src/Pure/simplifier.ML
author obua
Sun May 29 12:39:12 2005 +0200 (2005-05-29)
changeset 16108 cf468b93a02e
parent 16014 85f4b0f81f62
child 16458 4c6fd0c01d28
permissions -rw-r--r--
Implement cycle-free overloading, so that definitions cannot harm consistency any more (except of course via interaction with axioms).
     1 (*  Title:      Pure/simplifier.ML
     2     ID:         $Id$
     3     Author:     Tobias Nipkow and Markus Wenzel, TU Muenchen
     4 
     5 Generic simplifier, suitable for most logics (see also
     6 meta_simplifier.ML for the actual meta-level rewriting engine).
     7 *)
     8 
     9 (* added: put_delta_simpset, get_delta_simpset
    10    changed: simp_add_local
    11    07/01/05
    12 *)
    13 
    14 
    15 signature BASIC_SIMPLIFIER =
    16 sig
    17   include BASIC_META_SIMPLIFIER
    18   type context_solver
    19   val mk_context_solver: string -> (Proof.context -> thm list -> int -> tactic)
    20     -> context_solver
    21   type context_simproc
    22   val mk_context_simproc: string -> cterm list ->
    23     (Proof.context -> simpset -> term -> thm option) -> context_simproc
    24   val print_simpset: theory -> unit
    25   val simpset_ref_of_sg: Sign.sg -> simpset ref
    26   val simpset_ref_of: theory -> simpset ref
    27   val simpset_of_sg: Sign.sg -> simpset
    28   val simpset_of: theory -> simpset
    29   val SIMPSET: (simpset -> tactic) -> tactic
    30   val SIMPSET': (simpset -> 'a -> tactic) -> 'a -> tactic
    31   val simpset: unit -> simpset
    32   val simpset_ref: unit -> simpset ref
    33   val Addsimps: thm list -> unit
    34   val Delsimps: thm list -> unit
    35   val Addsimprocs: simproc list -> unit
    36   val Delsimprocs: simproc list -> unit
    37   val Addcongs: thm list -> unit
    38   val Delcongs: thm list -> unit
    39   val local_simpset_of: Proof.context -> simpset
    40   val safe_asm_full_simp_tac: simpset -> int -> tactic
    41   val               simp_tac: simpset -> int -> tactic
    42   val           asm_simp_tac: simpset -> int -> tactic
    43   val          full_simp_tac: simpset -> int -> tactic
    44   val        asm_lr_simp_tac: simpset -> int -> tactic
    45   val      asm_full_simp_tac: simpset -> int -> tactic
    46   val               Simp_tac:            int -> tactic
    47   val           Asm_simp_tac:            int -> tactic
    48   val          Full_simp_tac:            int -> tactic
    49   val        Asm_lr_simp_tac:            int -> tactic
    50   val      Asm_full_simp_tac:            int -> tactic
    51   val          simplify: simpset -> thm -> thm
    52   val      asm_simplify: simpset -> thm -> thm
    53   val     full_simplify: simpset -> thm -> thm
    54   val   asm_lr_simplify: simpset -> thm -> thm
    55   val asm_full_simplify: simpset -> thm -> thm
    56 end;
    57 
    58 signature SIMPLIFIER =
    59 sig
    60   include BASIC_SIMPLIFIER
    61   val simproc_i: Sign.sg -> string -> term list
    62     -> (Sign.sg -> simpset -> term -> thm option) -> simproc
    63   val simproc: Sign.sg -> string -> string list
    64     -> (Sign.sg -> simpset -> term -> thm option) -> simproc
    65   val context_simproc_i: Sign.sg -> string -> term list
    66     -> (Proof.context -> simpset -> term -> thm option) -> context_simproc
    67   val context_simproc: Sign.sg -> string -> string list
    68     -> (Proof.context -> simpset -> term -> thm option) -> context_simproc
