eliminated raise_ast;

--- a/src/Pure/Syntax/ast.ML	Mon Oct 06 18:20:15 1997 +0200
+++ b/src/Pure/Syntax/ast.ML	Mon Oct 06 18:21:00 1997 +0200
@@ -29,7 +29,6 @@
 signature AST =
   sig
   include AST1
-  val raise_ast: string -> ast list -> 'a
   val head_of_rule: ast * ast -> string
   val rule_error: ast * ast -> string option
   val fold_ast: string -> ast list -> ast
@@ -68,7 +67,6 @@
 
 exception AST of string * ast list;
 
-fun raise_ast msg asts = raise AST (msg, asts);
 
 
 (** print asts in a LISP-like style **)