diff --git a/src/Pure/Thy/export_theory.ML b/src/Pure/Thy/export_theory.ML
--- a/src/Pure/Thy/export_theory.ML
+++ b/src/Pure/Thy/export_theory.ML
@@ -1,480 +1,480 @@
 (*  Title:      Pure/Thy/export_theory.ML
     Author:     Makarius
 
 Export foundational theory content and locale/class structure.
 *)
 
 signature EXPORT_THEORY =
 sig
   val other_name_space: (theory -> Name_Space.T) -> theory -> theory
   val export_enabled: Thy_Info.presentation_context -> bool
   val export_body: theory -> string -> XML.body -> unit
 end;
 
 structure Export_Theory: EXPORT_THEORY =
 struct
 
 (* other name spaces *)
 
 fun err_dup_kind kind = error ("Duplicate name space kind " ^ quote kind);
 
 structure Data = Theory_Data
 (
   type T = (theory -> Name_Space.T) Inttab.table;
   val empty = Inttab.empty;
   val merge = Inttab.merge (K true);
 );
 
 val other_name_spaces = map #2 o Inttab.dest o Data.get;
 fun other_name_space get_space thy = Data.map (Inttab.update (serial (), get_space)) thy;
 
 val _ = Theory.setup
  (other_name_space Thm.oracle_space #>
   other_name_space Global_Theory.fact_space #>
   other_name_space (Bundle.bundle_space o Context.Theory) #>
   other_name_space (Attrib.attribute_space o Context.Theory) #>
   other_name_space (Method.method_space o Context.Theory));
 
 
 (* approximative syntax *)
 
 val get_syntax = Syntax.get_approx o Proof_Context.syn_of;
 fun get_syntax_type ctxt = get_syntax ctxt o Lexicon.mark_type;
 fun get_syntax_const ctxt = get_syntax ctxt o Lexicon.mark_const;
 fun get_syntax_fixed ctxt = get_syntax ctxt o Lexicon.mark_fixed;
 
 fun get_syntax_param ctxt loc x =
   let val thy = Proof_Context.theory_of ctxt in
     if Class.is_class thy loc then
       (case AList.lookup (op =) (Class.these_params thy [loc]) x of
         NONE => NONE
       | SOME (_, (c, _)) => get_syntax_const ctxt c)
     else get_syntax_fixed ctxt x
   end;
 
 val encode_syntax =
   XML.Encode.variant
    [fn NONE => ([], []),
     fn SOME (Syntax.Prefix delim) => ([delim], []),
     fn SOME (Syntax.Infix {assoc, delim, pri}) =>
       let
         val ass =
           (case assoc of
             Printer.No_Assoc => 0
           | Printer.Left_Assoc => 1
           | Printer.Right_Assoc => 2);
         open XML.Encode Term_XML.Encode;
       in ([], triple int string int (ass, delim, pri)) end];
 
 
 (* free variables: not declared in the context *)
 
 val is_free = not oo Name.is_declared;
 
 fun add_frees used =
   fold_aterms (fn Free (x, T) => is_free used x ? insert (op =) (x, T) | _ => I);
 
 fun add_tfrees used =
   (fold_types o fold_atyps) (fn TFree (a, S) => is_free used a ? insert (op =) (a, S) | _ => I);
 
 
 (* locales *)
 
 fun locale_content thy loc =
   let
     val ctxt = Locale.init loc thy;
     val args =
       Locale.params_of thy loc
       |> map (fn ((x, T), _) => ((x, T), get_syntax_param ctxt loc x));
     val axioms =
       let
         val (asm, defs) = Locale.specification_of thy loc;
         val cprops = map (Thm.cterm_of ctxt) (the_list asm @ defs);
         val (intro1, intro2) = Locale.intros_of thy loc;
         val intros_tac = Method.try_intros_tac ctxt (the_list intro1 @ the_list intro2) [];
         val res =
           Goal.init (Conjunction.mk_conjunction_balanced cprops)
           |> (ALLGOALS Goal.conjunction_tac THEN intros_tac)
           |> try Seq.hd;
       in
         (case res of
           SOME goal => Thm.prems_of goal
         | NONE => raise Fail ("Cannot unfold locale " ^ quote loc))
       end;
     val typargs = build_rev (fold Term.add_tfrees (map (Free o #1) args @ axioms));
   in {typargs = typargs, args = args, axioms = axioms} end;
 
 fun get_locales thy =
   Locale.get_locales thy |> map_filter (fn loc =>
     if Experiment.is_experiment thy loc then NONE else SOME (loc, ()));
 
 fun get_dependencies prev_thys thy =
   Locale.dest_dependencies prev_thys thy |> map_filter (fn dep =>
     if Experiment.is_experiment thy (#source dep) orelse
       Experiment.is_experiment thy (#target dep) then NONE
     else
       let
         val (type_params, params) = Locale.parameters_of thy (#source dep);
         val typargs = fold (Term.add_tfreesT o #2 o #1) params type_params;
         val substT =
           typargs |> map_filter (fn v =>
             let
               val T = TFree v;
               val T' = Morphism.typ (#morphism dep) T;
             in if T = T' then NONE else SOME (v, T') end);
         val subst =
           params |> map_filter (fn (v, _) =>
             let
               val t = Free v;
               val t' = Morphism.term (#morphism dep) t;
             in if t aconv t' then NONE else SOME (v, t') end);
       in SOME (dep, (substT, subst)) end);
 
 
 (* presentation *)
 
 fun export_enabled (context: Thy_Info.presentation_context) =
   Options.bool (#options context) "export_theory";
 
 fun export_body thy name body =
   if XML.is_empty_body body then ()
   else Export.export thy (Path.binding0 (Path.make ("theory" :: space_explode "/" name))) body;
 
 val _ = (Theory.setup o Thy_Info.add_presentation) (fn context => fn thy =>
   let
     val rep_tsig = Type.rep_tsig (Sign.tsig_of thy);
     val consts = Sign.consts_of thy;
     val thy_ctxt = Proof_Context.init_global thy;
 
     val pos_properties = Thy_Info.adjust_pos_properties context;
 
     val enabled = export_enabled context;
 
 
     (* strict parents *)
 
     val parents = Theory.parents_of thy;
     val _ =
       Export.export thy \<^path_binding>\<open>theory/parents\<close>
-        (XML.Encode.string (cat_lines (map Context.theory_long_name parents)));
+        (XML.Encode.string (terminate_lines (map Context.theory_long_name parents)));
 
 
     (* spec rules *)
 
     fun spec_rule_content {pos, name, rough_classification, terms, rules} =
       let
         val spec =
           terms @ map Thm.plain_prop_of rules
           |> Term_Subst.zero_var_indexes_list
           |> map Logic.unvarify_global;
       in
        {props = pos_properties pos,
         name = name,
         rough_classification = rough_classification,
         typargs = build_rev (fold Term.add_tfrees spec),
         args = build_rev (fold Term.add_frees spec),
         terms = map (fn t => (t, Term.type_of t)) (take (length terms) spec),
         rules = drop (length terms) spec}
       end;
 
 
     (* entities *)
 
     fun make_entity_markup name xname pos serial =
       let val props = pos_properties pos @ Markup.serial_properties serial;
       in (Markup.entityN, (Markup.nameN, name) :: (Markup.xnameN, xname) :: props) end;
 
     fun entity_markup space name =
       let
         val xname = Name_Space.extern_shortest thy_ctxt space name;
         val {serial, pos, ...} = Name_Space.the_entry space name;
       in make_entity_markup name xname pos serial end;
 
     fun export_entities export_name get_space decls export =
       let
         val parent_spaces = map get_space parents;
         val space = get_space thy;
       in
         build (decls |> fold (fn (name, decl) =>
           if exists (fn space => Name_Space.declared space name) parent_spaces then I
           else
             (case export name decl of
               NONE => I
             | SOME make_body =>
                 let
                   val i = #serial (Name_Space.the_entry space name);
                   val body = if enabled then make_body () else [];
                 in cons (i, XML.Elem (entity_markup space name, body)) end)))
         |> sort (int_ord o apply2 #1) |> map #2
         |> export_body thy export_name
       end;
 
 
     (* types *)
 
     val encode_type =
       let open XML.Encode Term_XML.Encode
       in triple encode_syntax (list string) (option typ) end;
 
     val _ =
       export_entities "types" Sign.type_space (Name_Space.dest_table (#types rep_tsig))
         (fn c =>
           (fn Type.LogicalType n =>
                 SOME (fn () =>
                   encode_type (get_syntax_type thy_ctxt c, Name.invent Name.context Name.aT n, NONE))
             | Type.Abbreviation (args, U, false) =>
                 SOME (fn () =>
                   encode_type (get_syntax_type thy_ctxt c, args, SOME U))
             | _ => NONE));
 
 
     (* consts *)
 
     val encode_term = Term_XML.Encode.term consts;
 
     val encode_const =
       let open XML.Encode Term_XML.Encode
       in pair encode_syntax (pair (list string) (pair typ (pair (option encode_term) bool))) end;
 
     val _ =
       export_entities "consts" Sign.const_space (#constants (Consts.dest consts))
         (fn c => fn (T, abbrev) =>
           SOME (fn () =>
             let
               val syntax = get_syntax_const thy_ctxt c;
               val U = Logic.unvarifyT_global T;
               val U0 = Type.strip_sorts U;
               val trim_abbrev =
                 Proofterm.standard_vars_term Name.context #> map_types Type.strip_sorts;
               val abbrev' = Option.map trim_abbrev abbrev;
               val args = map (#1 o dest_TFree) (Consts.typargs consts (c, U0));
               val propositional = Object_Logic.is_propositional thy_ctxt (Term.body_type U0);
             in encode_const (syntax, (args, (U0, (abbrev', propositional)))) end));
 
 
     (* axioms *)
 
     fun standard_prop used extra_shyps raw_prop raw_proof =
       let
         val (prop, proof) = Proofterm.standard_vars used (raw_prop, raw_proof);
         val args = rev (add_frees used prop []);
         val typargs = rev (add_tfrees used prop []);
         val used_typargs = fold (Name.declare o #1) typargs used;
         val sorts = Name.invent used_typargs Name.aT (length extra_shyps) ~~ extra_shyps;
       in ((sorts @ typargs, args, prop), proof) end;
 
     fun standard_prop_of thm =
       standard_prop Name.context (Thm.extra_shyps thm) (Thm.full_prop_of thm);
 
     val encode_prop =
       let open XML.Encode Term_XML.Encode
       in triple (list (pair string sort)) (list (pair string typ)) encode_term end;
 
     fun encode_axiom used prop =
       encode_prop (#1 (standard_prop used [] prop NONE));
 
     val _ =
       export_entities "axioms" Theory.axiom_space (Theory.all_axioms_of thy)
         (fn _ => fn prop => SOME (fn () => encode_axiom Name.context prop));
 
