made SML/NJ happy (cf. 578a51fae383);

--- a/src/Pure/pure_setup.ML	Wed Apr 06 18:17:19 2011 +0200
+++ b/src/Pure/pure_setup.ML	Wed Apr 06 18:36:28 2011 +0200
@@ -30,7 +30,7 @@
 toplevel_pp ["Context", "theory"] "Context.pretty_thy";
 toplevel_pp ["Context", "theory_ref"] "Context.pretty_thy o Theory.deref";
 toplevel_pp ["Context", "Proof", "context"] "Proof_Display.pp_context";
-toplevel_pp ["Syntax", "ast"] "Ast.pretty_ast";
+toplevel_pp ["Ast", "ast"] "Ast.pretty_ast";
 toplevel_pp ["Path", "T"] "Pretty.str o Path.print";
 toplevel_pp ["SHA1", "digest"] "Pretty.str o quote o SHA1.rep";
 toplevel_pp ["Proof", "state"] "(fn _: Proof.state => Pretty.str \"<Proof.state>\")";