src/HOL/Tools/inductive_codegen.ML
author berghofe
Thu Mar 07 12:03:43 2002 +0100 (2002-03-07)
changeset 13038 e968745986f1
parent 12565 9df4b3934487
child 13105 3d1e7a199bdc
permissions -rw-r--r--
- made modes_of more robust
- assoc_code now has higher priority than inductive_codegen
     1 (*  Title:      HOL/inductive_codegen.ML
     2     ID:         $Id$
     3     Author:     Stefan Berghofer, TU Muenchen
     4     License:    GPL (GNU GENERAL PUBLIC LICENSE)
     5 
     6 Code generator for inductive predicates.
     7 *)
     8 
     9 signature INDUCTIVE_CODEGEN =
    10 sig
    11   val add : theory attribute
    12   val setup : (theory -> theory) list
    13 end;
    14 
    15 structure InductiveCodegen : INDUCTIVE_CODEGEN =
    16 struct
    17 
    18 open Codegen;
    19 
    20 (**** theory data ****)
    21 
    22 structure CodegenArgs =
    23 struct
    24   val name = "HOL/inductive_codegen";
    25   type T = thm list Symtab.table;
    26   val empty = Symtab.empty;
    27   val copy = I;
    28   val prep_ext = I;
    29   val merge = Symtab.merge_multi eq_thm;
    30   fun print _ _ = ();
    31 end;
    32 
    33 structure CodegenData = TheoryDataFun(CodegenArgs);
    34 
    35 fun warn thm = warning ("InductiveCodegen: Not a proper clause:\n" ^
    36   string_of_thm thm);
    37 
    38 fun add (p as (thy, thm)) =
    39   let val tab = CodegenData.get thy;
    40   in (case concl_of thm of
    41       _ $ (Const ("op :", _) $ _ $ t) => (case head_of t of
    42         Const (s, _) => (CodegenData.put (Symtab.update ((s,
    43           if_none (Symtab.lookup (tab, s)) [] @ [thm]), tab)) thy, thm)
    44       | _ => (warn thm; p))
    45     | _ => (warn thm; p))
    46   end;
    47 
    48 fun get_clauses thy s =
    49   (case Symtab.lookup (CodegenData.get thy, s) of
    50      None => (case InductivePackage.get_inductive thy s of
    51        None => None
    52      | Some ({names, ...}, {intrs, ...}) => Some (names, intrs))
    53    | Some thms => Some ([s], thms));
    54 
    55 
    56 (**** improper tuples ****)
    57 
    58 fun prod_factors p (Const ("Pair", _) $ t $ u) =
    59       p :: prod_factors (1::p) t @ prod_factors (2::p) u
    60   | prod_factors p _ = [];
    61 
    62 fun split_prod p ps t = if p mem ps then (case t of
    63        Const ("Pair", _) $ t $ u =>
    64          split_prod (1::p) ps t @ split_prod (2::p) ps u
    65      | _ => error "Inconsistent use of products") else [t];
    66 
    67 datatype factors = FVar of int list list | FFix of int list list;
    68 
    69 exception Factors;
    70 
    71 fun mg_factor (FVar f) (FVar f') = FVar (f inter f')
    72   | mg_factor (FVar f) (FFix f') =
    73       if f' subset f then FFix f' else raise Factors
    74   | mg_factor (FFix f) (FVar f') =
    75       if f subset f' then FFix f else raise Factors
    76   | mg_factor (FFix f) (FFix f') =
    77       if f subset f' andalso f' subset f then FFix f else raise Factors;
    78 
    79 fun dest_factors (FVar f) = f
    80   | dest_factors (FFix f) = f;
    81 
    82 fun infer_factors sg extra_fs (fs, (optf, t)) =
    83   let fun err s = error (s ^ "\n" ^ Sign.string_of_term sg t)
    84   in (case (optf, strip_comb t) of
    85       (Some f, (Const (name, _), args)) =>
    86         (case assoc (extra_fs, name) of
    87            None => overwrite (fs, (name, if_none
    88              (apsome (mg_factor f) (assoc (fs, name))) f))