    69   val          rewrite: simpset -> cterm -> thm
    70   val      asm_rewrite: simpset -> cterm -> thm
    71   val     full_rewrite: simpset -> cterm -> thm
    72   val   asm_lr_rewrite: simpset -> cterm -> thm
    73   val asm_full_rewrite: simpset -> cterm -> thm
    74   val add_context_simprocs: context_simproc list -> theory -> theory
    75   val del_context_simprocs: context_simproc list -> theory -> theory
    76   val set_context_subgoaler: (Proof.context -> simpset -> int -> tactic) -> theory -> theory
    77   val reset_context_subgoaler: theory -> theory
    78   val add_context_looper: string * (Proof.context -> int -> Tactical.tactic) ->
    79     theory -> theory
    80   val del_context_looper: string -> theory -> theory
    81   val add_context_unsafe_solver: context_solver -> theory -> theory
    82   val add_context_safe_solver: context_solver -> theory -> theory
    83   val print_local_simpset: Proof.context -> unit
    84   val get_local_simpset: Proof.context -> simpset
    85   val put_local_simpset: simpset -> Proof.context -> Proof.context
    86   val change_global_ss: (simpset * thm list -> simpset) -> theory attribute
    87   val change_local_ss: (simpset * thm list -> simpset) -> Proof.context attribute
    88   val simp_add_global: theory attribute
    89   val simp_del_global: theory attribute
    90   val simp_add_local: Proof.context attribute
    91   val simp_del_local: Proof.context attribute
    92   val cong_add_global: theory attribute
    93   val cong_del_global: theory attribute
    94   val cong_add_local: Proof.context attribute
    95   val cong_del_local: Proof.context attribute
    96   val change_simpset_of: (simpset * 'a -> simpset) -> 'a -> theory -> theory
    97   val simp_modifiers: (Args.T list -> (Method.modifier * Args.T list)) list
    98   val method_setup: (Args.T list -> (Method.modifier * Args.T list)) list
    99     -> (theory -> theory) list
   100   val easy_setup: thm -> thm list -> (theory -> theory) list
   101 
   102   val get_delta_simpset: ProofContext.context -> Thm.thm list
   103   val put_delta_simpset: Thm.thm list -> ProofContext.context -> ProofContext.context
   104 end;
   105 
   106 structure Simplifier: SIMPLIFIER =
   107 struct
   108 
   109 open MetaSimplifier;
   110 
   111 
   112 (** context dependent simpset components **)
   113 
   114 (* datatype context_solver *)
   115 
   116 datatype context_solver =
   117   ContextSolver of (string * (Proof.context -> thm list -> int -> tactic)) * stamp;
   118 
   119 fun mk_context_solver name f = ContextSolver ((name, f), stamp ());
   120 fun eq_context_solver (ContextSolver (_, id1), ContextSolver (_, id2)) = (id1 = id2);
   121 val merge_context_solvers = gen_merge_lists eq_context_solver;
   122 
   123 
   124 (* datatype context_simproc *)
   125 
   126 datatype context_simproc = ContextSimproc of
   127   (string * cterm list * (Proof.context -> simpset -> term -> thm option)) * stamp;
   128 
   129 fun mk_context_simproc name lhss f = ContextSimproc ((name, lhss, f), stamp ());
   130 fun eq_context_simproc (ContextSimproc (_, id1), ContextSimproc (_, id2)) = (id1 = id2);
   131 val merge_context_simprocs = gen_merge_lists eq_context_simproc;
   132 
   133 fun context_simproc_i sg name =
   134   mk_context_simproc name o map (Thm.cterm_of sg o Logic.varify);
   135 
   136 fun context_simproc sg name =
