- let rec aux metasenv k =
- function
- C.Rel i ->
- if i <= k then
- metasenv
- else
- (try
- match List.nth canonical_context (i-k-1) with
- Some (_,C.Decl t)
- | Some (_,C.Def t) -> aux metasenv k (S.lift i t)
- | None -> raise RelToHiddenHypothesis
- with
- Failure _ -> raise OpenTerm
- )
- | C.Var _ -> metasenv
- | C.Meta (i,l) -> restrict canonical_context i k l metasenv
- | C.Sort _ -> metasenv
- | C.Implicit -> metasenv
- | C.Cast (te,ty) ->
- let metasenv' = aux metasenv k te in
- aux metasenv' k ty
- | C.Prod (_,s,t)
- | C.Lambda (_,s,t)
- | C.LetIn (_,s,t) ->
- let metasenv' = aux metasenv k s in
- aux metasenv' (k+1) t
- | C.Appl l ->
- List.fold_left
- (function metasenv -> aux metasenv k) metasenv l
- | C.Const _
- | C.Abst _
- | C.MutInd _
- | C.MutConstruct _ -> metasenv
- | C.MutCase (_,_,_,outty,t,pl) ->
- let metasenv' = aux metasenv k outty in
- let metasenv'' = aux metasenv' k t in
- List.fold_left
- (function metasenv -> aux metasenv k) metasenv'' pl
- | C.Fix (i, fl) ->
- let len = List.length fl in
- List.fold_left
- (fun metasenv f ->
- let (_,_,ty,bo) = f in
- let metasenv' = aux metasenv k ty in
- aux metasenv' (k+len) bo
- ) metasenv fl
- | C.CoFix (i, fl) ->
- let len = List.length fl in
- List.fold_left
- (fun metasenv f ->
- let (_,ty,bo) = f in
- let metasenv' = aux metasenv k ty in
- aux metasenv' (k+len) bo
- ) metasenv fl
- in aux metasenv 0
-;;
-*)
+(* NUOVA UNIFICAZIONE *)
+(* A substitution is a (int * Cic.term) list that associates a
+ metavariable i with its body.
+ A metaenv is a (int * Cic.term) list that associate a metavariable
+ i with is type.
+ fo_unif_new takes a metasenv, a context, two terms t1 and t2 and gives back
+ a new substitution which is _NOT_ unwinded. It must be unwinded before
+ applying it. *)
+
+let rec fo_unif_subst subst context metasenv t1 t2 =
+ let module C = Cic in
+ let module R = CicReduction in
+ let module S = CicSubstitution in
+ match (t1, t2) with
+ (C.Meta (n,ln), C.Meta (m,lm)) when n=m ->
+ let ok =
+ List.fold_left2
+ (fun b t1 t2 ->
+ b &&
+ match t1,t2 with
+ None,_
+ | _,None -> true
+ | Some t1', Some t2' ->
+ (* First possibility: restriction *)
+ (* Second possibility: unification *)
+ (* Third possibility: convertibility *)
+ R.are_convertible context t1' t2'
+ ) true ln lm
+ in
+ if ok then subst,metasenv else raise UnificationFailed
+ | (C.Meta (n,l), C.Meta (m,_)) when n>m ->
+ fo_unif_subst subst context metasenv t2 t1
+ | (C.Meta (n,l), t)
+ | (t, C.Meta (n,l)) ->
+ let subst',metasenv' =
+ try
+ let oldt = (List.assoc n subst) in
+ let lifted_oldt = S.lift_meta l oldt in
+ fo_unif_subst subst context metasenv lifted_oldt t
+ with Not_found ->
+ let t',metasenv' = delift context metasenv l t in
+ (n, t')::subst, metasenv'
+ in
+ let (_,_,meta_type) =
+ List.find (function (m,_,_) -> m=n) metasenv' in
+ let tyt = CicTypeChecker.type_of_aux' metasenv' context t in
+ fo_unif_subst subst' context metasenv' (S.lift_meta l meta_type) tyt
