<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, 37); font-family:sans-serif">&nbsp;</span><a href="http://en.wikipedia.org/wiki/High-level_programming_language" style="font-familysize: sans14px; text-serifdecoration: none; font-sizefamily: 14px; linesans-height: 17.9200000762939pxserif; text-decorationbackground: nonetransparent scroll repeat 0% 0%; color: rgb(11, 0, 128); backgroundline-height: none;17px" title="High-level programming language">high-level</a><span style="color:rgb(37, 37, 37); font-family:sans-serif">,</span><span style="color:rgb(37, 37, 37); font-family:sans-serif">&nbsp;</span><a href="http://en.wikipedia.org/wiki/General-purpose_programming_language" style="font-familysize: sans14px; text-serifdecoration: none; font-sizefamily: 14px; linesans-height: 17.9200000762939pxserif; text-decorationbackground: nonetransparent scroll repeat 0% 0%; color: rgb(11, 0, 128); backgroundline-height: none;17px" title="General-purpose programming language">general-purpose</a><span style="color:rgb(37, 37, 37); font-family:sans-serif">,</span><span style="color:rgb(37, 37, 37); font-family:sans-serif">&nbsp;</span><a href="http://en.wikipedia.org/wiki/Interpreter_(computing)" style="font-familysize: sans14px; text-serifdecoration: none; font-sizefamily: 14px; linesans-height: 17.9200000762939pxserif; text-decorationbackground: nonetransparent scroll repeat 0% 0%; color: rgb(11, 0, 128); backgroundline-height: none;17px" title="Interpreter (computing)">interpreted</a><span style="color:rgb(37, 37, 37); font-family:sans-serif">,</span><span style="color:rgb(37, 37, 37); font-family:sans-serif">&nbsp;</span><a href="http://en.wikipedia.org/wiki/Dynamic_programming_language" style="font-familysize: sans14px; text-serifdecoration: none; font-sizefamily: 14px; linesans-height: 17.9200000762939pxserif; text-decorationbackground: nonetransparent scroll repeat 0% 0%; color: rgb(11, 0, 128); backgroundline-height: none;17px" title="Dynamic programming language">dynamic programming languages</a><span style="color:rgb(37, 37, 37); font-family:sans-serif">. The languages in this family include Perl 5 and</span><span style="color:rgb(37, 37, 37); font-family:sans-serif">&nbsp;</span><a href="http://en.wikipedia.org/wiki/Perl_6" style="font-familysize: sans14px; text-serifdecoration: none; font-sizefamily: 14px; linesans-height: 17.9200000762939pxserif; text-decorationbackground: nonetransparent scroll repeat 0% 0%; color: rgb(11, 0, 128); backgroundline-height: none;17px" title="Perl 6">Perl 6</a><span style="color:rgb(37, 37, 37); font-family:sans-serif">.</span>^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-4" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[4]</a>}</span></p>

<p><span style="font-size:16px">Though Perl is not officially an acronym,^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-5" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[5]</a>}&nbsp;there are various&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); background: none;" title="Backronym">backronyms</a>&nbsp;in use, the most well-known being &quot;Practical&nbsp;<a href="http://en.wikipedia.org/wiki/Data_extraction" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Data extraction">Extraction</a>and Reporting Language&quot;.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-6" style="text-decoration: none; colorbackground: rgb(11, none transparent scroll repeat 0% 0, 128)%; white-space: nowrap; background: none;">[6]</a>}&nbsp;Perl was originally developed by&nbsp;<a href="http://en.wikipedia.org/wiki/Larry_Wall" style="text-decoration: none; color: rgb(11, 0, 128); background: none;" title="Larry Wall">Larry Wall</a>&nbsp;in 1987 as a general-purpose&nbsp;<a href="http://en.wikipedia.org/wiki/Unix" style="text-decoration: none; color: rgb(11, 0, 128); background: none;" title="Unix">Unix</a>&nbsp;scripting language to make report processing easier.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-sheppard00-7" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[76]</a>}&nbsp;Since then, it has undergone many changes and revisions.&nbsp;<a href="http://en.wikipedia.org/wiki/Perl_6" style="text-decoration: none; color: rgb(11, 0, 128); background: none;" title="Perl 6">Perl 6</a>, 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.</span></p>

