src/Pure/Isar/token.ML

--- a/src/Pure/Isar/token.ML	Tue Jul 31 21:11:24 2018 +0200
+++ b/src/Pure/Isar/token.ML	Tue Jul 31 21:21:20 2018 +0200
@@ -43,7 +43,6 @@
   val is_command_modifier: T -> bool
   val ident_with: (string -> bool) -> T -> bool
   val is_proper: T -> bool
-  val is_improper: T -> bool
   val is_comment: T -> bool
   val is_informal_comment: T -> bool
   val is_formal_comment: T -> bool
@@ -236,8 +235,6 @@
   | is_proper (Token (_, (Comment _, _), _)) = false
   | is_proper _ = true;
 
-val is_improper = not o is_proper;
-
 fun is_comment (Token (_, (Comment _, _), _)) = true
   | is_comment _ = false;