Module::CoreList looks neat .. you can also browse the perl distributions on cpan -- start at the newer end with http://search.cpan.org/~nwclark/perl-5.8.8/ and use the 'Other Releases' drop box to go back in time and see which distros include Carp (you can see it there in perl5.003_07 just like Module::CoreList says).. You use this techinique w/any distro, too.