src/Pure/Isar/method.ML
author wenzelm
Fri Jul 30 13:41:43 1999 +0200 (1999-07-30)
changeset 7130 a17f7b5ac40f
parent 6981 eaade7e398a7
child 7268 315655dc361b
permissions -rw-r--r--
added erule;
renamed same to -;
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(*  Title:      Pure/Isar/method.ML
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    ID:         $Id$
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    Author:     Markus Wenzel, TU Muenchen
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Proof methods.
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*)
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signature BASIC_METHOD =
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sig
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  val print_methods: theory -> unit
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  val Method: bstring -> (Args.src -> Proof.context -> Proof.method) -> string -> unit
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end;
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signature METHOD =
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sig
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  include BASIC_METHOD
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  val multi_resolve: thm list -> thm -> thm Seq.seq
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  val FINISHED: tactic -> tactic
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  val METHOD: (thm list -> tactic) -> Proof.method
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  val METHOD0: tactic -> Proof.method
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  val fail: Proof.method
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  val succeed: Proof.method
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  val same_tac: thm list -> int -> tactic
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  val same: Proof.method
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  val assumption_tac: thm list -> int -> tactic
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  val assumption: Proof.method
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  val forward_chain: thm list -> thm list -> thm Seq.seq
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  val rule_tac: thm list -> thm list -> int -> tactic
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  val erule_tac: thm list -> thm list -> int -> tactic
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  val rule: thm list -> Proof.method
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  val erule: thm list -> Proof.method
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  exception METHOD_FAIL of (string * Position.T) * exn
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  val method: theory -> Args.src -> Proof.context -> Proof.method
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  val add_methods: (bstring * (Args.src -> Proof.context -> Proof.method) * string) list
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    -> theory -> theory
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  val syntax: (Proof.context * Args.T list -> 'a * (Proof.context * Args.T list)) ->
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    Proof.context -> Args.src -> Proof.context * 'a
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  val no_args: Proof.method -> Args.src -> Proof.context -> Proof.method
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  val sectioned_args: ((Args.T list -> Proof.context attribute * Args.T list) list ->
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      Proof.context * Args.T list -> 'a * (Proof.context * Args.T list)) ->
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    (Args.T list -> Proof.context attribute * Args.T list) list ->
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    ('a -> Proof.context -> Proof.method) -> Args.src -> Proof.context -> Proof.method
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  val default_sectioned_args: Proof.context attribute ->
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    (Args.T list -> Proof.context attribute * Args.T list) list ->
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    (Proof.context -> Proof.method) -> Args.src -> Proof.context -> Proof.method
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  val only_sectioned_args: (Args.T list -> Proof.context attribute * Args.T list) list ->
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    (Proof.context -> Proof.method) -> Args.src -> Proof.context -> Proof.method
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  val thms_args: (thm list -> Proof.method) -> Args.src -> Proof.context -> Proof.method
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  datatype text =
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    Basic of (Proof.context -> Proof.method) |
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    Source of Args.src |
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    Then of text list |
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    Orelse of text list |
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    Try of text |
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    Repeat of text |
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    Repeat1 of text
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  val refine: text -> Proof.state -> Proof.state Seq.seq
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  val tac: text -> Proof.state -> Proof.state Seq.seq
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  val then_tac: text -> Proof.state -> Proof.state Seq.seq
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  val proof: text option -> Proof.state -> Proof.state Seq.seq
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  val local_qed: text option
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    -> ({kind: string, name: string, thm: thm} -> unit) * (thm -> unit)
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    -> Proof.state -> Proof.state Seq.seq
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  val local_terminal_proof: text * text option
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    -> ({kind: string, name: string, thm: thm} -> unit) * (thm -> unit)
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    -> Proof.state -> Proof.state Seq.seq
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  val local_immediate_proof: ({kind: string, name: string, thm: thm} -> unit) * (thm -> unit)
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    -> Proof.state -> Proof.state Seq.seq
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  val local_default_proof: ({kind: string, name: string, thm: thm} -> unit) * (thm -> unit)
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    -> Proof.state -> Proof.state Seq.seq
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  val global_qed: text option -> Proof.state -> theory * {kind: string, name: string, thm: thm}
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  val global_terminal_proof: text * text option
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    -> Proof.state -> theory * {kind: string, name: string, thm: thm}
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  val global_immediate_proof: Proof.state -> theory * {kind: string, name: string, thm: thm}
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  val global_default_proof: Proof.state -> theory * {kind: string, name: string, thm: thm}
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  val setup: (theory -> theory) list
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end;
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structure Method: METHOD =
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struct
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(** utils **)
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val FINISHED = FILTER (equal 0 o Thm.nprems_of);
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(** proof methods **)
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(* method from tactic *)
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val METHOD = Proof.method;
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fun METHOD0 tac = METHOD (fn [] => tac | _ => error "Method may not be used with facts");
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(* primitive *)
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val fail = METHOD (K no_tac);
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val succeed = METHOD (K all_tac);
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(* same *)
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fun cut_rule_tac raw_rule =
