perldelta - what is new for perl v5.31.10


This document describes differences between the 5.31.9 release and the 5.31.10 release.

If you are upgrading from an earlier release such as 5.31.8, first read perl5319delta, which describes differences between 5.31.8 and 5.31.9.

Core Enhancements

Unicode 13.0 is supported

See for details.

It is now possible to write qr/\p{Name=...}/, or qr!\p{na=/(SMILING|GRINNING) FACE/}!

The Unicode Name property is now accessible in regular expression patterns, as an alternative to \N{...}. A comparison of the two methods is given in "Comparison of \N{...} and \p{name=...}" in perlunicode.

The second example above shows that wildcard subpatterns are also usable in this property. See "Wildcards in Property Values" in perlunicode.

Chained comparisons capability

Some comparison operators, as their associativity, chain with some operators of the same precedence (but never with operators of different precedence).

if ( $x < $y <= $z ) {...}

behaves exactly like:

if ( $x < $y && $y <= $z ) {...}

(assuming that "$y" is as simple a scalar as it looks.)

You can read more about this in perlop under "Operator Precedence and Associativity" in perlop.


Jeff Goff (JGOFF or DrForr), an integral part of the Perl and Raku communities and a dear friend to all of us, has passed away on March 13th, 2020. DrForr was a prominent member of the communities, attending and speaking at countless events, contributing to numerous projects, and assisting and helping in any way he could.

His passing leaves a hole in our hearts and in our communities and he will be sorely missed.


Perl 5.31.10 represents approximately 4 weeks of development since Perl 5.31.9 and contains approximately 17,000 lines of changes across 180 files from 29 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 9,000 lines of changes to 85 .pm, .t, .c and .h files.

Perl continues to flourish into its fourth decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.31.10:

Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan Book, Daniel Dragan, Dave Rolsky, David Cantrell, David Mitchell, Hauke D, H.Merijn Brand, Hugo van der Sanden, James E Keenan, John Lightsey, Karen Etheridge, Karl Williamson, Nicolas R., Pali, Paul Evans, Peter Oliver, Renee Baecker, Richard Leach, Sawyer X, Shlomi Fish, Stefan Seifert, Steve Hay, Tomasz Konojacki, Tony Cook, Yves Orton, Zefram.

The list above is almost certainly incomplete as it is automatically generated from version control history. In particular, it does not include the names of the (very much appreciated) contributors who reported issues to the Perl bug tracker.

Many of the changes included in this version originated in the CPAN modules included in Perl's core. We're grateful to the entire CPAN community for helping Perl to flourish.

For a more complete list of all of Perl's historical contributors, please see the AUTHORS file in the Perl source distribution.

Reporting Bugs

If you find what you think is a bug, you might check the perl bug database at There may also be information at, the Perl Home Page.

If you believe you have an unreported bug, please open an issue at Be sure to trim your bug down to a tiny but sufficient test case.

If the bug you are reporting has security implications which make it inappropriate to send to a public issue tracker, then see "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for details of how to report the issue.

Give Thanks

If you wish to thank the Perl 5 Porters for the work we had done in Perl 5, you can do so by running the perlthanks program:


This will send an email to the Perl 5 Porters list with your show of thanks.


The Changes file for an explanation of how to view exhaustive details on what changed.

The INSTALL file for how to build Perl.

The README file for general stuff.

The Artistic and Copying files for copyright information.