# HG changeset patch
# User berghofe
# Date 1037197961 -3600
# Node ID 75bec2c1bfd583118cd16828b123d4d79f003cf3
# Parent  ec00ba43aee82d2f72f26cd9074935fd34bbcae7
New package for constructing realizers for introduction and elimination
rules of inductive predicates.

diff -r ec00ba43aee8 -r 75bec2c1bfd5 src/HOL/Tools/inductive_realizer.ML
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/Tools/inductive_realizer.ML	Wed Nov 13 15:32:41 2002 +0100
@@ -0,0 +1,493 @@
+(*  Title:      HOL/Tools/inductive_realizer.ML
+    ID:         $Id$
+    Author:     Stefan Berghofer, TU Muenchen
+    License:    GPL (GNU GENERAL PUBLIC LICENSE)
+
+Porgram extraction from proofs involving inductive predicates:
+Realizers for induction and elimination rules
+*)
+
+signature INDUCTIVE_REALIZER =
+sig
+  val add_ind_realizers: string -> string list -> theory -> theory
+  val setup: (theory -> theory) list
+end;
+
+structure InductiveRealizer : INDUCTIVE_REALIZER =
+struct
+
+val all_simps = map (symmetric o mk_meta_eq) (thms "HOL.all_simps");
+
+fun prf_of thm =
+  let val {sign, prop, der = (_, prf), ...} = rep_thm thm
+  in Reconstruct.reconstruct_proof sign prop prf end;
+
+fun forall_intr_prf (t, prf) =
+  let val (a, T) = (case t of Var ((a, _), T) => (a, T) | Free p => p)
+  in Abst (a, Some T, Proofterm.prf_abstract_over t prf) end;
+
+fun subsets [] = [[]]
+  | subsets (x::xs) =
+      let val ys = subsets xs
+      in ys @ map (cons x) ys end;
+
+val set_of = fst o dest_Const o head_of o snd o HOLogic.dest_mem;
+
+fun strip_all t =
+  let
+    fun strip used (Const ("all", _) $ Abs (s, T, t)) =
+          let val s' = variant used s
+          in strip (s'::used) (subst_bound (Free (s', T), t)) end
+      | strip used ((t as Const ("==>", _) $ P) $ Q) = t $ strip used Q
+      | strip _ t = t;
+  in strip (add_term_free_names (t, [])) t end;
+
+fun relevant_vars prop = foldr (fn
+      (Var ((a, i), T), vs) => (case strip_type T of
+        (_, Type (s, _)) => if s mem ["bool", "set"] then (a, T) :: vs else vs
+      | _ => vs)
+    | (_, vs) => vs) (term_vars prop, []);
+
+fun params_of intr = map (fst o fst o dest_Var) (term_vars
+  (snd (HOLogic.dest_mem (HOLogic.dest_Trueprop
+    (Logic.strip_imp_concl intr)))));
+
+fun dt_of_intrs thy vs intrs =
+  let
+    val iTs = term_tvars (prop_of (hd intrs));
+    val Tvs = map TVar iTs;
+    val (_ $ (_ $ _ $ S)) = Logic.strip_imp_concl (prop_of (hd intrs));
+    val (Const (s, _), ts) = strip_comb S;
+    val params = map dest_Var ts;
+    val tname = space_implode "_" (Sign.base_name s ^ "T" :: vs);
+    fun constr_of_intr intr = (Sign.base_name (Thm.name_of_thm intr),
+      map (Type.unvarifyT o snd) (rev (Term.add_vars ([], prop_of intr)) \\ params) @
+        filter_out (equal Extraction.nullT) (map
+          (Type.unvarifyT o Extraction.etype_of thy vs []) (prems_of intr)),
+            NoSyn);
+  in (map (fn a => "'" ^ a) vs @ map (fst o fst) iTs, tname, NoSyn,
+    map constr_of_intr intrs)
+  end;
+
+fun gen_realizes (Const ("realizes", Type ("fun", [T, _])) $ t $
+      (Const ("op :", Type ("fun", [U, _])) $ x $ Var (ixn, _))) =
+        Var (ixn, [T, U] ---> HOLogic.boolT) $ t $ x
