src/Pure/Isar/parse.ML

 
 (* group atomic parsers (no cuts!) *)
 
 fun fail_with s = Scan.fail_with
   (fn [] => s ^ " expected (past end-of-file!)"
-    | (tok :: _) =>
+    | tok :: _ =>
         (case Token.text_of tok of
           (txt, "") =>
             s ^ " expected,\nbut " ^ txt ^ Token.pos_of tok ^ " was found"
         | (txt1, txt2) =>
             s ^ " expected,\nbut " ^ txt1 ^ Token.pos_of tok ^ " was found:\n" ^ txt2));