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  let
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    val rule = Drule.forall_intr_vars raw_rule;
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    val revcut_rl = Drule.incr_indexes_wrt [] [] [] [rule] Drule.revcut_rl;
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  in Tactic.rtac (rule COMP revcut_rl) THEN' Tactic.rotate_tac ~1 end;
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fun same_tac [] i = all_tac
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  | same_tac facts i = EVERY (map (fn th => cut_rule_tac th i) facts);
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val same = METHOD (ALLGOALS o same_tac);
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(* assumption *)
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fun assumption_tac facts = same_tac facts THEN' assume_tac;
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val assumption = METHOD (FIRSTGOAL o assumption_tac);
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val asm_finish = METHOD (K (FINISHED (ALLGOALS assume_tac)));
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(* fold / unfold definitions *)
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val fold = METHOD0 o fold_goals_tac;
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val unfold = METHOD0 o rewrite_goals_tac;
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(* rule *)
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fun res th i rule = Thm.biresolution false [(false, th)] i rule handle THM _ => Seq.empty;
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fun multi_resolve facts rule =
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  let
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    fun multi_res i [] = Seq.single rule
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      | multi_res i (th :: ths) = Seq.flat (Seq.map (res th i) (multi_res (i + 1) ths))
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  in multi_res 1 facts end;
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fun forward_chain facts rules = Seq.flat (Seq.map (multi_resolve facts) (Seq.of_list rules));
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fun gen_rule_tac tac rules [] = tac rules
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  | gen_rule_tac tac erules facts =
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      let
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        val rules = forward_chain facts erules;
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        fun tactic i state = Seq.flat (Seq.map (fn rule => tac [rule] i state) rules);
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      in tactic end;
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val rule_tac = gen_rule_tac Tactic.resolve_tac;
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val erule_tac = gen_rule_tac Tactic.eresolve_tac;
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fun rule rules = METHOD (FIRSTGOAL o rule_tac rules);
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fun erule rules = METHOD (FIRSTGOAL o erule_tac rules);
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(** methods theory data **)
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(* data kind 'Isar/methods' *)
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structure MethodsDataArgs =
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struct
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  val name = "Isar/methods";
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  type T =
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    {space: NameSpace.T,
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     meths: (((Args.src -> Proof.context -> Proof.method) * string) * stamp) Symtab.table};
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  val empty = {space = NameSpace.empty, meths = Symtab.empty};
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  val copy = I;
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  val prep_ext = I;
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  fun merge ({space = space1, meths = meths1}, {space = space2, meths = meths2}) =
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    {space = NameSpace.merge (space1, space2),
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      meths = Symtab.merge eq_snd (meths1, meths2) handle Symtab.DUPS dups =>
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        error ("Attempt to merge different versions of methods " ^ commas_quote dups)};
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  fun print _ {space, meths} =
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    let
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      fun prt_meth (name, ((_, comment), _)) = Pretty.block
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        [Pretty.str (name ^ ":"), Pretty.brk 2, Pretty.str comment];
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    in
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      Pretty.writeln (Display.pretty_name_space ("method name space", space));
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      Pretty.writeln (Pretty.big_list "methods:"
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        (map prt_meth (NameSpace.cond_extern_table space meths)))
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    end;
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end;
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structure MethodsData = TheoryDataFun(MethodsDataArgs);
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val print_methods = MethodsData.print;
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(* get methods *)
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exception METHOD_FAIL of (string * Position.T) * exn;
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fun method thy =
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  let
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    val {space, meths} = MethodsData.get thy;
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    fun meth src =
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      let
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        val ((raw_name, _), pos) = Args.dest_src src;
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        val name = NameSpace.intern space raw_name;
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      in
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        (case Symtab.lookup (meths, name) of
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          None => error ("Unknown proof method: " ^ quote name ^ Position.str_of pos)
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        | Some ((mth, _), _) => transform_failure (curry METHOD_FAIL (name, pos)) (mth src))
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      end;
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  in meth end;
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(* add_methods *)
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fun add_methods raw_meths thy =
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  let
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    val full = Sign.full_name (Theory.sign_of thy);
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    val new_meths =
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      map (fn (name, f, comment) => (full name, ((f, comment), stamp ()))) raw_meths;
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    val {space, meths} = MethodsData.get thy;
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    val space' = NameSpace.extend (space, map fst new_meths);
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    val meths' = Symtab.extend (meths, new_meths) handle Symtab.DUPS dups =>
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      error ("Duplicate declaration of method(s) " ^ commas_quote dups);
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  in
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    thy |> MethodsData.put {space = space', meths = meths'}
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  end;
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(*implicit version*)
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fun Method name meth cmt = Context.>> (add_methods [(name, meth, cmt)]);
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(** method syntax **)
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(* basic *)
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fun syntax (scan: (Proof.context * Args.T list -> 'a * (Proof.context * Args.T list))) =