+  | gen_realizes (Const ("op :", Type ("fun", [U, _])) $ x $ Var (ixn, _)) =
+      Var (ixn, U --> HOLogic.boolT) $ x
+  | gen_realizes (bla as Const ("realizes", Type ("fun", [T, _])) $ t $ P) =
+      if T = Extraction.nullT then P
+      else (case strip_comb P of
+          (Var (ixn, U), ts) => list_comb (Var (ixn, T --> U), t :: ts)
+        | _ => error "gen_realizes: variable expected")
+  | gen_realizes (t $ u) = gen_realizes t $ gen_realizes u
+  | gen_realizes (Abs (s, T, t)) = Abs (s, T, gen_realizes t)
+  | gen_realizes t = t;
+
+fun mk_rlz T = Const ("realizes", [T, HOLogic.boolT] ---> HOLogic.boolT);
+fun mk_rlz' T = Const ("realizes", [T, propT] ---> propT);
+
+(** turn "P" into "%r x. realizes r (P x)" or "%r x. realizes r (x : P)" **)
+
+fun gen_rvar vs (t as Var ((a, 0), T)) =
+      let val U = TVar (("'" ^ a, 0), HOLogic.typeS)
+      in case try HOLogic.dest_setT T of
+          None => if body_type T <> HOLogic.boolT then t else
+            let
+              val Ts = binder_types T;
+              val i = length Ts;
+              val xs = map (pair "x") Ts;
+              val u = list_comb (t, map Bound (i - 1 downto 0))
+            in 
+              if a mem vs then
+                list_abs (("r", U) :: xs, mk_rlz U $ Bound i $ u)
+              else list_abs (xs, mk_rlz Extraction.nullT $ Extraction.nullt $ u)
+            end
+        | Some T' => if a mem vs then
+              Abs ("r", U, Abs ("x", T', mk_rlz U $ Bound 1 $
+                (HOLogic.mk_mem (Bound 0, t))))
+            else Abs ("x", T', mk_rlz Extraction.nullT $ Extraction.nullt $
+              (HOLogic.mk_mem (Bound 0, t)))
+      end
+  | gen_rvar _ t = t;
+
+fun mk_realizes_eqn n vs intrs =
+  let
+    val iTs = term_tvars (prop_of (hd intrs));
+    val Tvs = map TVar iTs;
+    val _ $ (_ $ _ $ S) = concl_of (hd intrs);
+    val (Const (s, T), ts') = strip_comb S;
+    val setT = body_type T;
+    val elT = HOLogic.dest_setT setT;
+    val x = Var (("x", 0), elT);
+    val rT = if n then Extraction.nullT
+      else Type (space_implode "_" (s ^ "T" :: vs),
+        map (fn a => TVar (("'" ^ a, 0), HOLogic.typeS)) vs @ Tvs);
+    val r = if n then Extraction.nullt else Var ((Sign.base_name s, 0), rT);
+    val rvs = relevant_vars S;
+    val vs' = map fst rvs \\ vs;
+    val rname = space_implode "_" (s ^ "R" :: vs);
+
+    fun mk_Tprem n v =
+      let val Some T = assoc (rvs, v)
+      in (Const ("typeof", T --> Type ("Type", [])) $ Var ((v, 0), T),
+        Extraction.mk_typ (if n then Extraction.nullT
+          else TVar (("'" ^ v, 0), HOLogic.typeS)))
+      end;
+
+    val prems = map (mk_Tprem true) vs' @ map (mk_Tprem false) vs;
+    val ts = map (gen_rvar vs) ts';
+    val argTs = map fastype_of ts;
+
+  in ((prems, (Const ("typeof", setT --> Type ("Type", [])) $ S,
+       Extraction.mk_typ rT)),
+    (prems, (mk_rlz rT $ r $ HOLogic.mk_mem (x, S),
+       if n then
+         HOLogic.mk_mem (x, list_comb (Const (rname, argTs ---> setT), ts))
+       else HOLogic.mk_mem (HOLogic.mk_prod (r, x), list_comb (Const (rname,
+         argTs ---> HOLogic.mk_setT (HOLogic.mk_prodT (rT, elT))), ts)))))