 
     (* theorems and proof terms *)
 
     val clean_thm = Thm.check_hyps (Context.Theory thy) #> Thm.strip_shyps;
     val prep_thm = clean_thm #> Thm.unconstrainT #> Thm.strip_shyps;
 
     val lookup_thm_id = Global_Theory.lookup_thm_id thy;
 
     fun expand_name thm_id (header: Proofterm.thm_header) =
       if #serial header = #serial thm_id then ""
       else
         (case lookup_thm_id (Proofterm.thm_header_id header) of
           NONE => ""
         | SOME thm_name => Thm_Name.print thm_name);
 
     fun entity_markup_thm (serial, (name, i)) =
       let
         val space = Global_Theory.fact_space thy;
         val xname = Name_Space.extern_shortest thy_ctxt space name;
         val {pos, ...} = Name_Space.the_entry space name;
       in make_entity_markup (Thm_Name.print (name, i)) (Thm_Name.print (xname, i)) pos serial end;
 
     fun encode_thm thm_id raw_thm =
       let
         val deps = map (Thm_Name.print o #2) (Thm_Deps.thm_deps thy [raw_thm]);
         val thm = prep_thm raw_thm;
 
         val proof0 =
           if Proofterm.export_standard_enabled () then
             Proof_Syntax.standard_proof_of
               {full = true, expand_name = SOME o expand_name thm_id} thm
           else if Proofterm.export_enabled () then Thm.reconstruct_proof_of thm
           else MinProof;
         val (prop, SOME proof) = standard_prop_of thm (SOME proof0);
         val _ = Thm.expose_proofs thy [thm];
       in
         (prop, deps, proof) |>
           let
             open XML.Encode Term_XML.Encode;
             val encode_proof = Proofterm.encode_standard_proof consts;
           in triple encode_prop (list string) encode_proof end
       end;
 
     fun export_thm (thm_id, thm_name) =
       let
         val markup = entity_markup_thm (#serial thm_id, thm_name);
         val body =
           if enabled then
             Global_Theory.get_thm_name thy (thm_name, Position.none)
             |> encode_thm thm_id
           else [];
       in XML.Elem (markup, body) end;
 
     val _ = export_body thy "thms" (map export_thm (Global_Theory.dest_thm_names thy));
 
 
     (* type classes *)
 
     val encode_class =
       let open XML.Encode Term_XML.Encode
       in pair (list (pair string typ)) (list (encode_axiom Name.context)) end;
 
     val _ =
       export_entities "classes" Sign.class_space
         (map (rpair ()) (Graph.keys (Sorts.classes_of (#2 (#classes rep_tsig)))))
         (fn name => fn () => SOME (fn () =>
           (case try (Axclass.get_info thy) name of
             NONE => ([], [])
           | SOME {params, axioms, ...} => (params, map (Thm.plain_prop_of o clean_thm) axioms))
           |> encode_class));
 
 
     (* sort algebra *)
 
     val _ =
       if enabled then
         let
           val prop = encode_axiom Name.context o Logic.varify_global;
 
           val encode_classrel =
             let open XML.Encode
             in list (pair prop (pair string string)) end;
 
           val encode_arities =
             let open XML.Encode Term_XML.Encode
             in list (pair prop (triple string (list sort) string)) end;
 
           val export_classrel =
             maps (fn (c, cs) => map (pair c) cs) #> map (`Logic.mk_classrel) #> encode_classrel;
 
           val export_arities = map (`Logic.mk_arity) #> encode_arities;
 
           val {classrel, arities} =
             Sorts.dest_algebra (map (#2 o #classes o Type.rep_tsig o Sign.tsig_of) parents)
               (#2 (#classes rep_tsig));
         in
           if null classrel then () else export_body thy "classrel" (export_classrel classrel);
           if null arities then () else export_body thy "arities" (export_arities arities)
         end
       else ();
 
 
     (* locales *)
 
     fun encode_locale used =
       let open XML.Encode Term_XML.Encode in
         triple (list (pair string sort)) (list (pair (pair string typ) encode_syntax))
           (list (encode_axiom used))
       end;
 
     val _ =
       export_entities "locales" Locale.locale_space (get_locales thy)
         (fn loc => fn () => SOME (fn () =>
           let
             val {typargs, args, axioms} = locale_content thy loc;
             val used = fold Name.declare (map #1 typargs @ map (#1 o #1) args) Name.context;
           in encode_locale used (typargs, args, axioms) end
           handle ERROR msg =>
             cat_error msg ("The error(s) above occurred in locale " ^
               quote (Locale.markup_name thy_ctxt loc))));
 
 
     (* locale dependencies *)
 
     fun encode_locale_dependency (dep: Locale.locale_dependency, subst) =
       (#source dep, (#target dep, (#prefix dep, subst))) |>
         let
           open XML.Encode Term_XML.Encode;
           val encode_subst =
             pair (list (pair (pair string sort) typ)) (list (pair (pair string typ) (term consts)));
         in pair string (pair string (pair (list (pair string bool)) encode_subst)) end;
 
     val _ =
       if enabled then
         get_dependencies parents thy |> map_index (fn (i, dep) =>
           let
             val xname = string_of_int (i + 1);
             val name = Long_Name.implode [Context.theory_name thy, xname];
             val markup = make_entity_markup name xname (#pos (#1 dep)) (#serial (#1 dep));
             val body = encode_locale_dependency dep;
           in XML.Elem (markup, body) end)
         |> export_body thy "locale_dependencies"
       else ();
 
 
     (* constdefs *)
 
     val _ =
       if enabled then
         let
           val constdefs =
             Defs.dest_constdefs (map Theory.defs_of (Theory.parents_of thy)) (Theory.defs_of thy)
             |> sort_by #1;
           val encode =
             let open XML.Encode
             in list (pair string string) end;
         in if null constdefs then () else export_body thy "constdefs" (encode constdefs) end
       else ();
 
 
     (* spec rules *)
 
     val encode_specs =
       let open XML.Encode Term_XML.Encode in
         list (fn {props, name, rough_classification, typargs, args, terms, rules} =>
           pair properties (pair string (pair Spec_Rules.encode_rough_classification
             (pair (list (pair string sort)) (pair (list (pair string typ))
               (pair (list (pair encode_term typ)) (list encode_term))))))
               (props, (name, (rough_classification, (typargs, (args, (terms, rules)))))))
       end;
 
     val _ =
       if enabled then
         (case Spec_Rules.dest_theory thy of
           [] => ()
         | spec_rules =>
             export_body thy "spec_rules" (encode_specs (map spec_rule_content spec_rules)))
       else ();
 
 
     (* other entities *)
 
     fun export_other get_space =
       let
         val space = get_space thy;
         val export_name = "other/" ^ Name_Space.kind_of space;
         val decls = Name_Space.get_names space |> map (rpair ());
       in export_entities export_name get_space decls (fn _ => fn () => SOME (K [])) end;
 
     val other_spaces = other_name_spaces thy;
     val other_kinds = map (fn get_space => Name_Space.kind_of (get_space thy)) other_spaces;
     val _ =
       if null other_kinds then ()
       else
         Export.export thy \<^path_binding>\<open>theory/other_kinds\<close>
           (XML.Encode.string (cat_lines other_kinds));
     val _ = List.app export_other other_spaces;
 
   in () end);
 
 end;
diff --git a/src/Pure/Thy/export_theory.scala b/src/Pure/Thy/export_theory.scala
--- a/src/Pure/Thy/export_theory.scala
+++ b/src/Pure/Thy/export_theory.scala
@@ -1,780 +1,776 @@
 /*  Title:      Pure/Thy/export_theory.scala
     Author:     Makarius
 
 Export foundational theory content.
 */
 
 package isabelle
 
 
 import scala.collection.immutable.SortedMap
 
 
 object Export_Theory {
   /** session content **/
 
   sealed case class Session(name: String, theory_graph: Graph[String, Option[Theory]]) {
     override def toString: String = name
 
     def theory(theory_name: String): Option[Theory] =
       if (theory_graph.defined(theory_name)) theory_graph.get_node(theory_name)
       else None
 
     def theories: List[Theory] =
       theory_graph.topological_order.flatMap(theory)
   }
 
   def read_session(
     store: Sessions.Store,
     sessions_structure: Sessions.Structure,
     session_name: String,
     progress: Progress = new Progress,
     cache: Term.Cache = Term.Cache.make()): Session = {
     val thys =
       sessions_structure.build_requirements(List(session_name)).flatMap(session =>
         using(store.open_database(session)) { db =>
           val provider = Export.Provider.database(db, store.cache, session)
           for (theory <- provider.theory_names)
           yield {
             progress.echo("Reading theory " + theory)
             read_theory(provider, session, theory, cache = cache)
           }
         })
 
     val graph0 =
       thys.foldLeft(Graph.string[Option[Theory]]) {
         case (g, thy) => g.default_node(thy.name, Some(thy))
       }
     val graph1 =
       thys.foldLeft(graph0) {
         case (g0, thy) =>
           thy.parents.foldLeft(g0) {
             case (g1, parent) => g1.default_node(parent, None).add_edge_acyclic(parent, thy.name)
           }
       }
 
     Session(session_name, graph1)
   }
 
 
 
   /** theory content **/
 
   sealed case class Theory(name: String, parents: List[String],
     types: List[Entity[Type]],
     consts: List[Entity[Const]],
     axioms: List[Entity[Axiom]],
     thms: List[Entity[Thm]],
     classes: List[Entity[Class]],
     locales: List[Entity[Locale]],
     locale_dependencies: List[Entity[Locale_Dependency]],
     classrel: List[Classrel],
     arities: List[Arity],
     constdefs: List[Constdef],
     typedefs: List[Typedef],
     datatypes: List[Datatype],
     spec_rules: List[Spec_Rule],
     others: Map[String, List[Entity[Other]]]
   ) {
     override def toString: String = name
 
     def entity_iterator: Iterator[Entity0] =
       types.iterator.map(_.no_content) ++
       consts.iterator.map(_.no_content) ++
       axioms.iterator.map(_.no_content) ++
       thms.iterator.map(_.no_content) ++
       classes.iterator.map(_.no_content) ++
       locales.iterator.map(_.no_content) ++
       locale_dependencies.iterator.map(_.no_content) ++
       (for { (_, xs) <- others; x <- xs.iterator } yield x.no_content)
 
     def cache(cache: Term.Cache): Theory =
       Theory(cache.string(name),
         parents.map(cache.string),
         types.map(_.cache(cache)),
         consts.map(_.cache(cache)),
         axioms.map(_.cache(cache)),
         thms.map(_.cache(cache)),
         classes.map(_.cache(cache)),
         locales.map(_.cache(cache)),
         locale_dependencies.map(_.cache(cache)),
         classrel.map(_.cache(cache)),
         arities.map(_.cache(cache)),
         constdefs.map(_.cache(cache)),
         typedefs.map(_.cache(cache)),
         datatypes.map(_.cache(cache)),
         spec_rules.map(_.cache(cache)),
         (for ((k, xs) <- others.iterator) yield cache.string(k) -> xs.map(_.cache(cache))).toMap)
   }
 
