author | wenzelm |
Mon, 04 Aug 2008 19:25:59 +0200 | |
changeset 27725 | 6d133c2b681f |
parent 26424 | a6cad32a27b0 |
child 28083 | 103d9282a946 |
permissions | -rw-r--r-- |
18830 | 1 |
(* Title: Pure/Isar/local_defs.ML |
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ID: $Id$ |
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Author: Makarius |
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Local definitions. |
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*) |
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signature LOCAL_DEFS = |
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sig |
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val cert_def: Proof.context -> term -> (string * typ) * term |
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val abs_def: term -> (string * typ) * term |
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val mk_def: Proof.context -> (string * term) list -> term list |
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val expand: cterm list -> thm -> thm |
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val def_export: Assumption.export |
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val add_defs: ((string * mixfix) * ((bstring * attribute list) * term)) list -> Proof.context -> |
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(term * (bstring * thm)) list * Proof.context |
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val add_def: (string * mixfix) * term -> Proof.context -> (term * thm) * Proof.context |
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val fixed_abbrev: (string * mixfix) * term -> Proof.context -> (term * term) * Proof.context |
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val export: Proof.context -> Proof.context -> thm -> thm list * thm |
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val export_cterm: Proof.context -> Proof.context -> cterm -> cterm * thm |
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val trans_terms: Proof.context -> thm list -> thm |
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val trans_props: Proof.context -> thm list -> thm |
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val print_rules: Proof.context -> unit |
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val defn_add: attribute |
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val defn_del: attribute |
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val meta_rewrite_conv: Proof.context -> conv |
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val meta_rewrite_rule: Proof.context -> thm -> thm |
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val unfold: Proof.context -> thm list -> thm -> thm |
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val unfold_goals: Proof.context -> thm list -> thm -> thm |
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val unfold_tac: Proof.context -> thm list -> tactic |
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val fold: Proof.context -> thm list -> thm -> thm |
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val fold_tac: Proof.context -> thm list -> tactic |
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val derived_def: Proof.context -> bool -> term -> |
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((string * typ) * term) * (Proof.context -> thm -> thm) |
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end; |
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structure LocalDefs: LOCAL_DEFS = |
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struct |
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(** primitive definitions **) |
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(* prepare defs *) |
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fun cert_def ctxt eq = |
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let |
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fun err msg = cat_error msg ("The error(s) above occurred in definition: " ^ |
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quote (Syntax.string_of_term ctxt eq)); |
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val ((lhs, _), eq') = eq |
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|> Sign.no_vars (Syntax.pp ctxt) |
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|> PrimitiveDefs.dest_def ctxt Term.is_Free (Variable.is_fixed ctxt) (K true) |
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handle TERM (msg, _) => err msg | ERROR msg => err msg; |
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in (Term.dest_Free (Term.head_of lhs), eq') end; |
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val abs_def = PrimitiveDefs.abs_def #>> Term.dest_Free; |
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fun mk_def ctxt args = |
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let |
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val (xs, rhss) = split_list args; |
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val (bind, _) = ProofContext.bind_fixes xs ctxt; |
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val lhss = map (fn (x, rhs) => bind (Free (x, Term.fastype_of rhs))) args; |
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in map Logic.mk_equals (lhss ~~ rhss) end; |
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(* export defs *) |
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val head_of_def = |
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#1 o Term.dest_Free o Term.head_of o #1 o Logic.dest_equals o Term.strip_all_body; |
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(* |
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[x, x == a] |
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: |
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B x |
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----------- |
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B a |
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*) |
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fun expand defs = |
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Drule.implies_intr_list defs |
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#> Drule.generalize ([], map (head_of_def o Thm.term_of) defs) |
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#> funpow (length defs) (fn th => Drule.reflexive_thm RS th); |
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val expand_term = Envir.expand_term_frees o map (abs_def o Thm.term_of); |
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fun def_export _ defs = (expand defs, expand_term defs); |
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(* add defs *) |
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fun add_defs defs ctxt = |
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let |
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val ((xs, mxs), specs) = defs |> split_list |>> split_list; |
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val ((names, atts), rhss) = specs |> split_list |>> split_list; |
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val names' = map2 Thm.def_name_optional xs names; |
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val eqs = mk_def ctxt (xs ~~ rhss); |
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val lhss = map (fst o Logic.dest_equals) eqs; |
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in |
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ctxt |
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|> ProofContext.add_fixes_i (map2 (fn x => fn mx => (x, NONE, mx)) xs mxs) |> #2 |
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|> fold Variable.declare_term eqs |
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|> ProofContext.add_assms_i def_export |
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(map2 (fn a => fn eq => (a, [(eq, [])])) (names' ~~ atts) eqs) |
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|>> map2 (fn lhs => fn (name, [th]) => (lhs, (name, th))) lhss |
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end; |
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fun add_def (var, rhs) ctxt = |
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let val ([(lhs, (_, th))], ctxt') = add_defs [(var, (("", []), rhs))] ctxt |
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in ((lhs, th), ctxt') end; |
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(* fixed_abbrev *) |
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fun fixed_abbrev ((x, mx), rhs) ctxt = |
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let |
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val T = Term.fastype_of rhs; |
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val ([x'], ctxt') = ctxt |
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|> Variable.declare_term rhs |
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|> ProofContext.add_fixes_i [(x, SOME T, mx)]; |
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val lhs = Free (x', T); |
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val _ = cert_def ctxt' (Logic.mk_equals (lhs, rhs)); |