+  end;
+
+fun fun_of_prem thy rsets vs params rule intr =
+  let
+    (* add_term_vars and Term.add_vars may return variables in different order *)
+    val args = map (Free o apfst fst o dest_Var)
+      (add_term_vars (prop_of intr, []) \\ map Var params);
+    val args' = map (Free o apfst fst)
+      (Term.add_vars ([], prop_of intr) \\ params);
+    val rule' = strip_all rule;
+    val conclT = Extraction.etype_of thy vs [] (Logic.strip_imp_concl rule');
+    val used = map (fst o dest_Free) args;
+
+    fun is_rec t = not (null (term_consts t inter rsets));
+
+    fun is_meta (Const ("all", _) $ Abs (s, _, P)) = is_meta P
+      | is_meta (Const ("==>", _) $ _ $ Q) = is_meta Q
+      | is_meta (Const ("Trueprop", _) $ (Const ("op :", _) $ _ $ _)) = true
+      | is_meta _ = false;
+
+    fun fun_of ts rts args used (prem :: prems) =
+          let
+            val T = Extraction.etype_of thy vs [] prem;
+            val [x, r] = variantlist (["x", "r"], used)
+          in if T = Extraction.nullT
+            then fun_of ts rts args used prems
+            else if is_rec prem then
+              if is_meta prem then
+                let
+                  val prem' :: prems' = prems;
+                  val U = Extraction.etype_of thy vs [] prem';
+                in if U = Extraction.nullT
+                  then fun_of (Free (x, T) :: ts)
+                    (Free (r, binder_types T ---> HOLogic.unitT) :: rts)
+                    (Free (x, T) :: args) (x :: r :: used) prems'
+                  else fun_of (Free (x, T) :: ts) (Free (r, U) :: rts)
+                    (Free (r, U) :: Free (x, T) :: args) (x :: r :: used) prems'
+                end
+              else (case strip_type T of
+                  (Ts, Type ("*", [T1, T2])) =>
+                    let
+                      val fx = Free (x, Ts ---> T1);
+                      val fr = Free (r, Ts ---> T2);
+                      val bs = map Bound (length Ts - 1 downto 0);
+                      val t = list_abs (map (pair "z") Ts,
+                        HOLogic.mk_prod (list_comb (fx, bs), list_comb (fr, bs)))
+                    in fun_of (fx :: ts) (fr :: rts) (t::args)
+                      (x :: r :: used) prems
+                    end
+                | (Ts, U) => fun_of (Free (x, T) :: ts)
+                    (Free (r, binder_types T ---> HOLogic.unitT) :: rts)
+                    (Free (x, T) :: args) (x :: r :: used) prems)
+            else fun_of (Free (x, T) :: ts) rts (Free (x, T) :: args)
+              (x :: used) prems
+          end
+      | fun_of ts rts args used [] =
+          let val xs = rev (rts @ ts)
+          in if conclT = Extraction.nullT
+            then list_abs_free (map dest_Free xs, HOLogic.unit)
+            else list_abs_free (map dest_Free xs, list_comb
+              (Free ("r" ^ Sign.base_name (Thm.name_of_thm intr),
+                map fastype_of (rev args) ---> conclT), rev args))
+          end
+
+  in fun_of (rev args) [] args' used (Logic.strip_imp_prems rule') end;
+
+fun indrule_realizer thy induct raw_induct rsets params vs rec_names rss intrs dummies =
+  let