   137   context_simproc_i sg name o map (Sign.simple_read_term sg TypeInfer.logicT);
   138 
   139 
   140 (* datatype context_ss *)
   141 
   142 datatype context_ss = ContextSS of
   143  {simprocs: context_simproc list,
   144   subgoal_tac: (Proof.context -> simpset -> int -> tactic) option,
   145   loop_tacs: (string * (Proof.context -> int -> tactic)) list,
   146   unsafe_solvers: context_solver list,
   147   solvers: context_solver list};
   148 
   149 fun context_ss ctxt ss ctxt_ss =
   150   let
   151     val ContextSS {simprocs, subgoal_tac, loop_tacs, unsafe_solvers, solvers} = ctxt_ss;
   152     fun prep_simproc (ContextSimproc ((name, lhss, f), _)) =
   153       mk_simproc name lhss (K (f ctxt));
   154     fun add_loop (name, f) simpset = simpset addloop (name, f ctxt);
   155     fun add_solver add (ContextSolver ((name, f), _)) simpset =
   156       add (simpset, mk_solver name (f ctxt));
   157   in
   158     ((case subgoal_tac of NONE => ss | SOME tac => ss setsubgoaler tac ctxt)
   159       addsimprocs map prep_simproc simprocs)
   160     |> fold_rev add_loop loop_tacs
   161     |> fold_rev (add_solver (op addSolver)) unsafe_solvers
   162     |> fold_rev (add_solver (op addSSolver)) solvers
   163   end;
   164 
   165 fun make_context_ss (simprocs, subgoal_tac, loop_tacs, unsafe_solvers, solvers) =
   166   ContextSS {simprocs = simprocs, subgoal_tac = subgoal_tac, loop_tacs = loop_tacs,
   167     unsafe_solvers = unsafe_solvers, solvers = solvers};
   168 
   169 val empty_context_ss = make_context_ss ([], NONE, [], [], []);
   170 
   171 fun merge_context_ss (ctxt_ss1, ctxt_ss2) =
   172   let
   173     val ContextSS {simprocs = simprocs1, subgoal_tac = subgoal_tac1, loop_tacs = loop_tacs1,
   174       unsafe_solvers = unsafe_solvers1, solvers = solvers1} = ctxt_ss1;
   175     val ContextSS {simprocs = simprocs2, subgoal_tac = subgoal_tac2, loop_tacs = loop_tacs2,
   176       unsafe_solvers = unsafe_solvers2, solvers = solvers2} = ctxt_ss2;
   177 
   178     val simprocs' = merge_context_simprocs simprocs1 simprocs2;
   179     val subgoal_tac' = (case subgoal_tac1 of NONE => subgoal_tac2 | some => some);
   180     val loop_tacs' = merge_alists loop_tacs1 loop_tacs2;
   181     val unsafe_solvers' = merge_context_solvers unsafe_solvers1 unsafe_solvers2;
   182     val solvers' = merge_context_solvers solvers1 solvers2;
   183   in make_context_ss (simprocs', subgoal_tac', loop_tacs', unsafe_solvers', solvers') end;
   184 
   185 
   186 
   187 (** global and local simpset data **)
   188 
   189 (* theory data kind 'Pure/simpset' *)
   190 
   191 structure GlobalSimpsetArgs =
   192 struct
   193   val name = "Pure/simpset";
   194   type T = simpset ref * context_ss;
   195 
   196   val empty = (ref empty_ss, empty_context_ss);
   197   fun copy (ref ss, ctxt_ss) = (ref ss, ctxt_ss): T;            (*create new reference!*)
   198   val prep_ext = copy;
   199   fun merge ((ref ss1, ctxt_ss1), (ref ss2, ctxt_ss2)) =
   200     (ref (merge_ss (ss1, ss2)), merge_context_ss (ctxt_ss1, ctxt_ss2));
   201   fun print _ (ref ss, _) = print_ss ss;
   202 end;
   203 
   204 structure GlobalSimpset = TheoryDataFun(GlobalSimpsetArgs);
   205 val _ = Context.add_setup [GlobalSimpset.init];
   206 val print_simpset = GlobalSimpset.print;
   207 
   208 val simpset_ref_of_sg = #1 o GlobalSimpset.get_sg;
   209 val simpset_ref_of = #1 o GlobalSimpset.get;