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  Args.syntax "method" scan;
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fun no_args (x: Proof.method) src ctxt = #2 (syntax (Scan.succeed x) ctxt src);
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(* sections *)
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fun sect ss = Scan.first (map (fn s => Scan.lift (s --| Args.$$$ ":")) ss);
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fun thms ss = Scan.unless (sect ss) Attrib.local_thms;
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fun thmss ss = Scan.repeat (thms ss) >> flat;
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fun apply att (ctxt, ths) = Thm.applys_attributes ((ctxt, ths), [att]);
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fun section ss = (sect ss -- thmss ss) :-- (fn (att, ths) => Scan.depend (fn ctxt =>
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  Scan.succeed (apply att (ctxt, ths)))) >> #2;
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fun sectioned args ss = args ss -- Scan.repeat (section ss);
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fun sectioned_args args ss f src ctxt =
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  let val (ctxt', (x, _)) = syntax (sectioned args ss) ctxt src
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  in f x ctxt' end;
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fun default_sectioned_args att ss f src ctxt =
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  sectioned_args thmss ss (fn ths => fn ctxt' => f (#1 (apply att (ctxt', ths)))) src ctxt;
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fun only_sectioned_args ss f = sectioned_args (K (Scan.succeed ())) ss (fn () => f);
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fun thms_args f = sectioned_args thmss [] (fn ths => fn _ => f ths);
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(** method text **)
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(* datatype text *)
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datatype text =
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  Basic of (Proof.context -> Proof.method) |
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  Source of Args.src |
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  Then of text list |
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  Orelse of text list |
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  Try of text |
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  Repeat of text |
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  Repeat1 of text;
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(* refine *)
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fun refine text state =
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  let
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    val thy = Proof.theory_of state;
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    fun eval (Basic mth) = Proof.refine mth
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      | eval (Source src) = Proof.refine (method thy src)
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      | eval (Then txts) = Seq.EVERY (map eval txts)
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      | eval (Orelse txts) = Seq.FIRST (map eval txts)
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      | eval (Try txt) = Seq.TRY (eval txt)
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      | eval (Repeat txt) = Seq.REPEAT (eval txt)
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      | eval (Repeat1 txt) = Seq.REPEAT1 (eval txt);
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  in eval text state end;
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fun named_method name = Source (Args.src ((name, []), Position.none));
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(* unstructured steps *)
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fun tac text state =
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  state
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  |> Proof.goal_facts (K [])
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  |> refine text;
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fun then_tac text state =
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  state
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  |> Proof.goal_facts Proof.the_facts
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  |> refine text;
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(* structured proof steps *)
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val default_text = named_method "default";
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val finish_text = named_method "finish";
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fun proof opt_text state =
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  state
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  |> Proof.assert_backward
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  |> refine (if_none opt_text default_text)
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  |> Seq.map Proof.enter_forward;
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fun local_qed opt_text = Proof.local_qed (refine (if_none opt_text finish_text));
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fun local_terminal_proof (text, opt_text) pr = Seq.THEN (proof (Some text), local_qed opt_text pr);
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val local_immediate_proof = local_terminal_proof (Basic (K same), None);
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val local_default_proof = local_terminal_proof (default_text, None);
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fun global_qeds opt_text = Proof.global_qed (refine (if_none opt_text finish_text));
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fun global_qed opt_text state =
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  state
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  |> global_qeds opt_text
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  |> Proof.check_result "Failed to finish proof" state
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  |> Seq.hd;
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fun global_terminal_proof (text, opt_text) state =
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  state
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  |> proof (Some text)
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  |> Proof.check_result "Terminal proof method failed" state
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  |> (Seq.flat o Seq.map (global_qeds opt_text))
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  |> Proof.check_result "Failed to finish proof (after successful terminal method)" state
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  |> Seq.hd;
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val global_immediate_proof = global_terminal_proof (Basic (K same), None);
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val global_default_proof = global_terminal_proof (default_text, None);
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(** theory setup **)
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(* pure_methods *)
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val pure_methods =
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 [("fail", no_args fail, "force failure"),
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  ("succeed", no_args succeed, "succeed"),
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  ("-", no_args same, "insert facts, nothing else"),
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  ("assumption", no_args assumption, "proof by assumption"),
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  ("finish", no_args asm_finish, "finish proof by assumption"),
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  ("fold", thms_args fold, "fold definitions"),
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  ("unfold", thms_args unfold, "unfold definitions"),
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  ("rule", thms_args rule, "apply some rule"),
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  ("erule", thms_args erule, "apply some erule (improper!)")];
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(* setup *)
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val setup = [MethodsData.init, add_methods pure_methods];
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end;
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structure BasicMethod: BASIC_METHOD = Method;
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open BasicMethod;