Difference between revisions of "Perl"

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<p>&nbsp;<b style="color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px; line-height: 17.9200000762939px;">Perl</b><span style="color: rgb(37, 37, 37); font-family: sans-serif;
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<p><span style="font-size:16px">&nbsp;<strong>Perl</strong><span style="color:rgb(37,37,37); font-family:sans-serif">&nbsp;</span><span style="color:rgb(37,37,37); font-family:sans-serif">is a family of</span><span style="color:rgb(37,37
 
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<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">Perl 5.6 was released on March 22, 2000. Major changes included&nbsp;<a href="http://en.wikipedia.org/wiki/64-bit_computing" title="64-bit computing" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">64-bit</a>&nbsp;support,&nbsp;<a href="http://en.wikipedia.org/wiki/Unicode" title="Unicode" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Unicode</a>&nbsp;string representation, large file support (i.e. files over 2 GiB) and the &quot;our&quot; keyword.<sup id="cite_ref-56delta_25-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-56delta-25" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[25]</a></sup><sup id="cite_ref-561delta_26-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-561delta-26" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[26]</a></sup>&nbsp;When developing Perl 5.6, the decision was made to switch the&nbsp;<a href="http://en.wikipedia.org/wiki/Software_versioning" title="Software versioning" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">versioning</a>&nbsp;scheme to one more similar to other open source projects; after 5.005_63, the next version became 5.5.640, with plans for development versions to have odd numbers and stable versions to have even numbers.</p>
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<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">In 2000, Wall put forth a call for suggestions for a new version of Perl from the community. The process resulted in 361 RFC (request for comments) documents that were to be used in guiding development of Perl 6. In 2001,<sup id="cite_ref-27" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-27" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[27]</a></sup>&nbsp;work began on the apocalypses for&nbsp;<a href="http://en.wikipedia.org/wiki/Perl_6" title="Perl 6" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Perl 6</a>, a series of documents meant to summarize the change requests and present the design of the next generation of Perl. They were presented as a digest of the RFCs, rather than a formal document. At this point, Perl 6 existed only as a description of a language.</p>
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<p>Perl 5.6 was released on March 22, 2000. Major changes included&nbsp;<a href="http://en.wikipedia.org/wiki/64-bit_computing" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="64-bit computing">64-bit</a>&nbsp;support,&nbsp;<a href="http://en.wikipedia.org/wiki/Unicode" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Unicode">Unicode</a>&nbsp;string representation, large file support (i.e. files over 2 GiB) and the &quot;our&quot; keyword.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-56delta-25" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[25]</a></sup><sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-561delta-26" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[26]</a></sup>&nbsp;When developing Perl 5.6, the decision was made to switch the&nbsp;<a href="http://en.wikipedia.org/wiki/Software_versioning" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Software versioning">versioning</a>&nbsp;scheme to one more similar to other open source projects; after 5.005_63, the next version became 5.5.640, with plans for development versions to have odd numbers and stable versions to have even numbers.</p>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">Perl 5.8 was first released on July 18, 2002, and had nearly yearly updates since then. Perl 5.8 improved Unicode support, added a new I/O implementation, added a new thread implementation, improved numeric accuracy, and added several new modules.<sup id="cite_ref-perl58delta_28-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-perl58delta-28" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[28]</a></sup>&nbsp;As of 2013 this version still remains the most popular version of Perl and is used by Red Hat 5, Suse 10, Solaris 10, HP-UX 11.33 and AIX 5.</p>
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<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">In 2004, work began on the Synopses &ndash; documents that originally summarized the Apocalypses, but which became the specification for the Perl 6 language. In February 2005,&nbsp;<a href="http://en.wikipedia.org/wiki/Audrey_Tang" title="Audrey Tang" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Audrey Tang</a>&nbsp;began work on&nbsp;<a href="http://en.wikipedia.org/wiki/Pugs" title="Pugs" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Pugs</a>, a Perl 6 interpreter written in&nbsp;<a href="http://en.wikipedia.org/wiki/Haskell_(programming_language)" title="Haskell (programming language)" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Haskell</a>.<sup id="cite_ref-29" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-29" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[29]</a></sup>&nbsp;This was the first concerted effort towards making Perl 6 a reality. This effort stalled in 2006.<sup id="cite_ref-30" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-30" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[30]</a></sup></p>
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<p>In 2000, Wall put forth a call for suggestions for a new version of Perl from the community. The process resulted in 361 RFC (request for comments) documents that were to be used in guiding development of Perl 6. In 2001,<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-27" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[27]</a></sup>&nbsp;work began on the apocalypses for&nbsp;<a href="http://en.wikipedia.org/wiki/Perl_6" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Perl 6">Perl 6</a>, a series of documents meant to summarize the change requests and present the design of the next generation of Perl. They were presented as a digest of the RFCs, rather than a formal document. At this point, Perl 6 existed only as a description of a language.</p>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">On December 18, 2007, the 20th anniversary of Perl 1.0, Perl 5.10.0 was released. Perl 5.10.0 included notable new features, which brought it closer to&nbsp;<a href="http://en.wikipedia.org/wiki/Perl_6" title="Perl 6" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Perl 6</a>. These included a&nbsp;<a href="http://en.wikipedia.org/wiki/Switch_statement" title="Switch statement" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">switch statement</a>&nbsp;(called &quot;given&quot;/&quot;when&quot;), regular expressions updates, and the smart match operator, &quot;~~&quot;.<sup id="cite_ref-5100delta_31-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5100delta-31" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[31]</a></sup><sup id="cite_ref-perlsyn-smart_32-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-perlsyn-smart-32" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[32]</a></sup>&nbsp;Around this same time, development began in earnest on another implementation of Perl 6 known as&nbsp;<a href="http://en.wikipedia.org/wiki/Rakudo_Perl" title="Rakudo Perl" class="mw-redirect" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Rakudo Perl</a>, developed in tandem with the&nbsp;<a href="http://en.wikipedia.org/wiki/Parrot_virtual_machine" title="Parrot virtual machine" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Parrot virtual machine</a>. As of November 2009, Rakudo Perl has had regular monthly releases and now is the most complete implementation of&nbsp;<a href="http://en.wikipedia.org/wiki/Perl_6" title="Perl 6" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Perl 6</a>.</p>
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<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">A major change in the development process of Perl 5 occurred with Perl 5.11; the development community has switched to a monthly release cycle of development releases, with a yearly schedule of stable releases. By that plan, bugfix point releases will follow the stable releases every three months.</p>
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<p>Perl 5.8 was first released on July 18, 2002, and had nearly yearly updates since then. Perl 5.8 improved Unicode support, added a new I/O implementation, added a new thread implementation, improved numeric accuracy, and added several new modules.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-perl58delta-28" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[28]</a></sup>&nbsp;As of 2013 this version still remains the most popular version of Perl and is used by Red Hat 5, Suse 10, Solaris 10, HP-UX 11.33 and AIX 5.</p>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">On April 12, 2010, Perl 5.12.0 was released. Notable core enhancements include new&nbsp;<code style="font-family: monospace, Courier; color: black; border: 1px solid rgb(221, 221, 221); border-radius: 2px; padding: 1px 4px; background-color: rgb(249, 249, 249);">package NAME VERSION</code>&nbsp;syntax, the Yada Yada operator (intended to mark placeholder code that is not yet implemented), implicit strictures, full&nbsp;<a href="http://en.wikipedia.org/wiki/Y2038" title="Y2038" class="mw-redirect" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Y2038</a>&nbsp;compliance, regex conversion overloading,&nbsp;<a href="http://en.wikipedia.org/wiki/DTrace" title="DTrace" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">DTrace</a>&nbsp;support, and&nbsp;<a href="http://en.wikipedia.org/wiki/Unicode" title="Unicode" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Unicode</a>&nbsp;5.2.<sup id="cite_ref-5120delta_33-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5120delta-33" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[33]</a></sup>&nbsp;On January 21, 2011, Perl 5.12.3 was released; it contains updated modules and some documentation changes.<sup id="cite_ref-5123delta_34-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5123delta-34" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[34]</a></sup>&nbsp;Version 5.12.4 was released on June 20, 2011. The latest version of that branch, 5.12.5, was released on November 10, 2012.</p>
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<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">On May 14, 2011, Perl 5.14 was released.&nbsp;<a href="http://en.wikipedia.org/wiki/JSON" title="JSON" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">JSON</a>&nbsp;support is built-in as of 5.14.2. The latest version of that branch, 5.14.4, was released on March 10, 2013.</p>
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<p>In 2004, work began on the Synopses &ndash; documents that originally summarized the Apocalypses, but which became the specification for the Perl 6 language. In February 2005,&nbsp;<a href="http://en.wikipedia.org/wiki/Audrey_Tang" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Audrey Tang">Audrey Tang</a>&nbsp;began work on&nbsp;<a href="http://en.wikipedia.org/wiki/Pugs" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Pugs">Pugs</a>, a Perl 6 interpreter written in&nbsp;<a href="http://en.wikipedia.org/wiki/Haskell_(programming_language)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Haskell (programming language)">Haskell</a>.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-29" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[29]</a></sup>&nbsp;This was the first concerted effort towards making Perl 6 a reality. This effort stalled in 2006.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-30" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[30]</a></sup></p>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">On May 20, 2012, Perl 5.16 was released. Notable new features include the ability to specify a given version of Perl that one wishes to emulate, allowing users to upgrade their version of Perl, but still run old scripts that would normally be incompatible.<sup id="cite_ref-5160delta_version_35-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5160delta_version-35" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[35]</a></sup>&nbsp;Perl 5.16 also updates the core to support&nbsp;<a href="http://en.wikipedia.org/wiki/Unicode" title="Unicode" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Unicode</a>&nbsp;6.1.<sup id="cite_ref-5160delta_version_35-1" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5160delta_version-35" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[35]</a></sup></p>
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<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">On May 18, 2013, Perl 5.18 was released. Notable new features include the new dtrace hooks, lexical subs, more CORE:: subs, overhaul of the hash for security reasons, support for Unicode 6.2.<sup id="cite_ref-5180delta_version_36-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5180delta_version-36" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[36]</a></sup></p>
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<p>On December 18, 2007, the 20th anniversary of Perl 1.0, Perl 5.10.0 was released. Perl 5.10.0 included notable new features, which brought it closer to&nbsp;<a href="http://en.wikipedia.org/wiki/Perl_6" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Perl 6">Perl 6</a>. These included a&nbsp;<a href="http://en.wikipedia.org/wiki/Switch_statement" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Switch statement">switch statement</a>&nbsp;(called &quot;given&quot;/&quot;when&quot;), regular expressions updates, and the smart match operator, &quot;~~&quot;.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5100delta-31" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[31]</a></sup><sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-perlsyn-smart-32" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[32]</a></sup>&nbsp;Around this same time, development began in earnest on another implementation of Perl 6 known as&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Rakudo_Perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Rakudo Perl">Rakudo Perl</a>, developed in tandem with the&nbsp;<a href="http://en.wikipedia.org/wiki/Parrot_virtual_machine" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Parrot virtual machine">Parrot virtual machine</a>. As of November 2009, Rakudo Perl has had regular monthly releases and now is the most complete implementation of&nbsp;<a href="http://en.wikipedia.org/wiki/Perl_6" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Perl 6">Perl 6</a>.</p>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">On May 27, 2014, Perl 5.20 was released. Notable new features include subroutine signatures, hash slices/new slice syntax, postfix dereferencing (experimental), Unicode 6.3, rand() using consistent random number generator.<sup id="cite_ref-5200delta_version_37-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5200delta_version-37" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[37]</a></sup></p>
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<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">Some observers credit the release of Perl 5.10 with the start of the Modern Perl movement.<sup id="cite_ref-38" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-38" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[38]</a></sup>&nbsp;In particular, this phrase describes a style of development that embraces the use of the CPAN, takes advantage of recent developments in the language, and is rigorous about creating high quality code.<sup id="cite_ref-39" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-39" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[39]</a></sup>&nbsp;While the book &quot;Modern Perl&quot;<sup id="cite_ref-40" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-40" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[40]</a></sup>&nbsp;may be the most visible standard-bearer of this idea, other groups such as the Enlightened Perl Organization<sup id="cite_ref-41" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-41" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[41]</a></sup>&nbsp;have taken up the cause.</p>
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<p>A major change in the development process of Perl 5 occurred with Perl 5.11; the development community has switched to a monthly release cycle of development releases, with a yearly schedule of stable releases. By that plan, bugfix point releases will follow the stable releases every three months.</p>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">In late 2012 and 2013 several projects for alternative implementations for Perl 5 started: Perl5 in&nbsp;<a href="http://en.wikipedia.org/wiki/Perl6" title="Perl6" class="mw-redirect" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Perl6</a>&nbsp;by the Rakudo Perl team,<sup id="cite_ref-42" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-42" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[42]</a></sup>&nbsp;<i>moe</i>&nbsp;by Stevan Little and friends,<sup id="cite_ref-43" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-43" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[43]</a></sup><i>p2</i><sup id="cite_ref-44" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-44" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[44]</a></sup>&nbsp;by the Perl11 team under Reini Urban,&nbsp;<i>gperl</i>&nbsp;by goccy,<sup id="cite_ref-45" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-45" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[45]</a></sup>&nbsp;and&nbsp;<i>rperl</i>&nbsp;a kickstarter project led by Will Braswell and affiliated with the Perll11 project.<sup id="cite_ref-46" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-46" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[46]</a></sup></p>
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<h3 style="margin: 0.3em 0px 0px; overflow: hidden; padding-top: 0.5em; padding-bottom: 0px; border-bottom-style: none; line-height: 1.6; font-family: sans-serif; background-image: none; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><span class="mw-headline" id="Name">Name</span></h3>
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<p>On April 12, 2010, Perl 5.12.0 was released. Notable core enhancements include new&nbsp;<code>package NAME VERSION</code>&nbsp;syntax, the Yada Yada operator (intended to mark placeholder code that is not yet implemented), implicit strictures, full&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Y2038" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Y2038">Y2038</a>&nbsp;compliance, regex conversion overloading,&nbsp;<a href="http://en.wikipedia.org/wiki/DTrace" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="DTrace">DTrace</a>&nbsp;support, and&nbsp;<a href="http://en.wikipedia.org/wiki/Unicode" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Unicode">Unicode</a>&nbsp;5.2.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5120delta-33" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[33]</a></sup>&nbsp;On January 21, 2011, Perl 5.12.3 was released; it contains updated modules and some documentation changes.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5123delta-34" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[34]</a></sup>&nbsp;Version 5.12.4 was released on June 20, 2011. The latest version of that branch, 5.12.5, was released on November 10, 2012.</p>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">Perl was originally named &quot;Pearl&quot;. Wall wanted to give the language a short name with positive connotations; he claims that he considered (and rejected) every three- and four-letter word in the dictionary. He also considered naming it after his wife Gloria. Wall discovered the existing&nbsp;<a href="http://en.wikipedia.org/wiki/PEARL_(programming_language)" title="PEARL (programming language)" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">PEARL</a>&nbsp;programming language before Perl's official release and changed the spelling of the name.<sup id="cite_ref-richardson1999_47-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-richardson1999-47" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[47]</a></sup></p>
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<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">When referring to the language, the name is normally capitalized (<i>Perl</i>) as a proper noun. When referring to the interpreter program itself, the name is often uncapitalized (<i>perl</i>) because most Unix-like file systems are case-sensitive. Before the release of the first edition of&nbsp;<i>Programming Perl</i>, it was common to refer to the language as&nbsp;<i>perl</i>;<a href="http://en.wikipedia.org/wiki/Randal_L._Schwartz" title="Randal L. Schwartz" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Randal L. Schwartz</a>, however, capitalized the language's name in the book to make it stand out better when typeset. This case distinction was subsequently documented as canonical.<sup id="cite_ref-capitalization_48-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-capitalization-48" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[48]</a></sup></p>
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<p>On May 14, 2011, Perl 5.14 was released.&nbsp;<a href="http://en.wikipedia.org/wiki/JSON" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="JSON">JSON</a>&nbsp;support is built-in as of 5.14.2. The latest version of that branch, 5.14.4, was released on March 10, 2013.</p>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">The name is occasionally expanded as&nbsp;<i>Practical Extraction and Report Language</i>, but this is a&nbsp;<a href="http://en.wikipedia.org/wiki/Backronym" title="Backronym" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">backronym</a>.<sup id="cite_ref-49" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-49" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[49]</a></sup>&nbsp;Other expansions have been suggested as equally canonical, including Wall's own humorous&nbsp;<i>Pathologically Eclectic Rubbish Lister</i>.<sup id="cite_ref-50" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-50" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[50]</a></sup>&nbsp;Indeed, Wall claims that the name was intended to inspire many different expansions.<sup id="cite_ref-51" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-51" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[51]</a></sup></p>
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<h3 style="margin: 0.3em 0px 0px; overflow: hidden; padding-top: 0.5em; padding-bottom: 0px; border-bottom-style: none; line-height: 1.6; font-family: sans-serif; background-image: none; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><span class="mw-headline" id="Camel_symbol">Camel symbol</span></h3>
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<p>On May 20, 2012, Perl 5.16 was released. Notable new features include the ability to specify a given version of Perl that one wishes to emulate, allowing users to upgrade their version of Perl, but still run old scripts that would normally be incompatible.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5160delta_version-35" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[35]</a></sup>&nbsp;Perl 5.16 also updates the core to support&nbsp;<a href="http://en.wikipedia.org/wiki/Unicode" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Unicode">Unicode</a>&nbsp;6.1.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5160delta_version-35" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[35]</a></sup></p>
<div class="thumb tright" style="clear: right; float: right; margin: 0.5em 0px 1.3em 1.4em; width: auto; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px; line-height: 17.9200000762939px;">
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<div class="thumbinner" style="min-width: 100px; border: 1px solid rgb(204, 204, 204); padding: 3px; font-size: 13.1600008010864px; text-align: center; overflow: hidden; width: 146px; background-color: rgb(249, 249, 249);"><a href="http://en.wikipedia.org/wiki/File:Perl-camel-small.png" class="image" style="text-decoration: none; color: rgb(11, 0, 128); background: none;"><img alt="" src="http://upload.wikimedia.org/wikipedia/en/0/00/Perl-camel-small.png" width="144" height="149" class="thumbimage" data-file-width="144" data-file-height="149" style="border: 1px solid rgb(204, 204, 204); vertical-align: middle; background-color: rgb(255, 255, 255);" /></a>
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<p>On May 18, 2013, Perl 5.18 was released. Notable new features include the new dtrace hooks, lexical subs, more CORE:: subs, overhaul of the hash for security reasons, support for Unicode 6.2.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5180delta_version-36" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[36]</a></sup></p>
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<div class="magnify" style="float: right; margin-left: 3px; margin-right: 0px;">&nbsp;</div>
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<p>On May 27, 2014, Perl 5.20 was released. Notable new features include subroutine signatures, hash slices/new slice syntax, postfix dereferencing (experimental), Unicode 6.3, rand() using consistent random number generator.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5200delta_version-37" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[37]</a></sup></p>
The Camel symbol used by O'Reilly Media</div>
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<p>Some observers credit the release of Perl 5.10 with the start of the Modern Perl movement.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-38" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[38]</a></sup>&nbsp;In particular, this phrase describes a style of development that embraces the use of the CPAN, takes advantage of recent developments in the language, and is rigorous about creating high quality code.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-39" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[39]</a></sup>&nbsp;While the book &quot;Modern Perl&quot;<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-40" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[40]</a></sup>&nbsp;may be the most visible standard-bearer of this idea, other groups such as the Enlightened Perl Organization<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-41" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[41]</a></sup>&nbsp;have taken up the cause.</p>
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<p>In late 2012 and 2013 several projects for alternative implementations for Perl 5 started: Perl5 in&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Perl6" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Perl6">Perl6</a>&nbsp;by the Rakudo Perl team,<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-42" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[42]</a></sup>&nbsp;<em>moe</em>&nbsp;by Stevan Little and friends,<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-43" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[43]</a></sup><em>p2</em><sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-44" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[44]</a></sup>&nbsp;by the Perl11 team under Reini Urban,&nbsp;<em>gperl</em>&nbsp;by goccy,<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-45" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[45]</a></sup>&nbsp;and&nbsp;<em>rperl</em>&nbsp;a kickstarter project led by Will Braswell and affiliated with the Perll11 project.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-46" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[46]</a></sup></p>
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<h3>Name</h3>
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<p>Perl was originally named &quot;Pearl&quot;. Wall wanted to give the language a short name with positive connotations; he claims that he considered (and rejected) every three- and four-letter word in the dictionary. He also considered naming it after his wife Gloria. Wall discovered the existing&nbsp;<a href="http://en.wikipedia.org/wiki/PEARL_(programming_language)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="PEARL (programming language)">PEARL</a>&nbsp;programming language before Perl&#39;s official release and changed the spelling of the name.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-richardson1999-47" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[47]</a></sup></p>
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<p>When referring to the language, the name is normally capitalized (<em>Perl</em>) as a proper noun. When referring to the interpreter program itself, the name is often uncapitalized (<em>perl</em>) because most Unix-like file systems are case-sensitive. Before the release of the first edition of&nbsp;<em>Programming Perl</em>, it was common to refer to the language as&nbsp;<em>perl</em>;<a href="http://en.wikipedia.org/wiki/Randal_L._Schwartz" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Randal L. Schwartz">Randal L. Schwartz</a>, however, capitalized the language&#39;s name in the book to make it stand out better when typeset. This case distinction was subsequently documented as canonical.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-capitalization-48" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[48]</a></sup></p>
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<p>The name is occasionally expanded as&nbsp;<em>Practical Extraction and Report Language</em>, but this is a&nbsp;<a href="http://en.wikipedia.org/wiki/Backronym" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Backronym">backronym</a>.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-49" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[49]</a></sup>&nbsp;Other expansions have been suggested as equally canonical, including Wall&#39;s own humorous&nbsp;<em>Pathologically Eclectic Rubbish Lister</em>.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-50" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[50]</a></sup>&nbsp;Indeed, Wall claims that the name was intended to inspire many different expansions.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-51" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[51]</a></sup></p>
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<h3>Camel symbol</h3>
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<div class="thumb tright" style="font-size: 14px; font-family: sans-serif; width: auto; float: right; color: rgb(37,37,37); clear: right; margin: 0.5em 0px 1.3em 1.4em; line-height: 17px">
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<div class="thumbinner" style="font-size: 13px; overflow: hidden; border-top: rgb(204,204,204) 1px solid; border-right: rgb(204,204,204) 1px solid; width: 146px; min-width: 100px; border-bottom: rgb(204,204,204) 1px solid; padding-bottom: 3px; text-align: center; padding-top: 3px; padding-left: 3px; border-left: rgb(204,204,204) 1px solid; padding-right: 3px; background-color: rgb(249,249,249)"><a class="image" href="http://en.wikipedia.org/wiki/File:Perl-camel-small.png" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)"><img alt="" class="thumbimage" src="http://upload.wikimedia.org/wikipedia/en/0/00/Perl-camel-small.png" style="background-color:rgb(255,255,255); border-bottom:rgb(204,204,204) 1px solid; border-left:rgb(204,204,204) 1px solid; border-right:rgb(204,204,204) 1px solid; border-top:rgb(204,204,204) 1px solid; height:149px; vertical-align:middle; width:144px" /></a>
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<div class="thumbcaption" style="font-size: 12px; border-top: medium none; border-right: medium none; border-bottom: medium none; padding-bottom: 3px; text-align: left; padding-top: 3px; padding-left: 3px; border-left: medium none; line-height: 1.4em; padding-right: 3px">
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<div class="magnify" style="float: right; margin-left: 3px; margin-right: 0px">&nbsp;</div>
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The Camel symbol used by O&#39;Reilly Media</div>
 
