src/HOL/Tools/function_package/fundef_package.ML
author krauss
Mon Jun 05 14:26:07 2006 +0200 (2006-06-05)
changeset 19770 be5c23ebe1eb
parent 19617 7cb4b67d4b97
child 19782 48c4632e2c28
permissions -rw-r--r--
HOL/Tools/function_package: Added support for mutual recursive definitions.
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(*  Title:      HOL/Tools/function_package/fundef_package.ML
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    ID:         $Id$
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    Author:     Alexander Krauss, TU Muenchen
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A package for general recursive function definitions. 
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Isar commands.
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*)
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signature FUNDEF_PACKAGE = 
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sig
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    val add_fundef : ((bstring * Attrib.src list) * string) list list -> theory -> Proof.state (* Need an _i variant *)
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    val cong_add: attribute
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    val cong_del: attribute
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    val setup : theory -> theory
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    val get_congs : theory -> thm list
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end
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structure FundefPackage : FUNDEF_PACKAGE =
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struct
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open FundefCommon
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val True_implies = thm "True_implies"
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fun add_simps label moreatts (MutualPart {f_name, ...}, psimps) (names, attss) thy =
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    let 
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      val thy = thy |> Theory.add_path f_name 
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      val thy = thy |> Theory.add_path label
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      val spsimps = map standard psimps
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      val add_list = (names ~~ spsimps) ~~ attss
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      val (_, thy) = PureThy.add_thms add_list thy
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      val thy = thy |> Theory.parent_path
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      val (_, thy) = PureThy.add_thmss [((label, spsimps), Simplifier.simp_add :: moreatts)] thy
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      val thy = thy |> Theory.parent_path
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    in
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      thy
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    end
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fun fundef_afterqed congs curry_info name data names atts thmss thy =
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    let
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	val (complete_thm :: compat_thms) = map hd thmss
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	val fundef_data = FundefMutual.mk_partial_rules_mutual thy congs curry_info data (freezeT complete_thm) (map freezeT compat_thms)
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	val FundefMResult {psimps, subset_pinducts, simple_pinducts, termination, domintros, ...} = fundef_data
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        val Mutual {parts, ...} = curry_info
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	val Prep {names = Names {acc_R=accR, ...}, ...} = data
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	val dom_abbrev = Logic.mk_equals (Free (name ^ "_dom", fastype_of accR), accR)
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	val (_, thy) = LocalTheory.mapping NONE (Specification.abbreviation_i ("", false) [(NONE, dom_abbrev)]) thy
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        val thy = fold2 (add_simps "psimps" []) (parts ~~ psimps) (names ~~ atts) thy
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	val thy = thy |> Theory.add_path name
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	val (_, thy) = PureThy.add_thms [(("cases", complete_thm), [RuleCases.case_names (flat names)])] thy
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	val (_, thy) = PureThy.add_thmss [(("domintros", domintros), [])] thy
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	val (_, thy) = PureThy.add_thms [(("termination", termination), [])] thy
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	val (_,thy) = PureThy.add_thmss [(("pinduct", map standard simple_pinducts), [RuleCases.case_names (flat names), InductAttrib.induct_set ""])] thy
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	val thy = thy |> Theory.parent_path
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    in
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	add_fundef_data name (fundef_data, curry_info, names, atts) thy
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    end
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fun gen_add_fundef prep_att eqns_attss thy =
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    let
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	fun split eqns_atts =
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	    let 
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		val (natts, eqns) = split_list eqns_atts
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		val (names, raw_atts) = split_list natts
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		val atts = map (map (prep_att thy)) raw_atts
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	    in
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		((names, atts), eqns)
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	    end
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	val (natts, eqns) = split_list (map split_list eqns_attss)
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	val (names, raw_atts) = split_list (map split_list natts)
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	val atts = map (map (map (prep_att thy))) raw_atts
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	val congs = get_fundef_congs (Context.Theory thy)
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	val t_eqns = map (map (Sign.read_prop thy)) eqns
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			 |> map (map (term_of o cterm_of thy)) (* HACK to prevent strange things from happening with abbreviations *)
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	val (curry_info, name, (data, thy)) = FundefMutual.prepare_fundef_mutual congs t_eqns thy
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	val Prep {complete, compat, ...} = data
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	val props = (complete :: compat) (*(complete :: fst (chop 110 compat))*)
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    in
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	thy |> ProofContext.init
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	    |> Proof.theorem_i PureThy.internalK NONE (fundef_afterqed congs curry_info name data names atts) NONE ("", [])
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	    (map (fn t => (("", []), [(t, [])])) props)
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    end
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fun total_termination_afterqed name (Mutual {parts, ...}) thmss thy =
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    let
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	val totality = hd (hd thmss)
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	val (FundefMResult {psimps, simple_pinducts, ... }, Mutual {parts, ...}, names, atts)
