6 ['<code>use warnings</code>', 'pragma to enable warnings in lexical scope'],
7 ['<code>use utf8</code>', 'experimental unicode semantics <small>(completed in v5.8)</small>', {experimental => 0, stable => v5.8}],
8 ['<code>use charnames</code>', 'string escape <code>\N{}</code> to insert named character'],
9 ['<code>our</code>', 'declare global variables'],
10 ['<code>v1.2.3</code>', q"represent strings as vector of ordinals, useful in version numbers (<code>printf '%vd'</code> to display)"],
11 ['<code>0b0</code>', q"binary numbers in literals, <code>printf '%b'</code>, and <code>oct</code>"],
12 ['<code>sub :lvalue</code>', 'subroutine attribute to return a modifiable value', {experimental => 0, stable => v5.20}],
13 # ['<code>sub :locked :method</code>', 'syntax to declare subroutine attributes'], # can be inferred from :lvalue support
14 ['<code>open my $fh, $mode, $expr</code>', 'file handles in scoped scalars, third argument for unambiguous file name'],
15 [q"<code>pack 'q'</code>", '64-bit integer support (also large files >2GiB)', {experimental => 0, stable => v5.8.1}],
16 ['<code>sort $coderef ()</code>', 'comparison function can be a subroutine reference; prototype <code>($$)</code> to pass elements as normal <code>@_</code>'],
17 ['<code>CHECK {}</code>', 'special block called at end of compilation'],
18 ['<code>/[[:…:]]/</code>', 'POSIX character class syntax such as <code>/[[:alpha:]]/</code>'],
19 # quite a lot more, but leave it at this
21 release => '2000-03-23',
24 rhel => '2', # v5.6.0; also in red hat 7.0
25 solaris => '9', # v5.6.1; 2002-05 eol 2014-10
26 aix => '5.1', # 2001-05 eol 2006-04
33 [q"<code>no utf8</code>", 'full unicode support, <code>utf8</code> pragma only for script encoding'],
34 [q"<code>binmode $fh, ':perlio'</code>", 'file handle behaviour altered by PerlIO layers'],
35 [q"<code>open $fh, '-|', @cmd</code>", 'open list to fork a command without spawning a shell'],
36 [q"<code>open $fh, '>', \$var</code>", 'perl scalars as virtual files'],
37 [q"<code>printf '%1$s', @args</code>", 'syntax to use parameters out of order'],
38 [q"<code>1_2_3 == 123</code>", 'underscores between digits allowed in numeric constants'],
39 # [q"<code>use if</code>", 'conditional module inclusion'], # also installable in earlier versions
41 release => '2002-07-18',
44 rhel => '3', # v5.8.0; v5.8.8 in RHEL6 (2007-2014)
45 solaris => '10', # v5.8.4; 2005-01 eol 2021-01
46 centos => '3-5', # v5.8.0 in v3 (2004-03); v5.8.8 in v5 (eol 2017-03)
48 aix => '5.2', # v5.8.0; v5.8.2 in 5.3 and 6.1 (eol 2017-04-30)
55 ['<code>//</code>', 'defined-or operator'],
56 ['<code>~~</code>', 'smart-match operator to compare different data types <small>(updated in v5.10.1)</small>', {experimental => 'smartmatch'}],
57 ['<code>say</code>', 'print with newline, equivalent to <code>print @_, "\n"</code>', {feature => 'say'}],
58 ['<code>given</code>', 'switch statement to smart-match with <code>when</code>/<code>default</code>', {feature => 'switch', experimental => 'smartmatch'}],
59 ['<code>/(?<name>)/</code>', 'named capture buffers into <code>%+</code>'],
60 ['<code>/(?1)/</code>', 'recursive regular expression patterns'],
61 ['<code>/.++/</code>', 'possessive quantifiers <code>?+</code>, <code>*+</code>, <code>++</code> to match greedily'],
62 ['<code>s/keep\K//</code>', 'floating positive lookbehind, efficient alternative for <code>s/(keep)/$1/</code>'],
63 ['<code>/\v/, /\h/</code>', 'vertical and horizontal whitespace escapes'],
64 ['<code>my $_</code>', 'lexically scoped version of the default variable', {experimental => 'lexical_topic', dropped => v5.23.4}],
65 ['<code>state</code>', 'persistent <code>my</code> variables', {feature => 'state'}],
67 release => '2007-12-18',
70 rhel => '6', # v5.10.1
71 centos => '6', # v5.10.1 (2011-07 eol 2020-11)
72 ubuntu => '8.10', # v5.10.1 in 10.04 LTS
73 aix => '7.1', # v5.10.1 (2010-09 eol 2020?)