-  def read_theory_parents(provider: Export.Provider, theory_name: String): Option[List[String]] = {
-    if (theory_name == Thy_Header.PURE) Some(Nil)
-    else {
-      provider.focus(theory_name)(Export.THEORY_PREFIX + "parents")
-        .map(entry => split_lines(entry.uncompressed.text))
-    }
-  }
+  def read_theory_parents(provider: Export.Provider, theory_name: String): Option[List[String]] =
+    provider.focus(theory_name)(Export.THEORY_PREFIX + "parents")
+      .map(entry => Library.trim_split_lines(entry.uncompressed.text))
 
   def no_theory: Theory =
     Theory("", Nil, Nil, Nil, Nil, Nil, Nil, Nil, Nil, Nil, Nil, Nil, Nil, Nil, Nil, Map.empty)
 
   def read_theory(
     provider: Export.Provider,
     session_name: String,
     theory_name: String,
     permissive: Boolean = false,
     cache: Term.Cache = Term.Cache.none
   ): Theory = {
     val theory_provider = provider.focus(theory_name)
     read_theory_parents(theory_provider, theory_name) match {
       case None if permissive => no_theory
       case None =>
         error("Missing theory export in session " + quote(session_name) + ": " + quote(theory_name))
       case Some(parents) =>
         val theory =
           Theory(theory_name, parents,
             read_types(theory_provider),
             read_consts(theory_provider),
             read_axioms(theory_provider),
             read_thms(theory_provider),
             read_classes(theory_provider),
             read_locales(theory_provider),
             read_locale_dependencies(theory_provider),
             read_classrel(theory_provider),
             read_arities(theory_provider),
             read_constdefs(theory_provider),
             read_typedefs(theory_provider),
             read_datatypes(theory_provider),
             read_spec_rules(theory_provider),
             read_others(theory_provider))
         if (cache.no_cache) theory else theory.cache(cache)
     }
   }
 
   def read_pure[A](store: Sessions.Store, read: (Export.Provider, String, String) => A): A = {
     val session_name = Thy_Header.PURE
     val theory_name = Thy_Header.PURE
 
     using(store.open_database(session_name)) { db =>
       val provider = Export.Provider.database(db, store.cache, session_name)
       read(provider, session_name, theory_name)
     }
   }
 
   def read_pure_theory(store: Sessions.Store, cache: Term.Cache = Term.Cache.none): Theory =
     read_pure(store, read_theory(_, _, _, cache = cache))
 
   def read_pure_proof(
       store: Sessions.Store, id: Thm_Id, cache: Term.Cache = Term.Cache.none): Option[Proof] =
     read_pure(store, (provider, _, _) => read_proof(provider, id, cache = cache))
 
 
   /* entities */
 
   object Kind {
     val TYPE = "type"
     val CONST = "const"
     val THM = "thm"
     val PROOF = "proof"
     val LOCALE_DEPENDENCY = "locale_dependency"
     val DOCUMENT_HEADING = "document_heading"
     val DOCUMENT_TEXT = "document_text"
     val PROOF_TEXT = "proof_text"
   }
 
   def export_kind(kind: String): String =
     if (kind == Markup.TYPE_NAME) Kind.TYPE
     else if (kind == Markup.CONSTANT) Kind.CONST
     else kind
 
   def export_kind_name(kind: String, name: String): String =
     name + "|" + export_kind(kind)
 
   abstract class Content[T] {
     def cache(cache: Term.Cache): T
   }
   sealed case class No_Content() extends Content[No_Content] {
     def cache(cache: Term.Cache): No_Content = this
   }
   sealed case class Entity[A <: Content[A]](
     kind: String,
     name: String,
     xname: String,
     pos: Position.T,
     id: Option[Long],
     serial: Long,
     content: Option[A]
   ) {
     val kname: String = export_kind_name(kind, name)
     val range: Symbol.Range = Position.Range.unapply(pos).getOrElse(Text.Range.offside)
 
     def export_kind: String = Export_Theory.export_kind(kind)
     override def toString: String = export_kind + " " + quote(name)
 
     def the_content: A =
       if (content.isDefined) content.get else error("No content for " + toString)
 
     def no_content: Entity0 = copy(content = None)
 
     def cache(cache: Term.Cache): Entity[A] =
       Entity(
         cache.string(kind),
         cache.string(name),
         cache.string(xname),
         cache.position(pos),
         id,
         serial,
         content.map(_.cache(cache)))
   }
   type Entity0 = Entity[No_Content]
 
   def read_entities[A <: Content[A]](
     provider: Export.Provider,
     export_name: String,
     kind: String,
     decode: XML.Decode.T[A]
   ): List[Entity[A]] = {
     def decode_entity(tree: XML.Tree): Entity[A] = {
       def err(): Nothing = throw new XML.XML_Body(List(tree))
 
       tree match {
         case XML.Elem(Markup(Markup.ENTITY, props), body) =>
           val name = Markup.Name.unapply(props) getOrElse err()
           val xname = Markup.XName.unapply(props) getOrElse err()
           val pos = props.filter(p => Markup.position_property(p) && p._1 != Markup.ID)
           val id = Position.Id.unapply(props)
           val serial = Markup.Serial.unapply(props) getOrElse err()
           val content = if (body.isEmpty) None else Some(decode(body))
           Entity(kind, name, xname, pos, id, serial, content)
         case _ => err()
       }
     }
     provider.uncompressed_yxml(export_name).map(decode_entity)
   }
 
 
   /* approximative syntax */
 
   object Assoc extends Enumeration {
     val NO_ASSOC, LEFT_ASSOC, RIGHT_ASSOC = Value
   }
 
   sealed abstract class Syntax
   case object No_Syntax extends Syntax
   case class Prefix(delim: String) extends Syntax
   case class Infix(assoc: Assoc.Value, delim: String, pri: Int) extends Syntax
 
   def decode_syntax: XML.Decode.T[Syntax] =
     XML.Decode.variant(List(
       { case (Nil, Nil) => No_Syntax },
       { case (List(delim), Nil) => Prefix(delim) },
       { case (Nil, body) =>
           import XML.Decode._
           val (ass, delim, pri) = triple(int, string, int)(body)
           Infix(Assoc(ass), delim, pri) }))
 
 
   /* types */
 
   sealed case class Type(syntax: Syntax, args: List[String], abbrev: Option[Term.Typ])
   extends Content[Type] {
     override def cache(cache: Term.Cache): Type =
       Type(
         syntax,
         args.map(cache.string),
         abbrev.map(cache.typ))
   }
 
   def read_types(provider: Export.Provider): List[Entity[Type]] =
     read_entities(provider, Export.THEORY_PREFIX + "types", Markup.TYPE_NAME,
       { body =>
         import XML.Decode._
         val (syntax, args, abbrev) =
           triple(decode_syntax, list(string), option(Term_XML.Decode.typ))(body)
         Type(syntax, args, abbrev)
       })
 
 
   /* consts */
 
   sealed case class Const(
     syntax: Syntax,
     typargs: List[String],
     typ: Term.Typ,
     abbrev: Option[Term.Term],
     propositional: Boolean
   ) extends Content[Const] {
     override def cache(cache: Term.Cache): Const =
       Const(
         syntax,
         typargs.map(cache.string),
         cache.typ(typ),
         abbrev.map(cache.term),
         propositional)
   }
 
   def read_consts(provider: Export.Provider): List[Entity[Const]] =
     read_entities(provider, Export.THEORY_PREFIX + "consts", Markup.CONSTANT,
       { body =>
         import XML.Decode._
         val (syntax, (typargs, (typ, (abbrev, propositional)))) =
           pair(decode_syntax,
             pair(list(string),
               pair(Term_XML.Decode.typ,
                 pair(option(Term_XML.Decode.term), bool))))(body)
         Const(syntax, typargs, typ, abbrev, propositional)
       })
 
 
   /* axioms */
 
   sealed case class Prop(
     typargs: List[(String, Term.Sort)],
     args: List[(String, Term.Typ)],
     term: Term.Term
   ) extends Content[Prop] {
     override def cache(cache: Term.Cache): Prop =
       Prop(
         typargs.map({ case (name, sort) => (cache.string(name), cache.sort(sort)) }),
         args.map({ case (name, typ) => (cache.string(name), cache.typ(typ)) }),
         cache.term(term))
   }
 
   def decode_prop(body: XML.Body): Prop = {
     val (typargs, args, t) = {
       import XML.Decode._
       import Term_XML.Decode._
       triple(list(pair(string, sort)), list(pair(string, typ)), term)(body)
     }
     Prop(typargs, args, t)
   }
 
   sealed case class Axiom(prop: Prop) extends Content[Axiom] {
     override def cache(cache: Term.Cache): Axiom = Axiom(prop.cache(cache))
   }
 
   def read_axioms(provider: Export.Provider): List[Entity[Axiom]] =
     read_entities(provider, Export.THEORY_PREFIX + "axioms", Markup.AXIOM,
       body => Axiom(decode_prop(body)))
 
 
   /* theorems */
 
   sealed case class Thm_Id(serial: Long, theory_name: String) {
     def pure: Boolean = theory_name == Thy_Header.PURE
   }
 
   sealed case class Thm(
     prop: Prop,
     deps: List[String],
     proof: Term.Proof)
   extends Content[Thm] {
     override def cache(cache: Term.Cache): Thm =
       Thm(
         prop.cache(cache),
         deps.map(cache.string),
         cache.proof(proof))
   }
 
   def read_thms(provider: Export.Provider): List[Entity[Thm]] =
     read_entities(provider, Export.THEORY_PREFIX + "thms", Kind.THM,
       { body =>
         import XML.Decode._
         import Term_XML.Decode._
         val (prop, deps, prf) = triple(decode_prop, list(string), proof)(body)
         Thm(prop, deps, prf)
       })
 
   sealed case class Proof(
     typargs: List[(String, Term.Sort)],
     args: List[(String, Term.Typ)],
     term: Term.Term,
     proof: Term.Proof
   ) {
     def prop: Prop = Prop(typargs, args, term)
 
     def cache(cache: Term.Cache): Proof =
       Proof(
         typargs.map({ case (name, sort) => (cache.string(name), cache.sort(sort)) }),
         args.map({ case (name, typ) => (cache.string(name), cache.typ(typ)) }),
         cache.term(term),
         cache.proof(proof))
   }
 
   def read_proof(
     provider: Export.Provider,
     id: Thm_Id,
     cache: Term.Cache = Term.Cache.none
   ): Option[Proof] = {
     for { entry <- provider.focus(id.theory_name)(Export.PROOFS_PREFIX + id.serial) }
     yield {
       val body = entry.uncompressed_yxml
       val (typargs, (args, (prop_body, proof_body))) = {
         import XML.Decode._
         import Term_XML.Decode._
         pair(list(pair(string, sort)), pair(list(pair(string, typ)), pair(x => x, x => x)))(body)
       }
       val env = args.toMap
       val prop = Term_XML.Decode.term_env(env)(prop_body)
       val proof = Term_XML.Decode.proof_env(env)(proof_body)
 
       val result = Proof(typargs, args, prop, proof)
       if (cache.no_cache) result else result.cache(cache)
     }
   }
 
   def read_proof_boxes(
     store: Sessions.Store,
     provider: Export.Provider,
     proof: Term.Proof,
     suppress: Thm_Id => Boolean = _ => false,
     cache: Term.Cache = Term.Cache.none
   ): List[(Thm_Id, Proof)] = {
     var seen = Set.empty[Long]
     var result = SortedMap.empty[Long, (Thm_Id, Proof)]
 
