src/HOL/Tools/recdef.ML
author wenzelm
Mon May 03 14:25:56 2010 +0200 (2010-05-03)
changeset 36610 bafd82950e24
parent 35756 cfde251d03a5
child 36865 7330e4eefbd7
permissions -rw-r--r--
renamed ProofContext.init to ProofContext.init_global to emphasize that this is not the real thing;
     1 (*  Title:      HOL/Tools/recdef.ML
     2     Author:     Markus Wenzel, TU Muenchen
     3 
     4 Wrapper module for Konrad Slind's TFL package.
     5 *)
     6 
     7 signature RECDEF =
     8 sig
     9   val get_recdef: theory -> string
    10     -> {lhs: term, simps: thm list, rules: thm list list, induct: thm, tcs: term list} option
    11   val get_hints: Proof.context -> {simps: thm list, congs: (string * thm) list, wfs: thm list}
    12   val simp_add: attribute
    13   val simp_del: attribute
    14   val cong_add: attribute
    15   val cong_del: attribute
    16   val wf_add: attribute
    17   val wf_del: attribute
    18   val add_recdef: bool -> xstring -> string -> ((binding * string) * Attrib.src list) list ->
    19     Attrib.src option -> theory -> theory
    20       * {lhs: term, simps: thm list, rules: thm list list, induct: thm, tcs: term list}
    21   val add_recdef_i: bool -> xstring -> term -> ((binding * term) * attribute list) list ->
    22     theory -> theory * {lhs: term, simps: thm list, rules: thm list list, induct: thm, tcs: term list}
    23   val defer_recdef: xstring -> string list -> (Facts.ref * Attrib.src list) list
    24     -> theory -> theory * {induct_rules: thm}
    25   val defer_recdef_i: xstring -> term list -> thm list -> theory -> theory * {induct_rules: thm}
    26   val recdef_tc: bstring * Attrib.src list -> xstring -> int option -> bool ->
    27     local_theory -> Proof.state
    28   val recdef_tc_i: bstring * Attrib.src list -> string -> int option -> bool ->
    29     local_theory -> Proof.state
    30   val setup: theory -> theory
    31 end;
    32 
    33 structure Recdef: RECDEF =
    34 struct
    35 
    36 
    37 (** recdef hints **)
    38 
    39 (* type hints *)
    40 
    41 type hints = {simps: thm list, congs: (string * thm) list, wfs: thm list};
    42 
    43 fun mk_hints (simps, congs, wfs) = {simps = simps, congs = congs, wfs = wfs}: hints;
    44 fun map_hints f ({simps, congs, wfs}: hints) = mk_hints (f (simps, congs, wfs));
    45 
    46 fun map_simps f = map_hints (fn (simps, congs, wfs) => (f simps, congs, wfs));
    47 fun map_congs f = map_hints (fn (simps, congs, wfs) => (simps, f congs, wfs));
    48 fun map_wfs f = map_hints (fn (simps, congs, wfs) => (simps, congs, f wfs));
    49 
    50 
    51 (* congruence rules *)
    52 
    53 local
    54 
    55 val cong_head =
    56   fst o Term.dest_Const o Term.head_of o fst o Logic.dest_equals o Thm.concl_of;
    57 
    58 fun prep_cong raw_thm =
    59   let val thm = safe_mk_meta_eq raw_thm in (cong_head thm, thm) end;
    60 
    61 in
    62 
    63 fun add_cong raw_thm congs =
    64   let
    65     val (c, thm) = prep_cong raw_thm;
    66     val _ = if AList.defined (op =) congs c
    67       then warning ("Overwriting recdef congruence rule for " ^ quote c)
    68       else ();
    69   in AList.update (op =) (c, thm) congs end;
    70 
    71 fun del_cong raw_thm congs =
    72   let
    73     val (c, thm) = prep_cong raw_thm;
    74     val _ = if AList.defined (op =) congs c
    75       then ()