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<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;"><i>Programming Perl</i>, published by&nbsp;<a href="http://en.wikipedia.org/wiki/O%27Reilly_Media" title="O'Reilly Media" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">O'Reilly Media</a>, features a picture of a&nbsp;<a href="http://en.wikipedia.org/wiki/Camel" title="Camel" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">dromedary camel</a>&nbsp;on the cover and is commonly called the &quot;Camel Book&quot;.<sup id="cite_ref-schwartz01_52-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-schwartz01-52" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[52]</a></sup>&nbsp;This image of a camel has become an unofficial symbol of Perl as well as a general&nbsp;<a href="http://en.wikipedia.org/wiki/Hacker_(programmer_subculture)" title="Hacker (programmer subculture)" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">hacker</a>&nbsp;emblem, appearing on T-shirts and other clothing items.</p>
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<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">O'Reilly owns the image as a&nbsp;<a href="http://en.wikipedia.org/wiki/Trademark" title="Trademark" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">trademark</a>&nbsp;but licenses it for&nbsp;<a href="http://en.wikipedia.org/wiki/Non-commercial" title="Non-commercial" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">non-commercial</a>&nbsp;use, requiring only an acknowledgement and a link to www.perl.com. Licensing for commercial use is decided on a case by case basis.<sup id="cite_ref-camel_53-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-camel-53" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[53]</a></sup>&nbsp;O'Reilly also provides &quot;Programming Republic of Perl&quot; logos for non-commercial sites and &quot;Powered by Perl&quot; buttons for any site that uses Perl.<sup id="cite_ref-camel_53-1" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-camel-53" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[53]</a></sup></p>
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<p><em>Programming Perl</em>, published by&nbsp;<a href="http://en.wikipedia.org/wiki/O%27Reilly_Media" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="O'Reilly Media">O&#39;Reilly Media</a>, features a picture of a&nbsp;<a href="http://en.wikipedia.org/wiki/Camel" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Camel">dromedary camel</a>&nbsp;on the cover and is commonly called the &quot;Camel Book&quot;.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-schwartz01-52" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[52]</a></sup>&nbsp;This image of a camel has become an unofficial symbol of Perl as well as a general&nbsp;<a href="http://en.wikipedia.org/wiki/Hacker_(programmer_subculture)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Hacker (programmer subculture)">hacker</a>&nbsp;emblem, appearing on T-shirts and other clothing items.</p>
<h3 style="margin: 0.3em 0px 0px; overflow: hidden; padding-top: 0.5em; padding-bottom: 0px; border-bottom-style: none; line-height: 1.6; font-family: sans-serif; background-image: none; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><span class="mw-headline" id="Onion_symbol">Onion symbol</span></h3>
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<div class="thumb tright" style="clear: right; float: right; margin: 0.5em 0px 1.3em 1.4em; width: auto; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px; line-height: 17.9200000762939px;">
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<p>O&#39;Reilly owns the image as a&nbsp;<a href="http://en.wikipedia.org/wiki/Trademark" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Trademark">trademark</a>&nbsp;but licenses it for&nbsp;<a href="http://en.wikipedia.org/wiki/Non-commercial" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Non-commercial">non-commercial</a>&nbsp;use, requiring only an acknowledgement and a link to www.perl.com. Licensing for commercial use is decided on a case by case basis.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-camel-53" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[53]</a></sup>&nbsp;O&#39;Reilly also provides &quot;Programming Republic of Perl&quot; logos for non-commercial sites and &quot;Powered by Perl&quot; buttons for any site that uses Perl.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-camel-53" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[53]</a></sup></p>
<div class="thumbinner" style="min-width: 100px; border: 1px solid rgb(204, 204, 204); padding: 3px; font-size: 13.1600008010864px; text-align: center; overflow: hidden; width: 66px; background-color: rgb(249, 249, 249);"><a href="http://en.wikipedia.org/wiki/File:Onion_64x64.png" class="image" style="text-decoration: none; color: rgb(11, 0, 128); background: none;"><img alt="" src="http://upload.wikimedia.org/wikipedia/en/a/a4/Onion_64x64.png" width="64" height="64" class="thumbimage" data-file-width="64" data-file-height="64" style="border: 1px solid rgb(204, 204, 204); vertical-align: middle; background-color: rgb(255, 255, 255);" /></a>
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<div class="thumbcaption" style="border: none; line-height: 1.4em; padding: 3px; font-size: 12.370400428772px; text-align: left;">
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<h3>Onion symbol</h3>
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<div class="thumb tright" style="font-size: 14px; font-family: sans-serif; width: auto; float: right; color: rgb(37,37,37); clear: right; margin: 0.5em 0px 1.3em 1.4em; line-height: 17px">
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<div class="thumbinner" style="font-size: 13px; overflow: hidden; border-top: rgb(204,204,204) 1px solid; border-right: rgb(204,204,204) 1px solid; width: 66px; min-width: 100px; border-bottom: rgb(204,204,204) 1px solid; padding-bottom: 3px; text-align: center; padding-top: 3px; padding-left: 3px; border-left: rgb(204,204,204) 1px solid; padding-right: 3px; background-color: rgb(249,249,249)"><a class="image" href="http://en.wikipedia.org/wiki/File:Onion_64x64.png" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)"><img alt="" class="thumbimage" src="http://upload.wikimedia.org/wikipedia/en/a/a4/Onion_64x64.png" style="background-color:rgb(255,255,255); border-bottom:rgb(204,204,204) 1px solid; border-left:rgb(204,204,204) 1px solid; border-right:rgb(204,204,204) 1px solid; border-top:rgb(204,204,204) 1px solid; height:64px; vertical-align:middle; width:64px" /></a>
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<div class="thumbcaption" style="font-size: 12px; border-top: medium none; border-right: medium none; border-bottom: medium none; padding-bottom: 3px; text-align: left; padding-top: 3px; padding-left: 3px; border-left: medium none; line-height: 1.4em; padding-right: 3px">
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<div class="magnify" style="float: right; margin-left: 3px; margin-right: 0px">&nbsp;</div>
 
The onion logo used by The Perl Foundation</div>
 
The onion logo used by The Perl Foundation</div>
 
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</div>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;"><a href="http://en.wikipedia.org/wiki/
+
 
 +
<p><a class="mw-redirect" href="http://en.wikipedia.org/wiki/The_Perl_Foundation" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="The Perl Foundation">The Perl Foundation</a>&nbsp;owns an alternative symbol, an onion, which it licenses to its subsidiaries,&nbsp;<a href="http://en.wikipedia.org/wiki/Perl_Mongers" style="text-decoration: none;
 
</div>
 
</div>
 
</div>
 
</div>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">At the 2000&nbsp;<a href="http://en.wikipedia.org/wiki/O%27Reilly_Open_Source_Convention" title="O'Reilly Open Source Convention" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Perl Conference</a>,&nbsp;<a href="http://en.wikipedia.org/w/index.php?title=Jon_Orwant&amp;action=edit&amp;redlink=1" class="new" title="Jon Orwant (page does not exist)" style="text-decoration: none; color: rgb(165, 88, 88); background: none;">Jon Orwant</a>&nbsp;made a case for a major new language-initiative.<sup id="cite_ref-85" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-85" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[85]</a></sup>&nbsp;This led to a decision to begin work on a redesign of the language, to be called Perl 6. Proposals for new language features were solicited from the Perl community at large, which submitted more than 300&nbsp;<a href="http://en.wikipedia.org/wiki/Request_for_Comments" title="Request for Comments" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">RFCs</a>.</p>
+
 
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">Wall spent the next few years digesting the RFCs and synthesizing them into a coherent framework for Perl 6. He has presented his design for Perl 6 in a series of documents called &quot;apocalypses&quot; - numbered to correspond to chapters in&nbsp;<i>Programming Perl</i>. As of January 2011, the developing specification of Perl 6 is encapsulated in design documents called Synopses - numbered to correspond to Apocalypses.<sup id="cite_ref-syn6_86-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-syn6-86" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[86]</a></sup></p>
+
<p>At the 2000&nbsp;<a href="http://en.wikipedia.org/wiki/O%27Reilly_Open_Source_Convention" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="O'Reilly Open Source Convention">Perl Conference</a>,&nbsp;<a class="new" href="http://en.wikipedia.org/w/index.php?title=Jon_Orwant&amp;action=edit&amp;redlink=1" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(165,88,88)" title="Jon Orwant (page does not exist)">Jon Orwant</a>&nbsp;made a case for a major new language-initiative.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-85" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[85]</a></sup>&nbsp;This led to a decision to begin work on a redesign of the language, to be called Perl 6. Proposals for new language features were solicited from the Perl community at large, which submitted more than 300&nbsp;<a href="http://en.wikipedia.org/wiki/Request_for_Comments" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Request for Comments">RFCs</a>.</p>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">Perl 6 is not intended to be backward compatible, although there will be a compatibility mode. Perl 6 and Perl 5 are distinct languages with a common ancestry.<sup id="cite_ref-perl6dev_87-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-perl6dev-87" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[87]</a></sup></p>
+
 
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">Thesis work by&nbsp;<a href="http://en.wikipedia.org/wiki/Bradley_M._Kuhn" title="Bradley M. Kuhn" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Bradley M. Kuhn</a>, overseen by Wall, considered the possible use of the&nbsp;<a href="http://en.wikipedia.org/wiki/Java_virtual_machine" title="Java virtual machine" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Java virtual machine</a>&nbsp;as a runtime for Perl.<sup id="cite_ref-88" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-88" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[88]</a></sup>&nbsp;Kuhn's thesis showed this approach to be problematic. In 2001, it was decided that Perl 6 would run on a cross-language&nbsp;<a href="http://en.wikipedia.org/wiki/Virtual_machine" title="Virtual machine" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">virtual machine</a>&nbsp;called&nbsp;<a href="http://en.wikipedia.org/wiki/Parrot_virtual_machine" title="Parrot virtual machine" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Parrot</a>. This will mean that other languages targeting the Parrot will gain native access to&nbsp;<a href="http://en.wikipedia.org/wiki/CPAN" title="CPAN" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">CPAN</a>, allowing some level of cross-language development.</p>
+
<p>Wall spent the next few years digesting the RFCs and synthesizing them into a coherent framework for Perl 6. He has presented his design for Perl 6 in a series of documents called &quot;apocalypses&quot; - numbered to correspond to chapters in&nbsp;<em>Programming Perl</em>. As of January 2011, the developing specification of Perl 6 is encapsulated in design documents called Synopses - numbered to correspond to Apocalypses.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-syn6-86" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[86]</a></sup></p>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">In 2005,&nbsp;<a href="http://en.wikipedia.org/wiki/Audrey_Tang" title="Audrey Tang" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Audrey Tang</a>&nbsp;created the&nbsp;<a href="http://en.wikipedia.org/wiki/Pugs" title="Pugs" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">pugs</a>&nbsp;project, an implementation of Perl 6 in&nbsp;<a href="http://en.wikipedia.org/wiki/Haskell_(programming_language)" title="Haskell (programming language)" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Haskell</a>. This acted as, and continues to act as, a test platform for the Perl 6 language (separate from the development of the actual implementation) - allowing the language designers to explore. The pugs project spawned an active Perl/Haskell cross-language community centered around the&nbsp;<a href="http://en.wikipedia.org/wiki/Freenode" title="Freenode" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">freenode</a>&nbsp;#perl6 IRC channel.</p>
+
 
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">As of 2012, a number of features in the Perl 6 language show similarities to Haskell.</p>
+
<p>Perl 6 is not intended to be backward compatible, although there will be a compatibility mode. Perl 6 and Perl 5 are distinct languages with a common ancestry.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-perl6dev-87" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[87]</a></sup></p>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">As of 2012, Perl 6 development centers primarily around two compilers:<sup id="cite_ref-89" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-89" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[89]</a></sup></p>
+
 
<ol style="line-height: 1.5em; margin: 0.3em 0px 0px 3.2em; padding: 0px; list-style-image: none; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">
+
<p>Thesis work by&nbsp;<a href="http://en.wikipedia.org/wiki/Bradley_M._Kuhn" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Bradley M. Kuhn">Bradley M. Kuhn</a>, overseen by Wall, considered the possible use of the&nbsp;<a href="http://en.wikipedia.org/wiki/Java_virtual_machine" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Java virtual machine">Java virtual machine</a>&nbsp;as a runtime for Perl.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-88" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[88]</a></sup>&nbsp;Kuhn&#39;s thesis showed this approach to be problematic. In 2001, it was decided that Perl 6 would run on a cross-language&nbsp;<a href="http://en.wikipedia.org/wiki/Virtual_machine" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Virtual machine">virtual machine</a>&nbsp;called&nbsp;<a href="http://en.wikipedia.org/wiki/Parrot_virtual_machine" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Parrot virtual machine">Parrot</a>. This will mean that other languages targeting the Parrot will gain native access to&nbsp;<a href="http://en.wikipedia.org/wiki/CPAN" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="CPAN">CPAN</a>, allowing some level of cross-language development.</p>
    <li style="margin-bottom: 0.1em;"><a href="http://en.wikipedia.org/wiki/Rakudo_Perl_6" title="Rakudo Perl 6" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Rakudo Perl 6</a>, an implementation running on the&nbsp;<a href="http://en.wikipedia.org/wiki/Parrot_virtual_machine" title="Parrot virtual machine" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Parrot virtual machine</a>&nbsp;and the&nbsp;<a href="http://en.wikipedia.org/wiki/Java_virtual_machine" title="Java virtual machine" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Java virtual machine</a>.<sup id="cite_ref-90" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-90" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[90]</a></sup>&nbsp;Developers are also working on&nbsp;<a href="http://en.wikipedia.org/wiki/MoarVM" title="MoarVM" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">MoarVM</a>, a C language-based virtual machine designed specifically for Rakudo.<sup id="cite_ref-91" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-91" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[91]</a></sup></li>
+
 
    <li style="margin-bottom: 0.1em;"><a href="http://en.wikipedia.org/wiki/Niecza" title="Niecza" class="mw-redirect" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Niecza</a>, which targets the&nbsp;<a href="http://en.wikipedia.org/wiki/Common_Language_Runtime" title="Common Language Runtime" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Common Language Runtime</a>.</li>
+
<p>In 2005,&nbsp;<a href="http://en.wikipedia.org/wiki/Audrey_Tang" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Audrey Tang">Audrey Tang</a>&nbsp;created the&nbsp;<a href="http://en.wikipedia.org/wiki/Pugs" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Pugs">pugs</a>&nbsp;project, an implementation of Perl 6 in&nbsp;<a href="http://en.wikipedia.org/wiki/Haskell_(programming_language)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Haskell (programming language)">Haskell</a>. This acted as, and continues to act as, a test platform for the Perl 6 language (separate from the development of the actual implementation) - allowing the language designers to explore. The pugs project spawned an active Perl/Haskell cross-language community centered around the&nbsp;<a href="http://en.wikipedia.org/wiki/Freenode" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Freenode">freenode</a>&nbsp;#perl6 IRC channel.</p>
 +
 
 +
<p>As of 2012, a number of features in the Perl 6 language show similarities to Haskell.</p>
 +
 
 +
<p>As of 2012, Perl 6 development centers primarily around two compilers:<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-89" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[89]</a></sup></p>
 +
 
