- (mk_appl ~upto:(List.length args) term args)
-
- | NCic.Appl (NCic.Meta (i,_)::_ as l1),
- NCic.Appl (NCic.Meta (j,_)::_ as l2) when i=j ->
- (try
- List.fold_left2
- (fun (metasenv, subst) t1 t2 ->
- unify rdb test_eq_only metasenv subst context t1 t2)
- (metasenv,subst) l1 l2
- with Invalid_argument _ ->
- raise (fail_exc metasenv subst context t1 t2))
-
- | NCic.Appl (NCic.Meta (i,l)::args), _ ->
- let metasenv, subst, lambda_Mj =
- lambda_intros rdb metasenv subst context t1 args
- in
- let metasenv, subst =
- unify rdb test_eq_only metasenv subst context
- (C.Meta (i,l)) lambda_Mj
- in
- let metasenv, subst =
- unify rdb test_eq_only metasenv subst context t1 t2
- in
- (try
- let name, ctx, term, ty = NCicUtils.lookup_subst i subst in
- let term = eta_reduce subst term in
- let subst = List.filter (fun (j,_) -> j <> i) subst in
- metasenv, ((i, (name, ctx, term, ty)) :: subst)
- with Not_found -> assert false)
-
- | _, NCic.Appl (NCic.Meta (i,l)::args) ->
- let metasenv, subst, lambda_Mj =
- lambda_intros rdb metasenv subst context t2 args
- in
- let metasenv, subst =
- unify rdb test_eq_only metasenv subst context
- lambda_Mj (C.Meta (i,l))
- in
- let metasenv, subst =
- unify rdb test_eq_only metasenv subst context t1 t2
- in
- (try
- let name, ctx, term, ty = NCicUtils.lookup_subst i subst in
- let term = eta_reduce subst term in
- let subst = List.filter (fun (j,_) -> j <> i) subst in
- metasenv, ((i, (name, ctx, term, ty)) :: subst)
- with Not_found -> assert false)
+ (mk_appl ~upto:(List.length args) term args) swap
+ | NCic.Appl (NCic.Meta (i,_)::_), _ when List.mem_assoc i subst ->
+ unify rdb test_eq_only metasenv subst context t2 t1 (not swap)
+
+ | C.Meta (n,_), C.Meta (m,lc') when
+ let _,cc1,_ = NCicUtils.lookup_meta n metasenv in
+ let _,cc2,_ = NCicUtils.lookup_meta m metasenv in
+ (n < m && cc1 = cc2) ||
+ let len1 = List.length cc1 in
+ let len2 = List.length cc2 in
+ len2 < len1 && cc2 = fst (HExtlib.split_nth len2 cc1) ->
+ instantiate rdb test_eq_only metasenv subst context m lc'
+ (NCicReduction.head_beta_reduce ~subst t1) (not swap)
+ | C.Meta (n,lc), C.Meta (m,lc') when
+ let _,_,tyn = NCicUtils.lookup_meta n metasenv in
+ let _,_,tym = NCicUtils.lookup_meta m metasenv in
+ let tyn = NCicSubstitution.subst_meta lc tyn in
+ let tym = NCicSubstitution.subst_meta lc tym in
+ match tyn,tym with
+ NCic.Sort NCic.Type u1, NCic.Sort NCic.Type u2 ->
+ NCicEnvironment.universe_lt u1 u2
+ | _,_ -> false ->
+ instantiate rdb test_eq_only metasenv subst context m lc'
+ (NCicReduction.head_beta_reduce ~subst t1) (not swap)
+ | C.Meta (n,lc), t ->
+ instantiate rdb test_eq_only metasenv subst context n lc
+ (NCicReduction.head_beta_reduce ~subst t) swap
+ | t, C.Meta (n,lc) ->
+ instantiate rdb test_eq_only metasenv subst context n lc
+ (NCicReduction.head_beta_reduce ~subst t) (not swap)
+
+ (* higher order unification case *)
+ | NCic.Appl (NCic.Meta (i,l) as meta :: args), _ ->
+ (* this easy_case handles "(? ?) =?= (f a)", same number of
+ * args, preferring the instantiation "f" over "\_.f a" for the
+ * metavariable in head position. Since the arguments of the meta
+ * are flexible, delift would ignore them generating a constant
+ * function even in the easy case above *)
+ let easy_case =
+ match t2 with
+ | NCic.Appl (f :: f_args)
+ when
+ List.exists (NCicMetaSubst.is_flexible context ~subst) args ->
+ let mlen = List.length args in
+ let flen = List.length f_args in
+ let min_len = min mlen flen in
+ let mhe,margs = HExtlib.split_nth (mlen - min_len) args in
+ let fhe,fargs = HExtlib.split_nth (flen - min_len) f_args in
+ (try
+ Some (List.fold_left2
+ (fun (m, s) t1 t2 ->
+ unify rdb test_eq_only m s context t1 t2 swap
+ ) (metasenv,subst)
+ ((NCicUntrusted.mk_appl meta mhe)::margs)
+ ((NCicUntrusted.mk_appl f fhe)::fargs))
+ with UnificationFailure _ | Uncertain _ | KeepReducing _ ->
+ None)
+ | _ -> None
+ in
+ (match easy_case with
+ | Some ms -> ms
+ | None ->
+ (* This case handles "(?_f ..ti..) =?= t2", abstracting every
+ * non flexible ti (delift skips local context items that are
+ * flexible) from t2 in two steps:
+ * 1) ?_f := \..xi.. .?
+ * 2) ?_f ..ti.. =?= t2 --unif_machines-->
+ ?_f[..ti..] =?= t2 --instantiate-->
+ delift [..ti..] t2 *)
+ let metasenv, lambda_Mj =
+ lambda_intros rdb metasenv subst context (List.length args)
+ (NCicTypeChecker.typeof ~metasenv ~subst context meta)
+ in
+ let metasenv, subst =
+ unify rdb test_eq_only metasenv subst context
+ (C.Meta (i,l)) lambda_Mj swap
+ in
+ let metasenv, subst =
+ unify rdb test_eq_only metasenv subst context t1 t2 swap
+ in
+ (try
+ let name, ctx, term, ty = NCicUtils.lookup_subst i subst in
+ let term = eta_reduce subst term in
+ let subst = List.filter (fun (j,_) -> j <> i) subst in
+ metasenv, ((i, (name, ctx, term, ty)) :: subst)
+ with Not_found -> assert false))
+
+ | _, NCic.Appl (NCic.Meta (_,_) :: _) ->
+ unify rdb test_eq_only metasenv subst context t2 t1 (not swap)