    76       else warning ("No recdef congruence rule for " ^ quote c);
    77   in AList.delete (op =) c congs end;
    78 
    79 end;
    80 
    81 
    82 
    83 (** global and local recdef data **)
    84 
    85 (* theory data *)
    86 
    87 type recdef_info = {lhs: term, simps: thm list, rules: thm list list, induct: thm, tcs: term list};
    88 
    89 structure GlobalRecdefData = Theory_Data
    90 (
    91   type T = recdef_info Symtab.table * hints;
    92   val empty = (Symtab.empty, mk_hints ([], [], [])): T;
    93   val extend = I;
    94   fun merge
    95    ((tab1, {simps = simps1, congs = congs1, wfs = wfs1}),
    96     (tab2, {simps = simps2, congs = congs2, wfs = wfs2})) : T =
    97       (Symtab.merge (K true) (tab1, tab2),
    98         mk_hints (Thm.merge_thms (simps1, simps2),
    99           AList.merge (op =) (K true) (congs1, congs2),
   100           Thm.merge_thms (wfs1, wfs2)));
   101 );
   102 
   103 val get_recdef = Symtab.lookup o #1 o GlobalRecdefData.get;
   104 
   105 fun put_recdef name info thy =
   106   let
   107     val (tab, hints) = GlobalRecdefData.get thy;
   108     val tab' = Symtab.update_new (name, info) tab
   109       handle Symtab.DUP _ => error ("Duplicate recursive function definition " ^ quote name);
   110   in GlobalRecdefData.put (tab', hints) thy end;
   111 
   112 val get_global_hints = #2 o GlobalRecdefData.get;
   113 
   114 
   115 (* proof data *)
   116 
   117 structure LocalRecdefData = Proof_Data
   118 (
   119   type T = hints;
   120   val init = get_global_hints;
   121 );
   122 
   123 val get_hints = LocalRecdefData.get;
   124 fun map_hints f = Context.mapping (GlobalRecdefData.map (apsnd f)) (LocalRecdefData.map f);
   125 
   126 
   127 (* attributes *)
   128 
   129 fun attrib f = Thm.declaration_attribute (map_hints o f);
   130 
   131 val simp_add = attrib (map_simps o Thm.add_thm);
   132 val simp_del = attrib (map_simps o Thm.del_thm);
   133 val cong_add = attrib (map_congs o add_cong);
   134 val cong_del = attrib (map_congs o del_cong);
   135 val wf_add = attrib (map_wfs o Thm.add_thm);
   136 val wf_del = attrib (map_wfs o Thm.del_thm);
   137 
   138 
   139 (* modifiers *)
   140 
   141 val recdef_simpN = "recdef_simp";
   142 val recdef_congN = "recdef_cong";
   143 val recdef_wfN = "recdef_wf";
   144 
   145 val recdef_modifiers =
   146  [Args.$$$ recdef_simpN -- Args.colon >> K ((I, simp_add): Method.modifier),
   147   Args.$$$ recdef_simpN -- Args.add -- Args.colon >> K (I, simp_add),
   148   Args.$$$ recdef_simpN -- Args.del -- Args.colon >> K (I, simp_del),
   149   Args.$$$ recdef_congN -- Args.colon >> K (I, cong_add),
   150   Args.$$$ recdef_congN -- Args.add -- Args.colon >> K (I, cong_add),
   151   Args.$$$ recdef_congN -- Args.del -- Args.colon >> K (I, cong_del),
   152   Args.$$$ recdef_wfN -- Args.colon >> K (I, wf_add),
   153   Args.$$$ recdef_wfN -- Args.add -- Args.colon >> K (I, wf_add),
   154   Args.$$$ recdef_wfN -- Args.del -- Args.colon >> K (I, wf_del)] @
   155   Clasimp.clasimp_modifiers;
   156 
   157 
   158 
   159 (** prepare_hints(_i) **)
   160 
   161 fun prepare_hints thy opt_src =
   162   let
   163     val ctxt0 = ProofContext.init_global thy;
   164     val ctxt =
   165       (case opt_src of
   166         NONE => ctxt0
   167       | SOME src => #2 (Method.syntax (Method.sections recdef_modifiers) src ctxt0));
   168     val {simps, congs, wfs} = get_hints ctxt;