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	  = the (get_fundef_data name thy)
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	val remove_domain_condition = full_simplify (HOL_basic_ss addsimps [totality, True_implies])
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	val tsimps = map (map remove_domain_condition) psimps
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	val tinduct = map remove_domain_condition simple_pinducts
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        val thy = fold2 (add_simps "simps" [RecfunCodegen.add NONE]) (parts ~~ tsimps) (names ~~ atts) thy
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	val thy = Theory.add_path name thy
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	val (_, thy) = PureThy.add_thmss [(("induct", map standard tinduct), [])] thy 
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	val thy = Theory.parent_path thy
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    in
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	thy
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    end
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(*
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fun mk_partial_rules name D_name D domT idomT thmss thy =
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    let
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	val [subs, dcl] = (hd thmss)
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	val {f_const, f_curried_const, G_const, R_const, G_elims, completeness, f_simps, names_attrs, subset_induct, ... }
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	  = the (Symtab.lookup (FundefData.get thy) name)
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	val D_implies_dom = subs COMP (instantiate' [SOME (ctyp_of thy idomT)] 
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						    [SOME (cterm_of thy D)]
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						    subsetD)
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	val D_simps = map (curry op RS D_implies_dom) f_simps
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	val D_induct = subset_induct
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			   |> cterm_instantiate [(cterm_of thy (Var (("D",0), fastype_of D)) ,cterm_of thy D)]
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			   |> curry op COMP subs
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			   |> curry op COMP (dcl |> forall_intr (cterm_of thy (Var (("z",0), idomT)))
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						 |> forall_intr (cterm_of thy (Var (("x",0), idomT))))
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	val ([tinduct'], thy2) = PureThy.add_thms [((name ^ "_" ^ D_name ^ "_induct", D_induct), [])] thy
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	val ([tsimps'], thy3) = PureThy.add_thmss [((name ^ "_" ^ D_name ^ "_simps", D_simps), [])] thy2
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    in
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	thy3
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    end
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*)
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fun fundef_setup_termination_proof name NONE thy = 
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    let
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	val name = if name = "" then get_last_fundef thy else name
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	val data = the (get_fundef_data name thy)
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	val (res as FundefMResult {termination, ...}, mutual, _, _) = data
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	val goal = FundefTermination.mk_total_termination_goal data
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    in
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	thy |> ProofContext.init
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	    |> ProofContext.note_thmss_i [(("termination", 
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					    [ContextRules.intro_query NONE]), [([termination], [])])] |> snd
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	    |> Proof.theorem_i PureThy.internalK NONE (total_termination_afterqed name mutual) NONE ("", [])
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	    [(("", []), [(goal, [])])]
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    end	
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  | fundef_setup_termination_proof name (SOME (dom_name, dom)) thy =
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    let
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	val name = if name = "" then get_last_fundef thy else name
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	val data = the (get_fundef_data name thy)
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	val (subs, dcl) = FundefTermination.mk_partial_termination_goal thy data dom
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    in
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	thy |> ProofContext.init
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	    |> Proof.theorem_i PureThy.internalK NONE (K I) NONE ("", [])
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	    [(("", []), [(subs, []), (dcl, [])])]
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    end	
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val add_fundef = gen_add_fundef Attrib.attribute
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(* congruence rules *)
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val cong_add = Thm.declaration_attribute (map_fundef_congs o Drule.add_rule o safe_mk_meta_eq);
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val cong_del = Thm.declaration_attribute (map_fundef_congs o Drule.del_rule o safe_mk_meta_eq);
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(* setup *)
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val setup = FundefData.init #> FundefCongs.init 
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	#>  Attrib.add_attributes
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		[("fundef_cong", Attrib.add_del_args cong_add cong_del, "declaration of congruence rule for function definitions")]
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val get_congs = FundefCommon.get_fundef_congs o Context.Theory
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(* outer syntax *)
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local structure P = OuterParse and K = OuterKeyword in
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val function_decl =
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    Scan.repeat1 (P.opt_thm_name ":" -- P.prop);
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val functionP =
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  OuterSyntax.command "function" "define general recursive functions" K.thy_goal
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    (P.and_list1 function_decl >> (fn eqnss =>
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      Toplevel.print o Toplevel.theory_to_proof (add_fundef eqnss)));
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val terminationP =
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  OuterSyntax.command "termination" "prove termination of a recursive function" K.thy_goal
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  ((Scan.optional P.name "" -- Scan.option (P.$$$ "(" |-- Scan.optional (P.name --| P.$$$ ":") "dom" -- P.term --| P.$$$ ")"))
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       >> (fn (name,dom) =>
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	      Toplevel.print o Toplevel.theory_to_proof (fundef_setup_termination_proof name dom)));
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val _ = OuterSyntax.add_parsers [functionP];
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val _ = OuterSyntax.add_parsers [terminationP];
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end;
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end