+    val concls = HOLogic.dest_conj (HOLogic.dest_Trueprop (concl_of raw_induct));
+    val premss = mapfilter (fn (s, rs) => if s mem rsets then
+      Some (map (fn r => nth_elem (find_index_eq (prop_of r) (map prop_of intrs),
+        prems_of raw_induct)) rs) else None) rss;
+    val concls' = mapfilter (fn (s, _) => if s mem rsets then
+        find_first (fn concl => s mem term_consts concl) concls
+      else None) rss;
+    val fs = flat (snd (foldl_map (fn (intrs, (prems, dummy)) =>
+      let
+        val (intrs1, intrs2) = splitAt (length prems, intrs);
+        val fs = map (fn (rule, intr) =>
+          fun_of_prem thy rsets vs params rule intr) (prems ~~ intrs1)
+      in (intrs2, if dummy then Const ("arbitrary",
+          HOLogic.unitT --> body_type (fastype_of (hd fs))) :: fs
+        else fs)
+      end) (intrs, (premss ~~ dummies))));
+    val frees = foldl Term.add_frees ([], fs);
+    val Ts = map fastype_of fs;
+    val rlzs = mapfilter (fn (a, concl) =>
+      let val T = Extraction.etype_of thy vs [] concl
+      in if T = Extraction.nullT then None
+        else Some (list_comb (Const (a, Ts ---> T), fs))
+      end) (rec_names ~~ concls')
+  in if null rlzs then Extraction.nullt else
+    let
+      val r = foldr1 HOLogic.mk_prod rlzs;
+      val x = Free ("x", Extraction.etype_of thy vs [] (hd (prems_of induct)));
+      fun name_of_fn intr = "r" ^ Sign.base_name (Thm.name_of_thm intr);
+      val r' = list_abs_free (mapfilter (fn intr =>
+        apsome (pair (name_of_fn intr)) (assoc (frees, name_of_fn intr))) intrs,
+          if length concls = 1 then r $ x else r)
+    in
+      if length concls = 1 then lambda x r' else r'
+    end
+  end;
+
+val nonempty_msg = explode "Nonemptiness check failed for datatype ";
+
+fun add_dummy name dname (x as (_, (vs, s, mfx, cs))) =
+  if name = s then (true, (vs, s, mfx, (dname, [HOLogic.unitT], NoSyn) :: cs))
+  else x;
+
+fun add_dummies f dts used thy =
+  apsnd (pair (map fst dts)) (transform_error (f (map snd dts)) thy)
+  handle ERROR_MESSAGE msg => if nonempty_msg prefix explode msg then
+      let
+        val name = Sign.base_name
+          (implode (drop (length nonempty_msg, explode msg)));
+        val dname = variant used "Dummy"
+      in add_dummies f (map (add_dummy name dname) dts) (dname :: used) thy
+      end
+    else error msg;
+
+fun mk_realizer thy vs params ((rule, rrule), rt) =
+  let
+    val prems = prems_of rule;
+    val xs = rev (Term.add_vars ([], prop_of rule));
+    val rs = gen_rems (op = o pairself fst)
+      (rev (Term.add_vars ([], prop_of rrule)), xs);
+
+    fun mk_prf _ [] prf = prf
+      | mk_prf rs (prem :: prems) prf =
+          let val T = Extraction.etype_of thy vs [] prem
+          in if T = Extraction.nullT
+            then AbsP ("H", Some (mk_rlz' T $ Extraction.nullt $ prem),
+              mk_prf rs prems prf)
+            else forall_intr_prf (Var (hd rs), AbsP ("H", Some (mk_rlz' T $
+              Var (hd rs) $ prem), mk_prf (tl rs) prems prf))
+          end;
+
+    val subst = map (fn v as (ixn, _) => (ixn, gen_rvar vs (Var v))) xs;
+    val prf = Proofterm.map_proof_terms