<p>The Perl languages borrow features from other programming languages including&nbsp;<a href="http://en.wikipedia.org/wiki/C_(programming_language)" span style="textfont-decoration: none; color: rgb(11, 0, 128); backgroundsize: none;" title="C (programming language)16px">C</a>,Perl was originally developed by&nbsp;<a href="http://en.wikipedia.org/wiki/Shell_scriptLarry_Wall" style="text-decoration: none; color: rgb(11, 0, 128); background: none;" title="Shell script">shell scripting</a>&nbsp;(<a href="http://en.wikipedia.org/wiki/Bourne_shell" style="text-decoration: nonetransparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Bourne shellLarry Wall">shLarry Wall</a>),&nbsp;<in 1987 as a class="mwgeneral-redirect" href="http://en.wikipedia.org/wiki/AWK_(programming_language)" style="text-decoration: none; color: rgb(11, 0, 128); background: none;" title="AWK (programming language)">AWK</a>, andpurpose&nbsp;<a href="http://en.wikipedia.org/wiki/SedUnix" style="text-decoration: none; color: rgb(11, 0, 128); background: none;" title="Sed">sed</a>.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-perltimeline-8" style="text-decoration: none; color: rgb(11, transparent scroll repeat 0% 0, 128); white-space: nowrap; background: none;">[8]</a>}&nbsp;They provide powerful text processing facilities without the arbitrary data-length limits of many contemporary&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Unix_commandline_tools" style="text-decoration: none%; color: rgb(11, 0, 128); background: none;" title="Unix commandline tools">Unix commandline tools</a>,^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-programmingperl-9" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[9]</a>}&nbsp;facilitating easy manipulation of&nbsp;<a href="http://en.wikipedia.org/wiki/Text_file" style="text-decoration: none; color: rgb(11, 0, 128); background: none;" title="Text file">text files</a>. Perl 5 gained widespread popularity in the late 1990s as a&nbsp;<a href="http://en.wikipedia.org/wiki/Common_Gateway_Interface" style="text-decoration: none; color: rgb(11, 0, 128); background: none;" title="Common Gateway Interface">CGI scripting</a>language, in part due to its unsurpassedmake report processing easier.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-10sheppard00-7" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[10]</a>}^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-11" style="text-decoration: none; color: rgb(11, transparent scroll repeat 0% 0, 128)%; white-space: nowrap; background: none;">[11]</a>}^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-12" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[127]</a>}&nbsp;<a href="http://en.wikipedia.org/wiki/Regular_expression" style="text-decoration: none; color: rgb(11, 0, 128); background: none;" title="Regular expression">regular expression</a>&nbsp;and&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/String_(computing)" style="text-decoration: none; color: rgb(11, 0, 128); background: none;" title="String (computing)">string</a>&nbsp;<a href="http://en.wikipedia.org/wiki/Parsing" style="text-decoration: none; color: rgb(11, 0, 128); background: none;" title="Parsing">parsing</a>&nbsp;abilities.<sup><a href="http://en.wikipedia.org/wiki/Perl#cite_note-roderick02-13" style="text-decoration: none; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[13]</a></supspan></p>

<p><span style="font-size:16px">Since then, it has undergone many changes and revisions.&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>, which began as a redesign of Perl 5 in 2000, eventually evolved into a separate language. </span></p> <p><span style="font-size:16px">Both languages continue to be developed independently by different development teams and liberally borrow ideas from one another.</span></p> <p>&nbsp;</p> <p><span style="font-size:16px">The Perl languages borrow features from other programming languages including&nbsp;<a href="http://en.wikipedia.org/wiki/C_(programming_language)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="C (programming language)">C</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/Shell_script" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Shell script">shell scripting</a>&nbsp;(<a href="http://en.wikipedia.org/wiki/Bourne_shell" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Bourne shell">sh</a>),&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/AWK_(programming_language)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="AWK (programming language)">AWK</a>, and&nbsp;<a href="http://en.wikipedia.org/wiki/Sed" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Sed">sed</a>.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-perltimeline-8" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[8]</a>}&nbsp;They provide powerful text processing facilities without the arbitrary data-length limits of many contemporary&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Unix_commandline_tools" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Unix commandline tools">Unix commandline tools</a>,^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-programmingperl-9" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[9]</a>}&nbsp;facilitating easy manipulation of&nbsp;<a href="http://en.wikipedia.org/wiki/Text_file" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Text file">text files</a>. Perl 5 gained widespread popularity in the late 1990s as a&nbsp;<a href="http://en.wikipedia.org/wiki/Common_Gateway_Interface" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Common Gateway Interface">CGI scripting</a>language, in part due to its unsurpassed^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-10" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[10]</a>}^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-11" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[11]</a>}^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-12" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[12]</a>}&nbsp;<a href="http://en.wikipedia.org/wiki/Regular_expression" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Regular expression">regular expression</a>&nbsp;and&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/String_(computing)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="String (computing)">string</a>&nbsp;<a href="http://en.wikipedia.org/wiki/Parsing" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11,0,128)" title="Parsing">parsing</a>&nbsp;abilities.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-roderick02-13" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11,0,128)">[13]</a>}</span></p> <p><span style="font-size:16px">In addition to CGI, Perl 5 is used for&nbsp;<a href="http://en.wikipedia.org/wiki/Computer_graphics_(computer_science)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Computer graphics (computer science)">graphics programming</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/System_administrator" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="System administrator">system administration</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/Computer_network_programming" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Computer network programming">network programming</a>, finance,<a href="http://en.wikipedia.org/wiki/Bioinformatics" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Bioinformatics">bioinformatics</a>, and other applications. It has been nicknamed &quot;the Swiss Army chainsaw of scripting languages&quot; because of its flexibility and power,^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-14" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[14]</a>}&nbsp;and possibly also because of its &quot;ugliness&quot;.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-15" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[15]</a>}&nbsp;In 1998, it was also referred to as the &quot;<a href="http://en.wikipedia.org/wiki/Duct_tape" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Duct tape">duct tape</a>&nbsp;that holds the Internet together&quot;, in reference to both its ubiquitous use as a&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Glue_language" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Glue language">glue language</a>&nbsp;and its perceived inelegance.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-leonard98-16" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[16]</a>}</span></p>