+ | (C.Var (uri1,exp_named_subst1),C.Var (uri2,exp_named_subst2))
+ | (C.Const (uri1,exp_named_subst1),C.Const (uri2,exp_named_subst2)) ->
+ if UriManager.eq uri1 uri2 then
+ fo_unif_subst_exp_named_subst subst context metasenv
+ exp_named_subst1 exp_named_subst2
+ else
+ raise UnificationFailed
+ | C.MutInd (uri1,i1,exp_named_subst1),C.MutInd (uri2,i2,exp_named_subst2) ->
+ if UriManager.eq uri1 uri2 && i1 = i2 then
+ fo_unif_subst_exp_named_subst subst context metasenv
+ exp_named_subst1 exp_named_subst2
+ else
+ raise UnificationFailed
+ | C.MutConstruct (uri1,i1,j1,exp_named_subst1),
+ C.MutConstruct (uri2,i2,j2,exp_named_subst2) ->
+ if UriManager.eq uri1 uri2 && i1 = i2 && j1 = j2 then
+ fo_unif_subst_exp_named_subst subst context metasenv
+ exp_named_subst1 exp_named_subst2
+ else
+ raise UnificationFailed
+ | (C.Rel _, _)
+ | (_, C.Rel _)
+ | (C.Sort _ ,_)
+ | (_, C.Sort _)
+ | (C.Implicit, _)
+ | (_, C.Implicit) ->
+ if R.are_convertible context t1 t2 then
+ subst, metasenv
+ else
+ raise UnificationFailed
+ | (C.Cast (te,ty), t2) -> fo_unif_subst subst context metasenv te t2
+ | (t1, C.Cast (te,ty)) -> fo_unif_subst subst context metasenv t1 te
+ | (C.Prod (n1,s1,t1), C.Prod (_,s2,t2)) ->
+ let subst',metasenv' = fo_unif_subst subst context metasenv s1 s2 in
+ fo_unif_subst subst' ((Some (n1,(C.Decl s1)))::context) metasenv' t1 t2
+ | (C.Lambda (n1,s1,t1), C.Lambda (_,s2,t2)) ->
+ let subst',metasenv' = fo_unif_subst subst context metasenv s1 s2 in
+ fo_unif_subst subst' ((Some (n1,(C.Decl s1)))::context) metasenv' t1 t2
+ | (C.LetIn (_,s1,t1), t2)
+ | (t2, C.LetIn (_,s1,t1)) ->
+ fo_unif_subst subst context metasenv t2 (S.subst s1 t1)
+ | (C.Appl l1, C.Appl l2) ->
+ let lr1 = List.rev l1 in
+ let lr2 = List.rev l2 in
+ let rec fo_unif_l subst metasenv =
+ function
+ [],_
+ | _,[] -> assert false
+ | ([h1],[h2]) ->
+ fo_unif_subst subst context metasenv h1 h2
+ | ([h],l)
+ | (l,[h]) ->
+ fo_unif_subst subst context metasenv h (C.Appl (List.rev l))
+ | ((h1::l1),(h2::l2)) ->
+ let subst', metasenv' =
+ fo_unif_subst subst context metasenv h1 h2
+ in
+ fo_unif_l subst' metasenv' (l1,l2)
+ in
+ fo_unif_l subst metasenv (lr1, lr2)
+ | (C.Const _, _)
+ | (_, C.Const _)
+ | (C.MutInd _, _)
+ | (_, C.MutInd _)
+ | (C.MutConstruct _, _)
+ | (_, C.MutConstruct _) ->
+ if R.are_convertible context t1 t2 then
+ subst, metasenv
+ else
+ raise UnificationFailed
+ | (C.MutCase (_,_,outt1,t1,pl1), C.MutCase (_,_,outt2,t2,pl2))->
+ let subst', metasenv' =
+ fo_unif_subst subst context metasenv outt1 outt2 in
+ let subst'',metasenv'' =
+ fo_unif_subst subst' context metasenv' t1 t2 in
+ List.fold_left2
+ (function (subst,metasenv) ->
+ fo_unif_subst subst context metasenv
+ ) (subst'',metasenv'') pl1 pl2
+ | (C.Fix _, _)
+ | (_, C.Fix _)
+ | (C.CoFix _, _)
+ | (_, C.CoFix _) ->
+ if R.are_convertible context t1 t2 then
+ subst, metasenv
+ else
+ raise UnificationFailed
+ | (_,_) ->
+ if R.are_convertible context t1 t2 then
+ subst, metasenv
+ else
+ raise UnificationFailed