+      (subst_vars ([], subst)) I (prf_of rrule);
+
+  in (Thm.name_of_thm rule, (vs,
+    if rt = Extraction.nullt then rt else
+      foldr (uncurry lambda) (map Var xs, rt),
+    foldr forall_intr_prf (map Var xs, mk_prf rs prems (Proofterm.proof_combP
+      (prf, map PBound (length prems - 1 downto 0))))))
+  end;
+
+fun add_rule (rss, r) =
+  let
+    val _ $ (_ $ _ $ S) = concl_of r;
+    val (Const (s, _), _) = strip_comb S;
+    val rs = if_none (assoc (rss, s)) [];
+  in overwrite (rss, (s, rs @ [r])) end;
+
+fun add_ind_realizer rsets intrs induct raw_induct elims (thy, vs) =
+  let
+    val iTs = term_tvars (prop_of (hd intrs));
+    val ar = length vs + length iTs;
+    val (_ $ (_ $ _ $ S)) = Logic.strip_imp_concl (prop_of (hd intrs));
+    val (_, params) = strip_comb S;
+    val params' = map dest_Var params;
+    val rss = foldl add_rule ([], intrs);
+    val (prfx, _) = split_last (NameSpace.unpack (fst (hd rss)));
+    val tnames = map (fn s => space_implode "_" (s ^ "T" :: vs)) rsets;
+    val {path, ...} = Sign.rep_sg (sign_of thy);
+    val thy1 = thy |>
+      Theory.root_path |>
+      Theory.add_path (NameSpace.pack prfx);
+    val (ty_eqs, rlz_eqs) = split_list
+      (map (fn (s, rs) => mk_realizes_eqn (not (s mem rsets)) vs rs) rss);
+
+    val thy1' = thy1 |>
+      Theory.copy |>
+      Theory.add_types (map (fn s => (Sign.base_name s, ar, NoSyn)) tnames) |>
+      Theory.add_arities_i (map (fn s =>
+        (s, replicate ar HOLogic.typeS, HOLogic.typeS)) tnames) |>
+        Extraction.add_typeof_eqns_i ty_eqs;
+    val dts = mapfilter (fn (s, rs) => if s mem rsets then
+      Some (dt_of_intrs thy1' vs rs) else None) rss;
+
+    (** datatype representing computational content of inductive set **)
+
+    val (thy2, (dummies, dt_info)) = thy1 |>
+      (if null dts then rpair ([], None) else
+        apsnd (apsnd Some) o add_dummies (DatatypePackage.add_datatype_i false
+          (map #2 dts)) (map (pair false) dts) []) |>>
+      Extraction.add_typeof_eqns_i ty_eqs |>>
+      Extraction.add_realizes_eqns_i rlz_eqs;
+    fun get f x = if_none (apsome f x) [];
+    val rec_names = distinct (map (fst o dest_Const o head_of o fst o
+      HOLogic.dest_eq o HOLogic.dest_Trueprop o prop_of) (get #rec_thms dt_info));
+    val (_, constrss) = foldl_map (fn ((recs, dummies), (s, rs)) =>
+      if s mem rsets then
+        let
+          val (d :: dummies') = dummies;
+          val (recs1, recs2) = splitAt (length rs, if d then tl recs else recs)
+        in ((recs2, dummies'), map (head_of o hd o rev o snd o strip_comb o
+          fst o HOLogic.dest_eq o HOLogic.dest_Trueprop o prop_of) recs1)
+        end
+      else ((recs, dummies), replicate (length rs) Extraction.nullt))
+        ((get #rec_thms dt_info, dummies), rss);
+    val rintrs = map (fn (intr, c) => Pattern.eta_contract (gen_realizes
+      (Extraction.realizes_of thy2 vs
+        c (prop_of (forall_intr_list (map (cterm_of (sign_of thy2) o Var)
+          (rev (Term.add_vars ([], prop_of intr)) \\ params')) intr)))))
+            (intrs ~~ flat constrss);
+    val rlzsets = distinct (map (fn rintr => snd (HOLogic.dest_mem