<p><a href="http://en.wikipedia.org/wiki/Larry_Wall" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Larry Wall">Larry Wall</a>&nbsp;began work on Perl in 1987, while working as a programmer at&nbsp;<a href="http://en.wikipedia.org/wiki/Unisys" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Unisys">Unisys</a>,^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-programmingperl-9" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[9]</a>}&nbsp;and released version 1.0 to the comp.sources.misc&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Newsgroup" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Newsgroup">newsgroup</a>&nbsp;on December 18, 1987.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-17" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[17]</a>}The language expanded rapidly over the next few years.</p>

<p>Perl 2, released in 1988, featured a better regular expression engine. Perl 3, released in 1989, added support for&nbsp;<a href="http://en.wikipedia.org/wiki/Binary_data" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Binary data">binary data</a>&nbsp;streams.</p>

<p>Originally the only documentation for Perl was a single (increasingly lengthy)&nbsp;<a href="http://en.wikipedia.org/wiki/Man_page" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Man page">man page</a>. In 1991,&nbsp;<em><a href="http://en.wikipedia.org/wiki/Programming_Perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Programming Perl">Programming Perl</a></em>, known to many Perl programmers as the &quot;Camel Book&quot; because of its cover, was published and became the&nbsp;<em>de facto</em>&nbsp;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.</p>

<p>Perl 4 went through a series of&nbsp;<a href="http://en.wikipedia.org/wiki/Maintenance_release" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Maintenance release">maintenance releases</a>, 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&nbsp;<em>perl5-porters</em>&nbsp;<a href="http://en.wikipedia.org/wiki/Mailing_list" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Mailing list">mailing list</a>&nbsp;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.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-18" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[18]</a>}</p>

<p>Perl 5.000 was released on October 17, 1994.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-19" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[19]</a>}&nbsp;It was a nearly complete rewrite of the&nbsp;<a href="http://en.wikipedia.org/wiki/Interpreter_(computing)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Interpreter (computing)">interpreter</a>, and it added many new features to the language, including&nbsp;<a href="http://en.wikipedia.org/wiki/Object_(computer_science)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Object (computer science)">objects</a>,<a href="http://en.wikipedia.org/wiki/Reference_(computer_science)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Reference (computer science)">references</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/Local_variable" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Local variable">lexical (my) variables</a>, and&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Module_(programming)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Module (programming)">modules</a>. 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.</p>

<p>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&nbsp;<a href="http://en.wikipedia.org/wiki/Subroutine" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Subroutine">subroutines</a>that behaved like Perl&nbsp;<a href="http://en.wikipedia.org/wiki/Shell_builtin" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Shell builtin">builtins</a>. Perl 5.003 was released June 25, 1996, as a security release.</p>

<p>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, the<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Comprehensive_Perl_Archive_Network" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Comprehensive Perl Archive Network">Comprehensive Perl Archive Network</a>&nbsp;(CPAN) was established as a&nbsp;<a href="http://en.wikipedia.org/wiki/Software_repository" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Software repository">repository</a>&nbsp;for&nbsp;<a href="http://en.wikipedia.org/wiki/Perl_module" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Perl module">Perl modules</a>&nbsp;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.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-20" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[20]</a>}</p>

<p>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&nbsp;<a href="http://en.wikipedia.org/wiki/Class_(computer_programming)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Class (computer programming)">classes</a>&nbsp;were automatically derived and the ability to require versions of modules. Another significant development was the inclusion of the&nbsp;<a href="http://en.wikipedia.org/wiki/CGI.pm" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="CGI.pm">CGI.pm</a>&nbsp;module,^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-5004delta-21" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[21]</a>}&nbsp;which contributed to Perl&#39;s popularity as a CGI scripting language.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-patwardhan02-22" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[22]</a>}</p>

<p>Perl is also now supported running under&nbsp;<a href="http://en.wikipedia.org/wiki/Microsoft_Windows" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Microsoft Windows">Microsoft Windows</a>&nbsp;and several other operating systems.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-5004delta-21" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[21]</a>}</p>

<p>Perl 5.005 was released on July 22, 1998. This release included several enhancements to the&nbsp;<a href="http://en.wikipedia.org/wiki/Regular_expression" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Regular expression">regex</a>&nbsp;engine, new hooks into the backend through the&nbsp;<code>B::*</code>&nbsp;modules, the<code>qr//</code>&nbsp;regex quote operator, a large selection of other new core modules, and added support for several more operating systems, including&nbsp;<a href="http://en.wikipedia.org/wiki/BeOS" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="BeOS">BeOS</a>.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-5005delta-23" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[23]</a>}</p>

<table class="floatright wikitable" style="background-color:rgb(249, 249, 249); border-bottom:0px; border-collapse:collapse; border-left:0px; border-right:0px; border-top:0px; clear:right; color:black; float:right; font-family:sans-serif; font-size:14px; line-height:17.9200000762939px17px; margin:0px 0px 0.5em 0.5em; position:relative">