   210 val get_context_ss = #2 o GlobalSimpset.get o ProofContext.theory_of;
   211 
   212 fun map_context_ss f = GlobalSimpset.map (apsnd
   213   (fn ContextSS {simprocs, subgoal_tac, loop_tacs, unsafe_solvers, solvers} =>
   214     make_context_ss (f (simprocs, subgoal_tac, loop_tacs, unsafe_solvers, solvers))));
   215 
   216 
   217 (* access global simpset *)
   218 
   219 val simpset_of_sg = ! o simpset_ref_of_sg;
   220 val simpset_of = simpset_of_sg o Theory.sign_of;
   221 
   222 fun SIMPSET tacf state = tacf (simpset_of_sg (Thm.sign_of_thm state)) state;
   223 fun SIMPSET' tacf i state = tacf (simpset_of_sg (Thm.sign_of_thm state)) i state;
   224 
   225 val simpset = simpset_of o Context.the_context;
   226 val simpset_ref = simpset_ref_of_sg o Theory.sign_of o Context.the_context;
   227 
   228 
   229 (* change global simpset *)
   230 
   231 fun change_simpset_of f x thy =
   232   let val r = simpset_ref_of thy
   233   in r := f (! r, x); thy end;
   234 
   235 fun change_simpset f x = (change_simpset_of f x (Context.the_context ()); ());
   236 
   237 val Addsimps = change_simpset (op addsimps);
   238 val Delsimps = change_simpset (op delsimps);
   239 val Addsimprocs = change_simpset (op addsimprocs);
   240 val Delsimprocs = change_simpset (op delsimprocs);
   241 val Addcongs = change_simpset (op addcongs);
   242 val Delcongs = change_simpset (op delcongs);
   243 
   244 
   245 (* change context dependent components *)
   246 
   247 fun add_context_simprocs procs =
   248   map_context_ss (fn (simprocs, subgoal_tac, loop_tacs, unsafe_solvers, solvers) =>
   249     (merge_context_simprocs procs simprocs, subgoal_tac, loop_tacs,
   250       unsafe_solvers, solvers));
   251 
   252 fun del_context_simprocs procs =
   253   map_context_ss (fn (simprocs, subgoal_tac, loop_tacs, unsafe_solvers, solvers) =>
   254     (gen_rems eq_context_simproc (simprocs, procs), subgoal_tac, loop_tacs,
   255       unsafe_solvers, solvers));
   256 
   257 fun set_context_subgoaler tac =
   258   map_context_ss (fn (simprocs, _, loop_tacs, unsafe_solvers, solvers) =>
   259     (simprocs, SOME tac, loop_tacs, unsafe_solvers, solvers));
   260 
   261 val reset_context_subgoaler =
   262   map_context_ss (fn (simprocs, _, loop_tacs, unsafe_solvers, solvers) =>
   263     (simprocs, NONE, loop_tacs, unsafe_solvers, solvers));
   264 
   265 fun add_context_looper (name, tac) =
   266   map_context_ss (fn (simprocs, subgoal_tac, loop_tacs, unsafe_solvers, solvers) =>
   267     (simprocs, subgoal_tac, merge_alists [(name, tac)] loop_tacs,
   268       unsafe_solvers, solvers));
   269 
   270 fun del_context_looper name =
   271   map_context_ss (fn (simprocs, subgoal_tac, loop_tacs, unsafe_solvers, solvers) =>
   272     (simprocs, subgoal_tac, filter_out (equal name o #1) loop_tacs,
   273       unsafe_solvers, solvers));
   274 
   275 fun add_context_unsafe_solver solver =
   276   map_context_ss (fn (simprocs, subgoal_tac, loop_tacs, unsafe_solvers, solvers) =>
   277     (simprocs, subgoal_tac, loop_tacs,
   278       merge_context_solvers [solver] unsafe_solvers, solvers));
   279 
   280 fun add_context_safe_solver solver =
   281   map_context_ss (fn (simprocs, subgoal_tac, loop_tacs, unsafe_solvers, solvers) =>
   282     (simprocs, subgoal_tac, loop_tacs, unsafe_solvers,
   283       merge_context_solvers [solver] solvers));
   284 
   285 
   286 (* proof data kind 'Pure/simpset' *)