 +
<ol>
 +
<li><a href="http://en.wikipedia.org/wiki/Rakudo_Perl_6" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Rakudo Perl 6">Rakudo Perl 6</a>, an implementation running on the&nbsp;<a href="http://en.wikipedia.org/wiki/Parrot_virtual_machine" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Parrot virtual machine">Parrot virtual machine</a>&nbsp;and the&nbsp;<a href="http://en.wikipedia.org/wiki/Java_virtual_machine" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Java virtual machine">Java virtual machine</a>.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-90" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[90]</a></sup>&nbsp;Developers are also working on&nbsp;<a href="http://en.wikipedia.org/wiki/MoarVM" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="MoarVM">MoarVM</a>, a C language-based virtual machine designed specifically for Rakudo.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-91" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[91]</a></sup></li>
 +
<li><a class="mw-redirect" href="http://en.wikipedia.org/wiki/Niecza" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Niecza">Niecza</a>, which targets the&nbsp;<a href="http://en.wikipedia.org/wiki/Common_Language_Runtime" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Common Language Runtime">Common Language Runtime</a>.</li>
 
</ol>
 
</ol>
<h2 style="font-weight: normal; margin: 1em 0px 0.25em; overflow: hidden; padding: 0px; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(170, 170, 170); font-family: 'Linux Libertine', Georgia, Times, serif; line-height: 1.3; background-image: none; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><span class="mw-headline" id="Future_of_Perl_5">Future of Perl 5</span><span class="mw-editsection" style="-webkit-user-select: none; font-size: small; margin-left: 1em; vertical-align: baseline; line-height: 1em; display: inline-block; white-space: nowrap; unicode-bidi: -webkit-isolate; font-family: sans-serif;"><span class="mw-editsection-bracket" style="margin-right: 0px; color: rgb(85, 85, 85); margin-left: 0px;">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=19" title="Edit section: Future of Perl 5" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">edit</a><span class="mw-editsection-bracket" style="margin-left: 0px; color: rgb(85, 85, 85); margin-right: 0px;">]</span></span></h2>
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<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">Development of Perl 5 is also continuing. Perl 5.12.0 was released in April 2010 with some new features influenced by the design of Perl 6.,<sup id="cite_ref-5120delta_33-1" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5120delta-33" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[33]</a></sup><sup id="cite_ref-heise2010_92-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-heise2010-92" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[92]</a></sup>&nbsp;followed by Perl 5.14.1 (released on June 17, 2011), Perl 5.16.1 (released on August 9, 2012.<sup id="cite_ref-93" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-93" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[93]</a></sup>), and Perl 5.18.0 (released on May 18, 2013). Perl 5 development versions are released on a monthly basis, with major releases coming out once per year.<sup id="cite_ref-94" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-94" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[94]</a></sup></p>
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<h2>Future of Perl 5<span style="font-family:sans-serif; font-size:small"><span style="color:rgb(85,85,85)">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=19" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Edit section: Future of Perl 5">edit</a><span style="color:rgb(85,85,85)">]</span></span></h2>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">Future plans for Perl 5 include making the core language easier to extend from modules, and providing a small, extensible&nbsp;<a href="http://en.wikipedia.org/wiki/Meta-object_protocol" title="Meta-object protocol" class="mw-redirect" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Meta-object protocol</a>&nbsp;in core.<sup id="cite_ref-95" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-95" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[95]</a></sup></p>
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<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">The relative proportion of searches for 'Perl programming', as compared with similar searches for other programming languages, steadily declined from about 10% in 2005 to about 2% in 2011, and has remained around the 2% level since.<sup id="cite_ref-96" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-96" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[96]</a></sup></p>
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<p>Development of Perl 5 is also continuing. Perl 5.12.0 was released in April 2010 with some new features influenced by the design of Perl 6.,<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-5120delta-33" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[33]</a></sup><sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-heise2010-92" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[92]</a></sup>&nbsp;followed by Perl 5.14.1 (released on June 17, 2011), Perl 5.16.1 (released on August 9, 2012.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-93" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[93]</a></sup>), and Perl 5.18.0 (released on May 18, 2013). Perl 5 development versions are released on a monthly basis, with major releases coming out once per year.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-94" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[94]</a></sup></p>
<h2 style="font-weight: normal; margin: 1em 0px 0.25em; overflow: hidden; padding: 0px; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(170, 170, 170); font-family: 'Linux Libertine', Georgia, Times, serif; line-height: 1.3; background-image: none; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><span class="mw-headline" id="Perl_community">Perl community</span><span class="mw-editsection" style="-webkit-user-select: none; font-size: small; margin-left: 1em; vertical-align: baseline; line-height: 1em; display: inline-block; white-space: nowrap; unicode-bidi: -webkit-isolate; font-family: sans-serif;"><span class="mw-editsection-bracket" style="margin-right: 0px; color: rgb(85, 85, 85); margin-left: 0px;">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=20" title="Edit section: Perl community" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">edit</a><span class="mw-editsection-bracket" style="margin-left: 0px; color: rgb(85, 85, 85); margin-right: 0px;">]</span></span></h2>
+
 
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">Perl's culture and community has developed alongside the language itself.&nbsp;<a href="http://en.wikipedia.org/wiki/Usenet" title="Usenet" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Usenet</a>&nbsp;was the first public venue in which Perl was introduced, but over the course of its evolution, Perl's community was shaped by the growth of broadening Internet-based services including the introduction of the World Wide Web. The community that surrounds Perl was, in fact, the topic of Wall's first &quot;State of the Onion&quot; talk.<sup id="cite_ref-97" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-97" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[97]</a></sup></p>
+
<p>Future plans for Perl 5 include making the core language easier to extend from modules, and providing a small, extensible&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Meta-object_protocol" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Meta-object protocol">Meta-object protocol</a>&nbsp;in core.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-95" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[95]</a></sup></p>
<h3 style="margin: 0.3em 0px 0px; overflow: hidden; padding-top: 0.5em; padding-bottom: 0px; border-bottom-style: none; line-height: 1.6; font-family: sans-serif; background-image: none; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><span class="mw-headline" id="State_of_the_Onion">State of the Onion</span><span class="mw-editsection" style="-webkit-user-select: none; font-size: small; font-weight: normal; margin-left: 1em; vertical-align: baseline; line-height: 1em; display: inline-block; white-space: nowrap; unicode-bidi: -webkit-isolate;"><span class="mw-editsection-bracket" style="margin-right: 0px; color: rgb(85, 85, 85); margin-left: 0px;">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=21" title="Edit section: State of the Onion" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">edit</a><span class="mw-editsection-bracket" style="margin-left: 0px; color: rgb(85, 85, 85); margin-right: 0px;">]</span></span></h3>
+
 
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">State of the Onion is the name for Wall&rsquo;s yearly&nbsp;<a href="http://en.wikipedia.org/wiki/Keynote" title="Keynote" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">keynote</a>-style summaries on the progress of Perl and its community. They are characterized by his hallmark humor, employing references to Perl&rsquo;s culture, the wider hacker culture, Wall&rsquo;s linguistic background, sometimes his family life, and occasionally even his&nbsp;<a href="http://en.wikipedia.org/wiki/Christian" title="Christian" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Christian</a>&nbsp;background.<sup id="cite_ref-98" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-98" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[98]</a></sup></p>
+
<p>The relative proportion of searches for &#39;Perl programming&#39;, as compared with similar searches for other programming languages, steadily declined from about 10% in 2005 to about 2% in 2011, and has remained around the 2% level since.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-96" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[96]</a></sup></p>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">Each talk is first given at various Perl conferences and is eventually also published online.</p>
+
 
<h3 style="margin: 0.3em 0px 0px; overflow: hidden; padding-top: 0.5em; padding-bottom: 0px; border-bottom-style: none; line-height: 1.6; font-family: sans-serif; background-image: none; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><span class="mw-headline" id="Perl_pastimes">Perl pastimes</span><span class="mw-editsection" style="-webkit-user-select: none; font-size: small; font-weight: normal; margin-left: 1em; vertical-align: baseline; line-height: 1em; display: inline-block; white-space: nowrap; unicode-bidi: -webkit-isolate;"><span class="mw-editsection-bracket" style="margin-right: 0px; color: rgb(85, 85, 85); margin-left: 0px;">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=22" title="Edit section: Perl pastimes" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">edit</a><span class="mw-editsection-bracket" style="margin-left: 0px; color: rgb(85, 85, 85); margin-right: 0px;">]</span></span></h3>
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<h2>Perl community<span style="font-family:sans-serif; font-size:small"><span style="color:rgb(85,85,85)">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=20" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Edit section: Perl community">edit</a><span style="color:rgb(85,85,85)">]</span></span></h2>
<dl style="margin-top: 0.2em; margin-bottom: 0.5em; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px; line-height: 17.9200000762939px;"><dt style="font-weight: bold; margin-bottom: 0.1em;">JAPHs</dt><dd style="line-height: 1.5em; margin-left: 1.6em; margin-bottom: 0.1em; margin-right: 0px;">In email, Usenet, and message board postings, &quot;<a href="http://en.wikipedia.org/wiki/Just_another_Perl_hacker" title="Just another Perl hacker" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Just another Perl hacker</a>&quot; (JAPH) programs are a common trend, originated by&nbsp;<a href="http://en.wikipedia.org/wiki/Randal_L._Schwartz" title="Randal L. Schwartz" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Randal L. Schwartz</a>, one of the earliest professional Perl trainers.<sup id="cite_ref-99" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-99" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[99]</a></sup>&nbsp;In the parlance of Perl culture, Perl programmers are known as Perl hackers, and from this derives the practice of writing short programs to print out the phrase &quot;<a href="http://en.wikipedia.org/wiki/Just_another_Perl_hacker" title="Just another Perl hacker" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Just another Perl hacker</a>,&quot;. In the spirit of the original concept, these programs are moderately obfuscated and short enough to fit into the signature of an email or Usenet message. The &quot;canonical&quot; JAPH as developed by Schwartz includes the comma at the end, although this is often omitted.<sup id="cite_ref-100" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-100" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[100]</a></sup></dd><dt style="font-weight: bold; margin-bottom: 0.1em;">Perl golf</dt><dd style="line-height: 1.5em; margin-left: 1.6em; margin-bottom: 0.1em; margin-right: 0px;">Perl &quot;golf&quot; is the pastime of reducing the number of characters (key &quot;strokes&quot;) used in a Perl program to the bare minimum, much in the same way that&nbsp;<a href="http://en.wikipedia.org/wiki/Golf" title="Golf" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">golf</a>&nbsp;players seek to take as few shots as possible in a round. The phrase's first use<sup id="cite_ref-perl-golf-coined_101-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-perl-golf-coined-101" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[101]</a></sup>&nbsp;emphasized the difference between pedestrian code meant to teach a newcomer and terse hacks likely to amuse experienced Perl programmers, an example of the latter being&nbsp;<a href="http://en.wikipedia.org/wiki/JAPH" title="JAPH" class="mw-redirect" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">JAPHs</a>&nbsp;that were already used in signatures in Usenet postings and elsewhere. Similar stunts had been an unnamed pastime in the language&nbsp;<a href="http://en.wikipedia.org/wiki/APL_(programming_language)" title="APL (programming language)" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">APL</a>&nbsp;in previous decades. The use of Perl to write a program that performed&nbsp;<a href="http://en.wikipedia.org/wiki/RSA_(algorithm)" title="RSA (algorithm)" class="mw-redirect" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">RSA</a>&nbsp;encryption prompted a widespread and practical interest in this pastime.<sup id="cite_ref-rsa_102-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-rsa-102" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[102]</a></sup>&nbsp;In subsequent years, the term &quot;<a href="http://en.wikipedia.org/wiki/Code_golf" title="Code golf" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">code golf</a>&quot; has been applied to the pastime in other languages.<sup id="cite_ref-103" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-103" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[103]</a></sup>&nbsp;A&nbsp;<a href="http://en.wikipedia.org/wiki/Perl_Golf_Apocalypse" title="Perl Golf Apocalypse" class="mw-redirect" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Perl Golf Apocalypse</a>&nbsp;was held at Perl Conference 4.0 in Monterey, California in July 2000.</dd><dt style="font-weight: bold; margin-bottom: 0.1em;">Obfuscation</dt><dd style="line-height: 1.5em; margin-left: 1.6em; margin-bottom: 0.1em; margin-right: 0px;">As with C,&nbsp;<a href="http://en.wikipedia.org/wiki/Obfuscated_code" title="Obfuscated code" class="mw-redirect" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">obfuscated code</a>&nbsp;competitions were a well known pastime in the late 1990s. The&nbsp;<a href="http://en.wikipedia.org/wiki/Obfuscated_Perl_Contest" title="Obfuscated Perl Contest" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Obfuscated Perl Contest</a>&nbsp;was a competition held by&nbsp;<a href="http://en.wikipedia.org/w/index.php?title=The_Perl_Journal&amp;action=edit&amp;redlink=1" class="new" title="The Perl Journal (page does not exist)" style="text-decoration: none; color: rgb(165, 88, 88); background: none;">The Perl Journal</a>&nbsp;from 1996 to 2000 that made an arch virtue of Perl's syntactic flexibility. Awards were given for categories such as &quot;most powerful&quot;&mdash;programs that made efficient use of space&mdash;and &quot;best four-line signature&quot; for programs that fit into four lines of 76 characters in the style of a Usenet&nbsp;<a href="http://en.wikipedia.org/wiki/Signature_block" title="Signature block" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">signature block</a>.<sup id="cite_ref-gallo03_104-0" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-gallo03-104" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[104]</a></sup></dd><dt style="font-weight: bold; margin-bottom: 0.1em;">Poetry</dt><dd style="line-height: 1.5em; margin-left: 1.6em; margin-bottom: 0.1em; margin-right: 0px;">Perl poetry is the practice of writing poems that can be compiled as legal Perl code, for example the piece known as&nbsp;<a href="http://en.wikipedia.org/wiki/Black_Perl" title="Black Perl" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Black Perl</a>. Perl poetry is made possible by the large number of English words that are used in the Perl language. New poems are regularly submitted to the community at&nbsp;<a href="http://en.wikipedia.org/wiki/PerlMonks" title="PerlMonks" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">PerlMonks</a>.<sup id="cite_ref-105" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-105" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[105]</a></sup></dd></dl>
+
 
<h3 style="margin: 0.3em 0px 0px; overflow: hidden; padding-top: 0.5em; padding-bottom: 0px; border-bottom-style: none; line-height: 1.6; font-family: sans-serif; background-image: none; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><span class="mw-headline" id="Perl_on_IRC">Perl on IRC</span><span class="mw-editsection" style="-webkit-user-select: none; font-size: small; font-weight: normal; margin-left: 1em; vertical-align: baseline; line-height: 1em; display: inline-block; white-space: nowrap; unicode-bidi: -webkit-isolate;"><span class="mw-editsection-bracket" style="margin-right: 0px; color: rgb(85, 85, 85); margin-left: 0px;">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=23" title="Edit section: Perl on IRC" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">edit</a><span class="mw-editsection-bracket" style="margin-left: 0px; color: rgb(85, 85, 85); margin-right: 0px;">]</span></span></h3>
+
<p>Perl&#39;s culture and community has developed alongside the language itself.&nbsp;<a href="http://en.wikipedia.org/wiki/Usenet" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Usenet">Usenet</a>&nbsp;was the first public venue in which Perl was introduced, but over the course of its evolution, Perl&#39;s community was shaped by the growth of broadening Internet-based services including the introduction of the World Wide Web. The community that surrounds Perl was, in fact, the topic of Wall&#39;s first &quot;State of the Onion&quot; talk.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-97" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[97]</a></sup></p>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">There are a number of&nbsp;<a href="http://en.wikipedia.org/wiki/Internet_Relay_Chat" title="Internet Relay Chat" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">IRC</a>&nbsp;channels that offer support for the language and some modules.</p>
+
 
<table class="wikitable" style="font-size: 14px; margin: 1em 0px; border-style: solid; border-color: rgb(170, 170, 170); border-collapse: collapse; color: black; font-family: sans-serif; line-height: 17.9200000762939px; background-color: rgb(249, 249, 249);">
+
<h3>State of the Onion<span style="font-size:small"><span style="color:rgb(85,85,85)">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=21" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Edit section: State of the Onion">edit</a><span style="color:rgb(85,85,85)">]</span></span></h3>
    <tbody>
+
 
        <tr>
+
<p>State of the Onion is the name for Wall&rsquo;s yearly&nbsp;<a href="http://en.wikipedia.org/wiki/Keynote" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Keynote">keynote</a>-style summaries on the progress of Perl and its community. They are characterized by his hallmark humor, employing references to Perl&rsquo;s culture, the wider hacker culture, Wall&rsquo;s linguistic background, sometimes his family life, and occasionally even his&nbsp;<a href="http://en.wikipedia.org/wiki/Christian" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Christian">Christian</a>&nbsp;background.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-98" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[98]</a></sup></p>
            <th style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em; text-align: center; background-color: rgb(242, 242, 242);">IRC Network</th>
+
 
            <th style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em; text-align: center; background-color: rgb(242, 242, 242);">Channels</th>
+
<p>Each talk is first given at various Perl conferences and is eventually also published online.</p>
        </tr>
+
 
        <tr>
+
<h3>Perl pastimes<span style="font-size:small"><span style="color:rgb(85,85,85)">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=22" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Edit section: Perl pastimes">edit</a><span style="color:rgb(85,85,85)">]</span></span></h3>
            <td style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em;">irc.freenode.net</td>
+
 
            <td style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em;">#perl #perl6 #cbstream #perlcafe #poe</td>
+
<p>JAPHs</p>
        </tr>
+
 
        <tr>
+
<p>In email, Usenet, and message board postings, &quot;<a href="http://en.wikipedia.org/wiki/Just_another_Perl_hacker" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Just another Perl hacker">Just another Perl hacker</a>&quot; (JAPH) programs are a common trend, originated by&nbsp;<a href="http://en.wikipedia.org/wiki/Randal_L._Schwartz" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Randal L. Schwartz">Randal L. Schwartz</a>, one of the earliest professional Perl trainers.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-99" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[99]</a></sup>&nbsp;In the parlance of Perl culture, Perl programmers are known as Perl hackers, and from this derives the practice of writing short programs to print out the phrase &quot;<a href="http://en.wikipedia.org/wiki/Just_another_Perl_hacker" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Just another Perl hacker">Just another Perl hacker</a>,&quot;. In the spirit of the original concept, these programs are moderately obfuscated and short enough to fit into the signature of an email or Usenet message. The &quot;canonical&quot; JAPH as developed by Schwartz includes the comma at the end, although this is often omitted.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-100" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[100]</a></sup></p>
            <td style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em;">irc.perl.org</td>
+
 
            <td style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em;">#moose #poe #catalyst #dbix-class #perl-help #distzilla #epo #corehackers #sdl #win32 #toolchain #padre #dancer</td>
+
<p>Perl golf</p>
        </tr>
+
 