<th style="text-align: center; background-color:rgb(242, 242, 242); border-color:rgb(170, 170, 170); text-align:center">Major version</th> <th style="text-align: center; background-color:rgb(242, 242, 242); border-color:rgb(170, 170, 170); text-align:center">Latest update</th>

<td style="background-color:rgb(253, 179, 171); border-color:rgb(170, 170, 170)">5.5</td> <td style="border-color:rgb(170, 170, 170)">2004-02-23^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-cpan-src-24" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[24]</a>}</td>

<td style="background-color:rgb(253, 179, 171); border-color:rgb(170, 170, 170)">5.6</td> <td style="border-color:rgb(170, 170, 170)">2003-11-15^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-cpan-src-24" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[24]</a>}</td>

<td style="background-color:rgb(253, 179, 171); border-color:rgb(170, 170, 170)">5.8</td> <td style="border-color:rgb(170, 170, 170)">2008-12-14^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-cpan-src-24" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[24]</a>}</td>

<td style="background-color:rgb(253, 179, 171); border-color:rgb(170, 170, 170)">5.10</td> <td style="border-color:rgb(170, 170, 170)">2009-08-23^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-cpan-src-24" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[24]</a>}</td>

<td style="background-color:rgb(253, 179, 171); border-color:rgb(170, 170, 170)">5.12</td> <td style="border-color:rgb(170, 170, 170)">2012-11-10^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-cpan-src-24" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[24]</a>}</td>

<td style="background-color:rgb(253, 179, 171); border-color:rgb(170, 170, 170)">5.14</td> <td style="border-color:rgb(170, 170, 170)">2013-03-10^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-cpan-src-24" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[24]</a>}</td>

<td style="background-color:rgb(253, 179, 171); border-color:rgb(170, 170, 170)">5.16</td> <td style="border-color:rgb(170, 170, 170)">2013-03-11^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-cpan-src-24" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[24]</a>}</td>

<td style="background-color:rgb(254, 248, 198); border-color:rgb(170, 170, 170)">5.18</td> <td style="border-color:rgb(170, 170, 170)">2014-10-02^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-cpan-src-24" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[24]</a>}</td>

<td style="background-color:rgb(212, 244, 180); border-color:rgb(170, 170, 170)"><strong>5.20</strong></td> <td style="border-color:rgb(170, 170, 170)">2014-09-14^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-cpan-src-24" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[24]</a>}</td>

<td style="background-color:rgb(193, 230, 245); border-color:rgb(170, 170, 170)">5.21</td> <td style="border-color:rgb(170, 170, 170)">2015-01-20^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-cpan-src-24" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[24]</a>}</td>

<td colspan="99" style="border-color:rgb(170, 170, 170)"> <div class="templateVersion lv floatright" style="clearborder-top: 0px; border-right: 0px; border-bottom: 0px; position: relative; float: right; positionclear: right; border-left: relative0px; margin: 0px 0px 0.5em 0.5em; border: 0px;"><small>Old version<br />

<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); background: none;" 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); background: none;" title="Unicode">Unicode</a>&nbsp;string representation, large file support (i.e. files over 2 GiB) and the &quot;our&quot; keyword.^{<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); white-space: nowrap; background: none;">[25]</a>}^{<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); white-space: nowrap; background: none;">[26]</a>}&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); background: none;" 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>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,^{<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); white-space: nowrap; background: none;">[27]</a>}&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); background: none;" 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>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.^{<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); white-space: nowrap; background: none;">[28]</a>}&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>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); background: none;" 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); background: none;" 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); background: none;" title="Haskell (programming language)">Haskell</a>.^{<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); white-space: nowrap; background: none;">[29]</a>}&nbsp;This was the first concerted effort towards making Perl 6 a reality. This effort stalled in 2006.^{<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); white-space: nowrap; background: none;">[30]</a>}</p>

<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); background: none;" 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); background: none;" title="Switch statement">switch statement</a>&nbsp;(called &quot;given&quot;/&quot;when&quot;), regular expressions updates, and the smart match operator, &quot;~~&quot;.^{<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); white-space: nowrap; background: none;">[31]</a>}^{<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); white-space: nowrap; background: none;">[32]</a>}&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); background: none;" 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); background: none;" 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); background: none;" title="Perl 6">Perl 6</a>.</p>

<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); background: none;" 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); background: none;" 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); background: none;" title="Unicode">Unicode</a>&nbsp;5.2.^{<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); white-space: nowrap; background: none;">[33]</a>}&nbsp;On January 21, 2011, Perl 5.12.3 was released; it contains updated modules and some documentation changes.^{<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); white-space: nowrap; background: none;">[34]</a>}&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>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); background: none;" 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>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.^{<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); white-space: nowrap; background: none;">[35]</a>}&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); background: none;" title="Unicode">Unicode</a>&nbsp;6.1.^{<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); white-space: nowrap; background: none;">[35]</a>}</p>

