src/Pure/assumption.ML
author wenzelm
Tue Nov 28 00:35:21 2006 +0100 (2006-11-28)
changeset 21566 af2932baf068
parent 21517 b165c9120702
child 21577 3ff126ca39b4
permissions -rw-r--r--
dest_term: strip_imp_concl;
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(*  Title:      Pure/assumption.ML
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    ID:         $Id$
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    Author:     Makarius
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Local assumptions, parameterized by export rules.
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*)
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signature ASSUMPTION =
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sig
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  type export
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  val assume_export: export
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  val presume_export: export
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  val assume: cterm -> thm
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  val assms_of: Proof.context -> term list
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  val prems_of: Proof.context -> thm list
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  val extra_hyps: Proof.context -> thm -> term list
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  val add_assms: export -> cterm list -> Proof.context -> thm list * Proof.context
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  val add_assumes: cterm list -> Proof.context -> thm list * Proof.context
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  val add_view: Proof.context -> cterm list -> Proof.context -> Proof.context
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  val export: bool -> Proof.context -> Proof.context -> thm -> thm
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  val export_morphism: Proof.context -> Proof.context -> morphism
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end;
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structure Assumption: ASSUMPTION =
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struct
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(** basic rules **)
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type export = bool -> cterm list -> thm -> thm
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(*
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    [A]
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     :
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     B
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  --------
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  #A ==> B
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*)
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fun assume_export true = Drule.implies_intr_protected
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  | assume_export false = Drule.implies_intr_list;
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(*
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    [A]
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     :
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     B
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  -------
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  A ==> B
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*)
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fun presume_export _ = assume_export false;
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val assume = norm_hhf o Thm.assume;
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(** local context data **)
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datatype data = Data of
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 {assms: (export * cterm list) list,    (*assumes and views: A ==> _*)
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  prems: thm list};                     (*prems: A |- A*)
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fun make_data (assms, prems) = Data {assms = assms, prems = prems};
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structure Data = ProofDataFun
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(
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  val name = "Pure/assumption";
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  type T = data;
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  fun init _ = make_data ([], []);
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  fun print _ _ = ();
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);
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val _ = Context.add_setup Data.init;
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fun map_data f = Data.map (fn Data {assms, prems} => make_data (f (assms, prems)));
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fun rep_data ctxt = Data.get ctxt |> (fn Data args => args);
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val assumptions_of = #assms o rep_data;
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val assms_of = map Thm.term_of o maps #2 o assumptions_of;
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val prems_of = #prems o rep_data;
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fun extra_hyps ctxt th = subtract (op aconv) (assms_of ctxt) (Thm.hyps_of th);
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(* add assumptions *)
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fun add_assms export new_asms =
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  let val new_prems = map assume new_asms in
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    map_data (fn (asms, prems) => (asms @ [(export, new_asms)], prems @ new_prems)) #>
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    pair new_prems
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  end;
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val add_assumes = add_assms assume_export;
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fun add_view outer view = map_data (fn (asms, prems) =>
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  let
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    val (asms1, asms2) = chop (length (assumptions_of outer)) asms;
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    val asms' = asms1 @ [(assume_export, view)] @ asms2;
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  in (asms', prems) end);
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(* export *)
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fun export is_goal inner outer =
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  let val asms = Library.drop (length (assumptions_of outer), assumptions_of inner) in
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    norm_hhf_protect
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    #> fold_rev (fn (e, As) => e is_goal As) asms
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    #> norm_hhf_protect
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  end;
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fun export_morphism inner outer =
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  let
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    val thm = export false inner outer;
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    fun term t = Drule.term_rule (ProofContext.theory_of inner (*delayed until now*)) thm t;
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    val typ = Logic.type_map term;
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  in Morphism.morphism {name = I, var = I, typ = typ, term = term, fact = map thm} end;
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end;