This is Perl module List::UtilsBy::XS. INSTALLATION List::UtilsBy::XS installation is straightforward. If your CPAN shell is set up, you should just be able to do % cpan List::UtilsBy::XS Download it, unpack it, then build it as per the usual: % perl Makefile.PL % make && make test Then install it: % make install DOCUMENTATION List::UtilsBy::XS documentation is available as in POD. So you can do: % perldoc List::UtilsBy::XS to read the documentation online with your favorite pager. Syohei YOSHIDA