        <tr>
+
<p>Perl &quot;golf&quot; is the pastime of reducing the number of characters (key &quot;strokes&quot;) used in a Perl program to the bare minimum, much in the same way that&nbsp;<a href="http://en.wikipedia.org/wiki/Golf" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Golf">golf</a>&nbsp;players seek to take as few shots as possible in a round. The phrase&#39;s first use<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-perl-golf-coined-101" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[101]</a></sup>&nbsp;emphasized the difference between pedestrian code meant to teach a newcomer and terse hacks likely to amuse experienced Perl programmers, an example of the latter being&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/JAPH" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="JAPH">JAPHs</a>&nbsp;that were already used in signatures in Usenet postings and elsewhere. Similar stunts had been an unnamed pastime in the language&nbsp;<a href="http://en.wikipedia.org/wiki/APL_(programming_language)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="APL (programming language)">APL</a>&nbsp;in previous decades. The use of Perl to write a program that performed&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/RSA_(algorithm)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="RSA (algorithm)">RSA</a>&nbsp;encryption prompted a widespread and practical interest in this pastime.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-rsa-102" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[102]</a></sup>&nbsp;In subsequent years, the term &quot;<a href="http://en.wikipedia.org/wiki/Code_golf" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Code golf">code golf</a>&quot; has been applied to the pastime in other languages.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-103" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[103]</a></sup>&nbsp;A&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Perl_Golf_Apocalypse" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Perl Golf Apocalypse">Perl Golf Apocalypse</a>&nbsp;was held at Perl Conference 4.0 in Monterey, California in July 2000.</p>
            <td style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em;">irc.slashnet.org</td>
+
 
            <td style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em;">#perlmonks</td>
+
<p>Obfuscation</p>
        </tr>
+
 
        <tr>
+
<p>As with C,&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Obfuscated_code" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Obfuscated code">obfuscated code</a>&nbsp;competitions were a well known pastime in the late 1990s. The&nbsp;<a href="http://en.wikipedia.org/wiki/Obfuscated_Perl_Contest" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Obfuscated Perl Contest">Obfuscated Perl Contest</a>&nbsp;was a competition held by&nbsp;<a class="new" href="http://en.wikipedia.org/w/index.php?title=The_Perl_Journal&amp;action=edit&amp;redlink=1" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(165,88,88)" title="The Perl Journal (page does not exist)">The Perl Journal</a>&nbsp;from 1996 to 2000 that made an arch virtue of Perl&#39;s syntactic flexibility. Awards were given for categories such as &quot;most powerful&quot;&mdash;programs that made efficient use of space&mdash;and &quot;best four-line signature&quot; for programs that fit into four lines of 76 characters in the style of a Usenet&nbsp;<a href="http://en.wikipedia.org/wiki/Signature_block" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Signature block">signature block</a>.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-gallo03-104" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[104]</a></sup></p>
            <td style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em;">irc.oftc.net</td>
+
 
            <td style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em;">#perl</td>
+
<p>Poetry</p>
        </tr>
+
 
        <tr>
+
<p>Perl poetry is the practice of writing poems that can be compiled as legal Perl code, for example the piece known as&nbsp;<a href="http://en.wikipedia.org/wiki/Black_Perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Black Perl">Black Perl</a>. Perl poetry is made possible by the large number of English words that are used in the Perl language. New poems are regularly submitted to the community at&nbsp;<a href="http://en.wikipedia.org/wiki/PerlMonks" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="PerlMonks">PerlMonks</a>.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-105" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[105]</a></sup></p>
            <td style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em;">irc.efnet.net</td>
+
 
            <td style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em;">#perlhelp</td>
+
<h3>Perl on IRC<span style="font-size:small"><span style="color:rgb(85,85,85)">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=23" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Edit section: Perl on IRC">edit</a><span style="color:rgb(85,85,85)">]</span></span></h3>
        </tr>
+
 
        <tr>
+
<p>There are a number of&nbsp;<a href="http://en.wikipedia.org/wiki/Internet_Relay_Chat" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Internet Relay Chat">IRC</a>&nbsp;channels that offer support for the language and some modules.</p>
            <td style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em;">irc.rizon.net</td>
+
 
            <td style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em;">#perl</td>
+
<table class="wikitable" style="background-color:rgb(249,249,249); border-bottom-color:rgb(170,170,170); border-bottom-style:solid; border-collapse:collapse; border-left-color:rgb(170,170,170); border-left-style:solid; border-right-color:rgb(170,170,170); border-right-style:solid; border-top-color:rgb(170,170,170); border-top-style:solid; color:black; font-family:sans-serif; font-size:14px; line-height:17px; margin:1em 0px">
        </tr>
+
<tbody>
        <tr>
+
<tr>
            <td style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em;">irc.debian.org</td>
+
<th style="text-align: center; background-color: rgb(242,242,242)">IRC Network</th>
            <td style="border-style: solid; border-color: rgb(170, 170, 170); padding: 0.2em 0.4em;">#debian-perl</td>
+
<th style="text-align: center; background-color: rgb(242,242,242)">Channels</th>
        </tr>
+
</tr>
    </tbody>
+
<tr>
 +
<td>irc.freenode.net</td>
 +
<td>#perl #perl6 #cbstream #perlcafe #poe</td>
 +
</tr>
 +
<tr>
 +
<td>irc.perl.org</td>
 +
<td>#moose #poe #catalyst #dbix-class #perl-help #distzilla #epo #corehackers #sdl #win32 #toolchain #padre #dancer</td>
 +
</tr>
 +
<tr>
 +
<td>irc.slashnet.org</td>
 +
<td>#perlmonks</td>
 +
</tr>
 +
<tr>
 +
<td>irc.oftc.net</td>
 +
<td>#perl</td>
 +
</tr>
 +
<tr>
 +
<td>irc.efnet.net</td>
 +
<td>#perlhelp</td>
 +
</tr>
 +
<tr>
 +
<td>irc.rizon.net</td>
 +
<td>#perl</td>
 +
</tr>
 +
<tr>
 +
<td>irc.debian.org</td>
 +
<td>#debian-perl</td>
 +
</tr>
 +
</tbody>
 
</table>
 
</table>
<h3 style="margin: 0.3em 0px 0px; overflow: hidden; padding-top: 0.5em; padding-bottom: 0px; border-bottom-style: none; line-height: 1.6; font-family: sans-serif; background-image: none; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><span class="mw-headline" id="CPAN_Acme">CPAN Acme</span><span class="mw-editsection" style="-webkit-user-select: none; font-size: small; font-weight: normal; margin-left: 1em; vertical-align: baseline; line-height: 1em; display: inline-block; white-space: nowrap; unicode-bidi: -webkit-isolate;"><span class="mw-editsection-bracket" style="margin-right: 0px; color: rgb(85, 85, 85); margin-left: 0px;">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=24" title="Edit section: CPAN Acme" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">edit</a><span class="mw-editsection-bracket" style="margin-left: 0px; color: rgb(85, 85, 85); margin-right: 0px;">]</span></span></h3>
+
 
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">There are also many examples of code written purely for entertainment on the&nbsp;<a href="http://en.wikipedia.org/wiki/CPAN" title="CPAN" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">CPAN</a>.&nbsp;<code style="font-family: monospace, Courier; color: black; border: 1px solid rgb(221, 221, 221); border-radius: 2px; padding: 1px 4px; background-color: rgb(249, 249, 249);">Lingua::Romana::Perligata</code>, for example, allows writing programs in&nbsp;<a href="http://en.wikipedia.org/wiki/Latin" title="Latin" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Latin</a>.<sup id="cite_ref-106" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-106" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[106]</a></sup>&nbsp;Upon execution of such a program, the module translates its source code into regular Perl and runs it.</p>
+
<h3>CPAN Acme<span style="font-size:small"><span style="color:rgb(85,85,85)">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=24" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Edit section: CPAN Acme">edit</a><span style="color:rgb(85,85,85)">]</span></span></h3>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">The Perl community has set aside the &quot;<a href="http://en.wikipedia.org/wiki/Acme_Corporation" title="Acme Corporation" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Acme</a>&quot; namespace for modules that are fun in nature (but its scope has widened to include exploratory or experimental code or any other module that is not meant to ever be used in production). Some of the Acme modules are deliberately implemented in amusing ways. This includes&nbsp;<code style="font-family: monospace, Courier; color: black; border: 1px solid rgb(221, 221, 221); border-radius: 2px; padding: 1px 4px; background-color: rgb(249, 249, 249);">Acme::Bleach</code>, one of the first modules in the&nbsp;<code style="font-family: monospace, Courier; color: black; border: 1px solid rgb(221, 221, 221); border-radius: 2px; padding: 1px 4px; background-color: rgb(249, 249, 249);">Acme::</code>&nbsp;namespace,<sup id="cite_ref-107" class="reference" style="line-height: 1; unicode-bidi: -webkit-isolate; font-size: 11.1999998092651px;"><a href="http://en.wikipedia.org/wiki/Perl#cite_note-107" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[107]</a></sup>&nbsp;which allows the program's source code to be &quot;whitened&quot; (i.e., all characters replaced with whitespace) and yet still work.</p>
+
 
<h2 style="font-weight: normal; margin: 1em 0px 0.25em; overflow: hidden; padding: 0px; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(170, 170, 170); font-family: 'Linux Libertine', Georgia, Times, serif; line-height: 1.3; background-image: none; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><span class="mw-headline" id="Example_code">Example code</span><span class="mw-editsection" style="-webkit-user-select: none; font-size: small; margin-left: 1em; vertical-align: baseline; line-height: 1em; display: inline-block; white-space: nowrap; unicode-bidi: -webkit-isolate; font-family: sans-serif;"><span class="mw-editsection-bracket" style="margin-right: 0px; color: rgb(85, 85, 85); margin-left: 0px;">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=25" title="Edit section: Example code" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">edit</a><span class="mw-editsection-bracket" style="margin-left: 0px; color: rgb(85, 85, 85); margin-right: 0px;">]</span></span></h2>
+
<p>There are also many examples of code written purely for entertainment on the&nbsp;<a href="http://en.wikipedia.org/wiki/CPAN" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="CPAN">CPAN</a>.&nbsp;<code>Lingua::Romana::Perligata</code>, for example, allows writing programs in&nbsp;<a href="http://en.wikipedia.org/wiki/Latin" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Latin">Latin</a>.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-106" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[106]</a></sup>&nbsp;Upon execution of such a program, the module translates its source code into regular Perl and runs it.</p>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">In older versions of Perl, one would write the&nbsp;<a href="http://en.wikipedia.org/wiki/Hello_World" title="Hello World" class="mw-redirect" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Hello World</a>&nbsp;program as:</p>
+
 
<div dir="ltr" class="mw-geshi mw-code mw-content-ltr" style="direction: ltr; font-family: monospace, Courier; border: 1px solid rgb(221, 221, 221); padding: 1em; line-height: 1.3em; font-size: 14px; background-color: rgb(249, 249, 249);">
+
<p>The Perl community has set aside the &quot;<a href="http://en.wikipedia.org/wiki/Acme_Corporation" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Acme Corporation">Acme</a>&quot; namespace for modules that are fun in nature (but its scope has widened to include exploratory or experimental code or any other module that is not meant to ever be used in production). Some of the Acme modules are deliberately implemented in amusing ways. This includes&nbsp;<code>Acme::Bleach</code>, one of the first modules in the&nbsp;<code>Acme::</code>&nbsp;namespace,<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-107" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[107]</a></sup>&nbsp;which allows the program&#39;s source code to be &quot;whitened&quot; (i.e., all characters replaced with whitespace) and yet still work.</p>
<div class="perl source-perl" style="line-height: normal; tab-size: 4; font-family: monospace, monospace;">
+
 
<pre class="de1" style="font-family: monospace, monospace; border: 0px none white; padding: 0px; line-height: 1.2em; tab-size: 4; font-stretch: normal; font-size: 1em; margin-top: 0px; margin-bottom: 0px; vertical-align: top; background: none;">
+
<h2>Example code<span style="font-family:sans-serif; font-size:small"><span style="color:rgb(85,85,85)">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=25" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Edit section: Example code">edit</a><span style="color:rgb(85,85,85)">]</span></span></h2>
     <span class="kw3" style="color: rgb(0, 0, 102);">print</span> <span class="st0" style="color: rgb(255, 0, 0);">&quot;Hello World!<span class="es0" style="color: rgb(0, 0, 153); font-weight: bold;">\n</span>&quot;</span><span class="sy0" style="color: rgb(51, 153, 51);">;</span>
+
 
 +
<p>In older versions of Perl, one would write the&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Hello_World" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Hello World">Hello World</a>&nbsp;program as:</p>
 +
 
 +
<div class="mw-geshi mw-code mw-content-ltr" dir="ltr" style="font-size: 14px; border-top: rgb(221,221,221) 1px solid; font-family: monospace, Courier; border-right: rgb(221,221,221) 1px solid; border-bottom: rgb(221,221,221) 1px solid; padding-bottom: 1em; direction: ltr; padding-top: 1em; padding-left: 1em; border-left: rgb(221,221,221) 1px solid; line-height: 1.3em; padding-right: 1em; background-color: rgb(249,249,249)">
 +
<div class="perl source-perl" style="font-family: monospace, monospace; line-height: normal; tab-size: 4">
 +
<pre>
 +
     <span style="color:rgb(0,0,102)">print</span> <span style="color:rgb(255,0,0)">&quot;Hello World!<strong>\n</strong>&quot;</span><span style="color:rgb(51,153,51)">;</span>
 
</pre>
 
</pre>
 
</div>
 
</div>
 
</div>
 
</div>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">In later versions, which support the say statement, one can also write it as:</p>
+
 
<div dir="ltr" class="mw-geshi mw-code mw-content-ltr" style="direction: ltr; font-family: monospace, Courier; border: 1px solid rgb(221, 221, 221); padding: 1em; line-height: 1.3em; font-size: 14px; background-color: rgb(249, 249, 249);">
+
<p>In later versions, which support the say statement, one can also write it as:</p>
<div class="perl source-perl" style="line-height: normal; tab-size: 4; font-family: monospace, monospace;">
+
 
<pre class="de1" style="font-family: monospace, monospace; border: 0px none white; padding: 0px; line-height: 1.2em; tab-size: 4; font-stretch: normal; font-size: 1em; margin-top: 0px; margin-bottom: 0px; vertical-align: top; background: none;">
+
<div class="mw-geshi mw-code mw-content-ltr" dir="ltr" style="font-size: 14px; border-top: rgb(221,221,221) 1px solid; font-family: monospace, Courier; border-right: rgb(221,221,221) 1px solid; border-bottom: rgb(221,221,221) 1px solid; padding-bottom: 1em; direction: ltr; padding-top: 1em; padding-left: 1em; border-left: rgb(221,221,221) 1px solid; line-height: 1.3em; padding-right: 1em; background-color: rgb(249,249,249)">
     <span class="kw2" style="font-weight: bold;">use</span> <span class="nu0" style="color: rgb(204, 102, 204);">5.010</span><span class="sy0" style="color: rgb(51, 153, 51);">;</span>
+
<div class="perl source-perl" style="font-family: monospace, monospace; line-height: normal; tab-size: 4">
     say <span class="st0" style="color: rgb(255, 0, 0);">&quot;Hello World!&quot;</span><span class="sy0" style="color: rgb(51, 153, 51);">;</span>
+
<pre>
 +
     <strong>use</strong> <span style="color:rgb(204,102,204)">5.010</span><span style="color:rgb(51,153,51)">;</span>
 +
     say <span style="color:rgb(255,0,0)">&quot;Hello World!&quot;</span><span style="color:rgb(51,153,51)">;</span>
 
</pre>
 
</pre>
 
</div>
 
</div>
 
</div>
 
</div>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">Good Perl practices require more complex programs to add the&nbsp;<tt style="font-family: monospace, Courier;">use strict;</tt>&nbsp;and&nbsp;<tt style="font-family: monospace, Courier;">use warnings;</tt>&nbsp;<a href="http://en.wikipedia.org/wiki/Directive_(programming)" title="Directive (programming)" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">pragmas</a>, leading into something like:</p>
+
 
<div dir="ltr" class="mw-geshi mw-code mw-content-ltr" style="direction: ltr; font-family: monospace, Courier; border: 1px solid rgb(221, 221, 221); padding: 1em; line-height: 1.3em; font-size: 14px; background-color: rgb(249, 249, 249);">
+
<p>Good Perl practices require more complex programs to add the&nbsp;<tt>use strict;</tt>&nbsp;and&nbsp;<tt>use warnings;</tt>&nbsp;<a href="http://en.wikipedia.org/wiki/Directive_(programming)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Directive (programming)">pragmas</a>, leading into something like:</p>
<div class="perl source-perl" style="line-height: normal; tab-size: 4; font-family: monospace, monospace;">
+
 
<pre class="de1" style="font-family: monospace, monospace; border: 0px none white; padding: 0px; line-height: 1.2em; tab-size: 4; font-stretch: normal; font-size: 1em; margin-top: 0px; margin-bottom: 0px; vertical-align: top; background: none;">
+
<div class="mw-geshi mw-code mw-content-ltr" dir="ltr" style="font-size: 14px; border-top: rgb(221,221,221) 1px solid; font-family: monospace, Courier; border-right: rgb(221,221,221) 1px solid; border-bottom: rgb(221,221,221) 1px solid; padding-bottom: 1em; direction: ltr; padding-top: 1em; padding-left: 1em; border-left: rgb(221,221,221) 1px solid; line-height: 1.3em; padding-right: 1em; background-color: rgb(249,249,249)">
     <span class="kw2" style="font-weight: bold;">use</span> strict<span class="sy0" style="color: rgb(51, 153, 51);">;</span>
+
<div class="perl source-perl" style="font-family: monospace, monospace; line-height: normal; tab-size: 4">
     <span class="kw2" style="font-weight: bold;">use</span> warnings<span class="sy0" style="color: rgb(51, 153, 51);">;</span>
+
<pre>
 +
     <strong>use</strong> strict<span style="color:rgb(51,153,51)">;</span>
 +
     <strong>use</strong> warnings<span style="color:rgb(51,153,51)">;</span>
 
   
 
   
     <span class="kw3" style="color: rgb(0, 0, 102);">print</span> <span class="st0" style="color: rgb(255, 0, 0);">&quot;Hello World!<span class="es0" style="color: rgb(0, 0, 153); font-weight: bold;">\n</span>&quot;</span><span class="sy0" style="color: rgb(51, 153, 51);">;</span>
+
     <span style="color:rgb(0,0,102)">print</span> <span style="color:rgb(255,0,0)">&quot;Hello World!<strong>\n</strong>&quot;</span><span style="color:rgb(51,153,51)">;</span>
 
</pre>
 
</pre>
 
</div>
 
</div>
 
</div>
 
</div>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">Here is a more complex Perl program, that counts down the seconds up to a given threshold:</p>
+
 
<div dir="ltr" class="mw-geshi mw-code mw-content-ltr" style="direction: ltr; font-family: monospace, Courier; border: 1px solid rgb(221, 221, 221); padding: 1em; line-height: 1.3em; font-size: 14px; background-color: rgb(249, 249, 249);">
+
<p>Here is a more complex Perl program, that counts down the seconds up to a given threshold:</p>
<div class="perl source-perl" style="line-height: normal; tab-size: 4; font-family: monospace, monospace;">
+
 
<pre class="de1" style="font-family: monospace, monospace; border: 0px none white; padding: 0px; line-height: 1.2em; tab-size: 4; font-stretch: normal; font-size: 1em; margin-top: 0px; margin-bottom: 0px; vertical-align: top; background: none;">
+
<div class="mw-geshi mw-code mw-content-ltr" dir="ltr" style="font-size: 14px; border-top: rgb(221,221,221) 1px solid; font-family: monospace, Courier; border-right: rgb(221,221,221) 1px solid; border-bottom: rgb(221,221,221) 1px solid; padding-bottom: 1em; direction: ltr; padding-top: 1em; padding-left: 1em; border-left: rgb(221,221,221) 1px solid; line-height: 1.3em; padding-right: 1em; background-color: rgb(249,249,249)">
  <span class="co1" style="color: rgb(102, 102, 102); font-style: italic;">#!/usr/bin/perl</span>
+
<div class="perl source-perl" style="font-family: monospace, monospace; line-height: normal; tab-size: 4">
  <span class="kw2" style="font-weight: bold;">use</span> strict<span class="sy0" style="color: rgb(51, 153, 51);">;</span>
+
<pre>
  <span class="kw2" style="font-weight: bold;">use</span> warnings<span class="sy0" style="color: rgb(51, 153, 51);">;</span>
+
  <em>#!/usr/bin/perl</em>
  <span class="kw2" style="font-weight: bold;">use</span> IO<span class="sy0" style="color: rgb(51, 153, 51);">::</span><span class="me2" style="color: rgb(0, 102, 0);">Handle</span><span class="sy0" style="color: rgb(51, 153, 51);">;</span>
+
  <strong>use</strong> strict<span style="color:rgb(51,153,51)">;</span>
 +
  <strong>use</strong> warnings<span style="color:rgb(51,153,51)">;</span>
 +
  <strong>use</strong> IO<span style="color:rgb(51,153,51)">::</span><span style="color:rgb(0,102,0)">Handle</span><span style="color:rgb(51,153,51)">;</span>
 