80 ['<code>package</code> version', '<code>package</code> NAME VERSION shorthand for <code>our $VERSION</code>'],
81 ['<code>...</code>', 'yada-yada operator: code placeholder'],
82 ['<code>use 5.012</code>', 'implicit <code>strict</code> if use VERSION >= v5.12'],
83 ['<code>… when</code>', '<code>when</code> is now allowed to be used as a statement modifier'],
84 [q"<code>use overload 'qr'</code>", 'customisable conversion to regular expressions'],
85 ['<code>/\N/</code>', 'inverse \n to match any character except newline regardless of <code>/s</code>', {experimental => 0, stable => v5.18}],
87 release => '2010-04-12',
90 solaris => '11', # also v5.8.4; 2010-11 eol 2024-11
97 ['<code>s///r</code>', 'non-destructive substitution'],
98 ['<code>/(?^)/</code>', 'construct to reset to default modifiers'],
99 ['<code>/(?{ m() })/</code>', 'regular expressions can be nested in <code>/(?{})/</code> and <code>/(??{})/</code>', {experimental => 0, stable => v5.20}],
100 [q"<code>use re '/flags'</code>", 'customise default modifiers'],
101 ['<code>each $ref</code> e.a.', 'array and hash container functions accept references', {experimental => 'postderef', dropped => v5.23.1}],
102 ['<code>FH->method</code>', 'filehandle method calls load IO::File on demand (eg. <code>STDOUT->flush</code>)'],
104 release => '2011-05-14',
114 ['<code>__SUB__</code>', 'current subroutine reference', {feature => 'current_sub'}],
115 ['<code>fc, "\F"</code>', 'unicode foldcase to compare case-insensitively', {feature => 'fc'}],
116 ['<code>"\N{}"</code>', 'automatic <code>use charnames qw( :full :short )</code>'],
118 release => '2012-05-20',
120 rhel => '7', # v5.16.3
121 centos => '7', # v5.16.3 (2014-07 eol 2024-06)
128 ['<code>${^LAST_FH}</code>', 'last read filehandle (used by <code>$.</code>)'],
129 ['<code>/(?[ a + b ])/</code>', 'regex set operations (character substraction <code>-</code>, unions <code>&</code>)', {experimental => 'regex_sets'}],
130 ['<code>my sub</code>', 'lexical subroutines (also <code>state</code>, <code>our</code>); buggy before v5.22', {feature => 'lexical_subs', experimental => 'lexical_subs'}],
131 ['<code>next $expression</code>', 'loop controls allow runtime expressions'],
132 [q"<code>no warnings 'experimental::…'</code>", 'mechanism for experimental features, as of now required for <em>smartmatch</em>'],
134 release => '2013-05-18',
143 ['<code>sub ($var)</code>', 'subroutine signatures', {feature => 'signatures', experimental => 'signatures'}],
144 ['<code>%hash{…}</code>', 'hash slices return key+value pairs'],
145 ['<code>[]->@*</code>', 'postfix dereferencing (also e.g. <code>$scalar->$*</code> for <code>$$scalar</code>)', {feature => 'postderef, postderef_qq', experimental => 'postderef', stable => v5.23.1}],
146 [q"<code>use warnings 'once'; $a</code>", 'variables $a and $b are exempt from <em>used once</em> warnings'],
149 release => '2014-05-27',
159 ['<code>\$alias =</code>', 'aliasing via reference (scoped as of v5.25.3)', {experimental => 'refaliasing'}],
160 ['<code><<>></code>', 'safe <code>readline</code> ignoring open flags in arguments'],
161 ['<code>/()/n</code>', 'flag to disable numbered capturing, turning <code>()</code> into <code>(?:)</code>'],
162 ['<code>/\b{}/</code>', 'boundary types: <em>gcb</em> (grapheme cluster), <em>sb</em> (sentence), <em>wb</em> (word)'],
163 ['<code>&.</code>', '<code>& | ^ ~</code> consistently numeric, dotted operators for strings', {experimental => 'bitwise'}],
164 [q"<code>use re 'strict'</code>", 'apply stricter syntax rules to regular expression patterns', {experimental => 're_strict'}],
165 ['<code>0x.beep+0</code>', q"hexadecimal floating point notation with binary power; <code>printf '%a'</code> to display"],
168 release => '2015-06-01',
176 [q"<code>printf '%.*2$x'</code>", 'reordered precision arguments'],
177 ['<code>/\b{lb}/</code>', 'line break boundary type (position suitable for hyphenation)'],
178 ['<code>/faster/</code>', 'various significant speedups, notably matching fixed substrings, <code>/i</code> on caseless languages, 64-bit arithmetic, scope overhead'],
181 release => '2016-05-09',
186 ['<code><<~EOT</code>', 'indented here-docs, strips same whitespace before delimiter in each line'],
187 ['<code>@{^CAPTURE}</code>', q"array of last match's captures, so <code>${^CAPTURE}[0]</code> is <code>$1</code>"],
188 ['<code>//xx</code>', 'extended modifier to also ignore whitespace in bracketed character classes'],
190 unicode => '9.0', # also Script_Extensions/scx in "\p{script}"
191 release => '2017-02-20',