     def boxes(context: Option[(Long, Term.Proof)], prf: Term.Proof): Unit = {
       prf match {
         case Term.Abst(_, _, p) => boxes(context, p)
         case Term.AbsP(_, _, p) => boxes(context, p)
         case Term.Appt(p, _) => boxes(context, p)
         case Term.AppP(p, q) => boxes(context, p); boxes(context, q)
         case thm: Term.PThm if !seen(thm.serial) =>
           seen += thm.serial
           val id = Thm_Id(thm.serial, thm.theory_name)
           if (!suppress(id)) {
             val read =
               if (id.pure) Export_Theory.read_pure_proof(store, id, cache = cache)
               else Export_Theory.read_proof(provider, id, cache = cache)
             read match {
               case Some(p) =>
                 result += (thm.serial -> (id -> p))
                 boxes(Some((thm.serial, p.proof)), p.proof)
               case None =>
                 error("Missing proof " + thm.serial + " (theory " + quote (thm.theory_name) + ")" +
                   (context match {
                     case None => ""
                     case Some((i, p)) => " in proof " + i + ":\n" + p
                   }))
             }
           }
         case _ =>
       }
     }
 
     boxes(None, proof)
     result.iterator.map(_._2).toList
   }
 
 
   /* type classes */
 
   sealed case class Class(params: List[(String, Term.Typ)], axioms: List[Prop])
   extends Content[Class] {
     override def cache(cache: Term.Cache): Class =
       Class(
         params.map({ case (name, typ) => (cache.string(name), cache.typ(typ)) }),
         axioms.map(_.cache(cache)))
   }
 
   def read_classes(provider: Export.Provider): List[Entity[Class]] =
     read_entities(provider, Export.THEORY_PREFIX + "classes", Markup.CLASS,
       { body =>
         import XML.Decode._
         import Term_XML.Decode._
         val (params, axioms) = pair(list(pair(string, typ)), list(decode_prop))(body)
         Class(params, axioms)
       })
 
 
   /* locales */
 
   sealed case class Locale(
     typargs: List[(String, Term.Sort)],
     args: List[((String, Term.Typ), Syntax)],
     axioms: List[Prop]
   ) extends Content[Locale] {
     override def cache(cache: Term.Cache): Locale =
       Locale(
         typargs.map({ case (name, sort) => (cache.string(name), cache.sort(sort)) }),
         args.map({ case ((name, typ), syntax) => ((cache.string(name), cache.typ(typ)), syntax) }),
         axioms.map(_.cache(cache)))
   }
 
   def read_locales(provider: Export.Provider): List[Entity[Locale]] =
     read_entities(provider, Export.THEORY_PREFIX + "locales", Markup.LOCALE,
       { body =>
         import XML.Decode._
         import Term_XML.Decode._
         val (typargs, args, axioms) =
           triple(list(pair(string, sort)), list(pair(pair(string, typ), decode_syntax)),
             list(decode_prop))(body)
         Locale(typargs, args, axioms)
       })
 
 
   /* locale dependencies */
 
   sealed case class Locale_Dependency(
     source: String,
     target: String,
     prefix: List[(String, Boolean)],
     subst_types: List[((String, Term.Sort), Term.Typ)],
     subst_terms: List[((String, Term.Typ), Term.Term)]
   ) extends Content[Locale_Dependency] {
     override def cache(cache: Term.Cache): Locale_Dependency =
       Locale_Dependency(
         cache.string(source),
         cache.string(target),
         prefix.map({ case (name, mandatory) => (cache.string(name), mandatory) }),
         subst_types.map({ case ((a, s), ty) => ((cache.string(a), cache.sort(s)), cache.typ(ty)) }),
         subst_terms.map({ case ((x, ty), t) => ((cache.string(x), cache.typ(ty)), cache.term(t)) }))
 
     def is_inclusion: Boolean =
       subst_types.isEmpty && subst_terms.isEmpty
   }
 
   def read_locale_dependencies(provider: Export.Provider): List[Entity[Locale_Dependency]] =
     read_entities(provider, Export.THEORY_PREFIX + "locale_dependencies", Kind.LOCALE_DEPENDENCY,
       { body =>
         import XML.Decode._
         import Term_XML.Decode._
         val (source, (target, (prefix, (subst_types, subst_terms)))) =
           pair(string, pair(string, pair(list(pair(string, bool)),
             pair(list(pair(pair(string, sort), typ)), list(pair(pair(string, typ), term))))))(body)
         Locale_Dependency(source, target, prefix, subst_types, subst_terms)
       })
 
 
   /* sort algebra */
 
   sealed case class Classrel(class1: String, class2: String, prop: Prop) {
     def cache(cache: Term.Cache): Classrel =
       Classrel(cache.string(class1), cache.string(class2), prop.cache(cache))
   }
 
   def read_classrel(provider: Export.Provider): List[Classrel] = {
     val body = provider.uncompressed_yxml(Export.THEORY_PREFIX + "classrel")
     val classrel = {
       import XML.Decode._
       list(pair(decode_prop, pair(string, string)))(body)
     }
     for ((prop, (c1, c2)) <- classrel) yield Classrel(c1, c2, prop)
   }
 
   sealed case class Arity(
     type_name: String,
     domain: List[Term.Sort],
     codomain: String,
     prop: Prop
   ) {
     def cache(cache: Term.Cache): Arity =
       Arity(cache.string(type_name), domain.map(cache.sort), cache.string(codomain),
         prop.cache(cache))
   }
 
   def read_arities(provider: Export.Provider): List[Arity] = {
     val body = provider.uncompressed_yxml(Export.THEORY_PREFIX + "arities")
     val arities = {
       import XML.Decode._
       import Term_XML.Decode._
       list(pair(decode_prop, triple(string, list(sort), string)))(body)
     }
     for ((prop, (a, b, c)) <- arities) yield Arity(a, b, c, prop)
   }
 
 
   /* Pure constdefs */
 
   sealed case class Constdef(name: String, axiom_name: String) {
     def cache(cache: Term.Cache): Constdef =
       Constdef(cache.string(name), cache.string(axiom_name))
   }
 
   def read_constdefs(provider: Export.Provider): List[Constdef] = {
     val body = provider.uncompressed_yxml(Export.THEORY_PREFIX + "constdefs")
     val constdefs = {
       import XML.Decode._
       list(pair(string, string))(body)
     }
     for ((name, axiom_name) <- constdefs) yield Constdef(name, axiom_name)
   }
 
 
   /* HOL typedefs */
 
   sealed case class Typedef(
     name: String,
     rep_type: Term.Typ,
     abs_type: Term.Typ,
     rep_name: String,
     abs_name: String,
     axiom_name: String
   ) {
     def cache(cache: Term.Cache): Typedef =
       Typedef(cache.string(name),
         cache.typ(rep_type),
         cache.typ(abs_type),
         cache.string(rep_name),
         cache.string(abs_name),
         cache.string(axiom_name))
   }
 
   def read_typedefs(provider: Export.Provider): List[Typedef] = {
     val body = provider.uncompressed_yxml(Export.THEORY_PREFIX + "typedefs")
     val typedefs = {
       import XML.Decode._
       import Term_XML.Decode._
       list(pair(string, pair(typ, pair(typ, pair(string, pair(string, string))))))(body)
     }
     for { (name, (rep_type, (abs_type, (rep_name, (abs_name, axiom_name))))) <- typedefs }
     yield Typedef(name, rep_type, abs_type, rep_name, abs_name, axiom_name)
   }
 
 
   /* HOL datatypes */
 
   sealed case class Datatype(
     pos: Position.T,
     name: String,
     co: Boolean,
     typargs: List[(String, Term.Sort)],
     typ: Term.Typ,
     constructors: List[(Term.Term, Term.Typ)]
   ) {
     def id: Option[Long] = Position.Id.unapply(pos)
 
     def cache(cache: Term.Cache): Datatype =
       Datatype(
         cache.position(pos),
         cache.string(name),
         co,
         typargs.map({ case (name, sort) => (cache.string(name), cache.sort(sort)) }),
         cache.typ(typ),
         constructors.map({ case (term, typ) => (cache.term(term), cache.typ(typ)) }))
   }
 
   def read_datatypes(provider: Export.Provider): List[Datatype] = {
     val body = provider.uncompressed_yxml(Export.THEORY_PREFIX + "datatypes")
     val datatypes = {
       import XML.Decode._
       import Term_XML.Decode._
       list(pair(properties, pair(string, pair(bool, pair(list(pair(string, sort)),
             pair(typ, list(pair(term, typ))))))))(body)
     }
     for ((pos, (name, (co, (typargs, (typ, constructors))))) <- datatypes)
       yield Datatype(pos, name, co, typargs, typ, constructors)
   }
 
 
   /* Pure spec rules */
 
   sealed abstract class Recursion {
     def cache(cache: Term.Cache): Recursion =
       this match {
         case Primrec(types) => Primrec(types.map(cache.string))
         case Primcorec(types) => Primcorec(types.map(cache.string))
         case _ => this
       }
   }
   case class Primrec(types: List[String]) extends Recursion
   case object Recdef extends Recursion
   case class Primcorec(types: List[String]) extends Recursion
   case object Corec extends Recursion
   case object Unknown_Recursion extends Recursion
 
   val decode_recursion: XML.Decode.T[Recursion] = {
     import XML.Decode._
     variant(List(
       { case (Nil, a) => Primrec(list(string)(a)) },
       { case (Nil, Nil) => Recdef },
       { case (Nil, a) => Primcorec(list(string)(a)) },
       { case (Nil, Nil) => Corec },
       { case (Nil, Nil) => Unknown_Recursion }))
   }
 
 
   sealed abstract class Rough_Classification {
     def is_equational: Boolean = this.isInstanceOf[Equational]
     def is_inductive: Boolean = this == Inductive
     def is_co_inductive: Boolean = this == Co_Inductive
     def is_relational: Boolean = is_inductive || is_co_inductive
     def is_unknown: Boolean = this == Unknown
 
     def cache(cache: Term.Cache): Rough_Classification =
       this match {
         case Equational(recursion) => Equational(recursion.cache(cache))
         case _ => this
       }
   }
   case class Equational(recursion: Recursion) extends Rough_Classification
   case object Inductive extends Rough_Classification
   case object Co_Inductive extends Rough_Classification
   case object Unknown extends Rough_Classification
 
   val decode_rough_classification: XML.Decode.T[Rough_Classification] = {
     import XML.Decode._
     variant(List(
       { case (Nil, a) => Equational(decode_recursion(a)) },
       { case (Nil, Nil) => Inductive },
       { case (Nil, Nil) => Co_Inductive },
       { case (Nil, Nil) => Unknown }))
   }
 
 
   sealed case class Spec_Rule(
     pos: Position.T,
     name: String,
     rough_classification: Rough_Classification,
     typargs: List[(String, Term.Sort)],
     args: List[(String, Term.Typ)],
     terms: List[(Term.Term, Term.Typ)],
     rules: List[Term.Term]
   ) {
     def id: Option[Long] = Position.Id.unapply(pos)
 
     def cache(cache: Term.Cache): Spec_Rule =
       Spec_Rule(
         cache.position(pos),
         cache.string(name),
         rough_classification.cache(cache),
         typargs.map({ case (name, sort) => (cache.string(name), cache.sort(sort)) }),
         args.map({ case (name, typ) => (cache.string(name), cache.typ(typ)) }),
         terms.map({ case (term, typ) => (cache.term(term), cache.typ(typ)) }),
         rules.map(cache.term))
   }
 
   def read_spec_rules(provider: Export.Provider): List[Spec_Rule] = {
     val body = provider.uncompressed_yxml(Export.THEORY_PREFIX + "spec_rules")
     val spec_rules = {
       import XML.Decode._
       import Term_XML.Decode._
       list(
         pair(properties, pair(string, pair(decode_rough_classification,
           pair(list(pair(string, sort)), pair(list(pair(string, typ)),
             pair(list(pair(term, typ)), list(term))))))))(body)
     }
     for ((pos, (name, (rough_classification, (typargs, (args, (terms, rules)))))) <- spec_rules)
       yield Spec_Rule(pos, name, rough_classification, typargs, args, terms, rules)
   }
 