   
 
   
  <span class="kw1" style="color: rgb(177, 177, 0);">my</span> <span class="br0" style="color: rgb(0, 153, 0);">(</span> <span class="re0" style="color: rgb(0, 0, 255);">$remaining</span><span class="sy0" style="color: rgb(51, 153, 51);">,</span> <span class="re0" style="color: rgb(0, 0, 255);">$total</span> <span class="br0" style="color: rgb(0, 153, 0);">)</span><span class="sy0" style="color: rgb(51, 153, 51);">;</span>
+
  <span style="color:rgb(177,177,0)">my</span> <span style="color:rgb(0,153,0)">(</span> <span style="color:rgb(0,0,255)">$remaining</span><span style="color:rgb(51,153,51)">,</span> <span style="color:rgb(0,0,255)">$total</span> <span style="color:rgb(0,153,0)">)</span><span style="color:rgb(51,153,51)">;</span>
 
   
 
   
  <span class="re0" style="color: rgb(0, 0, 255);">$remaining</span> <span class="sy0" style="color: rgb(51, 153, 51);">=</span> <span class="re0" style="color: rgb(0, 0, 255);">$total</span> <span class="sy0" style="color: rgb(51, 153, 51);">=</span> <span class="kw3" style="color: rgb(0, 0, 102);">shift</span><span class="br0" style="color: rgb(0, 153, 0);">(</span><span class="sy0" style="color: rgb(51, 153, 51);">@</span><span class="kw2" style="font-weight: bold;">ARGV</span><span class="br0" style="color: rgb(0, 153, 0);">)</span><span class="sy0" style="color: rgb(51, 153, 51);">;</span>
+
  <span style="color:rgb(0,0,255)">$remaining</span> <span style="color:rgb(51,153,51)">=</span> <span style="color:rgb(0,0,255)">$total</span> <span style="color:rgb(51,153,51)">=</span> <span style="color:rgb(0,0,102)">shift</span><span style="color:rgb(0,153,0)">(</span><span style="color:rgb(51,153,51)">@</span><strong>ARGV</strong><span style="color:rgb(0,153,0)">)</span><span style="color:rgb(51,153,51)">;</span>
 
   
 
   
  STDOUT<span class="sy0" style="color: rgb(51, 153, 51);">-&gt;</span><span class="me1" style="color: rgb(0, 102, 0);">autoflush</span><span class="br0" style="color: rgb(0, 153, 0);">(</span><span class="nu0" style="color: rgb(204, 102, 204);">1</span><span class="br0" style="color: rgb(0, 153, 0);">)</span><span class="sy0" style="color: rgb(51, 153, 51);">;</span>
+
  STDOUT<span style="color:rgb(51,153,51)">-&gt;</span><span style="color:rgb(0,102,0)">autoflush</span><span style="color:rgb(0,153,0)">(</span><span style="color:rgb(204,102,204)">1</span><span style="color:rgb(0,153,0)">)</span><span style="color:rgb(51,153,51)">;</span>
 
   
 
   
  <span class="kw1" style="color: rgb(177, 177, 0);">while</span> <span class="br0" style="color: rgb(0, 153, 0);">(</span> <span class="re0" style="color: rgb(0, 0, 255);">$remaining</span> <span class="br0" style="color: rgb(0, 153, 0);">)</span> <span class="br0" style="color: rgb(0, 153, 0);">{</span>
+
  <span style="color:rgb(177,177,0)">while</span> <span style="color:rgb(0,153,0)">(</span> <span style="color:rgb(0,0,255)">$remaining</span> <span style="color:rgb(0,153,0)">)</span> <span style="color:rgb(0,153,0)">{</span>
   <span class="kw3" style="color: rgb(0, 0, 102);">printf</span> <span class="br0" style="color: rgb(0, 153, 0);">(</span> <span class="st0" style="color: rgb(255, 0, 0);">&quot;Remaining %s/%s <span class="es0" style="color: rgb(0, 0, 153); font-weight: bold;">\r</span>&quot;</span><span class="sy0" style="color: rgb(51, 153, 51);">,</span> <span class="re0" style="color: rgb(0, 0, 255);">$remaining</span><span class="sy0" style="color: rgb(51, 153, 51);">--,</span> <span class="re0" style="color: rgb(0, 0, 255);">$total</span> <span class="br0" style="color: rgb(0, 153, 0);">)</span><span class="sy0" style="color: rgb(51, 153, 51);">;</span>
+
   <span style="color:rgb(0,0,102)">printf</span> <span style="color:rgb(0,153,0)">(</span> <span style="color:rgb(255,0,0)">&quot;Remaining %s/%s <strong>\r</strong>&quot;</span><span style="color:rgb(51,153,51)">,</span> <span style="color:rgb(0,0,255)">$remaining</span><span style="color:rgb(51,153,51)">--,</span> <span style="color:rgb(0,0,255)">$total</span> <span style="color:rgb(0,153,0)">)</span><span style="color:rgb(51,153,51)">;</span>
   <span class="kw3" style="color: rgb(0, 0, 102);">sleep</span> <span class="nu0" style="color: rgb(204, 102, 204);">1</span><span class="sy0" style="color: rgb(51, 153, 51);">;</span>
+
   <span style="color:rgb(0,0,102)">sleep</span> <span style="color:rgb(204,102,204)">1</span><span style="color:rgb(51,153,51)">;</span>
  <span class="br0" style="color: rgb(0, 153, 0);">}</span>
+
  <span style="color:rgb(0,153,0)">}</span>
 
   
 
   
  <span class="kw3" style="color: rgb(0, 0, 102);">print</span> <span class="st0" style="color: rgb(255, 0, 0);">&quot;<span class="es0" style="color: rgb(0, 0, 153); font-weight: bold;">\n</span>&quot;</span><span class="sy0" style="color: rgb(51, 153, 51);">;</span>
+
  <span style="color:rgb(0,0,102)">print</span> <span style="color:rgb(255,0,0)">&quot;<strong>\n</strong>&quot;</span><span style="color:rgb(51,153,51)">;</span>
 
</pre>
 
</pre>
 
</div>
 
</div>
 
</div>
 
</div>
<p style="margin: 0.5em 0px; line-height: 17.9200000762939px; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">The perl interpreter can also be used for one-off scripts on the command line. The following example as invoked from an sh-compatible shell such as Bash translates the string &quot;Bob&quot; in all files ending with .txt in the current directory to &quot;Robert&quot;:</p>
+
 
<div dir="ltr" class="mw-geshi mw-code mw-content-ltr" style="direction: ltr; font-family: monospace, Courier; border: 1px solid rgb(221, 221, 221); padding: 1em; line-height: 1.3em; font-size: 14px; background-color: rgb(249, 249, 249);">
+
<p>The perl interpreter can also be used for one-off scripts on the command line. The following example as invoked from an sh-compatible shell such as Bash translates the string &quot;Bob&quot; in all files ending with .txt in the current directory to &quot;Robert&quot;:</p>
<div class="bash source-bash" style="line-height: normal; tab-size: 4; font-family: monospace, monospace;">
+
 
<pre class="de1" style="font-family: monospace, monospace; border: 0px none white; padding: 0px; line-height: 1.2em; tab-size: 4; font-stretch: normal; font-size: 1em; margin-top: 0px; margin-bottom: 0px; vertical-align: top; background: none;">
+
<div class="mw-geshi mw-code mw-content-ltr" dir="ltr" style="font-size: 14px; border-top: rgb(221,221,221) 1px solid; font-family: monospace, Courier; border-right: rgb(221,221,221) 1px solid; border-bottom: rgb(221,221,221) 1px solid; padding-bottom: 1em; direction: ltr; padding-top: 1em; padding-left: 1em; border-left: rgb(221,221,221) 1px solid; line-height: 1.3em; padding-right: 1em; background-color: rgb(249,249,249)">
     $ <span class="kw2" style="color: rgb(194, 12, 185); font-weight: bold;">perl</span> -i.bak <span class="re5" style="color: rgb(102, 0, 51);">-lp</span> <span class="re5" style="color: rgb(102, 0, 51);">-e</span> <span class="st_h" style="color: rgb(255, 0, 0);">'s/Bob/Robert/g'</span> <span class="sy0" style="font-weight: bold;">*</span>.txt
+
<div class="bash source-bash" style="font-family: monospace, monospace; line-height: normal; tab-size: 4">
 +
<pre>
 +
     $ <strong>perl</strong> -i.bak <span style="color:rgb(102,0,51)">-lp</span> <span style="color:rgb(102,0,51)">-e</span> <span style="color:rgb(255,0,0)">&#39;s/Bob/Robert/g&#39;</span> <strong>*</strong>.txt
 
</pre>
 
</pre>
 
</div>
 
</div>
 
</div>
 
</div>
<h2 style="font-weight: normal; margin: 1em 0px 0.25em; overflow: hidden; padding: 0px; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(170, 170, 170); font-family: 'Linux Libertine', Georgia, Times, serif; line-height: 1.3; background-image: none; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-
+
 
 +
<h2>Criticism<span style="font-family:sans-serif; font-size:small"><span style="color:rgb(85,85,85)">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=26" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Edit section: Criticism">
 
</ol>
 
</ol>
 
</div>
 
</div>
<h2 style="font-weight: normal; margin: 1em 0px 0.25em; overflow: hidden; padding: 0px; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(170, 170, 170); font-family: 'Linux Libertine', Georgia, Times, serif; line-height: 1.3; background-image: none; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><span class="mw-headline" id="Further_reading">Further reading</span></h2>
+
 
<ul style="line-height: 1.5em; margin: 0.3em 0px 0px 1.6em; padding: 0px; list-style-image: url(data:image/svg+xml,%3C%3Fxml%20version%3D%221.0%22%20encoding%3D%22UTF-8%22%3F%3E%0A%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20version%3D%221.1%22%20width%3D%225%22%20height%3D%2213%22%3E%0A%3Ccircle%20cx%3D%222.5%22%20cy%3D%229.5%22%20r%3D%222.5%22%20fill%3D%22%2300528c%22%2F%3E%0A%3C%2Fsvg%3E%0A); color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">
+
<h2>Further reading</h2>
    <li style="margin-bottom: 0.1em;"><a rel="nofollow" class="external text" href="http://shop.oreilly.com/product/0636920018452.do" style="text-decoration: none; color: rgb(102, 51, 102); padding-right: 13px; background: linear-gradient(transparent, transparent) 100% 50% no-repeat, url(data:image/svg+xml,%3C%3Fxml%20version%3D%221.0%22%20encoding%3D%22UTF-8%22%3F%3E%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2210%22%20height%3D%2210%22%3E%3Cg%20transform%3D%22translate%28-826.429%20-698.791%29%22%3E%3Crect%20width%3D%225.982%22%20height%3D%225.982%22%20x%3D%22826.929%22%20y%3D%22702.309%22%20fill%3D%22%23fff%22%20stroke%3D%22%2306c%22%2F%3E%3Cg%3E%3Cpath%20d%3D%22M831.194%20698.791h5.234v5.391l-1.571%201.545-1.31-1.31-2.725%202.725-2.689-2.689%202.808-2.808-1.311-1.311z%22%20fill%3D%22%2306f%22%2F%3E%3Cpath%20d%3D%22M835.424%20699.795l.022%204.885-1.817-1.817-2.881%202.881-1.228-1.228%202.881-2.881-1.851-1.851z%22%20fill%3D%22%23fff%22%2F%3E%3C%2Fg%3E%3C%2Fg%3E%3C%2Fsvg%3E) 100% 50%;">Learning Perl</a>&nbsp;6th Edition (2011), O'Reilly. Beginner-level introduction to Perl.</li>
+
 
    <li style="margin-bottom: 0.1em;"><a rel="nofollow" class="external text" href="http://ofps.oreilly.com/titles/9781118013847/index.html" style="text-decoration: none; color: rgb(102, 51, 102); padding-right: 13px; background: linear-gradient(transparent, transparent) 100% 50% no-repeat, url(data:image/svg+xml,%3C%3Fxml%20version%3D%221.0%22%20encoding%3D%22UTF-8%22%3F%3E%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2210%22%20height%3D%2210%22%3E%3Cg%20transform%3D%22translate%28-826.429%20-698.791%29%22%3E%3Crect%20width%3D%225.982%22%20height%3D%225.982%22%20x%3D%22826.929%22%20y%3D%22702.309%22%20fill%3D%22%23fff%22%20stroke%3D%22%2306c%22%2F%3E%3Cg%3E%3Cpath%20d%3D%22M831.194%20698.791h5.234v5.391l-1.571%201.545-1.31-1.31-2.725%202.725-2.689-2.689%202.808-2.808-1.311-1.311z%22%20fill%3D%22%2306f%22%2F%3E%3Cpath%20d%3D%22M835.424%20699.795l.022%204.885-1.817-1.817-2.881%202.881-1.228-1.228%202.881-2.881-1.851-1.851z%22%20fill%3D%22%23fff%22%2F%3E%3C%2Fg%3E%3C%2Fg%3E%3C%2Fsvg%3E) 100% 50%;">Beginning Perl</a>&nbsp;1st Edition (2012), Wrox. A beginner's tutorial for those new to programming or just new to Perl.</li>
+
<ul>
    <li style="margin-bottom: 0.1em;"><a rel="nofollow" class="external text" href="http://onyxneon.com/books/modern_perl/" style="text-decoration: none; color: rgb(102, 51, 102); padding-right: 13px; background: linear-gradient(transparent, transparent) 100% 50% no-repeat, url(data:image/svg+xml,%3C%3Fxml%20version%3D%221.0%22%20encoding%3D%22UTF-8%22%3F%3E%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2210%22%20height%3D%2210%22%3E%3Cg%20transform%3D%22translate%28-826.429%20-698.791%29%22%3E%3Crect%20width%3D%225.982%22%20height%3D%225.982%22%20x%3D%22826.929%22%20y%3D%22702.309%22%20fill%3D%22%23fff%22%20stroke%3D%22%2306c%22%2F%3E%3Cg%3E%3Cpath%20d%3D%22M831.194%20698.791h5.234v5.391l-1.571%201.545-1.31-1.31-2.725%202.725-2.689-2.689%202.808-2.808-1.311-1.311z%22%20fill%3D%22%2306f%22%2F%3E%3Cpath%20d%3D%22M835.424%20699.795l.022%204.885-1.817-1.817-2.881%202.881-1.228-1.228%202.881-2.881-1.851-1.851z%22%20fill%3D%22%23fff%22%2F%3E%3C%2Fg%3E%3C%2Fg%3E%3C%2Fsvg%3E) 100% 50%;">Modern Perl</a>&nbsp;2nd Edition (2012), Onyx Neon. Describes&nbsp;<a href="http://en.wikipedia.org/w/index.php?title=Modern_Perl&amp;action=edit&amp;redlink=1" class="new" title="Modern Perl (page does not exist)" style="text-decoration: none; color: rgb(165, 88, 88); background: none;">Modern Perl</a>&nbsp;programming techniques.</li>
+
<li><a class="external text" href="http://shop.oreilly.com/product/0636920018452.do" rel="nofollow" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(102,51,102); padding-right: 13px">Learning Perl</a>&nbsp;6th Edition (2011), O&#39;Reilly. Beginner-level introduction to Perl.</li>
    <li style="margin-bottom: 0.1em;"><a rel="nofollow" class="external text" href="http://shop.oreilly.com/product/9780596004927.do" style="text-decoration: none; color: rgb(102, 51, 102); padding-right: 13px; background: linear-gradient(transparent, transparent) 100% 50% no-repeat, url(data:image/svg+xml,%3C%3Fxml%20version%3D%221.0%22%20encoding%3D%22UTF-8%22%3F%3E%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2210%22%20height%3D%2210%22%3E%3Cg%20transform%3D%22translate%28-826.429%20-698.791%29%22%3E%3Crect%20width%3D%225.982%22%20height%3D%225.982%22%20x%3D%22826.929%22%20y%3D%22702.309%22%20fill%3D%22%23fff%22%20stroke%3D%22%2306c%22%2F%3E%3Cg%3E%3Cpath%20d%3D%22M831.194%20698.791h5.234v5.391l-1.571%201.545-1.31-1.31-2.725%202.725-2.689-2.689%202.808-2.808-1.311-1.311z%22%20fill%3D%22%2306f%22%2F%3E%3Cpath%20d%3D%22M835.424%20699.795l.022%204.885-1.817-1.817-2.881%202.881-1.228-1.228%202.881-2.881-1.851-1.851z%22%20fill%3D%22%23fff%22%2F%3E%3C%2Fg%3E%3C%2Fg%3E%3C%2Fsvg%3E) 100% 50%;">Programming Perl</a>&nbsp;4th Edition (2012), O'Reilly. The definitive Perl reference.</li>
+
<li><a class="external text" href="http://ofps.oreilly.com/titles/9781118013847/index.html" rel="nofollow" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(102,51,102); padding-right: 13px">Beginning Perl</a>&nbsp;1st Edition (2012), Wrox. A beginner&#39;s tutorial for those new to programming or just new to Perl.</li>
    <li style="margin-bottom: 0.1em;"><a rel="nofollow" class="external text" href="http://www.pearsonhighered.com/educator/product/Effective-Perl-Programming-Ways-to-Write-Better-More-Idiomatic-Perl-2E/9780321496942.page" style="text-decoration: none; color: rgb(102, 51, 102); padding-right: 13px; background: linear-gradient(transparent, transparent) 100% 50% no-repeat, url(data:image/svg+xml,%3C%3Fxml%20version%3D%221.0%22%20encoding%3D%22UTF-8%22%3F%3E%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2210%22%20height%3D%2210%22%3E%3Cg%20transform%3D%22translate%28-826.429%20-698.791%29%22%3E%3Crect%20width%3D%225.982%22%20height%3D%225.982%22%20x%3D%22826.929%22%20y%3D%22702.309%22%20fill%3D%22%23fff%22%20stroke%3D%22%2306c%22%2F%3E%3Cg%3E%3Cpath%20d%3D%22M831.194%20698.791h5.234v5.391l-1.571%201.545-1.31-1.31-2.725%202.725-2.689-2.689%202.808-2.808-1.311-1.311z%22%20fill%3D%22%2306f%22%2F%3E%3Cpath%20d%3D%22M835.424%20699.795l.022%204.885-1.817-1.817-2.881%202.881-1.228-1.228%202.881-2.881-1.851-1.851z%22%20fill%3D%22%23fff%22%2F%3E%3C%2Fg%3E%3C%2Fg%3E%3C%2Fsvg%3E) 100% 50%;">Effective Perl Programming</a>&nbsp;2nd Edition (2010), Addison-Wesley. Intermediate- to advanced-level guide to writing idiomatic Perl.</li>
+
<li><a class="external text" href="http://onyxneon.com/books/modern_perl/" rel="nofollow" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(102,51,102); padding-right: 13px">Modern Perl</a>&nbsp;2nd Edition (2012), Onyx Neon. Describes&nbsp;<a class="new" href="http://en.wikipedia.org/w/index.php?title=Modern_Perl&amp;action=edit&amp;redlink=1" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(165,88,88)" title="Modern Perl (page does not exist)">Modern Perl</a>&nbsp;programming techniques.</li>
    <li style="margin-bottom: 0.1em;"><i><a href="http://en.wikipedia.org/wiki/Perl_Cookbook" title="Perl Cookbook" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Perl Cookbook</a></i>,&nbsp;<a href="http://en.wikipedia.org/wiki/Special:BookSources/0596003137" class="internal mw-magiclink-isbn" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">ISBN 0-596-00313-7</a>. Practical Perl programming examples.</li>
+
<li><a class="external text" href="http://shop.oreilly.com/product/9780596004927.do" rel="nofollow" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(102,51,102); padding-right: 13px">Programming Perl</a>&nbsp;4th Edition (2012), O&#39;Reilly. The definitive Perl reference.</li>
    <li style="margin-bottom: 0.1em;"><span class="citation book" style="word-wrap: break-word;">Dominus, Mark Jason (2005).&nbsp;<a rel="nofollow" class="external text" href="http://hop.perl.plover.com/book/" style="text-decoration: none; color: rgb(102, 51, 102); padding-right: 13px; background: linear-gradient(transparent, transparent) 100% 50% no-repeat, url(data:image/svg+xml,%3C%3Fxml%20version%3D%221.0%22%20encoding%3D%22UTF-8%22%3F%3E%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2210%22%20height%3D%2210%22%3E%3Cg%20transform%3D%22translate%28-826.429%20-698.791%29%22%3E%3Crect%20width%3D%225.982%22%20height%3D%225.982%22%20x%3D%22826.929%22%20y%3D%22702.309%22%20fill%3D%22%23fff%22%20stroke%3D%22%2306c%22%2F%3E%3Cg%3E%3Cpath%20d%3D%22M831.194%20698.791h5.234v5.391l-1.571%201.545-1.31-1.31-2.725%202.725-2.689-2.689%202.808-2.808-1.311-1.311z%22%20fill%3D%22%2306f%22%2F%3E%3Cpath%20d%3D%22M835.424%20699.795l.022%204.885-1.817-1.817-2.881%202.881-1.228-1.228%202.881-2.881-1.851-1.851z%22%20fill%3D%22%23fff%22%2F%3E%3C%2Fg%3E%3C%2Fg%3E%3C%2Fsvg%3E) 100% 50%;"><i>Higher Order Perl</i></a>. Morgan Kaufmann.&nbsp;<a href="http://en.wikipedia.org/wiki/International_Standard_Book_Number" title="International Standard Book Number" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">ISBN</a>&nbsp;<a href="http://en.wikipedia.org/wiki/Special:BookSources/1-55860-701-3" title="Special:BookSources/1-55860-701-3" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">1-55860-701-3</a>.</span>&nbsp;Functional programming techniques in Perl.</li>
+
<li><a class="external text" href="http://www.pearsonhighered.com/educator/product/Effective-Perl-Programming-Ways-to-Write-Better-More-Idiomatic-Perl-2E/9780321496942.page" rel="nofollow" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(102,51,102); padding-right: 13px">Effective Perl Programming</a>&nbsp;2nd Edition (2010), Addison-Wesley. Intermediate- to advanced-level guide to writing idiomatic Perl.</li>
 +
<li><em><a href="http://en.wikipedia.org/wiki/Perl_Cookbook" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Perl Cookbook">Perl Cookbook</a></em>,&nbsp;<a class="internal mw-magiclink-isbn" href="http://en.wikipedia.org/wiki/Special:BookSources/0596003137" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)">ISBN 0-596-00313-7</a>. Practical Perl programming examples.</li>
 +
<li>Dominus, Mark Jason (2005).&nbsp;<a class="external text" href="http://hop.perl.plover.com/book/" rel="nofollow" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(102,51,102); padding-right: 13px"><em>Higher Order Perl</em></a>. Morgan Kaufmann.&nbsp;<a href="http://en.wikipedia.org/wiki/International_Standard_Book_Number" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="International Standard Book Number">ISBN</a>&nbsp;1-55860-701-3.&nbsp;Functional programming techniques in Perl.</li>
 