   287 
   288 structure LocalSimpsetArgs =
   289 struct
   290   val name = "Pure/simpset";
   291   type T = simpset;
   292   val init = simpset_of;
   293   fun print ctxt ss = print_ss (context_ss ctxt ss (get_context_ss ctxt));
   294 end;
   295 
   296 structure LocalSimpset = ProofDataFun(LocalSimpsetArgs);
   297 val _ = Context.add_setup [LocalSimpset.init];
   298 val print_local_simpset = LocalSimpset.print;
   299 
   300 val get_local_simpset = LocalSimpset.get;
   301 val put_local_simpset = LocalSimpset.put;
   302 fun map_local_simpset f ctxt = put_local_simpset (f (get_local_simpset ctxt)) ctxt;
   303 
   304 fun local_simpset_of ctxt =
   305   context_ss ctxt (get_local_simpset ctxt) (get_context_ss ctxt);
   306 
   307 
   308 (* Jia: added DeltaSimpsetArgs and DeltaSimpset for delta_simpset
   309 	also added methods to retrieve them. *)
   310 (* CB: changed "delta simpsets" to context data,
   311        moved counter to here, it is no longer a ref *)
   312 
   313 structure DeltaSimpsetArgs =
   314 struct
   315   val name = "Pure/delta_simpset";
   316   type T = Thm.thm list * int;  (*the type is thm list * int*)
   317   fun init _ = ([], 0);
   318   fun print ctxt thms = ();
   319 end;
   320 
   321 structure DeltaSimpsetData = ProofDataFun(DeltaSimpsetArgs);
   322 val _ = Context.add_setup [DeltaSimpsetData.init];
   323 
   324 val get_delta_simpset = #1 o DeltaSimpsetData.get;
   325 fun put_delta_simpset ss = DeltaSimpsetData.map (fn (_, i) => (ss, i));
   326 fun delta_increment ctxt =
   327   let val ctxt' = DeltaSimpsetData.map (fn (ss, i) => (ss, i+1)) ctxt
   328   in (ctxt', #2 (DeltaSimpsetData.get ctxt'))
   329   end;
   330 
   331 (* Jia: added to rename a local thm if necessary *) 
   332 local 
   333 fun rename_thm' (ctxt,thm) =
   334   let val (new_ctxt, new_id) = delta_increment ctxt
   335       val new_name = "anon_simp_" ^ (string_of_int new_id)
   336   in
   337     (new_ctxt, Thm.name_thm(new_name,thm))
   338 end;
   339 
   340 in
   341 
   342 fun rename_thm (ctxt,thm) = if (!Proof.call_atp) then rename_thm' (ctxt,thm) else (ctxt, thm);
   343 
   344 end
   345 
   346 (* attributes *)
   347 
   348 fun change_global_ss f (thy, th) =
   349   let val r = simpset_ref_of thy
   350   in r := f (! r, [th]); (thy, th) end;
   351 
   352 fun change_local_ss f (ctxt, th) =
   353   let val ss = f (get_local_simpset ctxt, [th])
   354   in (put_local_simpset ss ctxt, th) end;
   355 
   356 val simp_add_global = change_global_ss (op addsimps);
   357 val simp_del_global = change_global_ss (op delsimps);
   358 
   359 
   360 
   361 
   362 
   363 (* Jia: note: when simplifier rules are added to local_simpset, they are also added to delta_simpset in ProofContext.context, but not removed if simp_del_local is called *)
   364 fun simp_add_local (ctxt,th) = 
   365     let val delta_ss = get_delta_simpset ctxt
   366 	val thm_name = Thm.name_of_thm th
   367         val (ctxt', th') =
   368           if (thm_name = "") then rename_thm (ctxt,th)  else (ctxt, th)
   369 	val new_dss = th'::delta_ss
   370 	val ctxt'' = put_delta_simpset new_dss ctxt' 
   371     in
   372 	change_local_ss (op addsimps) (ctxt'',th)
   373     end;
   374 
   375 val simp_del_local = change_local_ss (op delsimps);
   376 
   377 val cong_add_global = change_global_ss (op addcongs);
   378 val cong_del_global = change_global_ss (op delcongs);