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fun abbrev_export _ _ = (I, Envir.expand_term_frees [((x', T), rhs)]); |
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val (_, ctxt'') = Assumption.add_assms abbrev_export [] ctxt'; |
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in ((lhs, rhs), ctxt'') end; |
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(* specific export -- result based on educated guessing *) |
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(* |
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[xs, xs == as] |
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: |
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B xs |
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-------------- |
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B as |
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*) |
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fun export inner outer = (*beware of closure sizes*) |
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let |
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val exp = Assumption.export false inner outer; |
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val prems = Assumption.prems_of inner; |
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in fn th => |
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let |
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val th' = exp th; |
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val still_fixed = map #1 (Thm.fold_terms Term.add_frees th' []); |
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val defs = prems |> filter_out (fn prem => |
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(case try (head_of_def o Thm.prop_of) prem of |
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SOME x => member (op =) still_fixed x |
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| NONE => true)); |
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in (map Drule.abs_def defs, th') end |
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end; |
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(* |
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[xs, xs == as] |
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: |
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TERM b xs |
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-------------- and -------------- |
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TERM b as b xs == b as |
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*) |
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fun export_cterm inner outer ct = |
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let val (defs, ct') = export inner outer (Drule.mk_term ct) ||> Drule.dest_term |
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in (ct', MetaSimplifier.rewrite true defs ct) end; |
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(* basic transitivity reasoning -- modulo beta-eta *) |
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local |
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val is_trivial = Pattern.aeconv o Logic.dest_equals o Thm.prop_of; |
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fun trans_list _ _ [] = raise Empty |
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| trans_list trans ctxt (th :: raw_eqs) = |
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(case filter_out is_trivial raw_eqs of |
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[] => th |
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| eqs => |
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let val ((_, th' :: eqs'), ctxt') = Variable.import_thms true (th :: eqs) ctxt |
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in singleton (Variable.export ctxt' ctxt) (fold trans eqs' th') end); |
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in |
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val trans_terms = trans_list (fn eq2 => fn eq1 => eq2 COMP (eq1 COMP Drule.transitive_thm)); |
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val trans_props = trans_list (fn eq => fn th => th COMP (eq COMP Drule.equal_elim_rule1)); |
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end; |
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(** defived definitions **) |
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(* transformation rules *) |
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structure Rules = GenericDataFun |
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( |
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type T = thm list; |
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val empty = [] |
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val extend = I; |
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fun merge _ = Thm.merge_thms; |
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); |
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fun print_rules ctxt = |
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Pretty.writeln (Pretty.big_list "definitional transformations:" |
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(map (ProofContext.pretty_thm ctxt) (Rules.get (Context.Proof ctxt)))); |
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renamed Drule.add/del/merge_rules to Thm.add/del/merge_thms;
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changeset
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val defn_add = Thm.declaration_attribute (Rules.map o Thm.add_thm); |
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renamed Drule.add/del/merge_rules to Thm.add/del/merge_thms;
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val defn_del = Thm.declaration_attribute (Rules.map o Thm.del_thm); |
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(* meta rewrite rules *) |
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fun meta_rewrite_conv ctxt = |
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MetaSimplifier.rewrite_cterm (false, false, false) (K (K NONE)) |
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(MetaSimplifier.context ctxt MetaSimplifier.empty_ss |
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addeqcongs [Drule.equals_cong] (*protect meta-level equality*) |
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addsimps (Rules.get (Context.Proof ctxt))); |
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val meta_rewrite_rule = Conv.fconv_rule o meta_rewrite_conv; |
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(* rewriting with object-level rules *) |
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fun meta f ctxt = f o map (meta_rewrite_rule ctxt); |
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val unfold = meta MetaSimplifier.rewrite_rule; |
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val unfold_goals = meta MetaSimplifier.rewrite_goals_rule; |
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val unfold_tac = meta MetaSimplifier.rewrite_goals_tac; |
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val fold = meta MetaSimplifier.fold_rule; |
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val fold_tac = meta MetaSimplifier.fold_goals_tac; |
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(* derived defs -- potentially within the object-logic *) |
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fun derived_def ctxt conditional prop = |
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let |
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val ((c, T), rhs) = prop |
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|> Thm.cterm_of (ProofContext.theory_of ctxt) |
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|> meta_rewrite_conv ctxt |
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|> (snd o Logic.dest_equals o Thm.prop_of) |
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|> conditional ? Logic.strip_imp_concl |
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|> (abs_def o #2 o cert_def ctxt); |
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fun prove ctxt' def = |
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let |
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val frees = Term.fold_aterms (fn Free (x, _) => |
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if Variable.is_fixed ctxt' x then I else insert (op =) x | _ => I) prop []; |
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in |
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Goal.prove ctxt' frees [] prop (K (ALLGOALS |
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(CONVERSION (meta_rewrite_conv ctxt') THEN' |
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MetaSimplifier.rewrite_goal_tac [def] THEN' |
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resolve_tac [Drule.reflexive_thm]))) |
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handle ERROR msg => cat_error msg "Failed to prove definitional specification." |
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end; |
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in (((c, T), rhs), prove) end; |
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end; |