</ul>
 
</ul>
<h2 style="font-weight: normal; margin: 1em 0px 0.25em; overflow: hidden; padding: 0px; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(170, 170, 170); font-family: 'Linux Libertine', Georgia, Times, serif; line-height: 1.3; background-image: none; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><span class="mw-headline" id="See_also">See also</span><span class="mw-editsection" style="-webkit-user-select: none; font-size: small; margin-left: 1em; vertical-align: baseline; line-height: 1em; display: inline-block; white-space: nowrap; unicode-bidi: -webkit-isolate; font-family: sans-serif;"><span class="mw-editsection-bracket" style="margin-right: 0px; color: rgb(85, 85, 85); margin-left: 0px;">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=29" title="Edit section: See also" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">edit</a><span class="mw-editsection-bracket" style="margin-left: 0px; color: rgb(85, 85, 85); margin-right: 0px;">]</span></span></h2>
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<div class="noprint portal tright" style="clear: right; float: right; margin: 0.5em 0px 0.5em 1em; color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px; line-height: 17.9200000762939px; border: 1px solid rgb(170, 170, 170);">
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<h2>See also<span style="font-family:sans-serif; font-size:small"><span style="color:rgb(85,85,85)">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=29" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Edit section: See also">edit</a><span style="color:rgb(85,85,85)">]</span></span></h2>
<table style="font-size: 11.8999996185303px; line-height: 13.0899991989136px; max-width: 175px; background: rgb(249, 249, 249);">
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<div class="noprint portal tright" style="font-size: 14px; border-top: rgb(170,170,170) 1px solid; font-family: sans-serif; border-right: rgb(170,170,170) 1px solid; border-bottom: rgb(170,170,170) 1px solid; float: right; color: rgb(37,37,37); clear: right; border-left: rgb(170,170,170) 1px solid; margin: 0.5em 0px 0.5em 1em; line-height: 17px">
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<table style="background:rgb(249,249,249); font-size:11px; line-height:13px; max-width:175px">
            <td style="text-align: center;"><a href="http://en.wikipedia.org/wiki/File:Free_and_open-source_software_logo_(2009).svg" class="image" style="text-decoration: none; color: rgb(11, 0, 128); background: none;"><img alt="Portal icon" src="http://upload.wikimedia.org/wikipedia/commons/thumb/3/31/Free_and_open-source_software_logo_%282009%29.svg/28px-Free_and_open-source_software_logo_%282009%29.svg.png" width="28" height="28" class="noviewer" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/31/Free_and_open-source_software_logo_%282009%29.svg/42px-Free_and_open-source_software_logo_%282009%29.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/31/Free_and_open-source_software_logo_%282009%29.svg/56px-Free_and_open-source_software_logo_%282009%29.svg.png 2x" data-file-width="512" data-file-height="512" style="border: none; vertical-align: middle;" /></a></td>
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<tbody>
            <td style="padding: 0px 0.2em; vertical-align: middle; font-style: italic; font-weight: bold;"><a href="http://en.wikipedia.org/wiki/Portal:Free_software" title="Portal:Free software" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Free software portal</a></td>
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        </tr>
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<td style="text-align: center"><a class="image" href="http://en.wikipedia.org/wiki/File:Free_and_open-source_software_logo_(2009).svg" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)"><img alt="Portal icon" class="noviewer" src="http://upload.wikimedia.org/wikipedia/commons/thumb/3/31/Free_and_open-source_software_logo_%282009%29.svg/28px-Free_and_open-source_software_logo_%282009%29.svg.png" style="border-bottom:medium none; border-left:medium none; border-right:medium none; border-top:medium none; height:28px; vertical-align:middle; width:28px" /></a></td>
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<td style="vertical-align: middle"><a href="http://en.wikipedia.org/wiki/Portal:Free_software" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Portal:Free software">Free software portal</a></td>
            <td style="text-align: center;"><a href="http://en.wikipedia.org/wiki/File:8bit-dynamiclist.gif" class="image" style="text-decoration: none; color: rgb(11, 0, 128); background: none;"><img alt="Portal icon" src="http://upload.wikimedia.org/wikipedia/commons/thumb/1/1d/8bit-dynamiclist.gif/28px-8bit-dynamiclist.gif" width="28" height="28" class="noviewer" srcset="//upload.wikimedia.org/wikipedia/commons/1/1d/8bit-dynamiclist.gif 1.5x, //upload.wikimedia.org/wikipedia/commons/1/1d/8bit-dynamiclist.gif 2x" data-file-width="32" data-file-height="32" style="border: none; vertical-align: middle;" /></a></td>
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</tr>
            <td style="padding: 0px 0.2em; vertical-align: middle; font-style: italic; font-weight: bold;"><a href="http://en.wikipedia.org/wiki/Portal:Computer_programming" title="Portal:Computer programming" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Computer programming portal</a></td>
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<tr>
        </tr>
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<td style="text-align: center"><a class="image" href="http://en.wikipedia.org/wiki/File:8bit-dynamiclist.gif" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)"><img alt="Portal icon" class="noviewer" src="http://upload.wikimedia.org/wikipedia/commons/thumb/1/1d/8bit-dynamiclist.gif/28px-8bit-dynamiclist.gif" style="border-bottom:medium none; border-left:medium none; border-right:medium none; border-top:medium none; height:28px; vertical-align:middle; width:28px" /></a></td>
    </tbody>
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<td style="vertical-align: middle"><a href="http://en.wikipedia.org/wiki/Portal:Computer_programming" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Portal:Computer programming">Computer programming portal</a></td>
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</tr>
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</tbody>
 
</table>
 
</table>
 
</div>
 
</div>
<ul style="line-height: 1.5em; margin: 0.3em 0px 0px 1.6em; padding: 0px; list-style-image: url(data:image/svg+xml,%3C%3Fxml%20version%3D%221.0%22%20encoding%3D%22UTF-8%22%3F%3E%0A%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20version%3D%221.1%22%20width%3D%225%22%20height%3D%2213%22%3E%0A%3Ccircle%20cx%3D%222.5%22%20cy%3D%229.5%22%20r%3D%222.5%22%20fill%3D%22%2300528c%22%2F%3E%0A%3C%2Fsvg%3E%0A); color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px;">
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    <li style="margin-bottom: 0.1em;"><a href="http://en.wikipedia.org/wiki/Outline_of_Perl" title="Outline of Perl" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Outline of Perl</a></li>
+
<ul>
    <li style="margin-bottom: 0.1em;"><a href="http://en.wikipedia.org/wiki/Perl_Data_Language" title="Perl Data Language" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Perl Data Language</a></li>
+
<li><a href="http://en.wikipedia.org/wiki/Outline_of_Perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Outline of Perl">Outline of Perl</a></li>
    <li style="margin-bottom: 0.1em;"><a href="http://en.wikipedia.org/wiki/Perl_Object_Environment" title="Perl Object Environment" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Perl Object Environment</a></li>
+
<li><a href="http://en.wikipedia.org/wiki/Perl_Data_Language" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Perl Data Language">Perl Data Language</a></li>
    <li style="margin-bottom: 0.1em;"><a href="http://en.wikipedia.org/wiki/Plain_Old_Documentation" title="Plain Old Documentation" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">Plain Old Documentation</a></li>
+
<li><a href="http://en.wikipedia.org/wiki/Perl_Object_Environment" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Perl Object Environment">Perl Object Environment</a></li>
 +
<li><a href="http://en.wikipedia.org/wiki/Plain_Old_Documentation" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Plain Old Documentation">Plain Old Documentation</a></li>
 
</ul>
 
</ul>
<h2 style="font-weight: normal; margin: 1em 0px 0.25em; overflow: hidden; padding: 0px; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(170, 170, 170); font-family: 'Linux Libertine', Georgia, Times, serif; line-height: 1.3; background-image: none; background-attachment: initial; background-size: initial; background-origin: initial; background-clip: initial; background-position: initial; background-repeat: initial;"><span class="mw-headline" id="External_links">External links</span><span class="mw-editsection" style="-webkit-user-select: none; font-size: small; margin-left: 1em; vertical-align: baseline; line-height: 1em; display: inline-block; white-space: nowrap; unicode-bidi: -webkit-isolate; font-family: sans-serif;"><span class="mw-editsection-bracket" style="margin-right: 0px; color: rgb(85, 85, 85); margin-left: 0px;">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=30" title="Edit section: External links" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">edit</a><span class="mw-editsection-bracket" style="margin-left: 0px; color: rgb(85, 85, 85); margin-right: 0px;">]</span></span></h2>
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<table class="metadata plainlinks mbox-small" style="font-size: 12.3199996948242px; clear: right; float: right; margin: 4px 0px 4px 1em; width: 238px; line-height: 1.25em; color: rgb(37, 37, 37); font-family: sans-serif; padding: 0.25em 0.5em 0.5em 0.75em; border-style: solid; border-color: rgb(170, 170, 170); background: rgb(249, 249, 249);">
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<h2>External links<span style="font-family:sans-serif; font-size:small"><span style="color:rgb(85,85,85)">[</span><a href="http://en.wikipedia.org/w/index.php?title=Perl&amp;action=edit&amp;section=30" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Edit section: External links">edit</a><span style="color:rgb(85,85,85)">]</span></span></h2>
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<table class="mbox-small metadata plainlinks" style="background:rgb(249,249,249); border-bottom-color:rgb(170,170,170); border-bottom-style:solid; border-left-color:rgb(170,170,170); border-left-style:solid; border-right-color:rgb(170,170,170); border-right-style:solid; border-top-color:rgb(170,170,170); border-top-style:solid; clear:right; color:rgb(37,37,37); float:right; font-family:sans-serif; font-size:12px; line-height:1.25em; margin:4px 0px 4px 1em; padding-bottom:0.5em; padding-left:0.75em; padding-right:0.5em; padding-top:0.25em; width:238px">
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<tbody>
            <div style="clear: both;">Find more about<br />
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<tr>
            <b>Perl</b><br />
+
<td colspan="2" style="text-align: center">
            at Wikipedia's&nbsp;<a href="http://en.wikipedia.org/wiki/Wikipedia:Wikimedia_sister_projects" title="Wikipedia:Wikimedia sister projects" style="text-decoration: none; color: rgb(11, 0, 128); background: none;">sister projects</a></div>
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<div style="clear: both">Find more about<br />
            </td>
+
<strong>Perl</strong><br />
        </tr>
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at Wikipedia&#39;s&nbsp;<a href="http://en.wikipedia.org/wiki/Wikipedia:Wikimedia_sister_projects" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Wikipedia:Wikimedia sister projects">sister projects</a></div>
        <tr style="height: 25px;">
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</td>
            <td style="padding-top: 0.75em;"><a href="http://en.wiktionary.org/wiki/Special:Search/Perl" title="Search Wiktionary" style="text-decoration: none; color: rgb(11, 0, 128); background: none;"><img alt="Search Wiktionary" src="http://upload.wikimedia.org/wikipedia/commons/thumb/f/f8/Wiktionary-logo-en.svg/23px-Wiktionary-logo-en.svg.png" width="23" height="25" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/f8/Wiktionary-logo-en.svg/35px-Wiktionary-logo-en.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/f8/Wiktionary-logo-en.svg/46px-Wiktionary-logo-en.svg.png 2x" data-file-width="1000" data-file-height="1089" style="border: none; vertical-align: middle;" /></a></td>
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</tr>
            <td style="padding-top: 0.75em;"><a href="http://en.wiktionary.org/wiki/Special:Search/Perl" class="extiw" title="wikt:Special:Search/Perl" style="text-decoration: none; color: rgb(102, 51, 102); background: none;">Definitions</a>&nbsp;from Wiktionary</td>
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<tr>
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<td><a href="http://en.wiktionary.org/wiki/Special:Search/Perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Search Wiktionary"><img alt="Search Wiktionary" src="http://upload.wikimedia.org/wikipedia/commons/thumb/f/f8/Wiktionary-logo-en.svg/23px-Wiktionary-logo-en.svg.png" style="border-bottom:medium none; border-left:medium none; border-right:medium none; border-top:medium none; height:25px; vertical-align:middle; width:23px" /></a></td>
        <tr style="height: 25px;">
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<td>Definitions&nbsp;from Wiktionary</td>
            <td><a href="http://en.wikiquote.org/wiki/Perl" title="Search Wikiquote" style="text-decoration: none; color: rgb(11, 0, 128); background: none;"><img alt="Search Wikiquote" src="http://upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Wikiquote-logo.svg/21px-Wikiquote-logo.svg.png" width="21" height="25" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Wikiquote-logo.svg/32px-Wikiquote-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Wikiquote-logo.svg/42px-Wikiquote-logo.svg.png 2x" data-file-width="300" data-file-height="355" style="border: none; vertical-align: middle;" /></a></td>
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            <td><a href="http://en.wikiquote.org/wiki/Perl" class="extiw" title="q:Perl" style="text-decoration: none; color: rgb(102, 51, 102); background: none;">Quotations</a>&nbsp;from Wikiquote</td>
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<tr>
        </tr>
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<td><a href="http://en.wikiquote.org/wiki/Perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Search Wikiquote"><img alt="Search Wikiquote" src="http://upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Wikiquote-logo.svg/21px-Wikiquote-logo.svg.png" style="border-bottom:medium none; border-left:medium none; border-right:medium none; border-top:medium none; height:25px; vertical-align:middle; width:21px" /></a></td>
        <tr style="height: 25px;">
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<td><a class="extiw" href="http://en.wikiquote.org/wiki/Perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(102,51,102)" title="q:Perl">Quotations</a>&nbsp;from Wikiquote</td>
            <td><a href="http://commons.wikimedia.org/wiki/Special:Search/Perl" title="Search Commons" style="text-decoration: none; color: rgb(11, 0, 128); background: none;"><img alt="Search Commons" src="http://upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/18px-Commons-logo.svg.png" width="18" height="25" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/28px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/37px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" style="border: none; vertical-align: middle;" /></a></td>
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            <td><a href="http://commons.wikimedia.org/wiki/Special:Search/Perl" class="extiw" title="c:Special:Search/Perl" style="text-decoration: none; color: rgb(102, 51, 102); background: none;">Media</a>&nbsp;from Commons</td>
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<td><a href="http://commons.wikimedia.org/wiki/Special:Search/Perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Search Commons"><img alt="Search Commons" src="http://upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/18px-Commons-logo.svg.png" style="border-bottom:medium none; border-left:medium none; border-right:medium none; border-top:medium none; height:25px; vertical-align:middle; width:18px" /></a></td>
        <tr style="height: 25px;">
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<td>Media&nbsp;from Commons</td>
            <td><a href="http://en.wikibooks.org/wiki/Perl_Programming" title="Search Wikibooks" style="text-decoration: none; color: rgb(11, 0, 128); background: none;"><img alt="Search Wikibooks" src="http://upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Wikibooks-logo.svg/25px-Wikibooks-logo.svg.png" width="25" height="25" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Wikibooks-logo.svg/38px-Wikibooks-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Wikibooks-logo.svg/50px-Wikibooks-logo.svg.png 2x" data-file-width="300" data-file-height="300" style="border: none; vertical-align: middle;" /></a></td>
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            <td><a href="http://en.wikibooks.org/wiki/Perl_Programming" class="extiw" title="b:Perl Programming" style="text-decoration: none; color: rgb(102, 51, 102); background: none;">Textbooks</a>&nbsp;from Wikibooks</td>
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<tr>
        </tr>
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<td><a href="http://en.wikibooks.org/wiki/Perl_Programming" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Search Wikibooks"><img alt="Search Wikibooks" src="http://upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Wikibooks-logo.svg/25px-Wikibooks-logo.svg.png" style="border-bottom:medium none; border-left:medium none; border-right:medium none; border-top:medium none; height:25px; vertical-align:middle; width:25px" /></a></td>
        <tr style="height: 25px;">
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<td><a class="extiw" href="http://en.wikibooks.org/wiki/Perl_Programming" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(102,51,102)" title="b:Perl Programming">Textbooks</a>&nbsp;from Wikibooks</td>
            <td><a href="http://en.wikiversity.org/wiki/Topic:Perl" title="Search Wikiversity" style="text-decoration: none; color: rgb(11, 0, 128); background: none;"><img alt="Search Wikiversity" src="http://upload.wikimedia.org/wikipedia/commons/thumb/1/1b/Wikiversity-logo-en.svg/25px-Wikiversity-logo-en.svg.png" width="25" height="23" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1b/Wikiversity-logo-en.svg/38px-Wikiversity-logo-en.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1b/Wikiversity-logo-en.svg/50px-Wikiversity-logo-en.svg.png 2x" data-file-width="1000" data-file-height="900" style="border: none; vertical-align: middle;" /></a></td>
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            <td><a href="http://en.wikiversity.org/wiki/Topic:Perl" class="extiw" title="v:Topic:Perl" style="text-decoration: none; color: rgb(102, 51, 102); background: none;">Learning resources</a>&nbsp;from Wikiversity</td>
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<tr>
        </tr>
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<td><a href="http://en.wikiversity.org/wiki/Topic:Perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Search Wikiversity"><img alt="Search Wikiversity" src="http://upload.wikimedia.org/wikipedia/commons/thumb/1/1b/Wikiversity-logo-en.svg/25px-Wikiversity-logo-en.svg.png" style="border-bottom:medium none; border-left:medium none; border-right:medium none; border-top:medium none; height:23px; vertical-align:middle; width:25px" /></a></td>
    </tbody>
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<td><a class="extiw" href="http://en.wikiversity.org/wiki/Topic:Perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(102,51,102)" title="v:Topic:Perl">Learning resources</a>&nbsp;from Wikiversity</td>
 +
</tr>
 +
</tbody>
 