 
   /* other entities */
 
   sealed case class Other() extends Content[Other] {
     override def cache(cache: Term.Cache): Other = this
   }
 
   def read_others(provider: Export.Provider): Map[String, List[Entity[Other]]] = {
     val kinds =
       provider(Export.THEORY_PREFIX + "other_kinds") match {
         case Some(entry) => split_lines(entry.uncompressed.text)
         case None => Nil
       }
     val other = Other()
     def read_other(kind: String): List[Entity[Other]] =
       read_entities(provider, Export.THEORY_PREFIX + "other/" + kind, kind, _ => other)
 
     kinds.map(kind => kind -> read_other(kind)).toMap
   }
 }
diff --git a/src/Pure/library.ML b/src/Pure/library.ML
--- a/src/Pure/library.ML
+++ b/src/Pure/library.ML
@@ -1,1110 +1,1113 @@
 (*  Title:      Pure/library.ML
     Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
     Author:     Markus Wenzel, TU Muenchen
 
 Basic library: functions, pairs, booleans, lists, integers,
 strings, lists as sets, orders, current directory, misc.
 
 See also General/basics.ML for the most fundamental concepts.
 *)
 
 infixr 0 |||
 infix 2 ?
 infix 3 o oo ooo oooo
 infix 4 ~~ upto downto
 infix orf andf
 
 signature BASIC_LIBRARY =
 sig
   (*functions*)
   val undefined: 'a -> 'b
   val I: 'a -> 'a
   val K: 'a -> 'b -> 'a
   val curry: ('a * 'b -> 'c) -> 'a -> 'b -> 'c
   val uncurry: ('a -> 'b -> 'c) -> 'a * 'b -> 'c
   val ? : bool * ('a -> 'a) -> 'a -> 'a
   val oo: ('a -> 'b) * ('c -> 'd -> 'a) -> 'c -> 'd -> 'b
   val ooo: ('a -> 'b) * ('c -> 'd -> 'e -> 'a) -> 'c -> 'd -> 'e -> 'b
   val oooo: ('a -> 'b) * ('c -> 'd -> 'e -> 'f -> 'a) -> 'c -> 'd -> 'e -> 'f -> 'b
   val funpow: int -> ('a -> 'a) -> 'a -> 'a
   val funpow_yield: int -> ('a -> 'b * 'a) -> 'a -> 'b list * 'a
 
   (*pairs*)
   val pair: 'a -> 'b -> 'a * 'b
   val rpair: 'a -> 'b -> 'b * 'a
   val fst: 'a * 'b -> 'a
   val snd: 'a * 'b -> 'b
   val eq_fst: ('a * 'c -> bool) -> ('a * 'b) * ('c * 'd) -> bool
   val eq_snd: ('b * 'd -> bool) -> ('a * 'b) * ('c * 'd) -> bool
   val eq_pair: ('a * 'c -> bool) -> ('b * 'd -> bool) -> ('a * 'b) * ('c * 'd) -> bool
   val swap: 'a * 'b -> 'b * 'a
   val apfst: ('a -> 'b) -> 'a * 'c -> 'b * 'c
   val apsnd: ('a -> 'b) -> 'c * 'a -> 'c * 'b
   val apply2: ('a -> 'b) -> 'a * 'a -> 'b * 'b
 
   (*booleans*)
   val equal: ''a -> ''a -> bool
   val not_equal: ''a -> ''a -> bool
   val orf: ('a -> bool) * ('a -> bool) -> 'a -> bool
   val andf: ('a -> bool) * ('a -> bool) -> 'a -> bool
   val exists: ('a -> bool) -> 'a list -> bool
   val forall: ('a -> bool) -> 'a list -> bool
 
   (*lists*)
   val build: ('a list -> 'a list) -> 'a list
   val build_rev: ('a list -> 'a list) -> 'a list
   val single: 'a -> 'a list
   val the_single: 'a list -> 'a
   val singleton: ('a list -> 'b list) -> 'a -> 'b
   val yield_singleton: ('a list -> 'c -> 'b list * 'c) -> 'a -> 'c -> 'b * 'c
   val perhaps_apply: ('a -> 'a option) list -> 'a -> 'a option
   val perhaps_loop: ('a -> 'a option) -> 'a -> 'a option
   val foldl1: ('a * 'a -> 'a) -> 'a list -> 'a
   val foldr1: ('a * 'a -> 'a) -> 'a list -> 'a
   val eq_list: ('a * 'a -> bool) -> 'a list * 'a list -> bool
   val maps: ('a -> 'b list) -> 'a list -> 'b list
   val filter: ('a -> bool) -> 'a list -> 'a list
   val filter_out: ('a -> bool) -> 'a list -> 'a list
   val map_filter: ('a -> 'b option) -> 'a list -> 'b list
   val take: int -> 'a list -> 'a list
   val drop: int -> 'a list -> 'a list
   val chop: int -> 'a list -> 'a list * 'a list
   val chop_groups: int -> 'a list -> 'a list list
   val nth: 'a list -> int -> 'a
   val nth_list: 'a list list -> int -> 'a list
   val nth_map: int -> ('a -> 'a) -> 'a list -> 'a list
   val nth_drop: int -> 'a list -> 'a list
   val map_index: (int * 'a -> 'b) -> 'a list -> 'b list
   val fold_index: (int * 'a -> 'b -> 'b) -> 'a list -> 'b -> 'b
   val map_range: (int -> 'a) -> int -> 'a list
   val fold_range: (int -> 'a -> 'a) -> int -> 'a -> 'a
   val split_last: 'a list -> 'a list * 'a
   val find_first: ('a -> bool) -> 'a list -> 'a option
   val find_index: ('a -> bool) -> 'a list -> int
   val get_first: ('a -> 'b option) -> 'a list -> 'b option
   val get_index: ('a -> 'b option) -> 'a list -> (int * 'b) option
   val flat: 'a list list -> 'a list
   val unflat: 'a list list -> 'b list -> 'b list list
   val grouped: int -> (('a list -> 'b list) -> 'c list list -> 'd list list) ->
     ('a -> 'b) -> 'c list -> 'd list
   val burrow: ('a list -> 'b list) -> 'a list list -> 'b list list
   val burrow_options: ('a list -> 'b list) -> 'a option list -> 'b option list
   val fold_burrow: ('a list -> 'c -> 'b list * 'd) -> 'a list list -> 'c -> 'b list list * 'd
   val separate: 'a -> 'a list -> 'a list
   val surround: 'a -> 'a list -> 'a list
   val replicate: int -> 'a -> 'a list
   val map_product: ('a -> 'b -> 'c) -> 'a list -> 'b list -> 'c list
   val fold_product: ('a -> 'b -> 'c -> 'c) -> 'a list -> 'b list -> 'c -> 'c
   val map2: ('a -> 'b -> 'c) -> 'a list -> 'b list -> 'c list
   val fold2: ('a -> 'b -> 'c -> 'c) -> 'a list -> 'b list -> 'c -> 'c
   val map_split: ('a -> 'b * 'c) -> 'a list -> 'b list * 'c list
   val zip_options: 'a list -> 'b option list -> ('a * 'b) list
   val ~~ : 'a list * 'b list -> ('a * 'b) list
   val split_list: ('a * 'b) list -> 'a list * 'b list
   val burrow_fst: ('a list -> 'b list) -> ('a * 'c) list -> ('b * 'c) list
   val take_prefix: ('a -> bool) -> 'a list -> 'a list
   val drop_prefix: ('a -> bool) -> 'a list -> 'a list
   val chop_prefix: ('a -> bool) -> 'a list -> 'a list * 'a list
   val take_suffix: ('a -> bool) -> 'a list -> 'a list
   val drop_suffix: ('a -> bool) -> 'a list -> 'a list
   val chop_suffix: ('a -> bool) -> 'a list -> 'a list * 'a list
   val is_prefix: ('a * 'a -> bool) -> 'a list -> 'a list -> bool
   val chop_common_prefix: ('a * 'b -> bool) -> 'a list * 'b list -> 'a list * ('a list * 'b list)
   val prefixes1: 'a list -> 'a list list
   val prefixes: 'a list -> 'a list list
   val suffixes1: 'a list -> 'a list list
   val suffixes: 'a list -> 'a list list
   val trim: ('a -> bool) -> 'a list -> 'a list
 
   (*integers*)
   val upto: int * int -> int list
   val downto: int * int -> int list
   val hex_digit: int -> string
   val radixpand: int * int -> int list
   val radixstring: int * string * int -> string
   val string_of_int: int -> string
   val signed_string_of_int: int -> string
   val string_of_indexname: string * int -> string
   val read_radix_int: int -> string list -> int * string list
   val read_int: string list -> int * string list
   val oct_char: string -> string
 
   (*strings*)
   val nth_string: string -> int -> string
   val fold_string: (string -> 'a -> 'a) -> string -> 'a -> 'a
   val exists_string: (string -> bool) -> string -> bool
   val forall_string: (string -> bool) -> string -> bool
   val member_string: string -> string -> bool
   val last_string: string -> string option
   val first_field: string -> string -> (string * string) option
   val enclose: string -> string -> string -> string
   val unenclose: string -> string
   val quote: string -> string
   val cartouche: string -> string
   val space_implode: string -> string list -> string
   val commas: string list -> string
   val commas_quote: string list -> string
   val cat_lines: string list -> string
+  val terminate_lines: string list -> string
   val space_explode: string -> string -> string list
   val split_lines: string -> string list
   val plain_words: string -> string
   val prefix_lines: string -> string -> string
   val prefix: string -> string -> string
   val suffix: string -> string -> string
   val unprefix: string -> string -> string
   val unsuffix: string -> string -> string
   val trim_line: string -> string
   val trim_split_lines: string -> string list
   val normalize_lines: string -> string
   val replicate_string: int -> string -> string
   val translate_string: (string -> string) -> string -> string
   val encode_lines: string -> string
   val decode_lines: string -> string
   val align_right: string -> int -> string -> string
   val match_string: string -> string -> bool
 