+      (HOLogic.dest_Trueprop (Logic.strip_assums_concl rintr)))) rintrs);
+
+    (** realizability predicate **)
+
+    val (thy3', ind_info) = thy2 |>
+      InductivePackage.add_inductive_i false true "" false false false
+        (map Logic.unvarify rlzsets) (map (fn (rintr, intr) =>
+          ((Sign.base_name (Thm.name_of_thm intr), strip_all
+            (Logic.unvarify rintr)), [])) (rintrs ~~ intrs)) [] |>>
+      Theory.absolute_path;
+    val thy3 = PureThy.hide_thms false
+      (map Thm.name_of_thm (#intrs ind_info)) thy3';
+
+    (** realizer for induction rule **)
+
+    val Ps = mapfilter (fn _ $ M $ P => if set_of M mem rsets then
+      Some (fst (fst (dest_Var (head_of P)))) else None)
+        (HOLogic.dest_conj (HOLogic.dest_Trueprop (concl_of raw_induct)));
+
+    fun add_ind_realizer (thy, Ps) =
+      let
+        val r = indrule_realizer thy induct raw_induct rsets params'
+          (vs @ Ps) rec_names rss intrs dummies;
+        val rlz = strip_all (Logic.unvarify (gen_realizes
+          (Extraction.realizes_of thy (vs @ Ps) r (prop_of induct))));
+        val rews = map mk_meta_eq
+          (fst_conv :: snd_conv :: get #rec_thms dt_info);
+        val thm = simple_prove_goal_cterm (cterm_of (sign_of thy) rlz) (fn prems =>
+          [if length rss = 1 then
+             cut_facts_tac [hd prems] 1 THEN etac (#induct ind_info) 1
+           else EVERY [rewrite_goals_tac (rews @ all_simps),
+             REPEAT (rtac allI 1), rtac (#induct ind_info) 1],
+           rewrite_goals_tac rews,
+           REPEAT ((resolve_tac prems THEN_ALL_NEW EVERY'
+             [K (rewrite_goals_tac rews), ObjectLogic.atomize_tac,
+              DEPTH_SOLVE_1 o FIRST' [atac, etac allE, etac impE]]) 1)]);
+        val (thy', thm') = PureThy.store_thm ((space_implode "_"
+          (Thm.name_of_thm induct :: vs @ Ps @ ["correctness"]), thm), []) thy
+      in
+        Extraction.add_realizers_i
+          [mk_realizer thy' (vs @ Ps) params' ((induct, thm'), r)] thy'
+      end;
+
+    (** realizer for elimination rules **)
+
+    val case_names = map (fst o dest_Const o head_of o fst o HOLogic.dest_eq o
+      HOLogic.dest_Trueprop o prop_of o hd) (get #case_thms dt_info);
+
+    fun add_elim_realizer Ps ((((elim, elimR), case_thms), case_name), dummy) thy =
+      let
+        val (prem :: prems) = prems_of elim;
+        val p = Logic.list_implies (prems @ [prem], concl_of elim);
+        val T' = Extraction.etype_of thy (vs @ Ps) [] p;
+        val T = if dummy then (HOLogic.unitT --> body_type T') --> T' else T';
+        val Ts = filter_out (equal Extraction.nullT)
+          (map (Extraction.etype_of thy (vs @ Ps) []) (prems_of elim));
+        val r = if null Ps then Extraction.nullt
+          else list_abs (map (pair "x") Ts, list_comb (Const (case_name, T),
+            (if dummy then
+               [Abs ("x", HOLogic.unitT, Const ("arbitrary", body_type T))]
+             else []) @
+            map Bound ((length prems - 1 downto 0) @ [length prems])));
+        val rlz = strip_all (Logic.unvarify (gen_realizes
+          (Extraction.realizes_of thy (vs @ Ps) r (prop_of elim))));
+        val rews = map mk_meta_eq case_thms;