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</table>
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Latest revision as of 09:18, 14 May 2016

 Perl is a family of high-level, general-purpose, interpreted, dynamic programming languages. The languages in this family include Perl 5 and Perl 6.[4]

Though Perl is not officially an acronym,[5] there are various backronyms in use, the most well-known being "Practical Extractionand Reporting Language".[6] 

Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier.[7] 

Since then, it has undergone many changes and revisions. Perl 6, which began as a redesign of Perl 5 in 2000, eventually evolved into a separate language.

Both languages continue to be developed independently by different development teams and liberally borrow ideas from one another.

 

The Perl languages borrow features from other programming languages including Cshell scripting (sh), AWK, and sed.[8] They provide powerful text processing facilities without the arbitrary data-length limits of many contemporary Unix commandline tools,[9] facilitating easy manipulation of text files. Perl 5 gained widespread popularity in the late 1990s as a CGI scriptinglanguage, in part due to its unsurpassed[10][11][12] regular expression and string parsing abilities.[13]

In addition to CGI, Perl 5 is used for graphics programmingsystem administrationnetwork programming, finance,bioinformatics, and other applications. It has been nicknamed "the Swiss Army chainsaw of scripting languages" because of its flexibility and power,[14] and possibly also because of its "ugliness".[15] In 1998, it was also referred to as the "duct tape that holds the Internet together", in reference to both its ubiquitous use as a glue language and its perceived inelegance.[16]

 

 

History

Early versions

Larry Wall began work on Perl in 1987, while working as a programmer at Unisys,[9] and released version 1.0 to the comp.sources.misc newsgroup on December 18, 1987.[17]The language expanded rapidly over the next few years.

Perl 2, released in 1988, featured a better regular expression engine. Perl 3, released in 1989, added support for binary data streams.

Originally the only documentation for Perl was a single (increasingly lengthy) man page. In 1991, Programming Perl, known to many Perl programmers as the "Camel Book" because of its cover, was published and became the de facto reference for the language. At the same time, the Perl version number was bumped to 4, not to mark a major change in the language but to identify the version that was well documented by the book.

Early Perl 5

Perl 4 went through a series of maintenance releases, culminating in Perl 4.036 in 1993. At that point, Wall abandoned Perl 4 to begin work on Perl 5. Initial design of Perl 5 continued into 1994. The perl5-porters mailing list was established in May 1994 to coordinate work on porting Perl 5 to different platforms. It remains the primary forum for development, maintenance, and porting of Perl 5.[18]

Perl 5.000 was released on October 17, 1994.[19] It was a nearly complete rewrite of the interpreter, and it added many new features to the language, including objects,referenceslexical (my) variables, and modules. Importantly, modules provided a mechanism for extending the language without modifying the interpreter. This allowed the core interpreter to stabilize, even as it enabled ordinary Perl programmers to add new language features. Perl 5 has been in active development since then.

Perl 5.001 was released on March 13, 1995. Perl 5.002 was released on February 29, 1996 with the new prototypes feature. This allowed module authors to make subroutinesthat behaved like Perl builtins. Perl 5.003 was released June 25, 1996, as a security release.

One of the most important events in Perl 5 history took place outside of the language proper and was a consequence of its module support. On October 26, 1995, theComprehensive Perl Archive Network (CPAN) was established as a repository for Perl modules and Perl itself; as of November 2014, it carries over 140,776 modules, written by more than 11,804 authors, and is mirrored worldwide at more than 250 locations.[20]

Perl 5.004 was released on May 15, 1997, and included among other things the UNIVERSAL package, giving Perl a base object to which all classes were automatically derived and the ability to require versions of modules. Another significant development was the inclusion of the CGI.pm module,[21] which contributed to Perl's popularity as a CGI scripting language.[22]

Perl is also now supported running under Microsoft Windows and several other operating systems.[21]

Perl 5.005 was released on July 22, 1998. This release included several enhancements to the regex engine, new hooks into the backend through the B::* modules, theqr// regex quote operator, a large selection of other new core modules, and added support for several more operating systems, including BeOS.[23]

2000–present

Major version Latest update
5.5 2004-02-23[24]
5.6 2003-11-15[24]
5.8 2008-12-14[24]
5.10 2009-08-23[24]
5.12 2012-11-10[24]
5.14 2013-03-10[24]
5.16 2013-03-11[24]
5.18 2014-10-02[24]
5.20 2014-09-14[24]
5.21 2015-01-20[24]
Old version

Older version, still supported
Current version

Future release

Perl 5.6 was released on March 22, 2000. Major changes included 64-bit support, Unicode string representation, large file support (i.e. files over 2 GiB) and the "our" keyword.[25][26] When developing Perl 5.6, the decision was made to switch the versioning scheme to one more similar to other open source projects; after 5.005_63, the next version became 5.5.640, with plans for development versions to have odd numbers and stable versions to have even numbers.

In 2000, Wall put forth a call for suggestions for a new version of Perl from the community. The process resulted in 361 RFC (request for comments) documents that were to be used in guiding development of Perl 6. In 2001,[27] work began on the apocalypses for Perl 6, a series of documents meant to summarize the change requests and present the design of the next generation of Perl. They were presented as a digest of the RFCs, rather than a formal document. At this point, Perl 6 existed only as a description of a language.

Perl 5.8 was first released on July 18, 2002, and had nearly yearly updates since then. Perl 5.8 improved Unicode support, added a new I/O implementation, added a new thread implementation, improved numeric accuracy, and added several new modules.[28] As of 2013 this version still remains the most popular version of Perl and is used by Red Hat 5, Suse 10, Solaris 10, HP-UX 11.33 and AIX 5.

In 2004, work began on the Synopses – documents that originally summarized the Apocalypses, but which became the specification for the Perl 6 language. In February 2005, Audrey Tang began work on Pugs, a Perl 6 interpreter written in Haskell.[29] This was the first concerted effort towards making Perl 6 a reality. This effort stalled in 2006.[30]

On December 18, 2007, the 20th anniversary of Perl 1.0, Perl 5.10.0 was released. Perl 5.10.0 included notable new features, which brought it closer to Perl 6. These included a switch statement (called "given"/"when"), regular expressions updates, and the smart match operator, "~~".[31][32] Around this same time, development began in earnest on another implementation of Perl 6 known as Rakudo Perl, developed in tandem with the Parrot virtual machine. As of November 2009, Rakudo Perl has had regular monthly releases and now is the most complete implementation of Perl 6.

A major change in the development process of Perl 5 occurred with Perl 5.11; the development community has switched to a monthly release cycle of development releases, with a yearly schedule of stable releases. By that plan, bugfix point releases will follow the stable releases every three months.

On April 12, 2010, Perl 5.12.0 was released. Notable core enhancements include new package NAME VERSION syntax, the Yada Yada operator (intended to mark placeholder code that is not yet implemented), implicit strictures, full Y2038 compliance, regex conversion overloading, DTrace support, and Unicode 5.2.[33] On January 21, 2011, Perl 5.12.3 was released; it contains updated modules and some documentation changes.[34] Version 5.12.4 was released on June 20, 2011. The latest version of that branch, 5.12.5, was released on November 10, 2012.

On May 14, 2011, Perl 5.14 was released. JSON support is built-in as of 5.14.2. The latest version of that branch, 5.14.4, was released on March 10, 2013.

On May 20, 2012, Perl 5.16 was released. Notable new features include the ability to specify a given version of Perl that one wishes to emulate, allowing users to upgrade their version of Perl, but still run old scripts that would normally be incompatible.[35] Perl 5.16 also updates the core to support Unicode 6.1.[35]

On May 18, 2013, Perl 5.18 was released. Notable new features include the new dtrace hooks, lexical subs, more CORE:: subs, overhaul of the hash for security reasons, support for Unicode 6.2.[36]

On May 27, 2014, Perl 5.20 was released. Notable new features include subroutine signatures, hash slices/new slice syntax, postfix dereferencing (experimental), Unicode 6.3, rand() using consistent random number generator.[37]

Some observers credit the release of Perl 5.10 with the start of the Modern Perl movement.[38] In particular, this phrase describes a style of development that embraces the use of the CPAN, takes advantage of recent developments in the language, and is rigorous about creating high quality code.[39] While the book "Modern Perl"[40] may be the most visible standard-bearer of this idea, other groups such as the Enlightened Perl Organization[41] have taken up the cause.

In late 2012 and 2013 several projects for alternative implementations for Perl 5 started: Perl5 in Perl6 by the Rakudo Perl team,[42] moe by Stevan Little and friends,[43]p2[44] by the Perl11 team under Reini Urban, gperl by goccy,[45] and rperl a kickstarter project led by Will Braswell and affiliated with the Perll11 project.[46]

Name

Perl was originally named "Pearl". Wall wanted to give the language a short name with positive connotations; he claims that he considered (and rejected) every three- and four-letter word in the dictionary. He also considered naming it after his wife Gloria. Wall discovered the existing PEARL programming language before Perl's official release and changed the spelling of the name.[47]

When referring to the language, the name is normally capitalized (Perl) as a proper noun. When referring to the interpreter program itself, the name is often uncapitalized (perl) because most Unix-like file systems are case-sensitive. Before the release of the first edition of Programming Perl, it was common to refer to the language as perl;Randal L. Schwartz, however, capitalized the language's name in the book to make it stand out better when typeset. This case distinction was subsequently documented as canonical.[48]

The name is occasionally expanded as Practical Extraction and Report Language, but this is a backronym.[49] Other expansions have been suggested as equally canonical, including Wall's own humorous Pathologically Eclectic Rubbish Lister.[50] Indeed, Wall claims that the name was intended to inspire many different expansions.[51]

Camel symbol

 
The Camel symbol used by O'Reilly Media

Programming Perl, published by O'Reilly Media, features a picture of a dromedary camel on the cover and is commonly called the "Camel Book".[52] This image of a camel has become an unofficial symbol of Perl as well as a general hacker emblem, appearing on T-shirts and other clothing items.

O'Reilly owns the image as a trademark but licenses it for non-commercial use, requiring only an acknowledgement and a link to www.perl.com. Licensing for commercial use is decided on a case by case basis.[53] O'Reilly also provides "Programming Republic of Perl" logos for non-commercial sites and "Powered by Perl" buttons for any site that uses Perl.[53]

Onion symbol

 
The onion logo used by The Perl Foundation

The Perl Foundation owns an alternative symbol, an onion, which it licenses to its subsidiaries, Perl MongersPerlMonks, Perl.org, and others.[54]The symbol is a visual pun on pearl onion.[55]

Overview

According to Wall, Perl has two slogans. The first is "There's more than one way to do it", commonly known as TMTOWTDI. The second slogan is "Easy things should be easy and hard things should be possible".[9]

Features

The overall structure of Perl derives broadly from C. Perl is procedural in nature, with variablesexpressionsassignment statementsbrace-delimited blockscontrol structures, and subroutines.

Perl also takes features from shell programming. All variables are marked with leading sigils, which allow variables to be interpolated directly into strings. However, unlike the shell, Perl uses sigils on all accesses to variables, and unlike most other programming languages that use sigils, the sigil doesn't denote the type of the variable but the type of the expression. So for example, to access a list of values in a hash, the sigil for an array ("@") is used, not the sigil for a hash ("%"). Perl also has many built-in functions that provide tools often used in shell programming (although many of these tools are implemented by programs external to the shell) such as sorting, and calling onoperating system facilities.

Perl takes lists from Lisphashes ("associative arrays") from AWK, and regular expressions from sed. These simplify and facilitate many parsing, text-handling, and data-management tasks. Also shared with Lisp are the implicit return of the last value in a block, and the fact that all statements have a value, and thus are also expressions and can be used in larger expressions themselves.

Perl 5 added features that support complex data structuresfirst-class functions (that is, closures as values), and an object-oriented programming model. These includereferences, packages, class-based method dispatch, and lexically scoped variables, along with compiler directives (for example, the strict pragma). A major additional feature introduced with Perl 5 was the ability to package code as reusable modules. Wall later stated that "The whole intent of Perl 5's module system was to encourage the growth of Perl culture rather than the Perl core."[56]

All versions of Perl do automatic data-typing and automatic memory management. The interpreter knows the type and storage requirements of every data object in the program; it allocates and frees storage for them as necessary using reference counting (so it cannot deallocate circular data structures without manual intervention). Legaltype conversions — for example, conversions from number to string — are done automatically at run time; illegal type conversions are fatal errors.

Design

The design of Perl can be understood as a response to three broad trends in the computer industry: falling hardware costs, rising labor costs, and improvements in compilertechnology. Many earlier computer languages, such as Fortran and C, aimed to make efficient use of expensive computer hardware. In contrast, Perl was designed so that computer programmers could write programs more quickly and easily.

Perl has many features that ease the task of the programmer at the expense of greater CPU and memory requirements. These include automatic memory management;dynamic typing; strings, lists, and hashes; regular expressions; introspection; and an eval() function. Perl follows the theory of "no built-in limits",[52] an idea similar to theZero One Infinity rule.

Wall was trained as a linguist, and the design of Perl is very much informed by linguistic principles. Examples include Huffman coding (common constructions should be short), good end-weighting (the important information should come first), and a large collection of language primitives. Perl favors language constructs that are concise and natural for humans to write, even where they complicate the Perl interpreter.

Perl's syntax reflects the idea that "things that are different should look different."[57] For example, scalars, arrays, and hashes have different leading sigils. Array indices and hash keys use different kinds of braces. Strings and regular expressions have different standard delimiters. This approach can be contrasted with languages such as Lisp, where the same S-expression construct and basic syntax are used for many different purposes.

Perl does not enforce any particular programming paradigm (proceduralobject-orientedfunctional, or others) or even require the programmer to choose among them.

There is a broad practical bent to both the Perl language and the community and culture that surround it. The preface to Programming Perl begins: "Perl is a language for getting your job done."[9] One consequence of this is that Perl is not a tidy language. It includes many features, tolerates exceptions to its rules, and employs heuristics to resolve syntactical ambiguities. Because of the forgiving nature of the compiler, bugs can sometimes be hard to find. Perl's function documentation remarks on the variant behavior of built-in functions in list and scalar contexts by saying, "In general, they do what you want, unless you want consistency."[58]

No written specification or standard for the Perl language exists for Perl versions through Perl 5, and there are no plans to create one for the current version of Perl. There has been only one implementation of the interpreter, and the language has evolved along with it. That interpreter, together with its functional tests, stands as a de factospecification of the language. Perl 6, however, started with a specification,[59] and several projects[60] aim to implement some or all of the specification.

Applications

Perl has many and varied applications, compounded by the availability of many standard and third-party modules.

Perl has chiefly been used to write CGI scripts: large projects written in Perl include cPanelSlashBugzillaRTTWiki, and Movable Type; high-traffic websites that use Perl extensively include Priceline.comCraigslist,[61] IMDb,[62] LiveJournalDuckDuckGo,[63][64] Slashdot and Ticketmaster. It is also an optional component of the popular LAMPtechnology stack for Web development, in lieu of PHP or Python.

Perl is often used as a glue language, tying together systems and interfaces that were not specifically designed to interoperate, and for "data munging",[65] that is, converting or processing large amounts of data for tasks such as creating reports. In fact, these strengths are intimately linked. The combination makes Perl a popular all-purpose language for system administrators, particularly because short programs, often called "one-liner programs", can be entered and run on a single command line.

Perl code can be made portable across Windows and Unix; such code is often used by suppliers of software (both COTS and bespoke) to simplify packaging and maintenance of software build- and deployment-scripts.

Graphical user interfaces (GUIs) may be developed using Perl. For example, Perl/Tk and WxPerl are commonly used to enable user interaction with Perl scripts. Such interaction may be synchronous or asynchronous, using callbacks to update the GUI.

Implementation

Perl is implemented as a core interpreter, written in C, together with a large collection of modules, written in Perl and C. As of 2010, the stable version (5.18.2) is 16.53 MBwhen packaged in a tar file and gzip compressed.[66] The interpreter is 150,000 lines of C code and compiles to a 1 MB executable on typical machine architectures. Alternatively, the interpreter can be compiled to a link library and embedded in other programs. There are nearly 500 modules in the distribution, comprising 200,000 lines of Perl and an additional 350,000 lines of C code. (Much of the C code in the modules consists of character encoding tables.)

The interpreter has an object-oriented architecture. All of the elements of the Perl language—scalars, arrays, hashes, coderefs, file handles—are represented in the interpreter by C structs. Operations on these structs are defined by a large collection of macrostypedefs, and functions; these constitute the Perl C API. The Perl API can be bewildering to the uninitiated, but its entry points follow a consistent naming scheme, which provides guidance to those who use it.

The life of a Perl interpreter divides broadly into a compile phase and a run phase.[67] In Perl, the phases are the major stages in the interpreter's life-cycle. Each interpreter goes through each phase only once, and the phases follow in a fixed sequence.

Most of what happens in Perl's compile phase is compilation, and most of what happens in Perl's run phase is execution, but there are significant exceptions. Perl makes important use of its capability to execute Perl code during the compile phase. Perl will also delay compilation into the run phase. The terms that indicate the kind of processing that is actually occurring at any moment are compile time and run time. Perl is in compile time at most points during the compile phase, but compile time may also be entered during the run phase. The compile time for code in a string argument passed to the eval built-in occurs during the run phase. Perl is often in run time during the compile phase and spends most of the run phase in run time. Code in BEGIN blocks executes at run time but in the compile phase.