    89          | Some (fs', f') => (mg_factor f (FFix f');
    90              foldl (infer_factors sg extra_fs)
    91                (fs, map (apsome FFix) fs' ~~ args)))
    92     | (Some f, (Var ((name, _), _), [])) =>
    93         overwrite (fs, (name, if_none
    94           (apsome (mg_factor f) (assoc (fs, name))) f))
    95     | (None, _) => fs
    96     | _ => err "Illegal term")
    97       handle Factors => err "Product factor mismatch in"
    98   end;
    99 
   100 fun string_of_factors p ps = if p mem ps then
   101     "(" ^ string_of_factors (1::p) ps ^ ", " ^ string_of_factors (2::p) ps ^ ")"
   102   else "_";
   103 
   104 
   105 (**** check if a term contains only constructor functions ****)
   106 
   107 fun is_constrt thy =
   108   let
   109     val cnstrs = flat (flat (map
   110       (map (fn (_, (_, _, cs)) => map (apsnd length) cs) o #descr o snd)
   111       (Symtab.dest (DatatypePackage.get_datatypes thy))));
   112     fun check t = (case strip_comb t of
   113         (Var _, []) => true
   114       | (Const (s, _), ts) => (case assoc (cnstrs, s) of
   115             None => false
   116           | Some i => length ts = i andalso forall check ts)
   117       | _ => false)
   118   in check end;
   119 
   120 (**** check if a type is an equality type (i.e. doesn't contain fun) ****)
   121 
   122 fun is_eqT (Type (s, Ts)) = s <> "fun" andalso forall is_eqT Ts
   123   | is_eqT _ = true;
   124 
   125 (**** mode inference ****)
   126 
   127 val term_vs = map (fst o fst o dest_Var) o term_vars;
   128 val terms_vs = distinct o flat o (map term_vs);
   129 
   130 fun assoc' s tab key = (case assoc (tab, key) of
   131       None => error ("Unable to determine " ^ s ^ " of " ^ quote key)
   132     | Some x => x);
   133 
   134 (** collect all Vars in a term (with duplicates!) **)
   135 fun term_vTs t = map (apfst fst o dest_Var)
   136   (filter is_Var (foldl_aterms (op :: o Library.swap) ([], t)));
   137 
   138 fun known_args _ _ [] = []
   139   | known_args vs i (t::ts) = if term_vs t subset vs then i::known_args vs (i+1) ts
   140       else known_args vs (i+1) ts;
   141 
   142 fun get_args _ _ [] = ([], [])
   143   | get_args is i (x::xs) = (if i mem is then apfst else apsnd) (cons x)
   144       (get_args is (i+1) xs);
   145 
   146 fun merge xs [] = xs
   147   | merge [] ys = ys
   148   | merge (x::xs) (y::ys) = if length x >= length y then x::merge xs (y::ys)
   149       else y::merge (x::xs) ys;
   150 
   151 fun subsets i j = if i <= j then
   152        let val is = subsets (i+1) j
   153        in merge (map (fn ks => i::ks) is) is end
   154      else [[]];
   155 
   156 fun cprod ([], ys) = []
   157   | cprod (x :: xs, ys) = map (pair x) ys @ cprod (xs, ys);
   158 
   159 fun cprods xss = foldr (map op :: o cprod) (xss, [[]]);
   160 
   161 datatype mode = Mode of (int list option list * int list) * mode option list;
   162 
   163 fun modes_of modes t =
   164   let
   165     fun mk_modes name args = flat
   166       (map (fn (m as (iss, is)) => map (Mode o pair m) (cprods (map
   167         (fn (None, _) => [None]
   168           | (Some js, arg) => map Some
   169               (filter (fn Mode ((_, js'), _) => js=js') (modes_of modes arg)))
   170                 (iss ~~ args)))) (assoc' "modes" modes name))
   171 
   172   in (case strip_comb t of
   173       (Const (name, _), args) => mk_modes name args
   174     | (Var ((name, _), _), args) => mk_modes name args
