clarified signature: more standard map_data;

--- a/src/Pure/Tools/adhoc_overloading.ML	Tue Jan 28 11:20:53 2025 +0100
+++ b/src/Pure/Tools/adhoc_overloading.ML	Tue Jan 28 11:29:42 2025 +0100
@@ -60,7 +60,7 @@
   type T =
     {variants : (term * typ) list Symtab.table,
      oconsts : string Termtab.table};
-  val empty = {variants = Symtab.empty, oconsts = Termtab.empty};
+  val empty : T = {variants = Symtab.empty, oconsts = Termtab.empty};
 
   fun merge
     ({variants = vtab1, oconsts = otab1},
@@ -75,9 +75,10 @@
     end;
 );
 
-fun map_tables f g =
-  Data.map (fn {variants = vtab, oconsts = otab} =>
-    {variants = f vtab, oconsts = g otab});
+fun map_data f =
+  Data.map (fn {variants, oconsts} =>
+    let val (variants', oconsts') = f (variants, oconsts)
+    in {variants = variants', oconsts = oconsts'} end);
 
 val is_overloaded = Symtab.defined o #variants o Data.get;
 val get_variants = Symtab.lookup o #variants o Data.get;
@@ -85,7 +86,7 @@
 
 fun generic_add_overloaded oconst context =
   if is_overloaded context oconst then context
-  else map_tables (Symtab.update (oconst, [])) I context;
+  else (map_data o apfst) (Symtab.update (oconst, [])) context;
 
 (*If the list of variants is empty at the end of "generic_remove_variant", then
   "generic_remove_overloaded" is called implicitly.*)
@@ -97,7 +98,10 @@
           (case get_variants context oconst of
             NONE => I
           | SOME vs => fold (Termtab.remove (op =) o rpair oconst o fst) vs);
-      in map_tables (Symtab.delete_safe oconst) remove_variants context end;
+      in
+        context |> map_data (fn (variants, oconsts) =>
+          (Symtab.delete_safe oconst variants, remove_variants oconsts))
+      end;
   in
     if is_overloaded context oconst then remove_oconst_and_variants context oconst
     else err_not_overloaded oconst
@@ -117,20 +121,22 @@
               NONE => ()
             | SOME oconst' => err_duplicate_variant oconst');
         in
-          map_tables (Symtab.cons_list (oconst, (t', T))) (Termtab.update (t', oconst)) context
+          context |> map_data (fn (variants, oconsts) =>
+            (Symtab.cons_list (oconst, (t', T)) variants, Termtab.update (t', oconst) oconsts))
         end
       else
         let
           val _ =
             if member variants_eq (the (get_variants context oconst)) (t', T) then ()
             else err_not_a_variant oconst;
+          val context' =
+            context |> map_data (fn (variants, oconsts) =>
+              (Symtab.map_entry oconst (remove1 variants_eq (t', T)) variants,
+               Termtab.delete_safe t' oconsts));
         in
-          map_tables (Symtab.map_entry oconst (remove1 variants_eq (t', T)))
-            (Termtab.delete_safe t') context
-          |> (fn context =>
-            (case get_variants context oconst of
-              SOME [] => generic_remove_overloaded oconst context
-            | _ => context))
+          (case get_variants context' oconst of
+            SOME [] => generic_remove_overloaded oconst context'
+          | _ => context')
         end
     end;
 in