<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.^{<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); white-space: nowrap; background: none;">[36]</a>}</p>

<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.^{<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); white-space: nowrap; background: none;">[37]</a>}</p>

<p>Some observers credit the release of Perl 5.10 with the start of the Modern Perl movement.^{<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); white-space: nowrap; background: none;">[38]</a>}&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.^{<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); white-space: nowrap; background: none;">[39]</a>}&nbsp;While the book &quot;Modern Perl&quot;^{<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); white-space: nowrap; background: none;">[40]</a>}&nbsp;may be the most visible standard-bearer of this idea, other groups such as the Enlightened Perl Organization^{<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); white-space: nowrap; background: none;">[41]</a>}&nbsp;have taken up the cause.</p>

<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); background: none;" title="Perl6">Perl6</a>&nbsp;by the Rakudo Perl team,^{<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); white-space: nowrap; background: none;">[42]</a>}&nbsp;<em>moe</em>&nbsp;by Stevan Little and friends,^{<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); white-space: nowrap; background: none;">[43]</a>}<em>p2</em>^{<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); white-space: nowrap; background: none;">[44]</a>}&nbsp;by the Perl11 team under Reini Urban,&nbsp;<em>gperl</em>&nbsp;by goccy,^{<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); white-space: nowrap; background: none;">[45]</a>}&nbsp;and&nbsp;<em>rperl</em>&nbsp;a kickstarter project led by Will Braswell and affiliated with the Perll11 project.^{<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); white-space: nowrap; background: none;">[46]</a>}</p>

<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); background: none;" title="PEARL (programming language)">PEARL</a>&nbsp;programming language before Perl&#39;s official release and changed the spelling of the name.^{<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); white-space: nowrap; background: none;">[47]</a>}</p>

<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); background: none;" 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.^{<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); white-space: nowrap; background: none;">[48]</a>}</p>

<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); background: none;" title="Backronym">backronym</a>.^{<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); white-space: nowrap; background: none;">[49]</a>}&nbsp;Other expansions have been suggested as equally canonical, including Wall&#39;s own humorous&nbsp;<em>Pathologically Eclectic Rubbish Lister</em>.^{<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); white-space: nowrap; background: none;">[50]</a>}&nbsp;Indeed, Wall claims that the name was intended to inspire many different expansions.^{<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); white-space: nowrap; background: none;">[51]</a>}</p>

<div class="thumb tright" style="clearfont-size: right14px; floatfont-family: rightsans-serif; marginwidth: 0.5em 0px 1.3em 1.4emauto; widthfloat: autoright; color: rgb(37, 37, 37); font-familyclear: sans-serifright; font-sizemargin: 14px0.5em 0px 1.3em 1.4em; line-height: 17.9200000762939px;17px"><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: 1px solid rgb(204, 204, 204)1px solid; padding-bottom: 3px; fonttext-align: center; padding-sizetop: 13.1600008010864px3px; textpadding-alignleft: center3px; overflowborder-left: hiddenrgb(204,204,204) 1px solid; widthpadding-right: 146px3px; 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); background: none;"><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>

<div class="thumbcaption" style="font-size: 12px; border-top: medium none; border-right: medium none; lineborder-heightbottom: 1.4emmedium none; padding-bottom: 3px; fonttext-align: left; padding-sizetop: 12.370400428772px3px; textpadding-alignleft: 3px; border-left: medium none;line-height: 1.4em; padding-right: 3px"><div class="magnify" style="float: right; margin-left: 3px; margin-right: 0px;">&nbsp;</div>

<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); background: none;" 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); background: none;" title="Camel">dromedary camel</a>&nbsp;on the cover and is commonly called the &quot;Camel Book&quot;.^{<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); white-space: nowrap; background: none;">[52]</a>}&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); background: none;" title="Hacker (programmer subculture)">hacker</a>&nbsp;emblem, appearing on T-shirts and other clothing items.</p>

<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); background: none;" 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); background: none;" 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.^{<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); white-space: nowrap; background: none;">[53]</a>}&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.^{<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); white-space: nowrap; background: none;">[53]</a>}</p>

<div class="thumb tright" style="clearfont-size: right14px; floatfont-family: rightsans-serif; marginwidth: 0.5em 0px 1.3em 1.4emauto; widthfloat: autoright; color: rgb(37, 37, 37); font-familyclear: sans-serifright; font-sizemargin: 14px0.5em 0px 1.3em 1.4em; line-height: 17.9200000762939px;17px"><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: 1px solid rgb(204, 204, 204)1px solid; padding-bottom: 3px; fonttext-align: center; padding-sizetop: 13.1600008010864px3px; textpadding-alignleft: center3px; overflowborder-left: hiddenrgb(204,204,204) 1px solid; widthpadding-right: 66px3px; 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); background: none;"><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>

<div class="thumbcaption" style="font-size: 12px; border-top: medium none; border-right: medium none; lineborder-heightbottom: 1.4emmedium none; padding-bottom: 3px; fonttext-align: left; padding-sizetop: 12.370400428772px3px; textpadding-alignleft: 3px; border-left: medium none;line-height: 1.4em; padding-right: 3px"><div class="magnify" style="float: right; margin-left: 3px; margin-right: 0px;">&nbsp;</div>

