tuned error / warning;

--- a/src/Pure/sign.ML	Tue Jul 22 18:46:44 1997 +0200
+++ b/src/Pure/sign.ML	Tue Jul 22 19:33:30 1997 +0200
@@ -241,7 +241,7 @@
 (*read and certify typ wrt a signature*)
 fun read_typ (Sg {tsig, syn, ...}, sort_of) str =
   Type.cert_typ tsig (read_raw_typ syn tsig sort_of str)
-    handle TYPE (msg, _, _) => (writeln msg; err_in_type str);
+    handle TYPE (msg, _, _) => (error_msg msg; err_in_type str);
 
 
 
@@ -371,7 +371,7 @@
     (case foldl process_term (Errs [], ts ~~ (0 upto (length ts - 1))) of
       One res =>
        (if length ts > ! Syntax.ambiguity_level then
-          writeln "Fortunately, only one parse tree is type correct.\n\
+          warning "Fortunately, only one parse tree is type correct.\n\
             \It helps (speed!) if you disambiguate your grammar or your input."
         else (); res)
     | Errs errs => (warn (); error (cat_lines errs))
@@ -454,7 +454,7 @@
     fun prep_const (c, ty, mx) =
      (c, compress_type (Type.varifyT (Type.cert_typ tsig (Type.no_tvars ty))), mx)
        handle TYPE (msg, _, _)
-         => (writeln msg; err_in_const (Syntax.const_name c mx));
+         => (error_msg msg; err_in_const (Syntax.const_name c mx));
 
     val consts = map (prep_const o rd_const syn tsig) raw_consts;
     val decls =