Interesting blog post http://blogs.perl.org/users/stevan_little/2014/03/status-update-on-the-p5-mop-project.html Maybe in 5.22? https://metacpan.org/pod/release/STEVAN/mop-0.03-TRIAL/lib/mop.pm#What-version-of-Perl-do-you-expect-this-to-ship-with S