<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); background: none;" 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; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Perl Mongers">Perl Mongers</a>,&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); background: none;" title="PerlMonks">PerlMonks</a>, Perl.org, and others.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-onion-54" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[54]</a>}The symbol is a&nbsp;<a href="http://en.wikipedia.org/wiki/Visual_pun" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Visual pun">visual pun</a>&nbsp;on&nbsp;<a href="http://en.wikipedia.org/wiki/Pearl_onion" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Pearl onion">pearl onion</a>.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-gillmore98-55" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[55]</a>}</p>

<div class="hatnote relarticle mainarticle" style="font-stylesize: italic; padding-left: 1.6em14px; margin-bottom: 0.5em; font-family: sans-serif; color: rgb(37, 37, 37); font-familystyle: sans-serifitalic; fontpadding-sizeleft: 14px1.6em; line-height: 17.9200000762939px;17px">Main article:&nbsp;<a href="http://en.wikipedia.org/wiki/Perl_language_structure" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Perl language structure">Perl language structure</a></div>

<p>According to Wall, Perl has two slogans. The first is &quot;<a href="http://en.wikipedia.org/wiki/There%27s_more_than_one_way_to_do_it" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="There's more than one way to do it">There&#39;s more than one way to do it</a>&quot;, commonly known as TMTOWTDI. The second slogan is &quot;Easy things should be easy and hard things should be possible&quot;.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-programmingperl-9" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[9]</a>}</p>

<p>The overall structure of Perl derives broadly from C. Perl is&nbsp;<a href="http://en.wikipedia.org/wiki/Procedural_programming" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Procedural programming">procedural</a>&nbsp;in nature, with&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Variable_(programming)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Variable (programming)">variables</a>,&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Expression_(programming)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Expression (programming)">expressions</a>,&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Assignment_statement" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Assignment statement">assignment statements</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/Bracket" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Bracket">brace</a>-delimited&nbsp;<a href="http://en.wikipedia.org/wiki/Block_(programming)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Block (programming)">blocks</a>,&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Control_structure" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Control structure">control structures</a>, and&nbsp;<a href="http://en.wikipedia.org/wiki/Subroutine" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Subroutine">subroutines</a>.</p>

<p>Perl also takes features from shell programming. All variables are marked with leading&nbsp;<a href="http://en.wikipedia.org/wiki/Sigil_(computer_programming)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Sigil (computer programming)">sigils</a>, which allow variables to be&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Variable_interpolation" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Variable interpolation">interpolated</a>&nbsp;directly into&nbsp;<a href="http://en.wikipedia.org/wiki/String_(computer_science)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="String (computer science)">strings</a>. However, unlike the shell, Perl uses sigils on all accesses to variables, and unlike most other programming languages that use sigils, the sigil doesn&#39;t denote the type of the variable but the type of the expression. So for example, to access a list of values in a&nbsp;<a href="http://en.wikipedia.org/wiki/Associative_array" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Associative array">hash</a>, the sigil for an&nbsp;<a href="http://en.wikipedia.org/wiki/Array_data_type" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Array data type">array</a>&nbsp;(&quot;@&quot;) is used, not the sigil for a hash (&quot;%&quot;). 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&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Ascending_order" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Ascending order">sorting</a>, and calling on<a href="http://en.wikipedia.org/wiki/Operating_system" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Operating system">operating system</a>&nbsp;facilities.</p>

<p>Perl takes&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/List_(computing)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="List (computing)">lists</a>&nbsp;from&nbsp;<a href="http://en.wikipedia.org/wiki/Lisp_(programming_language)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Lisp (programming language)">Lisp</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/Associative_array" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Associative array">hashes</a>&nbsp;(&quot;associative arrays&quot;) from&nbsp;<a href="http://en.wikipedia.org/wiki/AWK" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="AWK">AWK</a>, and&nbsp;<a href="http://en.wikipedia.org/wiki/Regular_expression" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Regular expression">regular expressions</a>&nbsp;from&nbsp;<a href="http://en.wikipedia.org/wiki/Sed" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Sed">sed</a>. These simplify and facilitate many parsing, text-handling, and data-management tasks. Also shared with Lisp are the implicit&nbsp;<a href="http://en.wikipedia.org/wiki/Return_statement" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Return statement">return</a>&nbsp;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.</p>

<p>Perl 5 added features that support complex&nbsp;<a href="http://en.wikipedia.org/wiki/Data_structure" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Data structure">data structures</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/First-class_function" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="First-class function">first-class functions</a>&nbsp;(that is,&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Closure_(computer_science)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Closure (computer science)">closures</a>&nbsp;as values), and an object-oriented programming model. These include<a href="http://en.wikipedia.org/wiki/Reference_(computer_science)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Reference (computer science)">references</a>, packages, class-based&nbsp;<a href="http://en.wikipedia.org/wiki/Dynamic_dispatch" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Dynamic dispatch">method dispatch</a>, and&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Scope_(programming)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Scope (programming)">lexically scoped variables</a>, along with&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Compiler_directive" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Compiler directive">compiler directives</a>&nbsp;(for example, the&nbsp;<code>strict</code>&nbsp;pragma). A major additional feature introduced with Perl 5 was the ability to package code as reusable modules. Wall later stated that &quot;The whole intent of Perl 5&#39;s module system was to encourage the growth of Perl culture rather than the Perl core.&quot;^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-56" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[56]</a>}</p>

