better markup

--- a/src/HOL/Tools/datatype_package.ML	Mon Mar 02 12:34:03 2009 +0000
+++ b/src/HOL/Tools/datatype_package.ML	Mon Mar 02 16:58:39 2009 +0100
@@ -631,8 +631,8 @@
 
 local
 
-val sym_datatype = Pretty.str "\\isacommand{datatype}";
-val sym_binder = Pretty.str "\\ {\\isacharequal}";
+val sym_datatype = Pretty.command "datatype";
+val sym_binder = Pretty.str "\\ {\\isacharequal}"; (*FIXME use proper symbol*)
 val sym_sep = Pretty.str "{\\isacharbar}\\ ";
 
 in