diff --git a/src/Pure/ML/ml_thms.ML b/src/Pure/ML/ml_thms.ML
--- a/src/Pure/ML/ml_thms.ML
+++ b/src/Pure/ML/ml_thms.ML
@@ -1,143 +1,143 @@
 (*  Title:      Pure/ML/ml_thms.ML
     Author:     Makarius
 
 Attribute source and theorem values within ML.
 *)
 
 signature ML_THMS =
 sig
   val the_attributes: Proof.context -> int -> Token.src list
   val the_thmss: Proof.context -> thm list list
   val get_stored_thms: unit -> thm list
   val get_stored_thm: unit -> thm
   val store_thms: string * thm list -> unit
   val store_thm: string * thm -> unit
   val bind_thm: string * thm -> unit
   val bind_thms: string * thm list -> unit
 end;
 
 structure ML_Thms: ML_THMS =
 struct
 
 (* auxiliary data *)
 
 type thms = (string * bool) * thm list;  (*name, single, value*)
 
 structure Data = Proof_Data
 (
   type T = Token.src list Inttab.table * thms list;
   fun init _ = (Inttab.empty, []);
 );
 
 val put_attributes = Data.map o apfst o Inttab.update;
 fun the_attributes ctxt name = the (Inttab.lookup (fst (Data.get ctxt)) name);
 
 val get_thmss = snd o Data.get;
 val the_thmss = map snd o get_thmss;
 val cons_thms = Data.map o apsnd o cons;
 
 
 (* attribute source *)
 
 val _ = Theory.setup
   (ML_Antiquotation.declaration \<^binding>\<open>attributes\<close> Attrib.attribs
     (fn _ => fn srcs => fn ctxt =>
       let val i = serial () in
         ctxt
         |> put_attributes (i, srcs)
         |> ML_Context.value_decl "attributes"
             ("ML_Thms.the_attributes ML_context " ^ string_of_int i)
       end));
 
 
 (* fact references *)
 
 fun thm_binding kind is_single thms ctxt =
   let
     val initial = null (get_thmss ctxt);
     val (name, ctxt') = ML_Context.variant kind ctxt;
     val ctxt'' = cons_thms ((name, is_single), thms) ctxt';
 
     val ml_body = ML_Context.struct_name ctxt ^ "." ^ name;
     fun decl final_ctxt =
       if initial then
         let
           val binds = get_thmss final_ctxt |> map (fn ((a, b), _) => (b ? enclose "[" "]") a);
           val ml_env = "val [" ^ commas binds ^ "] = ML_Thms.the_thmss ML_context;\n";
         in (ml_env, ml_body) end
       else ("", ml_body);
   in (decl, ctxt'') end;
 
 val _ = Theory.setup
   (ML_Antiquotation.declaration \<^binding>\<open>thm\<close> (Attrib.thm >> single) (K (thm_binding "thm" true)) #>
    ML_Antiquotation.declaration \<^binding>\<open>thms\<close> Attrib.thms (K (thm_binding "thms" false)));
 
 
 (* ad-hoc goals *)
 
 val and_ = Args.$$$ "and";
 val by = Parse.reserved "by";
 val goal = Scan.unless (by || and_) Args.embedded_inner_syntax;
 
 val _ = Theory.setup
   (ML_Antiquotation.declaration \<^binding>\<open>lemma\<close>
     (Scan.lift (Args.mode "open" -- Parse.enum1 "and" (Scan.repeat1 goal) --
       (Parse.position by -- Method.parse -- Scan.option Method.parse)))
     (fn _ => fn ((is_open, raw_propss), (((_, by_pos), m1), m2)) => fn ctxt =>
       let
         val reports =
           (by_pos, Markup.keyword1 |> Markup.keyword_properties) ::
             maps Method.reports_of (m1 :: the_list m2);
         val _ = Context_Position.reports ctxt reports;
 
         val propss = burrow (map (rpair []) o Syntax.read_props ctxt) raw_propss;
         val prep_result = Goal.norm_result ctxt #> not is_open ? Thm.close_derivation \<^here>;
         fun after_qed res goal_ctxt =
           Proof_Context.put_thms false (Auto_Bind.thisN,
             SOME (map prep_result (Proof_Context.export goal_ctxt ctxt (flat res)))) goal_ctxt;
 
         val ctxt' = ctxt
           |> Proof.theorem NONE after_qed propss
           |> Proof.global_terminal_proof (m1, m2);
         val thms =
           Proof_Context.get_fact ctxt'
             (Facts.named (Proof_Context.full_name ctxt' (Binding.name Auto_Bind.thisN)));
       in thm_binding "lemma" (length (flat propss) = 1) thms ctxt end));
 
 
 (* old-style theorem bindings *)
 
-structure Stored_Thms = Theory_Data
+structure Data = Theory_Data
 (
   type T = thm list;
   val empty = [];
-  fun extend _ = [];
-  fun merge _ = [];
+  val extend = I;
+  val merge = #1;
 );
 
-fun get_stored_thms () = Stored_Thms.get (Context.the_global_context ());
+fun get_stored_thms () = Data.get (Context.the_global_context ());
 val get_stored_thm = hd o get_stored_thms;
 
 fun ml_store get (name, ths) =
   let
     val (_, ths') =
       Context.>>> (Context.map_theory_result
         (Global_Theory.note_thms "" ((Binding.name name, []), [(ths, [])])));
-    val _ = Theory.setup (Stored_Thms.put ths');
+    val _ = Theory.setup (Data.put ths');
     val _ =
       if name = "" then ()
       else if not (ML_Syntax.is_identifier name) then
         error ("Cannot bind theorem(s) " ^ quote name ^ " as ML value")
       else
         ML_Compiler.eval (ML_Compiler.verbose true ML_Compiler.flags) Position.none
           (ML_Lex.tokenize ("val " ^ name ^ " = " ^ get ^ " ();"));
-    val _ = Theory.setup (Stored_Thms.put []);
+    val _ = Theory.setup (Data.put []);
   in () end;
 
 val store_thms = ml_store "ML_Thms.get_stored_thms";
 fun store_thm (name, th) = ml_store "ML_Thms.get_stored_thm" (name, [th]);
 
 fun bind_thm (name, thm) = store_thm (name, Drule.export_without_context thm);
 fun bind_thms (name, thms) = store_thms (name, map Drule.export_without_context thms);
 
 end;