<p>All versions of Perl do automatic&nbsp;<a href="http://en.wikipedia.org/wiki/Type_system" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Type system">data-typing</a>&nbsp;and automatic&nbsp;<a href="http://en.wikipedia.org/wiki/Memory_management" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Memory management">memory management</a>. The interpreter knows the type and&nbsp;<a href="http://en.wikipedia.org/wiki/Computer_data_storage" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Computer data storage">storage</a>&nbsp;requirements of every data object in the program; it allocates and frees storage for them as necessary using&nbsp;<a href="http://en.wikipedia.org/wiki/Reference_counting" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Reference counting">reference counting</a>&nbsp;(so it cannot deallocate&nbsp;<a href="http://en.wikipedia.org/wiki/Circular_buffer" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Circular buffer">circular data structures</a>&nbsp;without manual intervention). Legal<a href="http://en.wikipedia.org/wiki/Type_conversion" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Type conversion">type conversions</a>&nbsp;&mdash; for example, conversions from number to string &mdash; are done automatically at&nbsp;<a href="http://en.wikipedia.org/wiki/Run_time_(program_lifecycle_phase)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Run time (program lifecycle phase)">run time</a>; illegal type conversions are fatal errors.</p>

<p>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&nbsp;<a href="http://en.wikipedia.org/wiki/Compiler" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Compiler">compiler</a>technology. Many earlier computer languages, such as&nbsp;<a href="http://en.wikipedia.org/wiki/Fortran" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Fortran">Fortran</a>&nbsp;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.</p>

<p>Perl has many features that ease the task of the programmer at the expense of greater&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/CPU" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="CPU">CPU</a>&nbsp;and memory requirements. These include automatic memory management;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Dynamic_typing" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Dynamic typing">dynamic typing</a>; strings, lists, and hashes; regular expressions; introspection; and an&nbsp;<code>eval()</code>&nbsp;function. Perl follows the theory of &quot;no built-in limits&quot;,^{<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); white-space: nowrap; background: none;">[52]</a>}&nbsp;an idea similar to the<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Zero_One_Infinity" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Zero One Infinity">Zero One Infinity</a>&nbsp;rule.</p>

<p>Wall was trained as a linguist, and the design of Perl is very much informed by&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Linguistic" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Linguistic">linguistic</a>&nbsp;principles. Examples include&nbsp;<a href="http://en.wikipedia.org/wiki/Huffman_coding" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Huffman coding">Huffman coding</a>&nbsp;(common constructions should be short), good end-weighting (the important information should come first), and a large collection of&nbsp;<a href="http://en.wikipedia.org/wiki/Language_primitive" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Language primitive">language primitives</a>. Perl favors language constructs that are concise and natural for humans to write, even where they complicate the Perl interpreter.</p>

<p>Perl&#39;s&nbsp;<a href="http://en.wikipedia.org/wiki/Syntax_(programming_languages)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Syntax (programming languages)">syntax</a>&nbsp;reflects the idea that &quot;things that are different should look different.&quot;^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-wall97-57" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[57]</a>}&nbsp;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&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Lisp_programming_language" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Lisp programming language">Lisp</a>, where the same&nbsp;<a href="http://en.wikipedia.org/wiki/S-expression" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="S-expression">S-expression</a>&nbsp;construct and basic syntax are used for many different purposes.</p>

<p>Perl does not enforce any particular&nbsp;<a href="http://en.wikipedia.org/wiki/Programming_paradigm" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Programming paradigm">programming paradigm</a>&nbsp;(<a href="http://en.wikipedia.org/wiki/Procedural_programming" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Procedural programming">procedural</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/Object-oriented_programming" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Object-oriented programming">object-oriented</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/Functional_programming" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Functional programming">functional</a>, or others) or even require the programmer to choose among them.</p>

<p>There is a broad practical bent to both the Perl language and the community and culture that surround it. The preface to&nbsp;<em>Programming Perl</em>&nbsp;begins: &quot;Perl is a language for getting your job done.&quot;^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-programmingperl-9" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[9]</a>}&nbsp;One consequence of this is that Perl is not a tidy language. It includes many features, tolerates exceptions to its rules, and employs&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Heuristics" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Heuristics">heuristics</a>&nbsp;to resolve syntactical ambiguities. Because of the forgiving nature of the compiler, bugs can sometimes be hard to find. Perl&#39;s function documentation remarks on the variant behavior of built-in functions in list and scalar contexts by saying, &quot;In general, they do what you want, unless you want consistency.&quot;^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-perlfunc-58" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[58]</a>}</p>