   169     val cs = claset_of ctxt;
   170     val ss = simpset_of ctxt addsimps simps;
   171   in (cs, ss, rev (map snd congs), wfs) end;
   172 
   173 fun prepare_hints_i thy () =
   174   let
   175     val ctxt0 = ProofContext.init_global thy;
   176     val {simps, congs, wfs} = get_global_hints thy;
   177   in (claset_of ctxt0, simpset_of ctxt0 addsimps simps, rev (map snd congs), wfs) end;
   178 
   179 
   180 
   181 (** add_recdef(_i) **)
   182 
   183 fun requires_recdef thy = Theory.requires thy "Recdef" "recursive functions";
   184 
   185 fun gen_add_recdef tfl_fn prep_att prep_hints not_permissive raw_name R eq_srcs hints thy =
   186   let
   187     val _ = legacy_feature ("\"recdef\"; prefer \"function\" instead");
   188     val _ = requires_recdef thy;
   189 
   190     val name = Sign.intern_const thy raw_name;
   191     val bname = Long_Name.base_name name;
   192     val _ = writeln ("Defining recursive function " ^ quote name ^ " ...");
   193 
   194     val ((eq_names, eqs), raw_eq_atts) = apfst split_list (split_list eq_srcs);
   195     val eq_atts = map (map (prep_att thy)) raw_eq_atts;
   196 
   197     val (cs, ss, congs, wfs) = prep_hints thy hints;
   198     (*We must remove imp_cong to prevent looping when the induction rule
   199       is simplified. Many induction rules have nested implications that would
   200       give rise to looping conditional rewriting.*)
   201     val (thy, {lhs, rules = rules_idx, induct, tcs}) =
   202         tfl_fn not_permissive thy cs (ss delcongs [imp_cong])
   203                congs wfs name R eqs;
   204     val rules = (map o map) fst (partition_eq (eq_snd (op = : int * int -> bool)) rules_idx);
   205     val simp_att =
   206       if null tcs then [Simplifier.simp_add, Nitpick_Simps.add, Code.add_default_eqn_attribute]
   207       else [];
   208     val ((simps' :: rules', [induct']), thy) =
   209       thy
   210       |> Sign.add_path bname
   211       |> PureThy.add_thmss
   212         (((Binding.name "simps", flat rules), simp_att) :: ((eq_names ~~ rules) ~~ eq_atts))
   213       ||>> PureThy.add_thms [((Binding.name "induct", induct), [])]
   214       ||> Spec_Rules.add_global Spec_Rules.Equational ([lhs], flat rules);
   215     val result = {lhs = lhs, simps = simps', rules = rules', induct = induct', tcs = tcs};
   216     val thy =
   217       thy
   218       |> put_recdef name result
   219       |> Sign.parent_path;
   220   in (thy, result) end;
   221 
   222 val add_recdef = gen_add_recdef Tfl.define Attrib.attribute prepare_hints;
   223 fun add_recdef_i x y z w = gen_add_recdef Tfl.define_i (K I) prepare_hints_i x y z w ();
   224 
   225 
   226 
   227 (** defer_recdef(_i) **)
   228 
   229 fun gen_defer_recdef tfl_fn eval_thms raw_name eqs raw_congs thy =
   230   let
   231     val name = Sign.intern_const thy raw_name;
   232     val bname = Long_Name.base_name name;
   233 
   234     val _ = requires_recdef thy;
   235     val _ = writeln ("Deferred recursive function " ^ quote name ^ " ...");
   236 
   237     val congs = eval_thms (ProofContext.init_global thy) raw_congs;
   238     val (thy2, induct_rules) = tfl_fn thy congs name eqs;
   239     val ([induct_rules'], thy3) =
   240       thy2
   241       |> Sign.add_path bname
   242       |> PureThy.add_thms [((Binding.name "induct_rules", induct_rules), [])]
   243       ||> Sign.parent_path;