   175     | (Free (name, _), args) => mk_modes name args)
   176   end;
   177 
   178 datatype indprem = Prem of term list * term | Sidecond of term;
   179 
   180 fun select_mode_prem thy modes vs ps =
   181   find_first (is_some o snd) (ps ~~ map
   182     (fn Prem (us, t) => find_first (fn Mode ((_, is), _) =>
   183           let
   184             val (_, out_ts) = get_args is 1 us;
   185             val vTs = flat (map term_vTs out_ts);
   186             val dupTs = map snd (duplicates vTs) @
   187               mapfilter (curry assoc vTs) vs;
   188           in
   189             is subset known_args vs 1 us andalso
   190             forall (is_constrt thy) (snd (get_args is 1 us)) andalso
   191             term_vs t subset vs andalso
   192             forall is_eqT dupTs
   193           end)
   194             (modes_of modes t)
   195       | Sidecond t => if term_vs t subset vs then Some (Mode (([], []), []))
   196           else None) ps);
   197 
   198 fun check_mode_clause thy arg_vs modes (iss, is) (ts, ps) =
   199   let
   200     val modes' = modes @ mapfilter
   201       (fn (_, None) => None | (v, Some js) => Some (v, [([], js)]))
   202         (arg_vs ~~ iss);
   203     fun check_mode_prems vs [] = Some vs
   204       | check_mode_prems vs ps = (case select_mode_prem thy modes' vs ps of
   205           None => None
   206         | Some (x, _) => check_mode_prems
   207             (case x of Prem (us, _) => vs union terms_vs us | _ => vs)
   208             (filter_out (equal x) ps));
   209     val (in_ts', _) = get_args is 1 ts;
   210     val in_ts = filter (is_constrt thy) in_ts';
   211     val in_vs = terms_vs in_ts;
   212     val concl_vs = terms_vs ts
   213   in
   214     forall is_eqT (map snd (duplicates (flat (map term_vTs in_ts')))) andalso
   215     (case check_mode_prems (arg_vs union in_vs) ps of
   216        None => false
   217      | Some vs => concl_vs subset vs)
   218   end;
   219 
   220 fun check_modes_pred thy arg_vs preds modes (p, ms) =
   221   let val Some rs = assoc (preds, p)
   222   in (p, filter (fn m => forall (check_mode_clause thy arg_vs modes m) rs) ms) end
   223 
   224 fun fixp f x =
   225   let val y = f x
   226   in if x = y then x else fixp f y end;
   227 
   228 fun infer_modes thy extra_modes factors arg_vs preds = fixp (fn modes =>
   229   map (check_modes_pred thy arg_vs preds (modes @ extra_modes)) modes)
   230     (map (fn (s, (fs, f)) => (s, cprod (cprods (map
   231       (fn None => [None]
   232         | Some f' => map Some (subsets 1 (length f' + 1))) fs),
   233       subsets 1 (length f + 1)))) factors);
   234 
   235 (**** code generation ****)
   236 
   237 fun mk_eq (x::xs) =
   238   let fun mk_eqs _ [] = []
   239         | mk_eqs a (b::cs) = Pretty.str (a ^ " = " ^ b) :: mk_eqs b cs
   240   in mk_eqs x xs end;
   241 
   242 fun mk_tuple xs = Pretty.block (Pretty.str "(" ::
   243   flat (separate [Pretty.str ",", Pretty.brk 1] (map single xs)) @
   244   [Pretty.str ")"]);
   245 
   246 fun mk_v ((names, vs), s) = (case assoc (vs, s) of
   247       None => ((names, (s, [s])::vs), s)
   248     | Some xs => let val s' = variant names s in
   249         ((s'::names, overwrite (vs, (s, s'::xs))), s') end);
   250 
   251 fun distinct_v (nvs, Var ((s, 0), T)) =
   252       apsnd (Var o rpair T o rpair 0) (mk_v (nvs, s))
   253   | distinct_v (nvs, t $ u) =
   254       let
   255         val (nvs', t') = distinct_v (nvs, t);
   256         val (nvs'', u') = distinct_v (nvs', u);
