src/HOL/NSA/transfer.ML

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/NSA/transfer.ML	Thu Jul 03 17:47:22 2008 +0200
@@ -0,0 +1,121 @@
+(*  Title       : HOL/Hyperreal/transfer.ML
+    ID          : $Id$
+    Author      : Brian Huffman
+
+Transfer principle tactic for nonstandard analysis.
+*)
+
+signature TRANSFER =
+sig
+  val transfer_tac: Proof.context -> thm list -> int -> tactic
+  val add_const: string -> theory -> theory
+  val setup: theory -> theory
+end;
+
+structure Transfer: TRANSFER =
+struct
+
+structure TransferData = GenericDataFun
+(
+  type T = {
+    intros: thm list,
+    unfolds: thm list,
+    refolds: thm list,
+    consts: string list
+  };
+  val empty = {intros = [], unfolds = [], refolds = [], consts = []};
+  val extend = I;
+  fun merge _
+    ({intros = intros1, unfolds = unfolds1,
+      refolds = refolds1, consts = consts1},
+     {intros = intros2, unfolds = unfolds2,
+      refolds = refolds2, consts = consts2}) =
+   {intros = Thm.merge_thms (intros1, intros2),
+    unfolds = Thm.merge_thms (unfolds1, unfolds2),
+    refolds = Thm.merge_thms (refolds1, refolds2),
+    consts = Library.merge (op =) (consts1, consts2)} : T;
+);
+
+fun unstar_typ (Type ("StarDef.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 unstar (Const(a,T) $ t) = if member (op =) consts 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
+
+fun transfer_thm_of ctxt ths t =
+  let
+    val thy = ProofContext.theory_of ctxt;
+    val {intros,unfolds,refolds,consts} = TransferData.get (Context.Proof ctxt);
+    val meta = LocalDefs.meta_rewrite_rule ctxt;
+    val ths' = map meta ths;
+    val unfolds' = map meta unfolds and refolds' = map meta refolds;
+    val (_$_$t') = concl_of (MetaSimplifier.rewrite true unfolds' (cterm_of thy t))
+    val u = unstar_term consts t'
+    val tac =
+      rewrite_goals_tac (ths' @ refolds' @ unfolds') THEN
+      ALLGOALS ObjectLogic.full_atomize_tac THEN
+      match_tac [transitive_thm] 1 THEN
+      resolve_tac [@{thm transfer_start}] 1 THEN
+      REPEAT_ALL_NEW (resolve_tac intros) 1 THEN
+      match_tac [reflexive_thm] 1
+  in Goal.prove ctxt [] [] (Logic.mk_equals (t,u)) (K tac) end
+
+fun transfer_tac ctxt ths =
+    SUBGOAL (fn (t,i) =>
+        (fn th =>
+            let
+              val tr = transfer_thm_of ctxt ths t
+              val (_$l$r) = concl_of tr;
+              val trs = if l aconv r then [] else [tr];
+            in rewrite_goals_tac trs 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})
+in
+val intro_add = Thm.declaration_attribute (map_intros o Thm.add_thm);
+val intro_del = Thm.declaration_attribute (map_intros o Thm.del_thm);
+
+val unfold_add = Thm.declaration_attribute (map_unfolds o Thm.add_thm);
+val unfold_del = Thm.declaration_attribute (map_unfolds o Thm.del_thm);
+
+val refold_add = Thm.declaration_attribute (map_refolds o Thm.add_thm);
+val refold_del = Thm.declaration_attribute (map_refolds o Thm.del_thm);
+end
+
+fun add_const c = Context.theory_map (TransferData.map
+  (fn {intros,unfolds,refolds,consts} =>
+    {intros=intros, unfolds=unfolds, refolds=refolds, consts=c::consts}))
+
+val setup =
+  Attrib.add_attributes
+    [("transfer_intro", Attrib.add_del_args intro_add intro_del,
+      "declaration of transfer introduction rule"),
+     ("transfer_unfold", Attrib.add_del_args unfold_add unfold_del,
+      "declaration of transfer unfolding rule"),
+     ("transfer_refold", Attrib.add_del_args refold_add refold_del,
+      "declaration of transfer refolding rule")] #>
+  Method.add_method ("transfer", Method.thms_ctxt_args (fn ths => fn ctxt =>
+    Method.SIMPLE_METHOD' (transfer_tac ctxt ths)), "transfer principle");
+
+end;