changes to Perl core features over time

This document mainly covers changes to the core Perl syntax. For when specific modules started to be included in the Perl core, see here.

• perl 5.004 delta — released May 15, 1997
  • new $PERL5OPT variable
• perl 5.005 delta — released Jul 22, 1998
  • new EXPR foreach EXPR syntax
    • (though I almost never see it used in the wild)
  • new qr// operator
• perl 5.6.0 delta — released Mar 28, 2000
  • 3-argument open()
  • our introduced
  • CHECK blocks added
  • sort subroutines can accept their arugments via @_, in addition to $a and $b
  • lexically-scoped warning categories
  • lvalue subroutines were added
    • (though the book "Perl Best Practices" recommends against using lvalue accessors, at least)
  • comments allowed in pack() templates
• perl 5.8.0 delta — released Jul 18, 2002
  • PerlIO is now the default
• (v5.8.1, v5.8.2, v5.8.3, v5.8.4, v5.8.5, v5.8.6, v5.8.7, v5.8.8)
• perl 5.10.0 delta — changes made between Perl v5.8.8 and Perl v5.10.0 — released Dec 18, 2007
  • new feature pragma
  • new defined-or operator (//)
  • new switch feature and related smart match operator (~~)
    • more about given, when, and default keywords
    • more about the ~~ smart match operator
  • new state keyword for declaring variables that only need to be initialized once
  • new say built-in
• perl 5.12.0 delta — released Apr 12, 2010
  • autodie, a new lexically-scoped alternative to the Fatal module
  • new ... operator
  • new package NAME VERSION syntax
• perl 5.14.0 delta — released May 14, 2011
  • non-destructive substitution (s///r)
• perl 5.16.0 delta — released May 20, 2012
  • TODO
• perl 5.18.0 delta — released May 18, 2013
  • lexical subroutines were added (marked as 'experimental' until Perl 5.26)
• perl 5.20.0 delta — released May 27, 2014
  • subroutine signatures (an experimental feature)
  • postfix dereferencing
  • key/value slice syntax
• perl 5.22.0 delta — released Jun 1, 2015
  • new double-diamond operator
  • disambiguated bitwise operators
  • variable aliasing (an experimental feature)
• perl 5.24.0 delta — released May 8, 2016
  • TODO
• perl 5.26.0 delta — released May 30, 2017
  • indented here-documents
• perl 5.28.0 delta — released Jun 22, 2018
  • TODO
• perl 5.30.0 delta — released May 22, 2019
  • TODO
• perl 5.32.0 delta — released Jun 20, 2020
  • TODO
• perl 5.34.0 delta — released May 20, 2021
  • TODO
• perl 5.36.0 delta — released May 28, 2022
  • experimental defer blocks
  • TODO