   257       in (nvs'', t' $ u') end
   258   | distinct_v x = x;
   259 
   260 fun compile_match nvs eq_ps out_ps success_p fail_p =
   261   let val eqs = flat (separate [Pretty.str " andalso", Pretty.brk 1]
   262     (map single (flat (map (mk_eq o snd) nvs) @ eq_ps)));
   263   in
   264     Pretty.block
   265      ([Pretty.str "(fn ", mk_tuple out_ps, Pretty.str " =>", Pretty.brk 1] @
   266       (Pretty.block ((if eqs=[] then [] else Pretty.str "if " ::
   267          [Pretty.block eqs, Pretty.brk 1, Pretty.str "then "]) @
   268          (success_p ::
   269           (if eqs=[] then [] else [Pretty.brk 1, Pretty.str "else ", fail_p]))) ::
   270        [Pretty.brk 1, Pretty.str "| _ => ", fail_p, Pretty.str ")"]))
   271   end;
   272 
   273 fun modename thy s (iss, is) = space_implode "__"
   274   (mk_const_id (sign_of thy) s ::
   275     map (space_implode "_" o map string_of_int) (mapfilter I iss @ [is]));
   276 
   277 fun compile_expr thy dep brack (gr, (None, t)) =
   278       apsnd single (invoke_codegen thy dep brack (gr, t))
   279   | compile_expr _ _ _ (gr, (Some _, Var ((name, _), _))) =
   280       (gr, [Pretty.str name])
   281   | compile_expr thy dep brack (gr, (Some (Mode (mode, ms)), t)) =
   282       let
   283         val (Const (name, _), args) = strip_comb t;
   284         val (gr', ps) = foldl_map
   285           (compile_expr thy dep true) (gr, ms ~~ args);
   286       in (gr', (if brack andalso not (null ps) then
   287         single o parens o Pretty.block else I)
   288           (flat (separate [Pretty.brk 1]
   289             ([Pretty.str (modename thy name mode)] :: ps))))
   290       end;
   291 
   292 fun compile_clause thy gr dep all_vs arg_vs modes (iss, is) (ts, ps) =
   293   let
   294     val modes' = modes @ mapfilter
   295       (fn (_, None) => None | (v, Some js) => Some (v, [([], js)]))
   296         (arg_vs ~~ iss);
   297 
   298     fun check_constrt ((names, eqs), t) =
   299       if is_constrt thy t then ((names, eqs), t) else
   300         let val s = variant names "x";
   301         in ((s::names, (s, t)::eqs), Var ((s, 0), fastype_of t)) end;
   302 
   303     val (in_ts, out_ts) = get_args is 1 ts;
   304     val ((all_vs', eqs), in_ts') =
   305       foldl_map check_constrt ((all_vs, []), in_ts);
   306 
   307     fun compile_prems out_ts' vs names gr [] =
   308           let
   309             val (gr2, out_ps) = foldl_map
   310               (invoke_codegen thy dep false) (gr, out_ts);
   311             val (gr3, eq_ps) = foldl_map (fn (gr, (s, t)) =>
   312               apsnd (Pretty.block o cons (Pretty.str (s ^ " = ")) o single)
   313                 (invoke_codegen thy dep false (gr, t))) (gr2, eqs);
   314             val (nvs, out_ts'') = foldl_map distinct_v
   315               ((names, map (fn x => (x, [x])) vs), out_ts');
   316             val (gr4, out_ps') = foldl_map
   317               (invoke_codegen thy dep false) (gr3, out_ts'');
   318           in
   319             (gr4, compile_match (snd nvs) eq_ps out_ps'
   320               (Pretty.block [Pretty.str "Seq.single", Pretty.brk 1, mk_tuple out_ps])
   321               (Pretty.str "Seq.empty"))
   322           end
   323       | compile_prems out_ts vs names gr ps =
   324           let
   325             val vs' = distinct (flat (vs :: map term_vs out_ts));
   326             val Some (p, mode as Some (Mode ((_, js), _))) =
