--- a/Lib/IMPL/lang.pm	Mon Feb 04 17:16:45 2013 +0400
+++ b/Lib/IMPL/lang.pm	Wed Feb 06 02:15:48 2013 +0400
@@ -6,6 +6,7 @@
 use IMPL::_core::version;
 use IMPL::clone qw(clone);
 use Scalar::Util qw(blessed);
+use Carp qw(carp);
 
 our @EXPORT      = qw(&is &isclass &typeof);
 our %EXPORT_TAGS = (
@@ -64,15 +65,17 @@
 use IMPL::Const qw(:all);
 
 sub is($$) {
+    carp "A typename can't be undefined" unless $_[1];
     eval {ref $_[0] and $_[0]->isa( $_[1] ) };
 }
 
 sub isclass {
+    carp "A typename can't be undefined" unless $_[1];
     eval {not ref $_[0] and $_[0]->isa( $_[1] ) };
 }
 
 sub typeof(*) {
-    eval { $_[0]->typeof } || blessed($_[0]);
+    eval { $_[0]->_typeof } || blessed($_[0]) || ref($_[0]) || $_[0];
 }
 
 sub public($) {