   (*reals*)
   val string_of_real: real -> string
   val signed_string_of_real: real -> string
 
   (*lists as sets -- see also Pure/General/ord_list.ML*)
   val member: ('b * 'a -> bool) -> 'a list -> 'b -> bool
   val insert: ('a * 'a -> bool) -> 'a -> 'a list -> 'a list
   val remove: ('b * 'a -> bool) -> 'b -> 'a list -> 'a list
   val update: ('a * 'a -> bool) -> 'a -> 'a list -> 'a list
   val union: ('a * 'a -> bool) -> 'a list -> 'a list -> 'a list
   val subtract: ('b * 'a -> bool) -> 'b list -> 'a list -> 'a list
   val inter: ('a * 'b -> bool) -> 'b list -> 'a list -> 'a list
   val merge: ('a * 'a -> bool) -> 'a list * 'a list -> 'a list
   val subset: ('a * 'b -> bool) -> 'a list * 'b list -> bool
   val eq_set: ('a * 'a -> bool) -> 'a list * 'a list -> bool
   val distinct: ('a * 'a -> bool) -> 'a list -> 'a list
   val duplicates: ('a * 'a -> bool) -> 'a list -> 'a list
   val has_duplicates: ('a * 'a -> bool) -> 'a list -> bool
   val map_transpose: ('a list -> 'b) -> 'a list list -> 'b list
 
   (*lists as multisets*)
   val remove1: ('b * 'a -> bool) -> 'b -> 'a list -> 'a list
   val combine: ('a * 'a -> bool) -> 'a list -> 'a list -> 'a list
   val submultiset: ('a * 'b -> bool) -> 'a list * 'b list -> bool
 
   (*orders*)
   type 'a ord = 'a * 'a -> order
   val is_equal: order -> bool
   val is_less: order -> bool
   val is_less_equal: order -> bool
   val is_greater: order -> bool
   val is_greater_equal: order -> bool
   val rev_order: order -> order
   val make_ord: ('a * 'a -> bool) -> 'a ord
   val pointer_eq_ord: ('a * 'a -> order) -> 'a * 'a -> order
   val bool_ord: bool ord
   val int_ord: int ord
   val string_ord: string ord
   val size_ord: string ord
   val fast_string_ord: string ord
   val option_ord: ('a * 'b -> order) -> 'a option * 'b option -> order
   val ||| : ('a -> order) * ('a -> order) -> 'a -> order
   val prod_ord: ('a * 'b -> order) -> ('c * 'd -> order) -> ('a * 'c) * ('b * 'd) -> order
   val dict_ord: ('a * 'b -> order) -> 'a list * 'b list -> order
   val length_ord: 'a list * 'b list -> order
   val list_ord: ('a * 'b -> order) -> 'a list * 'b list -> order
   val sort: 'a ord -> 'a list -> 'a list
   val sort_distinct: 'a ord -> 'a list -> 'a list
   val sort_strings: string list -> string list
   val sort_by: ('a -> string) -> 'a list -> 'a list
   val tag_list: int -> 'a list -> (int * 'a) list
   val untag_list: (int * 'a) list -> 'a list
   val order_list: (int * 'a) list -> 'a list
 
   (*misc*)
   val divide_and_conquer: ('a -> 'a list * ('b list -> 'b)) -> 'a -> 'b
   val divide_and_conquer': ('a -> 'b -> ('a list * ('c list * 'b -> 'c * 'b)) * 'b) ->
     'a -> 'b -> 'c * 'b
   val partition_eq: ('a * 'a -> bool) -> 'a list -> 'a list list
   val partition_list: (int -> 'a -> bool) -> int -> int -> 'a list -> 'a list list
   type serial = int
   val serial: unit -> serial
   val serial_string: unit -> string
   eqtype stamp
   val stamp: unit -> stamp
   structure Any: sig type T = exn end
   val getenv: string -> string
   val getenv_strict: string -> string
 end;
 
 signature LIBRARY =
 sig
   include BASIC_LIBRARY
   val foldl: ('a * 'b -> 'a) -> 'a * 'b list -> 'a
   val foldr: ('a * 'b -> 'b) -> 'a list * 'b -> 'b
 end;
 
 structure Library: LIBRARY =
 struct
 
 (* functions *)
 
 fun undefined _ = raise Match;
 
 fun I x = x;
 fun K x = fn _ => x;
 fun curry f x y = f (x, y);
 fun uncurry f (x, y) = f x y;
 
 (*conditional application*)
 fun b ? f = fn x => if b then f x else x;
 
 (*composition with multiple args*)
 fun (f oo g) x y = f (g x y);
 fun (f ooo g) x y z = f (g x y z);
 fun (f oooo g) x y z w = f (g x y z w);
 
 (*function exponentiation: f (... (f x) ...) with n applications of f*)
 fun funpow (0: int) _ x = x
   | funpow n f x = funpow (n - 1) f (f x);
 
 fun funpow_yield (0 : int) _ x = ([], x)
   | funpow_yield n f x = x |> f ||>> funpow_yield (n - 1) f |>> op ::;
 
 
 (* pairs *)
 
 fun pair x y = (x, y);
 fun rpair x y = (y, x);
 
 fun fst (x, y) = x;
 fun snd (x, y) = y;
 
 fun eq_fst eq ((x1, _), (x2, _)) = eq (x1, x2);
 fun eq_snd eq ((_, y1), (_, y2)) = eq (y1, y2);
 fun eq_pair eqx eqy ((x1, y1), (x2, y2)) = eqx (x1, x2) andalso eqy (y1, y2);
 
 fun swap (x, y) = (y, x);
 
 fun apfst f (x, y) = (f x, y);
 fun apsnd f (x, y) = (x, f y);
 fun apply2 f (x, y) = (f x, f y);
 
 
 (* booleans *)
 
 (*polymorphic equality*)
 fun equal x y = x = y;
 fun not_equal x y = x <> y;
 
 (*combining predicates*)
 fun p orf q = fn x => p x orelse q x;
 fun p andf q = fn x => p x andalso q x;
 
 val exists = List.exists;
 val forall = List.all;
 
 
 
 (** lists **)
 
 fun build (f: 'a list -> 'a list) = f [];
 fun build_rev f = build f |> rev;
 
 fun single x = [x];
 
 fun the_single [x] = x
   | the_single _ = raise List.Empty;
 
 fun singleton f x = the_single (f [x]);
 
 fun yield_singleton f x = f [x] #>> the_single;
 
 fun perhaps_apply funs arg =
   let
     fun app [] res = res
       | app (f :: fs) (changed, x) =
           (case f x of
             NONE => app fs (changed, x)
           | SOME x' => app fs (true, x'));
   in (case app funs (false, arg) of (false, _) => NONE | (true, arg') => SOME arg') end;
 
 fun perhaps_loop f arg =
   let
     fun loop (changed, x) =
       (case f x of
         NONE => (changed, x)
       | SOME x' => loop (true, x'));
   in (case loop (false, arg) of (false, _) => NONE | (true, arg') => SOME arg') end;
 
 
 (* fold -- old versions *)
 
 (*the following versions of fold are designed to fit nicely with infixes*)
 
 (*  (op @) (e, [x1, ..., xn])  ===>  ((e @ x1) @ x2) ... @ xn
     for operators that associate to the left (TAIL RECURSIVE)*)
 fun foldl (f: 'a * 'b -> 'a) : 'a * 'b list -> 'a =
   let fun itl (e, [])  = e
         | itl (e, a::l) = itl (f(e, a), l)
   in  itl end;
 
 (*  (op @) ([x1, ..., xn], e)  ===>   x1 @ (x2 ... @ (xn @ e))
     for operators that associate to the right (not tail recursive)*)
 fun foldr f (l, e) =
   let fun itr [] = e
         | itr (a::l) = f(a, itr l)
   in  itr l  end;
 
 (*  (op @) [x1, ..., xn]  ===>  ((x1 @ x2) @ x3) ... @ xn
     for operators that associate to the left (TAIL RECURSIVE)*)
 fun foldl1 f [] = raise List.Empty
   | foldl1 f (x :: xs) = foldl f (x, xs);
 
 (*  (op @) [x1, ..., xn]  ===>   x1 @ (x2 ... @ (x[n-1] @ xn))
     for n > 0, operators that associate to the right (not tail recursive)*)
 fun foldr1 f [] = raise List.Empty
   | foldr1 f l =
       let fun itr [x] = x
             | itr (x::l) = f(x, itr l)
       in  itr l  end;
 
 
 (* basic list functions *)
 
 fun eq_list eq (list1, list2) =
   pointer_eq (list1, list2) orelse
     let
       fun eq_lst (x :: xs, y :: ys) = eq (x, y) andalso eq_lst (xs, ys)
         | eq_lst _ = true;
     in length list1 = length list2 andalso eq_lst (list1, list2) end;
 
 fun maps f [] = []
   | maps f (x :: xs) = f x @ maps f xs;
 
 val filter = List.filter;
 fun filter_out f = filter (not o f);
 val map_filter = List.mapPartial;
 
 fun take (0: int) xs = []
   | take _ [] = []
   | take n (x :: xs) = x :: take (n - 1) xs;
 
 fun drop (0: int) xs = xs
   | drop _ [] = []
   | drop n (x :: xs) = drop (n - 1) xs;
 
 fun chop (0: int) xs = ([], xs)
   | chop _ [] = ([], [])
   | chop n (x :: xs) = chop (n - 1) xs |>> cons x;
 
 fun chop_groups n list =
   (case chop (Int.max (n, 1)) list of
     ([], _) => []
   | (g, rest) => g :: chop_groups n rest);
 
 
 (*return nth element of a list, where 0 designates the first element;
   raise Subscript if list too short*)
 fun nth xs i = List.nth (xs, i);
 
 fun nth_list xss i = nth xss i handle General.Subscript => [];
 
 fun nth_map 0 f (x :: xs) = f x :: xs
   | nth_map n f (x :: xs) = x :: nth_map (n - 1) f xs
   | nth_map (_: int) _ [] = raise Subscript;
 
 fun nth_drop n xs =
   List.take (xs, n) @ List.drop (xs, n + 1);
 
 fun map_index f =
   let
     fun map_aux (_: int) [] = []
       | map_aux i (x :: xs) = f (i, x) :: map_aux (i + 1) xs
   in map_aux 0 end;
 
 fun fold_index f =
   let
     fun fold_aux (_: int) [] y = y
       | fold_aux i (x :: xs) y = fold_aux (i + 1) xs (f (i, x) y)
   in fold_aux 0 end;
 
 fun map_range f i =
   let
     fun map_aux (k: int) =
       if k < i then f k :: map_aux (k + 1) else []
   in map_aux 0 end;
 
 fun fold_range f i =
   let
     fun fold_aux (k: int) y =
       if k < i then fold_aux (k + 1) (f k y) else y
   in fold_aux 0 end;
 
 
 (*rear decomposition*)
 fun split_last [] = raise List.Empty
   | split_last [x] = ([], x)
   | split_last (x :: xs) = apfst (cons x) (split_last xs);
 
 (*find first element satisfying predicate*)
 val find_first = List.find;
 