   379 val cong_add_local = change_local_ss (op addcongs);
   380 val cong_del_local = change_local_ss (op delcongs);
   381 
   382 
   383 val simp_tac = generic_simp_tac false (false, false, false);
   384 val asm_simp_tac = generic_simp_tac false (false, true, false);
   385 val full_simp_tac = generic_simp_tac false (true, false, false);
   386 val asm_lr_simp_tac = generic_simp_tac false (true, true, false);
   387 val asm_full_simp_tac = generic_simp_tac false (true, true, true);
   388 val safe_asm_full_simp_tac = generic_simp_tac true (true, true, true);
   389 
   390 
   391 
   392 (*the abstraction over the proof state delays the dereferencing*)
   393 fun          Simp_tac i st =          simp_tac (simpset ()) i st;
   394 fun      Asm_simp_tac i st =      asm_simp_tac (simpset ()) i st;
   395 fun     Full_simp_tac i st =     full_simp_tac (simpset ()) i st;
   396 fun   Asm_lr_simp_tac i st =   asm_lr_simp_tac (simpset ()) i st;
   397 fun Asm_full_simp_tac i st = asm_full_simp_tac (simpset ()) i st;
   398 
   399 val          simplify = simp_thm (false, false, false);
   400 val      asm_simplify = simp_thm (false, true, false);
   401 val     full_simplify = simp_thm (true, false, false);
   402 val   asm_lr_simplify = simp_thm (true, true, false);
   403 val asm_full_simplify = simp_thm (true, true, true);
   404 
   405 val          rewrite = simp_cterm (false, false, false);
   406 val      asm_rewrite = simp_cterm (false, true, false);
   407 val     full_rewrite = simp_cterm (true, false, false);
   408 val   asm_lr_rewrite = simp_cterm (true, true, false);
   409 val asm_full_rewrite = simp_cterm (true, true, true);
   410 
   411 
   412 
   413 (** concrete syntax of attributes **)
   414 
   415 (* add / del *)
   416 
   417 val simpN = "simp";
   418 val congN = "cong";
   419 val addN = "add";
   420 val delN = "del";
   421 val onlyN = "only";
   422 val no_asmN = "no_asm";
   423 val no_asm_useN = "no_asm_use";
   424 val no_asm_simpN = "no_asm_simp";
   425 val asm_lrN = "asm_lr";
   426 
   427 val simp_attr =
   428  (Attrib.add_del_args simp_add_global simp_del_global,
   429   Attrib.add_del_args simp_add_local simp_del_local);
   430 
   431 val cong_attr =
   432  (Attrib.add_del_args cong_add_global cong_del_global,
   433   Attrib.add_del_args cong_add_local cong_del_local);
   434 
   435 
   436 (* conversions *)
   437 
   438 local
   439 
   440 fun conv_mode x =
   441   ((Args.parens (Args.$$$ no_asmN) >> K simplify ||
   442     Args.parens (Args.$$$ no_asm_simpN) >> K asm_simplify ||
   443     Args.parens (Args.$$$ no_asm_useN) >> K full_simplify ||
   444     Scan.succeed asm_full_simplify) |> Scan.lift) x;
   445 
   446 fun simplified_att get args =
   447   Attrib.syntax (conv_mode -- args >> (fn (f, ths) =>
   448     Drule.rule_attribute (fn x => f ((if null ths then I else clear_ss) (get x) addsimps ths))));
   449 
   450 in
   451 
   452 val simplified_attr =
   453  (simplified_att simpset_of Attrib.global_thmss,
   454   simplified_att local_simpset_of Attrib.local_thmss);
   455 
   456 end;
   457 
   458 
   459 (* setup attributes *)
   460 
   461 val _ = Context.add_setup
   462  [Attrib.add_attributes
   463    [(simpN, simp_attr, "declaration of simplification rule"),
   464     (congN, cong_attr, "declaration of Simplifier congruence rule"),
   465     ("simplified", simplified_attr, "simplified rule")]];
   466 
   467 
   468 