   327               select_mode_prem thy modes' (arg_vs union vs') ps;
   328             val ps' = filter_out (equal p) ps;
   329           in
   330             (case p of
   331                Prem (us, t) =>
   332                  let
   333                    val (in_ts, out_ts') = get_args js 1 us;
   334                    val (gr1, in_ps) = foldl_map
   335                      (invoke_codegen thy dep false) (gr, in_ts);
   336                    val (nvs, out_ts'') = foldl_map distinct_v
   337                      ((names, map (fn x => (x, [x])) vs), out_ts);
   338                    val (gr2, out_ps) = foldl_map
   339                      (invoke_codegen thy dep false) (gr1, out_ts'');
   340                    val (gr3, ps) = compile_expr thy dep false (gr2, (mode, t));
   341                    val (gr4, rest) = compile_prems out_ts' vs' (fst nvs) gr3 ps';
   342                  in
   343                    (gr4, compile_match (snd nvs) [] out_ps
   344                       (Pretty.block (ps @
   345                          [Pretty.brk 1, mk_tuple in_ps,
   346                           Pretty.str " :->", Pretty.brk 1, rest]))
   347                       (Pretty.str "Seq.empty"))
   348                  end
   349              | Sidecond t =>
   350                  let
   351                    val (gr1, side_p) = invoke_codegen thy dep true (gr, t);
   352                    val (nvs, out_ts') = foldl_map distinct_v
   353                      ((names, map (fn x => (x, [x])) vs), out_ts);
   354                    val (gr2, out_ps) = foldl_map
   355                      (invoke_codegen thy dep false) (gr1, out_ts')
   356                    val (gr3, rest) = compile_prems [] vs' (fst nvs) gr2 ps';
   357                  in
   358                    (gr3, compile_match (snd nvs) [] out_ps
   359                       (Pretty.block [Pretty.str "?? ", side_p,
   360                         Pretty.str " :->", Pretty.brk 1, rest])
   361                       (Pretty.str "Seq.empty"))
   362                  end)
   363           end;
   364 
   365     val (gr', prem_p) = compile_prems in_ts' [] all_vs' gr ps;
   366   in
   367     (gr', Pretty.block [Pretty.str "Seq.single inp :->", Pretty.brk 1, prem_p])
   368   end;
   369 
   370 fun compile_pred thy gr dep prfx all_vs arg_vs modes s cls mode =
   371   let val (gr', cl_ps) = foldl_map (fn (gr, cl) =>
   372     compile_clause thy gr dep all_vs arg_vs modes mode cl) (gr, cls)
   373   in
   374     ((gr', "and "), Pretty.block
   375       ([Pretty.block (separate (Pretty.brk 1)
   376          (Pretty.str (prfx ^ modename thy s mode) :: map Pretty.str arg_vs) @
   377          [Pretty.str " inp ="]),
   378         Pretty.brk 1] @
   379        flat (separate [Pretty.str " ++", Pretty.brk 1] (map single cl_ps))))
   380   end;
   381 
   382 fun compile_preds thy gr dep all_vs arg_vs modes preds =
   383   let val ((gr', _), prs) = foldl_map (fn ((gr, prfx), (s, cls)) =>
   384     foldl_map (fn ((gr', prfx'), mode) =>
   385       compile_pred thy gr' dep prfx' all_vs arg_vs modes s cls mode)
   386         ((gr, prfx), the (assoc (modes, s)))) ((gr, "fun "), preds)
   387   in
   388     (gr', space_implode "\n\n" (map Pretty.string_of (flat prs)) ^ ";\n\n")
   389   end;
   390 
   391 (**** processing of introduction rules ****)
   392 
   393 exception Modes of
   394   (string * (int list option list * int list) list) list *
   395   (string * (int list list option list * int list list)) list;
   396 