   244   in (thy3, {induct_rules = induct_rules'}) end;
   245 
   246 val defer_recdef = gen_defer_recdef Tfl.defer Attrib.eval_thms;
   247 val defer_recdef_i = gen_defer_recdef Tfl.defer_i (K I);
   248 
   249 
   250 
   251 (** recdef_tc(_i) **)
   252 
   253 fun gen_recdef_tc prep_att prep_name (bname, raw_atts) raw_name opt_i int lthy =
   254   let
   255     val thy = ProofContext.theory_of lthy;
   256     val name = prep_name thy raw_name;
   257     val atts = map (prep_att thy) raw_atts;
   258     val tcs =
   259       (case get_recdef thy name of
   260         NONE => error ("No recdef definition of constant: " ^ quote name)
   261       | SOME {tcs, ...} => tcs);
   262     val i = the_default 1 opt_i;
   263     val tc = nth tcs (i - 1) handle Subscript =>
   264       error ("No termination condition #" ^ string_of_int i ^
   265         " in recdef definition of " ^ quote name);
   266   in
   267     Specification.theorem "" NONE (K I)
   268       (Binding.conceal (Binding.name bname), atts) []
   269       (Element.Shows [(Attrib.empty_binding, [(HOLogic.mk_Trueprop tc, [])])]) int lthy
   270   end;
   271 
   272 val recdef_tc = gen_recdef_tc Attrib.intern_src Sign.intern_const;
   273 val recdef_tc_i = gen_recdef_tc (K I) (K I);
   274 
   275 
   276 
   277 (** package setup **)
   278 
   279 (* setup theory *)
   280 
   281 val setup =
   282   Attrib.setup @{binding recdef_simp} (Attrib.add_del simp_add simp_del)
   283     "declaration of recdef simp rule" #>
   284   Attrib.setup @{binding recdef_cong} (Attrib.add_del cong_add cong_del)
   285     "declaration of recdef cong rule" #>
   286   Attrib.setup @{binding recdef_wf} (Attrib.add_del wf_add wf_del)
   287     "declaration of recdef wf rule";
   288 
   289 
   290 (* outer syntax *)
   291 
   292 local structure P = OuterParse and K = OuterKeyword in
   293 
   294 val _ = List.app OuterKeyword.keyword ["permissive", "congs", "hints"];
   295 
   296 val hints =
   297   P.$$$ "(" |-- P.!!! (P.position (P.$$$ "hints" -- Args.parse) --| P.$$$ ")") >> Args.src;
   298 
   299 val recdef_decl =
   300   Scan.optional (P.$$$ "(" -- P.!!! (P.$$$ "permissive" -- P.$$$ ")") >> K false) true --
   301   P.name -- P.term -- Scan.repeat1 (SpecParse.opt_thm_name ":" -- P.prop)
   302     -- Scan.option hints
   303   >> (fn ((((p, f), R), eqs), src) => #1 o add_recdef p f R (map P.triple_swap eqs) src);
   304 
   305 val _ =
   306   OuterSyntax.command "recdef" "define general recursive functions (TFL)" K.thy_decl
   307     (recdef_decl >> Toplevel.theory);
   308 
   309 
   310 val defer_recdef_decl =
   311   P.name -- Scan.repeat1 P.prop --
   312   Scan.optional (P.$$$ "(" |-- P.$$$ "congs" |-- P.!!! (SpecParse.xthms1 --| P.$$$ ")")) []
   313   >> (fn ((f, eqs), congs) => #1 o defer_recdef f eqs congs);
   314 
   315 val _ =
   316   OuterSyntax.command "defer_recdef" "defer general recursive functions (TFL)" K.thy_decl
   317     (defer_recdef_decl >> Toplevel.theory);
   318 
   319 val _ =
   320   OuterSyntax.local_theory_to_proof' "recdef_tc" "recommence proof of termination condition (TFL)"
   321     K.thy_goal
   322     ((SpecParse.opt_thm_name ":" >> apfst Binding.name_of) -- P.xname --
   323         Scan.option (P.$$$ "(" |-- P.nat --| P.$$$ ")")
   324       >> (fn ((thm_name, name), i) => recdef_tc thm_name name i));
   325 
   326 end;
   327 
   328 end;