   469 (** proof methods **)
   470 
   471 (* simplification *)
   472 
   473 val simp_options =
   474  (Args.parens (Args.$$$ no_asmN) >> K simp_tac ||
   475   Args.parens (Args.$$$ no_asm_simpN) >> K asm_simp_tac ||
   476   Args.parens (Args.$$$ no_asm_useN) >> K full_simp_tac ||
   477   Args.parens (Args.$$$ asm_lrN) >> K asm_lr_simp_tac ||
   478   Scan.succeed asm_full_simp_tac);
   479 
   480 val cong_modifiers =
   481  [Args.$$$ congN -- Args.colon >> K ((I, cong_add_local):Method.modifier),
   482   Args.$$$ congN -- Args.add -- Args.colon >> K (I, cong_add_local),
   483   Args.$$$ congN -- Args.del -- Args.colon >> K (I, cong_del_local)];
   484 
   485 val simp_modifiers =
   486  [Args.$$$ simpN -- Args.colon >> K (I, simp_add_local),
   487   Args.$$$ simpN -- Args.add -- Args.colon >> K (I, simp_add_local),
   488   Args.$$$ simpN -- Args.del -- Args.colon >> K (I, simp_del_local),
   489   Args.$$$ simpN -- Args.$$$ onlyN -- Args.colon >> K (map_local_simpset clear_ss, simp_add_local)]
   490    @ cong_modifiers;
   491 
   492 val simp_modifiers' =
   493  [Args.add -- Args.colon >> K (I, simp_add_local),
   494   Args.del -- Args.colon >> K (I, simp_del_local),
   495   Args.$$$ onlyN -- Args.colon >> K (map_local_simpset clear_ss, simp_add_local)]
   496    @ cong_modifiers;
   497 
   498 fun simp_args more_mods =
   499   Method.sectioned_args (Args.bang_facts -- Scan.lift simp_options) (more_mods @ simp_modifiers');
   500 
   501 
   502 fun simp_method (prems, tac) ctxt = Method.METHOD (fn facts =>
   503   ALLGOALS (Method.insert_tac (prems @ facts)) THEN
   504     (CHANGED_PROP o ALLGOALS o tac) (local_simpset_of ctxt));
   505 
   506 fun simp_method' (prems, tac) ctxt = Method.METHOD (fn facts =>
   507   HEADGOAL (Method.insert_tac (prems @ facts) THEN'
   508       (CHANGED_PROP oo tac) (local_simpset_of ctxt)));
   509 
   510 
   511 (* setup methods *)
   512 
   513 fun setup_methods more_mods = Method.add_methods
   514  [(simpN, simp_args more_mods simp_method', "simplification"),
   515   ("simp_all", simp_args more_mods simp_method, "simplification (all goals)")];
   516 
   517 fun method_setup mods = [setup_methods mods];
   518 
   519 
   520 (** easy_setup **)
   521 
   522 fun easy_setup reflect trivs =
   523   let
   524     val trivialities = Drule.reflexive_thm :: trivs;
   525 
   526     fun unsafe_solver_tac prems = FIRST' [resolve_tac (trivialities @ prems), assume_tac];
   527     val unsafe_solver = mk_solver "easy unsafe" unsafe_solver_tac;
   528 
   529     (*no premature instantiation of variables during simplification*)
   530     fun safe_solver_tac prems = FIRST' [match_tac (trivialities @ prems), eq_assume_tac];
   531     val safe_solver = mk_solver "easy safe" safe_solver_tac;
   532 
   533     fun mk_eq thm =
   534       if Logic.is_equals (Thm.concl_of thm) then [thm]
   535       else [thm RS reflect] handle THM _ => [];
   536 
   537     fun mksimps thm = mk_eq (Drule.forall_elim_vars (#maxidx (Thm.rep_thm thm) + 1) thm);
   538 
   539     fun init_ss thy =
   540       (simpset_ref_of thy :=
   541         empty_ss setsubgoaler asm_simp_tac
   542         setSSolver safe_solver
   543         setSolver unsafe_solver
   544         setmksimps mksimps; thy);
   545   in method_setup [] @ [init_ss] end;
   546 
   547 end;
   548 
   549 structure BasicSimplifier: BASIC_SIMPLIFIER = Simplifier;
   550 open BasicSimplifier;