ~context so2) + ))); + aux ((name, C.Decl so1)::context) + (mkapp (S.lift 1 ind) (C.Rel 1)) de1 de2 + | C.Sort _, C.Prod (name,so,ta) -> + if not (R.are_convertible ~subst ~metasenv context so ind) then + raise (TypeCheckerFailure (lazy (Printf.sprintf + "In outtype: expected %s, found %s" + (NCicPp.ppterm ~subst ~metasenv ~context ind) + (NCicPp.ppterm ~subst ~metasenv ~context so) + ))); + (match arity1,ta with + | (C.Sort (C.CProp | C.Type _), C.Sort _) + | (C.Sort C.Prop, C.Sort C.Prop) -> () + | (C.Sort C.Prop, C.Sort (C.CProp | C.Type _)) -> + (* TODO: we should pass all these parameters since we + * have them already *) + let inductive,leftno,itl,_,i = E.get_checked_indtys r in + let itl_len = List.length itl in + let _,name,ty,cl = List.nth itl i in + let cl_len = List.length cl in + (* is it a singleton or empty non recursive and non informative + definition? *) + if not + (cl_len = 0 || + (itl_len = 1 && cl_len = 1 && + is_non_informative [name,C.Decl ty] leftno + (let _,_,x = List.nth cl 0 in x))) + then + raise (TypeCheckerFailure (lazy + ("Sort elimination not allowed"))); + | _,_ -> ()) + | _,_ -> () + in + aux + + in + typeof_aux context term + +and check_mutual_inductive_defs uri ~metasenv ~subst is_ind leftno tyl = + (* let's check if the arity of the inductive types are well formed *) + List.iter (fun (_,_,x,_) -> ignore (typeof ~subst ~metasenv [] x)) tyl; + (* let's check if the types of the inductive constructors are well formed. *) + let len = List.length tyl in + let tys = List.rev (List.map (fun (_,n,ty,_) -> (n,(C.Decl ty))) tyl) in + ignore + (List.fold_right + (fun (_,_,_,cl) i -> + List.iter + (fun (_,name,te) -> + let debruijnedte = debruijn uri len te in + ignore (typeof ~subst ~metasenv tys debruijnedte); + (* let's check also the positivity conditions *) + if + not + (are_all_occurrences_positive ~subst tys uri leftno i 0 len + debruijnedte) + then + raise + (TypeCheckerFailure + (lazy ("Non positive occurence in "^NUri.string_of_uri uri)))) + cl; + i + 1) + tyl 1) + +and eat_lambdas ~subst ~metasenv context n te = + match (n, R.whd ~subst context te) with + | (0, _) -> (te, context) + | (n, C.Lambda (name,so,ta)) when n > 0 -> + eat_lambdas ~subst ~metasenv ((name,(C.Decl so))::context) (n - 1) ta + | (n, te) -> + raise (AssertFailure (lazy (Printf.sprintf "9 (%d, %s)" n + (NCicPp.ppterm ~subst ~metasenv ~context te)))) + +and guarded_by_destructors ~subst ~metasenv context recfuns t = + let recursor f k t = NCicUtils.fold shift_k k (fun k () -> f k) () t in + let rec aux (context, recfuns, x, safes as k) t = + match R.whd ~subst context t with (* TODO: use ~delta:false as mush as poss*) + | C.Rel m as t when List.mem_assoc m recfuns -> + raise (NotGuarded (lazy + (NCicPp.ppterm ~subst ~metasenv ~context t ^ " passed around"))) + | C.Rel m -> + (match List.nth context (m-1) with + | _,C.Decl _ -> () + | _,C.Def (bo,_) -> aux (context, recfuns, x, safes) (S.lift m bo)) + | C.Meta _ -> () + | C.Appl ((C.Rel m)::tl) as t when List.mem_assoc m recfuns -> + let rec_no = List.assoc m recfuns in + if not (List.length tl > rec_no) then + raise (NotGuarded (lazy + (NCicPp.ppterm ~context ~subst ~metasenv t ^ + " is a partial application of a fix"))) + else + let rec_arg = List.nth tl rec_no in + if not (is_really_smaller ~subst ~metasenv k rec_arg) then + raise (NotGuarded (lazy + (NCicPp.ppterm ~context ~subst ~metasenv rec_arg ^ " not smaller"))); + List.iter (aux k) tl + (* + | C.Appl (C.Const ((Ref.Ref (_,_,Ref.Fix (i,j))) as r)::args) -> + List.iter (aux k) args; + let fixes,_,_ = E.get_checked_fixes r in + let _,_,_,_,bo = List.nth fixes i in + let bo_wout_lam, context = eat_lambdas ~subst ~metasenv context j in + (* debruijna body..... *) assert false +*) + | C.Match (Ref.Ref (_,uri,_) as ref,outtype,term,pl) as t -> + (match R.whd ~subst context term with + | C.Rel m | C.Appl (C.Rel m :: _ ) as t when List.mem m