At compile time, the interpreter parses Perl code into a syntax tree. At run time, it executes the program by walking the tree. Text is parsed only once, and the syntax tree is subject to optimization before it is executed, so that execution is relatively efficient. Compile-time optimizations on the syntax tree include constant folding and context propagation, but peephole optimization is also performed.

Perl has a Turing-complete grammar because parsing can be affected by run-time code executed during the compile phase.[68] Therefore, Perl cannot be parsed by a straight Lex/Yacc lexer/parser combination. Instead, the interpreter implements its own lexer, which coordinates with a modified GNU bison parser to resolve ambiguities in the language.

It is often said that "Only perl can parse Perl",[69] meaning that only the Perl interpreter (perl) can parse the Perl language (Perl), but even this is not, in general, true. Because the Perl interpreter can simulate a Turing machine during its compile phase, it would need to decide the halting problem in order to complete parsing in every case. It is a long-standing result that the halting problem is undecidable, and therefore not even perl can always parse Perl. Perl makes the unusual choice of giving the user access to its full programming power in its own compile phase. The cost in terms of theoretical purity is high, but practical inconvenience seems to be rare.

Other programs that undertake to parse Perl, such as source-code analyzers and auto-indenters, have to contend not only with ambiguous syntactic constructs but also with the undecidability of Perl parsing in the general case. Adam Kennedy's PPI project focused on parsing Perl code as a document (retaining its integrity as a document), instead of parsing Perl as executable code (that not even Perl itself can always do). It was Kennedy who first conjectured that "parsing Perl suffers from the 'halting problem'",[70] which was later proved.[71]

Perl is distributed with over 250,000 functional tests for core Perl language and over 250,000 functional tests for core modules. These run as part of the normal build process and extensively exercise the interpreter and its core modules. Perl developers rely on the functional tests to ensure that changes to the interpreter do not introduce software bugs; additionally, Perl users who see that the interpreter passes its functional tests on their system can have a high degree of confidence that it is working properly.

Availability

Perl is dual licensed under both the Artistic License and the GNU General Public License. Distributions are available for most operating systems. It is particularly prevalent onUnix and Unix-like systems, but it has been ported to most modern (and many obsolete) platforms. With only six reported exceptions, Perl can be compiled from source code on all POSIX-compliant, or otherwise-Unix-compatible platforms.[72]

Because of unusual changes required for the Mac OS Classic environment, a special port called MacPerl was shipped independently.[73]

The Comprehensive Perl Archive Network carries a complete list of supported platforms with links to the distributions available on each.[74] CPAN is also the source for publicly available Perl modules that are not part of the core Perl distribution.

Windows[edit]

Users of Microsoft Windows typically install one of the native binary distributions of Perl for Win32, most commonly Strawberry Perl or ActivePerl. Compiling Perl fromsource code under Windows is possible, but most installations lack the requisite C compiler and build tools. This also makes it difficult to install modules from the CPAN, particularly those that are partially written in C.

ActivePerl is a closed source distribution from ActiveState that has regular releases that track the core Perl releases.[75] The distribution also includes the Perl package manager (PPM),[76] a popular tool for installing, removing, upgrading, and managing the use of common Perl modules. Included also is PerlScript, a Windows Script Host(WSH) engine implementing the Perl language. Visual Perl is an ActiveState tool that adds Perl to the Visual Studio .NET development suite.

Strawberry Perl is an open source distribution for Windows. It has had regular, quarterly releases since January 2008, including new modules as feedback and requests come in. Strawberry Perl aims to be able to install modules like standard Perl distributions on other platforms, including compiling XS modules.

The Cygwin emulation layer is another way of running Perl under Windows. Cygwin provides a Unix-like environment on Windows, and both Perl and CPAN are available as standard pre-compiled packages in the Cygwin setup program. Since Cygwin also includes gcc, compiling Perl from source is also possible.

A perl executable is included in several Windows Resource kits in the directory with other scripting tools.

Implementations of Perl come with the MKS Toolkit and UWIN.

Database interfaces[edit]

Perl's text-handling capabilities can be used for generating SQL queries; arrays, hashes, and automatic memory management make it easy to collect and process the returned data. For example, in Tim Bunce's Perl DBI application programming interface (API), the arguments to the API can be the text of SQL queries; thus it is possible to program in multiple languages at the same time (e.g., for generating a Web page using HTMLJavaScript, and SQL in a here document). The use of Perl variable interpolation to programmatically customize each of the SQL queries, and the specification of Perl arrays or hashes as the structures to programmatically hold the resultingdata sets from each SQL query, allows a high-level mechanism for handling large amounts of data for post-processing by a Perl subprogram.[77] In early versions of Perl, database interfaces were created by relinking the interpreter with a client-side database library. This was sufficiently difficult that it was done for only a few of the most-important and most widely used databases, and it restricted the resulting perl executable to using just one database interface at a time.

In Perl 5, database interfaces are implemented by Perl DBI modules. The DBI (Database Interface) module presents a single, database-independent interface to Perl applications, while the DBD (Database Driver) modules handle the details of accessing some 50 different databases; there are DBD drivers for most ANSI SQL databases.

DBI provides caching for database handles and queries, which can greatly improve performance in long-lived execution environments such as mod perl,[78] helping high-volume systems avert load spikes as in the Slashdot effect.

In modern Perl applications, especially those written using Web application frameworks such as Catalyst, the DBI module is often used indirectly via object-relational mappers such as DBIx::ClassClass::DBI or Rose::DB::Object that generate SQL queries and handle data transparently to the application author.

Comparative performance[edit]

The Computer Language Benchmarks Game, a project hosted by Alioth, compares the performance of implementations of typical programming problems in several programming languages.[79] The submitted Perl implementations typically perform toward the high end of the memory-usage spectrum and give varied speed results. Perl's performance in the benchmarks game is typical for interpreted languages.[80]

Large Perl programs start more slowly than similar programs in compiled languages because perl has to compile the source every time it runs. In a talk at the YAPC::Europe 2005 conference and subsequent article "A Timely Start", Jean-Louis Leroy found that his Perl programs took much longer to run than expected because the perl interpreter spent significant time finding modules within his over-large include path.[81] Unlike Java, Python, and Ruby, Perl has only experimental support for pre-compiling.[82]Therefore Perl programs pay this overhead penalty on every execution. The run phase of typical programs is long enough that amortized startup time is not substantial, but benchmarks that measure very short execution times are likely to be skewed due to this overhead.

A number of tools have been introduced to improve this situation. The first such tool was Apache's mod perl, which sought to address one of the most-common reasons that small Perl programs were invoked rapidly: CGI Web development. ActivePerl, via Microsoft ISAPI, provides similar performance improvements.

Once Perl code is compiled, there is additional overhead during the execution phase that typically isn't present for programs written in compiled languages such as C or C++. Examples of such overhead include bytecode interpretation, reference-counting memory management, and dynamic type-checking.

Optimizing[edit]

Because Perl is an interpreted language, it can give problems when efficiency is critical; in such situations, the most critical routines can be written in other languages such as C, which can be connected to Perl via simple Inline modules or the more complex but flexible XS mechanism.[83]

Perl 6[edit]

Main article: Perl 6
 
Camelia, the logo for the Perl 6 project.[84]

At the 2000 Perl ConferenceJon Orwant made a case for a major new language-initiative.[85] This led to a decision to begin work on a redesign of the language, to be called Perl 6. Proposals for new language features were solicited from the Perl community at large, which submitted more than 300 RFCs.

Wall spent the next few years digesting the RFCs and synthesizing them into a coherent framework for Perl 6. He has presented his design for Perl 6 in a series of documents called "apocalypses" - numbered to correspond to chapters in Programming Perl. As of January 2011, the developing specification of Perl 6 is encapsulated in design documents called Synopses - numbered to correspond to Apocalypses.[86]

Perl 6 is not intended to be backward compatible, although there will be a compatibility mode. Perl 6 and Perl 5 are distinct languages with a common ancestry.[87]

Thesis work by Bradley M. Kuhn, overseen by Wall, considered the possible use of the Java virtual machine as a runtime for Perl.[88] Kuhn's thesis showed this approach to be problematic. In 2001, it was decided that Perl 6 would run on a cross-language virtual machine called Parrot. This will mean that other languages targeting the Parrot will gain native access to CPAN, allowing some level of cross-language development.

In 2005, Audrey Tang created the pugs project, an implementation of Perl 6 in Haskell. This acted as, and continues to act as, a test platform for the Perl 6 language (separate from the development of the actual implementation) - allowing the language designers to explore. The pugs project spawned an active Perl/Haskell cross-language community centered around the freenode #perl6 IRC channel.

As of 2012, a number of features in the Perl 6 language show similarities to Haskell.

As of 2012, Perl 6 development centers primarily around two compilers:[89]

  1. Rakudo Perl 6, an implementation running on the Parrot virtual machine and the Java virtual machine.[90] Developers are also working on MoarVM, a C language-based virtual machine designed specifically for Rakudo.[91]
  2. Niecza, which targets the Common Language Runtime.

Future of Perl 5[edit]

Development of Perl 5 is also continuing. Perl 5.12.0 was released in April 2010 with some new features influenced by the design of Perl 6.,[33][92] followed by Perl 5.14.1 (released on June 17, 2011), Perl 5.16.1 (released on August 9, 2012.[93]), and Perl 5.18.0 (released on May 18, 2013). Perl 5 development versions are released on a monthly basis, with major releases coming out once per year.[94]

Future plans for Perl 5 include making the core language easier to extend from modules, and providing a small, extensible Meta-object protocol in core.[95]

The relative proportion of searches for 'Perl programming', as compared with similar searches for other programming languages, steadily declined from about 10% in 2005 to about 2% in 2011, and has remained around the 2% level since.[96]

Perl community[edit]

Perl's culture and community has developed alongside the language itself. Usenet was the first public venue in which Perl was introduced, but over the course of its evolution, Perl's community was shaped by the growth of broadening Internet-based services including the introduction of the World Wide Web. The community that surrounds Perl was, in fact, the topic of Wall's first "State of the Onion" talk.[97]

State of the Onion[edit]

State of the Onion is the name for Wall’s yearly keynote-style summaries on the progress of Perl and its community. They are characterized by his hallmark humor, employing references to Perl’s culture, the wider hacker culture, Wall’s linguistic background, sometimes his family life, and occasionally even his Christian background.[98]

Each talk is first given at various Perl conferences and is eventually also published online.

Perl pastimes[edit]

JAPHs

In email, Usenet, and message board postings, "Just another Perl hacker" (JAPH) programs are a common trend, originated by Randal L. Schwartz, one of the earliest professional Perl trainers.[99] In the parlance of Perl culture, Perl programmers are known as Perl hackers, and from this derives the practice of writing short programs to print out the phrase "Just another Perl hacker,". In the spirit of the original concept, these programs are moderately obfuscated and short enough to fit into the signature of an email or Usenet message. The "canonical" JAPH as developed by Schwartz includes the comma at the end, although this is often omitted.[100]

Perl golf

Perl "golf" is the pastime of reducing the number of characters (key "strokes") used in a Perl program to the bare minimum, much in the same way that golf players seek to take as few shots as possible in a round. The phrase's first use[101] emphasized the difference between pedestrian code meant to teach a newcomer and terse hacks likely to amuse experienced Perl programmers, an example of the latter being JAPHs that were already used in signatures in Usenet postings and elsewhere. Similar stunts had been an unnamed pastime in the language APL in previous decades. The use of Perl to write a program that performed RSA encryption prompted a widespread and practical interest in this pastime.[102] In subsequent years, the term "code golf" has been applied to the pastime in other languages.[103] A Perl Golf Apocalypse was held at Perl Conference 4.0 in Monterey, California in July 2000.

Obfuscation

As with C, obfuscated code competitions were a well known pastime in the late 1990s. The Obfuscated Perl Contest was a competition held by The Perl Journal from 1996 to 2000 that made an arch virtue of Perl's syntactic flexibility. Awards were given for categories such as "most powerful"—programs that made efficient use of space—and "best four-line signature" for programs that fit into four lines of 76 characters in the style of a Usenet signature block.[104]

Poetry

Perl poetry is the practice of writing poems that can be compiled as legal Perl code, for example the piece known as Black Perl. Perl poetry is made possible by the large number of English words that are used in the Perl language. New poems are regularly submitted to the community at PerlMonks.[105]

Perl on IRC[edit]

There are a number of IRC channels that offer support for the language and some modules.

IRC Network Channels
irc.freenode.net #perl #perl6 #cbstream #perlcafe #poe
irc.perl.org #moose #poe #catalyst #dbix-class #perl-help #distzilla #epo #corehackers #sdl #win32 #toolchain #padre #dancer
irc.slashnet.org #perlmonks
irc.oftc.net #perl
irc.efnet.net #perlhelp
irc.rizon.net #perl
irc.debian.org #debian-perl

CPAN Acme[edit]

There are also many examples of code written purely for entertainment on the CPANLingua::Romana::Perligata, for example, allows writing programs in Latin.[106] Upon execution of such a program, the module translates its source code into regular Perl and runs it.

The Perl community has set aside the "Acme" namespace for modules that are fun in nature (but its scope has widened to include exploratory or experimental code or any other module that is not meant to ever be used in production). Some of the Acme modules are deliberately implemented in amusing ways. This includes Acme::Bleach, one of the first modules in the Acme:: namespace,[107] which allows the program's source code to be "whitened" (i.e., all characters replaced with whitespace) and yet still work.

Example code[edit]

In older versions of Perl, one would write the Hello World program as:

    <span style="color:rgb(0,0,102)">print</span> <span style="color:rgb(255,0,0)">"Hello World!<strong>\n</strong>"</span><span style="color:rgb(51,153,51)">;</span>

In later versions, which support the say statement, one can also write it as:

    <strong>use</strong> <span style="color:rgb(204,102,204)">5.010</span><span style="color:rgb(51,153,51)">;</span>
    say <span style="color:rgb(255,0,0)">"Hello World!"</span><span style="color:rgb(51,153,51)">;</span>

Good Perl practices require more complex programs to add the use strict; and use warnings; pragmas, leading into something like:

    <strong>use</strong> strict<span style="color:rgb(51,153,51)">;</span>
    <strong>use</strong> warnings<span style="color:rgb(51,153,51)">;</span>
 
    <span style="color:rgb(0,0,102)">print</span> <span style="color:rgb(255,0,0)">"Hello World!<strong>\n</strong>"</span><span style="color:rgb(51,153,51)">;</span>

Here is a more complex Perl program, that counts down the seconds up to a given threshold:

 <em>#!/usr/bin/perl</em>
 <strong>use</strong> strict<span style="color:rgb(51,153,51)">;</span>
 <strong>use</strong> warnings<span style="color:rgb(51,153,51)">;</span>
 <strong>use</strong> IO<span style="color:rgb(51,153,51)">::</span><span style="color:rgb(0,102,0)">Handle</span><span style="color:rgb(51,153,51)">;</span>
 
 <span style="color:rgb(177,177,0)">my</span> <span style="color:rgb(0,153,0)">(</span> <span style="color:rgb(0,0,255)">$remaining</span><span style="color:rgb(51,153,51)">,</span> <span style="color:rgb(0,0,255)">$total</span> <span style="color:rgb(0,153,0)">)</span><span style="color:rgb(51,153,51)">;</span>
 
 <span style="color:rgb(0,0,255)">$remaining</span> <span style="color:rgb(51,153,51)">=</span> <span style="color:rgb(0,0,255)">$total</span> <span style="color:rgb(51,153,51)">=</span> <span style="color:rgb(0,0,102)">shift</span><span style="color:rgb(0,153,0)">(</span><span style="color:rgb(51,153,51)">@</span><strong>ARGV</strong><span style="color:rgb(0,153,0)">)</span><span style="color:rgb(51,153,51)">;</span>
 
 STDOUT<span style="color:rgb(51,153,51)">-></span><span style="color:rgb(0,102,0)">autoflush</span><span style="color:rgb(0,153,0)">(</span><span style="color:rgb(204,102,204)">1</span><span style="color:rgb(0,153,0)">)</span><span style="color:rgb(51,153,51)">;</span>
 
 <span style="color:rgb(177,177,0)">while</span> <span style="color:rgb(0,153,0)">(</span> <span style="color:rgb(0,0,255)">$remaining</span> <span style="color:rgb(0,153,0)">)</span> <span style="color:rgb(0,153,0)">{</span>
  <span style="color:rgb(0,0,102)">printf</span> <span style="color:rgb(0,153,0)">(</span> <span style="color:rgb(255,0,0)">"Remaining %s/%s <strong>\r</strong>"</span><span style="color:rgb(51,153,51)">,</span> <span style="color:rgb(0,0,255)">$remaining</span><span style="color:rgb(51,153,51)">--,</span> <span style="color:rgb(0,0,255)">$total</span> <span style="color:rgb(0,153,0)">)</span><span style="color:rgb(51,153,51)">;</span>
  <span style="color:rgb(0,0,102)">sleep</span> <span style="color:rgb(204,102,204)">1</span><span style="color:rgb(51,153,51)">;</span>
 <span style="color:rgb(0,153,0)">}</span>
 
 <span style="color:rgb(0,0,102)">print</span> <span style="color:rgb(255,0,0)">"<strong>\n</strong>"</span><span style="color:rgb(51,153,51)">;</span>

The perl interpreter can also be used for one-off scripts on the command line. The following example as invoked from an sh-compatible shell such as Bash translates the string "Bob" in all files ending with .txt in the current directory to "Robert":

     $ <strong>perl</strong> -i.bak <span style="color:rgb(102,0,51)">-lp</span> <span style="color:rgb(102,0,51)">-e</span> <span style="color:rgb(255,0,0)">'s/Bob/Robert/g'</span> <strong>*</strong>.txt

Criticism[edit]

Perl has been referred to as "line noise" by some programmers who claim its syntax makes it a write-only language. The earliest such mention was in the first edition of the book Learning Perl, a Perl 5 tutorial book written by Randal L. Schwartz,[108] in the first chapter of which he states: "Yes, sometimes Perl looks like line noise to the uninitiated, but to the seasoned Perl programmer, it looks like checksummed line noise with a mission in life."[109] He also stated that the accusation that Perl is a write-only language could be avoided by coding with "proper care".[109] The Perl overview document perlintro states that the names of built-in "magic" scalar variables "look like punctuation or line noise".[110] The perlstyle document states that line noise in regular expressions could be mitigated using the /x modifier to add whitespace.[111]

According to the Perl 6 FAQ, Perl 6 was designed to mitigate "the usual suspects" that elicit the "line noise" claim from Perl 5 critics, including the removal of "the majority of the punctuation variables" and the sanitization of the regex syntax.[112] The Perl 6 FAQ also states that what is sometimes referred to as Perl's line noise is "the actual syntax of the language" just as gerunds and prepositions are a part of the English language.[112] In a December 2012 blog posting, despite claiming that "Rakudo Perl 6 has failed and will continue to fail unless it gets some adult supervision", chromatic stated that the design of Perl 6 has a "well-defined grammar" as well as an "improved type system, a unified object system with an intelligent metamodel, metaoperators, and a clearer system of context that provides for such niceties as pervasive laziness".[113] He also stated that "Perl 6 has a coherence and a consistency that Perl 5 lacks."[113]

References[edit]

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Further reading

See also[edit]

External links[edit]