+(*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))))
+;;
+