pure_trfuns: added constraint;

--- a/src/Pure/Syntax/syn_trans.ML	Tue Sep 23 17:35:07 1997 +0200
+++ b/src/Pure/Syntax/syn_trans.ML	Wed Sep 24 10:51:52 1997 +0200
@@ -280,7 +280,7 @@
    ("_bigimpl", bigimpl_ast_tr)],
   [("_abs", abs_tr), ("_aprop", aprop_tr), ("_ofclass", ofclass_tr),
    ("_K", k_tr)],
-  [],
+  []: (string * (term list -> term)) list,
   [("_abs", abs_ast_tr'), ("_idts", idtyp_ast_tr' "_idts"),
    ("_pttrns", idtyp_ast_tr' "_pttrns"), ("==>", impl_ast_tr')]);