 (*find position of first element satisfying a predicate*)
 fun find_index pred =
   let fun find (_: int) [] = ~1
         | find n (x :: xs) = if pred x then n else find (n + 1) xs;
   in find 0 end;
 
 (*get first element by lookup function*)
 fun get_first _ [] = NONE
   | get_first f (x :: xs) =
       (case f x of
         NONE => get_first f xs
       | some => some);
 
 fun get_index f =
   let
     fun get_aux (_: int) [] = NONE
       | get_aux i (x :: xs) =
           (case f x of
             NONE => get_aux (i + 1) xs
           | SOME y => SOME (i, y))
   in get_aux 0 end;
 
 val flat = List.concat;
 
 fun unflat (xs :: xss) ys =
       let val (ps, qs) = chop (length xs) ys
       in ps :: unflat xss qs end
   | unflat [] [] = []
   | unflat _ _ = raise ListPair.UnequalLengths;
 
 fun grouped n comb f = chop_groups n #> comb (map f) #> flat;
 
 fun burrow f xss = unflat xss (f (flat xss));
 
 fun burrow_options f os = map (try hd) (burrow f (map the_list os));
 
 fun fold_burrow f xss s =
   apfst (unflat xss) (f (flat xss) s);
 
 (*separate s [x1, x2, ..., xn]  ===>  [x1, s, x2, s, ..., s, xn]*)
 fun separate s (x :: (xs as _ :: _)) = x :: s :: separate s xs
   | separate _ xs = xs;
 
 fun surround s (x :: xs) = s :: x :: surround s xs
   | surround s [] = [s];
 
 (*make the list [x, x, ..., x] of length n*)
 fun replicate (n: int) x =
   let fun rep (0, xs) = xs
         | rep (n, xs) = rep (n - 1, x :: xs)
   in
     if n < 0 then raise Subscript
     else rep (n, [])
   end;
 
 
 (* direct product *)
 
 fun map_product f _ [] = []
   | map_product f [] _ = []
   | map_product f (x :: xs) ys = map (f x) ys @ map_product f xs ys;
 
 fun fold_product f _ [] z = z
   | fold_product f [] _ z = z
   | fold_product f (x :: xs) ys z = z |> fold (f x) ys |> fold_product f xs ys;
 
 
 (* lists of pairs *)
 
 fun map2 _ [] [] = []
   | map2 f (x :: xs) (y :: ys) = f x y :: map2 f xs ys
   | map2 _ _ _ = raise ListPair.UnequalLengths;
 
 fun fold2 _ [] [] z = z
   | fold2 f (x :: xs) (y :: ys) z = fold2 f xs ys (f x y z)
   | fold2 _ _ _ _ = raise ListPair.UnequalLengths;
 
 fun map_split _ [] = ([], [])
   | map_split f (x :: xs) =
       let
         val (y, w) = f x;
         val (ys, ws) = map_split f xs;
       in (y :: ys, w :: ws) end;
 
 fun zip_options (x :: xs) (SOME y :: ys) = (x, y) :: zip_options xs ys
   | zip_options (_ :: xs) (NONE :: ys) = zip_options xs ys
   | zip_options _ [] = []
   | zip_options [] _ = raise ListPair.UnequalLengths;
 
 (*combine two lists forming a list of pairs:
   [x1, ..., xn] ~~ [y1, ..., yn]  ===>  [(x1, y1), ..., (xn, yn)]*)
 fun [] ~~ [] = []
   | (x :: xs) ~~ (y :: ys) = (x, y) :: (xs ~~ ys)
   | _ ~~ _ = raise ListPair.UnequalLengths;
 
 (*inverse of ~~; the old 'split':
   [(x1, y1), ..., (xn, yn)]  ===>  ([x1, ..., xn], [y1, ..., yn])*)
 val split_list = ListPair.unzip;
 
 fun burrow_fst f xs = split_list xs |>> f |> op ~~;
 
 
 (* take, drop, chop, trim according to predicate *)
 
 fun take_prefix pred list =
   let
     fun take res (x :: xs) = if pred x then take (x :: res) xs else rev res
       | take res [] = rev res;
   in take [] list end;
 
 fun drop_prefix pred list =
   let
     fun drop (x :: xs) = if pred x then drop xs else x :: xs
       | drop [] = [];
   in drop list end;
 
 fun chop_prefix pred list =
   let
     val prfx = take_prefix pred list;
     val sffx = drop (length prfx) list;
   in (prfx, sffx) end;
 
 fun take_suffix pred list =
   let
     fun take res (x :: xs) = if pred x then take (x :: res) xs else res
       | take res [] = res;
   in take [] (rev list) end;
 
 fun drop_suffix pred list =
   let
     fun drop (x :: xs) = if pred x then drop xs else rev (x :: xs)
       | drop [] = [];
   in drop (rev list) end;
 
 fun chop_suffix pred list =
   let
     val prfx = drop_suffix pred list;
     val sffx = drop (length prfx) list;
   in (prfx, sffx) end;
 
 fun trim pred = drop_prefix pred #> drop_suffix pred;
 
 
 (* prefixes, suffixes *)
 
 fun is_prefix _ [] _ = true
   | is_prefix eq (x :: xs) (y :: ys) = eq (x, y) andalso is_prefix eq xs ys
   | is_prefix eq _ _ = false;
 
 fun chop_common_prefix eq ([], ys) = ([], ([], ys))
   | chop_common_prefix eq (xs, []) = ([], (xs, []))
   | chop_common_prefix eq (xs as x :: xs', ys as y :: ys') =
       if eq (x, y) then
         let val (ps', xys'') = chop_common_prefix eq (xs', ys')
         in (x :: ps', xys'') end
       else ([], (xs, ys));
 
 fun prefixes1 [] = []
   | prefixes1 (x :: xs) = map (cons x) ([] :: prefixes1 xs);
 
 fun prefixes xs = [] :: prefixes1 xs;
 
 fun suffixes1 xs = map rev (prefixes1 (rev xs));
 fun suffixes xs = [] :: suffixes1 xs;
 
 
 
 (** integers **)
 
 (* lists of integers *)
 
 (*make the list [from, from + 1, ..., to]*)
 fun ((i: int) upto j) =
   if i > j then [] else i :: (i + 1 upto j);
 
 (*make the list [from, from - 1, ..., to]*)
 fun ((i: int) downto j) =
   if i < j then [] else i :: (i - 1 downto j);
 
 
 (* convert integers to strings *)
 
 (*hexadecimal*)
 fun hex_digit i =
   if i < 10 then chr (Char.ord #"0" + i) else chr (Char.ord #"a" + i - 10);
 
 (*expand the number in the given base;
   example: radixpand (2, 8) gives [1, 0, 0, 0]*)
 fun radixpand (base, num) : int list =
   let
     fun radix (n, tail) =
       if n < base then n :: tail
       else radix (n div base, (n mod base) :: tail)
   in radix (num, []) end;
 
 (*expands a number into a string of characters starting from "zerochar";
   example: radixstring (2, "0", 8) gives "1000"*)
 fun radixstring (base, zerochar, num) =
   let val offset = ord zerochar;
       fun chrof n = chr (offset + n)
   in implode (map chrof (radixpand (base, num))) end;
 
 
 local
   val zero = Char.ord #"0";
   val small_int = 10000: int;
   val small_int_table = Vector.tabulate (small_int, Int.toString);
 in
 
 fun string_of_int i =
   if i < 0 then Int.toString i
   else if i < 10 then chr (zero + i)
   else if i < small_int then Vector.sub (small_int_table, i)
   else Int.toString i;
 
 end;
 
 fun signed_string_of_int i =
   if i < 0 then "-" ^ string_of_int (~ i) else string_of_int i;
 
 fun string_of_indexname (a, 0) = a
   | string_of_indexname (a, i) = a ^ "_" ^ string_of_int i;
 
 
 (* read integers *)
 
 fun read_radix_int radix cs =
   let
     val zero = Char.ord #"0";
     val limit = zero + radix;
     fun scan (num, []) = (num, [])
       | scan (num, c :: cs) =
           if zero <= ord c andalso ord c < limit then
             scan (radix * num + (ord c - zero), cs)
           else (num, c :: cs);
   in scan (0, cs) end;
 
 val read_int = read_radix_int 10;
 
 fun oct_char s = chr (#1 (read_radix_int 8 (raw_explode s)));
 
 
 
 (** strings **)
 
 (* functions tuned for strings, avoiding explode *)
 
 fun nth_string str i =
   (case try String.substring (str, i, 1) of
     SOME s => s
   | NONE => raise Subscript);
 
 fun fold_string f str x0 =
   let
     val n = size str;
     fun iter (x, i) =
       if i < n then iter (f (String.substring (str, i, 1)) x, i + 1) else x;
   in iter (x0, 0) end;
 
 fun exists_string pred str =
   let
     val n = size str;
     fun ex i = i < n andalso (pred (String.substring (str, i, 1)) orelse ex (i + 1));
   in ex 0 end;
 
 fun forall_string pred = not o exists_string (not o pred);
 
 fun member_string str s = exists_string (fn s' => s = s') str;
 
 fun last_string "" = NONE
   | last_string s = SOME (str (String.sub (s, size s - 1)));
 
 fun first_field sep str =
   let
     val n = size sep;
     val len = size str;
     fun find i =
       if i + n > len then NONE
       else if String.substring (str, i, n) = sep then SOME i
       else find (i + 1);
   in
     (case find 0 of
       NONE => NONE
     | SOME i => SOME (String.substring (str, 0, i), String.extract (str, i + n, NONE)))
   end;
 
 (*enclose in brackets*)
 fun enclose lpar rpar str = lpar ^ str ^ rpar;
 fun unenclose str = String.substring (str, 1, size str - 2);
 
 (*simple quoting (does not escape special chars)*)
 val quote = enclose "\"" "\"";
 
 val cartouche = enclose "\<open>" "\<close>";
 
 val space_implode = String.concatWith;
 
 val commas = space_implode ", ";
 val commas_quote = commas o map quote;
 
 val cat_lines = space_implode "\n";
 
+fun terminate_lines lines = cat_lines lines ^ "\n";
+
 (*space_explode "." "h.e..l.lo" = ["h", "e", "", "l", "lo"]*)
 fun space_explode _ "" = []
   | space_explode sep s = String.fields (fn c => str c = sep) s;
 
 val split_lines = space_explode "\n";
 
 fun plain_words s = space_explode "_" s |> space_implode " ";
 
 fun prefix_lines "" txt = txt
   | prefix_lines prfx txt = txt |> split_lines |> map (fn s => prfx ^ s) |> cat_lines;
 
 fun prefix prfx s = prfx ^ s;
 fun suffix sffx s = s ^ sffx;
 
 fun unprefix prfx s =
   if String.isPrefix prfx s then String.substring (s, size prfx, size s - size prfx)
   else raise Fail "unprefix";
 
 fun unsuffix sffx s =
   if String.isSuffix sffx s then String.substring (s, 0, size s - size sffx)
   else raise Fail "unsuffix";
 
 fun trim_line s =
   if String.isSuffix "\r\n" s
   then String.substring (s, 0, size s - 2)
   else if String.isSuffix "\r" s orelse String.isSuffix "\n" s
   then String.substring (s, 0, size s - 1)
   else s;
 
 val trim_split_lines = trim_line #> split_lines #> map trim_line;
 
 fun normalize_lines str =
   if exists_string (fn s => s = "\r") str then
     split_lines str |> map trim_line |> cat_lines
   else str;
 
 fun replicate_string (0: int) _ = ""
   | replicate_string 1 a = a
   | replicate_string k a =
       if k mod 2 = 0 then replicate_string (k div 2) (a ^ a)
       else replicate_string (k div 2) (a ^ a) ^ a;
 
 fun translate_string f = String.translate (f o String.str);
 
 val encode_lines = translate_string (fn "\n" => "\v" | c => c);
 val decode_lines = translate_string (fn "\v" => "\n" | c => c);
 
 fun align_right c k s =
   let
     val _ = if size c <> 1 orelse size s > k
       then raise Fail "align_right" else ()
   in replicate_string (k - size s) c ^ s end;
 
