src/HOL/Hyperreal/transfer.ML

+signature TRANSFER_TAC =
+sig
+  val transfer_tac: thm list -> int -> tactic
+  val setup: (theory -> theory) list
+end;
+
+structure Transfer: TRANSFER_TAC =
+struct
+
+(* TODO: make this list extensible *)
+val star_consts =
+  [ "StarType.star_of", "StarType.Ifun"
+  , "StarType.unstar", "StarType.Iset" ]
+
+structure TransferData = TheoryDataFun
+(struct
+  val name = "HOL/transfer";
+  type T = {
+    intros: thm list,
+    unfolds: thm list,
+    refolds: thm list,
+    consts: string list
+  };
+  val empty = {intros = [], unfolds = [], refolds = [], consts = star_consts};
+  val copy = I;
+  val extend = I;
+  fun merge _
+    ({intros = intros1, unfolds = unfolds1,
+      refolds = refolds1, consts = consts1},
+     {intros = intros2, unfolds = unfolds2,
+      refolds = refolds2, consts = consts2}) =
+   {intros = Drule.merge_rules (intros1, intros2),
+    unfolds = Drule.merge_rules (unfolds1, unfolds2),
+    refolds = Drule.merge_rules (refolds1, refolds2),
+    consts = merge_lists consts1 consts2};
+  fun print _ _ = ();
+end);
+
+val transfer_start = thm "transfer_start"
+
+fun unstar_typ (Type ("StarType.star",[t])) = unstar_typ t
+  | unstar_typ (Type (a, Ts)) = Type (a, map unstar_typ Ts)
+  | unstar_typ T = T
+
+fun unstar_term consts term =
+  let
+    fun delete a = exists (fn x => x = a) consts
+    fun unstar (Const(a,T) $ t) = if (delete a) then (unstar t)
+          else (Const(a,unstar_typ T) $ unstar t)
+      | unstar (f $ t) = unstar f $ unstar t
+      | unstar (Const(a,T)) = Const(a,unstar_typ T)
+      | unstar (Abs(a,T,t)) = Abs(a,unstar_typ T,unstar t) 
+      | unstar t = t
+  in
+    unstar term
+  end
+
+val atomizers = map thm ["atomize_all", "atomize_imp", "atomize_eq"]
+
+fun transfer_thm_of thy ths t =
+  let
+    val {intros,unfolds,refolds,consts} = TransferData.get thy
+    val (_$_$t') = concl_of (Tactic.rewrite true unfolds (cterm_of thy t))
+    val u = unstar_term consts t'
+    val ct = cterm_of thy (Logic.mk_equals (t,u))
+    val tacs =
+      [ rewrite_goals_tac atomizers
+      , match_tac [transitive_thm] 1
+      , resolve_tac [transfer_start] 1
+      , REPEAT_ALL_NEW (resolve_tac intros) 1
+      , match_tac [reflexive_thm] 1 ]
+  in
+    prove_goalw_cterm (ths @ refolds @ unfolds) ct (fn _ => tacs)
+  end
+
+fun transfer_tac ths =
+    SUBGOAL (fn (t,i) =>
+        (fn th =>
+            let val thy = theory_of_thm th
+                val tr = transfer_thm_of thy ths t
+            in rewrite_goals_tac [tr] th
+            end
+        )
+    )
+
+local
+fun map_intros f = TransferData.map
+  (fn {intros,unfolds,refolds,consts} =>
+    {intros=f intros, unfolds=unfolds, refolds=refolds, consts=consts})
+
+fun map_unfolds f = TransferData.map
+  (fn {intros,unfolds,refolds,consts} =>
+    {intros=intros, unfolds=f unfolds, refolds=refolds, consts=consts})
+
+fun map_refolds f = TransferData.map
+  (fn {intros,unfolds,refolds,consts} =>
+    {intros=intros, unfolds=unfolds, refolds=f refolds, consts=consts})
+
+fun map_consts f = TransferData.map
+  (fn {intros,unfolds,refolds,consts} =>
+    {intros=intros, unfolds=unfolds, refolds=refolds, consts=f consts})
+in
+fun intro_add_global (thy, thm) = (map_intros (Drule.add_rule thm) thy, thm);
+fun intro_del_global (thy, thm) = (map_intros (Drule.del_rule thm) thy, thm);
+
+fun unfold_add_global (thy, thm) = (map_unfolds (Drule.add_rule thm) thy, thm);
+fun unfold_del_global (thy, thm) = (map_unfolds (Drule.del_rule thm) thy, thm);
+
+fun refold_add_global (thy, thm) = (map_refolds (Drule.add_rule thm) thy, thm);
+fun refold_del_global (thy, thm) = (map_refolds (Drule.del_rule thm) thy, thm);
+end
+
+local
+  val undef_local =
+    Attrib.add_del_args
+      Attrib.undef_local_attribute
+      Attrib.undef_local_attribute;
+in
+  val intro_attr =
+   (Attrib.add_del_args intro_add_global intro_del_global, undef_local);
+  val unfold_attr =
+   (Attrib.add_del_args unfold_add_global unfold_del_global, undef_local);
+  val refold_attr =
+   (Attrib.add_del_args refold_add_global refold_del_global, undef_local);
+end
+
+val transfer_method = Method.SIMPLE_METHOD' HEADGOAL o transfer_tac;
+
+val setup =
+  [ TransferData.init
+  , Attrib.add_attributes
+    [ ("transfer_intro", intro_attr, "transfer introduction rule")
+    , ("transfer_unfold", unfold_attr, "transfer unfolding rule")
+    , ("transfer_refold", refold_attr, "transfer refolding rule")
+    ]
+  , Method.add_method
+    ("transfer", Method.thms_args transfer_method, "transfer principle")
+  ];
+
+end;