   397 fun lookup_modes gr dep = apfst flat (apsnd flat (ListPair.unzip
   398   (map ((fn (Some (Modes x), _) => x | _ => ([], [])) o Graph.get_node gr)
   399     (Graph.all_preds gr [dep]))));
   400 
   401 fun string_of_mode (iss, is) = space_implode " -> " (map
   402   (fn None => "X"
   403     | Some js => enclose "[" "]" (commas (map string_of_int js)))
   404        (iss @ [Some is]));
   405 
   406 fun print_modes modes = message ("Inferred modes:\n" ^
   407   space_implode "\n" (map (fn (s, ms) => s ^ ": " ^ commas (map
   408     string_of_mode ms)) modes));
   409 
   410 fun print_factors factors = message ("Factors:\n" ^
   411   space_implode "\n" (map (fn (s, (fs, f)) => s ^ ": " ^
   412     space_implode " -> " (map
   413       (fn None => "X" | Some f' => string_of_factors [] f')
   414         (fs @ [Some f]))) factors));
   415 
   416 fun mk_extra_defs thy gr dep names ts =
   417   foldl (fn (gr, name) =>
   418     if name mem names then gr
   419     else (case get_clauses thy name of
   420         None => gr
   421       | Some (names, intrs) =>
   422           mk_ind_def thy gr dep names intrs))
   423             (gr, foldr add_term_consts (ts, []))
   424 
   425 and mk_ind_def thy gr dep names intrs =
   426   let val ids = map (mk_const_id (sign_of thy)) names
   427   in Graph.add_edge (hd ids, dep) gr handle Graph.UNDEF _ =>
   428     let
   429       fun dest_prem factors (_ $ (Const ("op :", _) $ t $ u)) =
   430             (case head_of u of
   431                Const (name, _) => Prem (split_prod []
   432                  (the (assoc (factors, name))) t, u)
   433              | Var ((name, _), _) => Prem (split_prod []
   434                  (the (assoc (factors, name))) t, u))
   435         | dest_prem factors (_ $ ((eq as Const ("op =", _)) $ t $ u)) =
   436             Prem ([t, u], eq)
   437         | dest_prem factors (_ $ t) = Sidecond t;
   438 
   439       fun add_clause factors (clauses, intr) =
   440         let
   441           val _ $ (_ $ t $ u) = Logic.strip_imp_concl intr;
   442           val Const (name, _) = head_of u;
   443           val prems = map (dest_prem factors) (Logic.strip_imp_prems intr);
   444         in
   445           (overwrite (clauses, (name, if_none (assoc (clauses, name)) [] @
   446              [(split_prod [] (the (assoc (factors, name))) t, prems)])))
   447         end;
   448 
   449       fun add_prod_factors extra_fs (fs, _ $ (Const ("op :", _) $ t $ u)) =
   450             infer_factors (sign_of thy) extra_fs
   451               (fs, (Some (FVar (prod_factors [] t)), u))
   452         | add_prod_factors _ (fs, _) = fs;
   453 
   454       val intrs' = map (rename_term o #prop o rep_thm o standard) intrs;
   455       val _ $ (_ $ _ $ u) = Logic.strip_imp_concl (hd intrs');
   456       val (_, args) = strip_comb u;
   457       val arg_vs = flat (map term_vs args);
   458       val gr' = mk_extra_defs thy
   459         (Graph.add_edge (hd ids, dep)
   460           (Graph.new_node (hd ids, (None, "")) gr)) (hd ids) names intrs';
   461       val (extra_modes', extra_factors) = lookup_modes gr' (hd ids);
   462       val extra_modes =
   463         ("op =", [([], [1]), ([], [2]), ([], [1, 2])]) :: extra_modes';
   464       val fs = map (apsnd dest_factors)
   465         (foldl (add_prod_factors extra_factors) ([], flat (map (fn t =>
   466           Logic.strip_imp_concl t :: Logic.strip_imp_prems t) intrs')));