safes || m = x -> + let isinductive, paramsno, tl, _, i = E.get_checked_indtys ref in + if not isinductive then recursor aux k t + else + let c_ctx,len,cl = fix_lefts_in_constrs ~subst uri paramsno tl i in + let args = match t with C.Appl (_::tl) -> tl | _ -> [] in + aux k outtype; + List.iter (aux k) args; + List.iter2 + (fun p (_,_,bruijnedc) -> + let rl = recursive_args ~subst ~metasenv c_ctx 0 len bruijnedc in + let p, k = get_new_safes ~subst k p rl in + aux k p) + pl cl + | _ -> recursor aux k t) + | t -> recursor aux k t + in + try aux (context, recfuns, 1, []) t + with NotGuarded s -> raise (TypeCheckerFailure s) + +(* + | C.Fix (_, fl) -> + let len = List.length fl in + let n_plus_len = n + len + and nn_plus_len = nn + len + and x_plus_len = x + len + and tys,_ = + List.fold_left + (fun (types,len) (n,_,ty,_) -> + (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types, + len+1) + ) ([],0) fl + and safes' = List.map (fun x -> x + len) safes in + List.fold_right + (fun (_,_,ty,bo) i -> + i && guarded_by_destructors ~subst context n nn kl x_plus_len safes' ty && + guarded_by_destructors ~subst (tys@context) n_plus_len nn_plus_len kl + x_plus_len safes' bo + ) fl true + | C.CoFix (_, fl) -> + let len = List.length fl in + let n_plus_len = n + len + and nn_plus_len = nn + len + and x_plus_len = x + len + and tys,_ = + List.fold_left + (fun (types,len) (n,ty,_) -> + (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types, + len+1) + ) ([],0) fl + and safes' = List.map (fun x -> x + len) safes in + List.fold_right + (fun (_,ty,bo) i -> + i && + guarded_by_destructors ~subst context n nn kl x_plus_len safes' ty && + guarded_by_destructors ~subst (tys@context) n_plus_len nn_plus_len kl + x_plus_len safes' bo + ) fl true +*) + +and guarded_by_constructors ~subst ~metasenv _ _ _ _ _ _ _ = true + +and recursive_args ~subst ~metasenv context n nn te = + match R.whd context te with + | C.Rel _ | C.Appl _ -> [] + | C.Prod (name,so,de) -> + (not (does_not_occur ~subst context n nn so)) :: + (recursive_args ~subst ~metasenv + ((name,(C.Decl so))::context) (n+1) (nn + 1) de) + | t -> + raise (AssertFailure (lazy ("recursive_args:" ^ NCicPp.ppterm ~subst + ~metasenv ~context:[] t))) + +and get_new_safes ~subst (context, recfuns, x, safes as k) p rl = + match R.whd ~subst context p, rl with + | C.Lambda (name,so,ta), b::tl -> + let safes = (if b then [0] else []) @ safes in + get_new_safes ~subst + (shift_k (name,(C.Decl so)) (context, recfuns, x, safes)) ta tl + | C.Meta _ as e, _ | e, [] -> e, k + | _ -> raise (AssertFailure (lazy "Ill formed pattern")) + +and split_prods ~subst context n te = + match n, R.whd ~subst context te with + | 0, _ -> context,te + | n, C.Prod (name,so,ta) when n > 0 -> + split_prods ~subst ((name,(C.Decl so))::context) (n - 1) ta + | _ -> raise (AssertFailure (lazy "split_prods")) + +and is_really_smaller ~subst ~metasenv (context, recfuns, x, safes as k) te = + match R.whd ~subst context te with + | C.Rel m when List.mem m safes -> true + | C.Lambda (name, s, t) -> + is_really_smaller ~subst ~metasenv (shift_k (name, C.Decl s) k) t + | C.Appl (he::_) -> + is_really_smaller ~subst ~metasenv k he + | C.Appl _ + | C.Rel _ + | C.Const (Ref.Ref (_,_,Ref.Con _)) -> false + | C.Const (Ref.Ref (_,_,Ref.Fix _)) -> assert false + (*| C.Fix (_, fl) -> + let len = List.length fl in + let n_plus_len = n + len + and nn_plus_len = nn + len + and x_plus_len = x + len + and tys,_ = + List.fold_left + (fun (types,len) (n,_,ty,_) -> + (Some (C.Name n,(C.Decl (CicSubstitution.lift len ty)))::types, + len+1) + ) ([],0) fl + and safes' = List.map (fun x -> x + len) safes in + List.fold_right + (fun (_,_,ty,bo) i -> + i && + is_really_smaller ~subst (tys@context) n_plus_len nn_plus_len kl + x_plus_len safes' bo + ) fl true*) + | C.Meta _ -> true + | C.Match (Ref.Ref (_,uri,_) as ref,outtype,term,pl) -> + (match term with + | C.Rel m | C.Appl (C.Rel m :: _ ) when List.mem m safes || m = x -> + let isinductive, paramsno, tl, _, i = E.get_checked_indtys ref in + if not isinductive then + List.for_all (is_really_smaller ~subst ~metasenv k) pl + else + let c_ctx,len,cl = fix_lefts_in_constrs ~subst uri paramsno tl i in + List.for_all2 + (fun p (_,_,debruijnedte) -> + let rl'=recursive_args ~subst ~metasenv c_ctx 0 len debruijnedte in + let e, k = get_new_safes ~subst k p rl' in + is_really_smaller ~subst ~metasenv k e) + pl cl + | _ -> List.for_all (is_really_smaller ~subst ~metasenv k) pl) + | _ -> assert false + +and returns_a_coinductive ~subst context ty = + match R.whd ~subst context ty with + | C.Const (Ref.Ref (_,uri,Ref.Ind _) as ref) + | C.Appl (C.Const (Ref.Ref (_,uri,Ref.Ind _) as ref)::_) -> + let isinductive, _, _, _, _ = E.get_checked_indtys ref in + if isinductive then None else (Some uri) + | C.Prod (n,so,de) -> + returns_a_coinductive ~subst ((n,C.Decl so)::context) de + | _ -> None + +and type_of_constant ((Ref.Ref (_,uri,_)) as ref) = + let cobj = + match E.get_obj uri with + | true, cobj -> cobj + | false, uobj -> + !logger (`Start_type_checking uri); + check_obj_well_typed uobj; + E.add_obj uobj; + !logger (`Type_checking_completed uri); + uobj + in + match cobj, ref with + | (_,_,_,_,C.Inductive (_,_,tl,_)), Ref.Ref (_,_,Ref.Ind i) -> + let _,_,arity,_ = List.nth tl i in arity + | (_,_,_,_,C.Inductive (_,_,tl,_)), Ref.Ref (_,_,Ref.Con (i,j)) -> + let _,_,_,cl = List.nth tl i in + let _,_,arity = List.nth cl (j-1) in + arity + | (_,_,_,_,C.Fixpoint (_,fl,_)), Ref.Ref (_,_,(Ref.Fix (i,_)|Ref.CoFix i)) -> + let _,_,_,arity,_ = List.nth fl i in + arity + | (_,_,_,_,C.Constant (_,_,_,ty,_)), Ref.Ref (_,_,(Ref.Def |Ref.Decl)) -> ty + | _ -> raise (AssertFailure (lazy "type_of_constant: environment/reference")) + +and check_obj_well_typed (uri,height,metasenv,subst,kind) = + (* CSC: here we should typecheck the metasenv and the subst *) + assert (metasenv = [] && subst = []); + match kind with + | C.Constant (_,_,Some te,ty,_) -> + let _ = typeof ~subst ~metasenv [] ty in + let ty_te = typeof ~subst ~metasenv [] te in + if not (R.are_convertible ~subst ~metasenv [] ty_te ty) then + raise (TypeCheckerFailure (lazy (Printf.sprintf ( + "the type of the body is not convertible with the declared one.\n"^^ + "inferred type:\n%s\nexpected type:\n%s") + (NCicPp.ppterm ~subst ~metasenv ~context:[] ty_te) + (NCicPp.ppterm ~subst ~metasenv ~context:[] ty)))) + | C.Constant (_,_,None,ty,_) -> ignore (typeof ~subst ~metasenv [] ty) + | C.Inductive (is_ind, leftno, tyl, _) -> + check_mutual_inductive_defs uri ~metasenv ~subst is_ind leftno tyl + | C.Fixpoint (inductive,fl,_) -> + let types,kl,len = + List.fold_left + (fun (types,kl,len) (_,name,k,ty,_) -> + let _ = typeof ~subst ~metasenv [] ty in + ((name,(C.Decl (S.lift len ty)))::types, k::kl,len+1) + ) ([],[],0) fl + in + List.iter (fun (_,name,x,ty,bo) -> + let bo = debruijn uri len bo in + let ty_bo = typeof ~subst ~metasenv types bo in + if not (R.are_convertible ~subst ~metasenv types ty_bo (S.lift len ty)) + then raise (TypeCheckerFailure (lazy ("(Co)Fix: ill-typed bodies"))) + else + if inductive then begin + let m, context = eat_lambdas ~subst ~metasenv types (x + 1) bo in + (* guarded by destructors conditions D{f,k,x,M} *) + let rec enum_from k = + function [] -> [] | v::tl -> (k,v)::enum_from (k+1) tl + in + guarded_by_destructors + ~subst ~metasenv context (enum_from (x+2) kl) m + end else + match returns_a_coinductive ~subst [] ty with + | None -> + raise (TypeCheckerFailure + (lazy "CoFix: does not return a coinductive type")) + | Some uri -> + (* guarded by constructors conditions C{f,M} *) + if not (guarded_by_constructors ~subst ~metasenv + types 0 len false bo [] uri) + then + raise (TypeCheckerFailure + (lazy "CoFix: not guarded by constructors")) + ) fl + +let typecheck_obj = check_obj_well_typed;; + +(* EOF *)