 (*crude matching of str against simple glob pat*)
 fun match_string pat str =
   let
     fun match [] _ = true
       | match (p :: ps) s =
           size p <= size s andalso
             (case try (unprefix p) s of
               SOME s' => match ps s'
             | NONE => match (p :: ps) (String.substring (s, 1, size s - 1)));
   in match (space_explode "*" pat) str end;
 
 
 
 (** reals **)
 
 val string_of_real = Real.fmt (StringCvt.GEN NONE);
 
 fun signed_string_of_real x =
   if x < 0.0 then "-" ^ string_of_real (~ x) else string_of_real x;
 
 
 
 (** lists as sets -- see also Pure/General/ord_list.ML **)
 
 (* canonical operations *)
 
 fun member eq list x =
   let
     fun memb [] = false
       | memb (y :: ys) = eq (x, y) orelse memb ys;
   in memb list end;
 
 fun insert eq x xs = if member eq xs x then xs else x :: xs;
 fun remove eq x xs = if member eq xs x then filter_out (fn y => eq (x, y)) xs else xs;
 fun update eq x xs = cons x (remove eq x xs);
 
 fun inter eq xs = filter (member eq xs);
 
 fun union eq = fold (insert eq);
 fun subtract eq = fold (remove eq);
 
 fun merge eq (xs, ys) =
   if pointer_eq (xs, ys) then xs
   else if null xs then ys
   else fold_rev (insert eq) ys xs;
 
 
 (* subset and set equality *)
 
 fun subset eq (xs, ys) = forall (member eq ys) xs;
 
 fun eq_set eq (xs, ys) =
   eq_list eq (xs, ys) orelse
     (subset eq (xs, ys) andalso subset (eq o swap) (ys, xs));
 
 
 (*makes a list of the distinct members of the input; preserves order, takes
   first of equal elements*)
 fun distinct eq lst =
   let
     fun dist (rev_seen, []) = rev rev_seen
       | dist (rev_seen, x :: xs) =
           if member eq rev_seen x then dist (rev_seen, xs)
           else dist (x :: rev_seen, xs);
   in dist ([], lst) end;
 
 (*returns a list containing all repeated elements exactly once; preserves
   order, takes first of equal elements*)
 fun duplicates eq lst =
   let
     fun dups (rev_dups, []) = rev rev_dups
       | dups (rev_dups, x :: xs) =
           if member eq rev_dups x orelse not (member eq xs x) then
             dups (rev_dups, xs)
           else dups (x :: rev_dups, xs);
   in dups ([], lst) end;
 
 fun has_duplicates eq =
   let
     fun dups [] = false
       | dups (x :: xs) = member eq xs x orelse dups xs;
   in dups end;
 
 
 (* matrices *)
 
 fun map_transpose f xss =
   let
     val n =
       (case distinct (op =) (map length xss) of
         [] => 0
       | [n] => n
       | _ => raise ListPair.UnequalLengths);
   in map_range (fn m => f (map (fn xs => nth xs m) xss)) n end;
 
 
 
 (** lists as multisets **)
 
 fun remove1 eq x [] = []
   | remove1 eq x (y :: ys) = if eq (x, y) then ys else y :: remove1 eq x ys;
 
 fun combine eq xs ys = fold (remove1 eq) ys xs @ ys;
 
 fun submultiset _ ([], _)  = true
   | submultiset eq (x :: xs, ys) = member eq ys x andalso submultiset eq (xs, remove1 eq x ys);
 
 
 
 (** orders **)
 
 type 'a ord = 'a * 'a -> order;
 
 fun is_equal ord = ord = EQUAL;
 fun is_less ord = ord = LESS;
 fun is_less_equal ord = ord = LESS orelse ord = EQUAL;
 fun is_greater ord = ord = GREATER;
 fun is_greater_equal ord = ord = GREATER orelse ord = EQUAL;
 
 fun rev_order LESS = GREATER
   | rev_order EQUAL = EQUAL
   | rev_order GREATER = LESS;
 
 (*compose orders*)
 fun (a_ord ||| b_ord) p = (case a_ord p of EQUAL => b_ord p | ord => ord);
 
 (*assume rel is a linear strict order*)
 fun make_ord rel (x, y) =
   if rel (x, y) then LESS
   else if rel (y, x) then GREATER
   else EQUAL;
 
 fun pointer_eq_ord ord (x, y) =
   if pointer_eq (x, y) then EQUAL else ord (x, y);
 
 fun bool_ord (false, true) = LESS
   | bool_ord (true, false) = GREATER
   | bool_ord _ = EQUAL;
 
 val int_ord = Int.compare;
 val string_ord = String.compare;
 
 val size_ord = int_ord o apply2 size;
 val fast_string_ord = pointer_eq_ord (size_ord ||| string_ord);
 
 fun option_ord ord (SOME x, SOME y) = ord (x, y)
   | option_ord _ (NONE, NONE) = EQUAL
   | option_ord _ (NONE, SOME _) = LESS
   | option_ord _ (SOME _, NONE) = GREATER;
 
 (*lexicographic product*)
 fun prod_ord a_ord b_ord ((x, y), (x', y')) =
   (case a_ord (x, x') of EQUAL => b_ord (y, y') | ord => ord);
 
 (*dictionary order -- in general NOT well-founded!*)
 fun dict_ord elem_ord (x :: xs, y :: ys) =
       (case elem_ord (x, y) of EQUAL => dict_ord elem_ord (xs, ys) | ord => ord)
   | dict_ord _ ([], []) = EQUAL
   | dict_ord _ ([], _ :: _) = LESS
   | dict_ord _ (_ :: _, []) = GREATER;
 
 (*lexicographic product of lists*)
 fun length_ord (xs, ys) = int_ord (length xs, length ys);
 fun list_ord elem_ord = length_ord ||| dict_ord elem_ord;
 
 
 (* sorting *)
 
 (*stable mergesort -- preserves order of equal elements*)
 fun mergesort unique ord =
   let
     fun merge (xs as x :: xs') (ys as y :: ys') =
           (case ord (x, y) of
             LESS => x :: merge xs' ys
           | EQUAL =>
               if unique then merge xs ys'
               else x :: merge xs' ys
           | GREATER => y :: merge xs ys')
       | merge [] ys = ys
       | merge xs [] = xs;
 
     fun merge_all [xs] = xs
       | merge_all xss = merge_all (merge_pairs xss)
     and merge_pairs (xs :: ys :: xss) = merge xs ys :: merge_pairs xss
       | merge_pairs xss = xss;
 
     fun runs (x :: y :: xs) =
           (case ord (x, y) of
              LESS => ascending y [x] xs
            | EQUAL =>
                if unique then runs (x :: xs)
                else ascending y [x] xs
            | GREATER => descending y [x] xs)
       | runs xs = [xs]
 
     and ascending x xs (zs as y :: ys) =
           (case ord (x, y) of
              LESS => ascending y (x :: xs) ys
            | EQUAL =>
                if unique then ascending x xs ys
                else ascending y (x :: xs) ys
            | GREATER => rev (x :: xs) :: runs zs)
       | ascending x xs [] = [rev (x :: xs)]
 
     and descending x xs (zs as y :: ys) =
           (case ord (x, y) of
              GREATER => descending y (x :: xs) ys
            | EQUAL =>
                if unique then descending x xs ys
                else (x :: xs) :: runs zs
            | LESS => (x :: xs) :: runs zs)
       | descending x xs [] = [x :: xs];
 
   in merge_all o runs end;
 
 fun sort ord = mergesort false ord;
 fun sort_distinct ord = mergesort true ord;
 
 val sort_strings = sort string_ord;
 fun sort_by key xs = sort (string_ord o apply2 key) xs;
 
 
 (* items tagged by integer index *)
 
 (*insert tags*)
 fun tag_list k [] = []
   | tag_list k (x :: xs) = (k:int, x) :: tag_list (k + 1) xs;
 
 (*remove tags and suppress duplicates -- list is assumed sorted!*)
 fun untag_list [] = []
   | untag_list [(k: int, x)] = [x]
   | untag_list ((k, x) :: (rest as (k', x') :: _)) =
       if k = k' then untag_list rest
       else x :: untag_list rest;
 
 (*return list elements in original order*)
 fun order_list list = untag_list (sort (int_ord o apply2 fst) list);
 
 
 
 (** misc **)
 
 fun divide_and_conquer decomp x =
   let val (ys, recomb) = decomp x
   in recomb (map (divide_and_conquer decomp) ys) end;
 
 fun divide_and_conquer' decomp x s =
   let val ((ys, recomb), s') = decomp x s
   in recomb (fold_map (divide_and_conquer' decomp) ys s') end;
 
 
 (*Partition a list into buckets  [ bi, b(i+1), ..., bj ]
    putting x in bk if p(k)(x) holds.  Preserve order of elements if possible.*)
 fun partition_list p i j =
   let
     fun part (k: int) xs =
       if k > j then
         (case xs of
           [] => []
         | _ => raise Fail "partition_list")
       else
         let val (ns, rest) = List.partition (p k) xs
         in ns :: part (k + 1) rest end;
   in part (i: int) end;
 
 fun partition_eq (eq: 'a * 'a -> bool) =
   let
     fun part [] = []
       | part (x :: ys) =
           let val (xs, xs') = List.partition (fn y => eq (x, y)) ys
           in (x :: xs) :: part xs' end;
   in part end;
 
 
 (* serial numbers and abstract stamps *)
 
 type serial = int;
 val serial = Counter.make ();
 val serial_string = string_of_int o serial;
 
 datatype stamp = Stamp of serial;
 fun stamp () = Stamp (serial ());
 
 
 (* values of any type *)
 
 (*note that the builtin exception datatype may be extended by new
   constructors at any time*)
 structure Any = struct type T = exn end;
 
 
 (* getenv *)
 
 fun getenv x =
   (case OS.Process.getEnv x of
     NONE => ""
   | SOME y => y);
 
 fun getenv_strict x =
   (case getenv x of
     "" => error ("Undefined Isabelle environment variable: " ^ quote x)
   | y => y);
 
 end;
 
 structure Basic_Library: BASIC_LIBRARY = Library;
 open Basic_Library;