   467       val _ = (case map fst fs \\ names \\ arg_vs of
   468           [] => ()
   469         | xs => error ("Non-inductive sets: " ^ commas_quote xs));
   470       val factors = mapfilter (fn (name, f) =>
   471         if name mem arg_vs then None
   472         else Some (name, (map (curry assoc fs) arg_vs, f))) fs;
   473       val clauses =
   474         foldl (add_clause (fs @ map (apsnd snd) extra_factors)) ([], intrs');
   475       val modes = infer_modes thy extra_modes factors arg_vs clauses;
   476       val _ = print_factors factors;
   477       val _ = print_modes modes;
   478       val (gr'', s) = compile_preds thy gr' (hd ids) (terms_vs intrs') arg_vs
   479         (modes @ extra_modes) clauses;
   480     in
   481       (Graph.map_node (hd ids) (K (Some (Modes (modes, factors)), s)) gr'')
   482     end      
   483   end;
   484 
   485 fun mk_ind_call thy gr dep t u is_query = (case head_of u of
   486   Const (s, T) => (case (get_clauses thy s, get_assoc_code thy s T) of
   487        (None, _) => None
   488      | (Some (names, intrs), None) =>
   489          let
   490           fun mk_mode (((ts, mode), i), Const ("dummy_pattern", _)) =
   491                 ((ts, mode), i+1)
   492             | mk_mode (((ts, mode), i), t) = ((ts @ [t], mode @ [i]), i+1);
   493 
   494            val gr1 = mk_extra_defs thy
   495              (mk_ind_def thy gr dep names intrs) dep names [u];
   496            val (modes, factors) = lookup_modes gr1 dep;
   497            val ts = split_prod [] (snd (the (assoc (factors, s)))) t;
   498            val (ts', is) = if is_query then
   499                fst (foldl mk_mode ((([], []), 1), ts))
   500              else (ts, 1 upto length ts);
   501            val mode = (case find_first (fn Mode ((_, js), _) => is=js)
   502                   (modes_of modes u) of
   503                 None => error ("No such mode for " ^ s ^ ": " ^
   504                   string_of_mode ([], is))
   505               | mode => mode);
   506            val (gr2, in_ps) = foldl_map
   507              (invoke_codegen thy dep false) (gr1, ts');
   508            val (gr3, ps) = compile_expr thy dep false (gr2, (mode, u))
   509          in
   510            Some (gr3, Pretty.block
   511              (ps @ [Pretty.brk 1, mk_tuple in_ps]))
   512          end
   513      | _ => None)
   514   | _ => None);
   515 
   516 fun inductive_codegen thy gr dep brack (Const ("op :", _) $ t $ u) =
   517       ((case mk_ind_call thy gr dep (Term.no_dummy_patterns t) u false of
   518          None => None
   519        | Some (gr', call_p) => Some (gr', (if brack then parens else I)
   520            (Pretty.block [Pretty.str "?! (", call_p, Pretty.str ")"])))
   521         handle TERM _ => mk_ind_call thy gr dep t u true)
   522   | inductive_codegen thy gr dep brack _ = None;
   523 
   524 val setup =
   525   [add_codegen "inductive" inductive_codegen,
   526    CodegenData.init,
   527    add_attribute "ind" add];
   528 
   529 end;
   530 
   531 
   532 (**** combinators for code generated from inductive predicates ****)
   533 
   534 infix 5 :->;
   535 infix 3 ++;
   536 
   537 fun s :-> f = Seq.flat (Seq.map f s);
   538 
   539 fun s1 ++ s2 = Seq.append (s1, s2);
   540 
   541 fun ?? b = if b then Seq.single () else Seq.empty;
   542 
   543 fun ?! s = is_some (Seq.pull s);    
   544 
   545 fun op__61__1 x = Seq.single x;
   546 
   547 val op__61__2 = op__61__1;
   548 
   549 fun op__61__1_2 (x, y) = ?? (x = y);