+        val thm = simple_prove_goal_cterm (cterm_of (sign_of thy) rlz) (fn prems =>
+          [cut_facts_tac [hd prems] 1,
+           etac elimR 1,
+           ALLGOALS (EVERY' [etac Pair_inject, asm_simp_tac HOL_basic_ss]),
+           rewrite_goals_tac rews,
+           REPEAT ((resolve_tac prems THEN_ALL_NEW (ObjectLogic.atomize_tac THEN'
+             DEPTH_SOLVE_1 o FIRST' [atac, etac allE, etac impE])) 1)]);
+        val (thy', thm') = PureThy.store_thm ((space_implode "_"
+          (Thm.name_of_thm elim :: vs @ Ps @ ["correctness"]), thm), []) thy
+      in
+        Extraction.add_realizers_i
+          [mk_realizer thy' (vs @ Ps) params' ((elim, thm'), r)] thy'
+      end;
+
+    (** add realizers to theory **)
+
+    val rintr_thms = flat (map (fn (_, rs) => map (fn r => nth_elem
+      (find_index_eq r intrs, #intrs ind_info)) rs) rss);
+    val thy4 = foldl add_ind_realizer (thy3, subsets Ps);
+    val thy5 = Extraction.add_realizers_i
+      (map (mk_realizer thy4 vs params')
+         (map (fn ((rule, rrule), c) => ((rule, rrule), list_comb (c,
+            map Var (rev (Term.add_vars ([], prop_of rule)) \\ params')))) 
+              (flat (map snd rss) ~~ rintr_thms ~~ flat constrss))) thy4;
+    val elimps = mapfilter (fn (s, _) => if s mem rsets then
+        find_first (fn (thm, _) => s mem term_consts (hd (prems_of thm)))
+          (elims ~~ #elims ind_info)
+      else None) rss;
+    val thy6 = foldl (fn (thy, p as ((((elim, _), _), _), _)) => thy |>
+      add_elim_realizer [] p |> add_elim_realizer [fst (fst (dest_Var
+        (HOLogic.dest_Trueprop (concl_of elim))))] p) (thy5,
+           elimps ~~ get #case_thms dt_info ~~ case_names ~~ dummies)
+
+  in Theory.add_path (NameSpace.pack (if_none path [])) thy6 end;
+
+fun add_ind_realizers name rsets thy =
+  let
+    val (_, {intrs, induct, raw_induct, elims, ...}) =
+      (case InductivePackage.get_inductive thy name of
+         None => error ("Unknown inductive set " ^ quote name)
+       | Some info => info);
+    val _ $ (_ $ _ $ S) = concl_of (hd intrs);
+    val vss = sort (int_ord o pairself length)
+      (subsets (map fst (relevant_vars S)))
+  in
+    foldl (add_ind_realizer rsets intrs induct raw_induct elims) (thy, vss)
+  end
+
+fun rlz_attrib arg (thy, thm) =
+  let
+    fun err () = error "ind_realizer: bad rule";
+    val sets =
+      (case HOLogic.dest_conj (HOLogic.dest_Trueprop (concl_of thm)) of
+           [_] => [set_of (HOLogic.dest_Trueprop (hd (prems_of thm)))]
+         | xs => map (set_of o fst o HOLogic.dest_imp) xs)
+         handle TERM _ => err () | LIST _ => err ();
+  in 
+    (add_ind_realizers (hd sets) (case arg of
+        None => sets | Some None => []
+      | Some (Some sets') => sets \\ map (Sign.intern_const (sign_of thy)) sets')
+      thy, thm)
+  end;
+
+val rlz_attrib_global = Attrib.syntax (Scan.lift
+  (Scan.option (Args.$$$ "irrelevant" |--
+    Scan.option (Args.colon |-- Scan.repeat1 Args.name))) >> rlz_attrib);
+
+val setup = [Attrib.add_attributes [("ind_realizer",
+  (rlz_attrib_global, K Attrib.undef_local_attribute),
+  "add realizers for inductive set")]];
+
+end;