<p>No written&nbsp;<a href="http://en.wikipedia.org/wiki/Formal_specification" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Formal specification">specification</a>&nbsp;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&nbsp;<em>de facto</em>specification of the language.&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); background: none;" title="Perl 6">Perl 6</a>, however, started with a specification,^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-59" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[59]</a>}&nbsp;and several projects^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-60" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[60]</a>}&nbsp;aim to implement some or all of the specification.</p>

<p>Perl has chiefly been used to write&nbsp;<a href="http://en.wikipedia.org/wiki/Common_Gateway_Interface" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Common Gateway Interface">CGI</a>&nbsp;scripts: large projects written in Perl include&nbsp;<a href="http://en.wikipedia.org/wiki/CPanel" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="CPanel">cPanel</a>,&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Slash_(weblog_system)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Slash (weblog system)">Slash</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/Bugzilla" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Bugzilla">Bugzilla</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/Request_Tracker" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Request Tracker">RT</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/TWiki" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="TWiki">TWiki</a>, and&nbsp;<a href="http://en.wikipedia.org/wiki/Movable_Type" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Movable Type">Movable Type</a>; high-traffic websites that use Perl extensively include&nbsp;<a href="http://en.wikipedia.org/wiki/Priceline.com" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Priceline.com">Priceline.com</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/Craigslist" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Craigslist">Craigslist</a>,^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-61" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[61]</a>}&nbsp;<a href="http://en.wikipedia.org/wiki/Internet_Movie_Database" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Internet Movie Database">IMDb</a>,^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-62" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[62]</a>}&nbsp;<a href="http://en.wikipedia.org/wiki/LiveJournal" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="LiveJournal">LiveJournal</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/DuckDuckGo" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="DuckDuckGo">DuckDuckGo</a>,^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-63" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[63]</a>}^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-64" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[64]</a>}&nbsp;<a href="http://en.wikipedia.org/wiki/Slashdot" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Slashdot">Slashdot</a>&nbsp;and&nbsp;<a href="http://en.wikipedia.org/wiki/Ticketmaster" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Ticketmaster">Ticketmaster</a>. It is also an optional component of the popular&nbsp;<a href="http://en.wikipedia.org/wiki/LAMP_(software_bundle)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="LAMP (software bundle)">LAMP</a>technology stack for&nbsp;<a href="http://en.wikipedia.org/wiki/Web_development" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Web development">Web development</a>, in lieu of&nbsp;<a href="http://en.wikipedia.org/wiki/PHP" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="PHP">PHP</a>&nbsp;or&nbsp;<a href="http://en.wikipedia.org/wiki/Python_(programming_language)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Python (programming language)">Python</a>.</p>

<p>Perl is often used as a&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Glue_language" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Glue language">glue language</a>, tying together systems and interfaces that were not specifically designed to interoperate, and for &quot;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Data_munging" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Data munging">data munging</a>&quot;,^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-65" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[65]</a>}&nbsp;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&nbsp;<a href="http://en.wikipedia.org/wiki/System_administrator" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="System administrator">system administrators</a>, particularly because short programs, often called &quot;<a href="http://en.wikipedia.org/wiki/One-liner_program" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="One-liner program">one-liner programs</a>&quot;, can be entered and run on a single&nbsp;<a href="http://en.wikipedia.org/wiki/Command-line_interface" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Command-line interface">command line</a>.</p>

<p>Perl code can be made portable across&nbsp;<a href="http://en.wikipedia.org/wiki/Microsoft_Windows" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Microsoft Windows">Windows</a>&nbsp;and Unix; such code is often used by suppliers of software (both&nbsp;<a href="http://en.wikipedia.org/wiki/Commercial_off-the-shelf" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Commercial off-the-shelf">COTS</a>&nbsp;and bespoke) to simplify packaging and maintenance of software build- and deployment-scripts.</p>

<p><a href="http://en.wikipedia.org/wiki/Graphical_user_interface" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Graphical user interface">Graphical user interfaces</a>&nbsp;(GUIs) may be developed using Perl. For example,&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Tk_(framework)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Tk (framework)">Perl/Tk</a>&nbsp;and&nbsp;<a href="http://en.wikipedia.org/wiki/WxPerl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="WxPerl">WxPerl</a>&nbsp;are commonly used to enable user interaction with Perl scripts. Such interaction may be synchronous or asynchronous, using&nbsp;<a href="http://en.wikipedia.org/wiki/Callback_(computer_programming)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Callback (computer programming)">callbacks</a>&nbsp;to update the GUI.</p>

<p>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&nbsp;<a href="http://en.wikipedia.org/wiki/Megabyte" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Megabyte">MB</a>when packaged in a&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Tar_(file_format)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Tar (file format)">tar file</a>&nbsp;and&nbsp;<a href="http://en.wikipedia.org/wiki/Gzip" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Gzip">gzip</a>&nbsp;compressed.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-66" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[66]</a>}&nbsp;The interpreter is 150,000 lines of C code and compiles to a 1&nbsp;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&nbsp;<a href="http://en.wikipedia.org/wiki/Character_encoding" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Character encoding">character encoding</a>&nbsp;tables.)</p>

<p>The interpreter has an object-oriented architecture. All of the elements of the Perl language&mdash;scalars, arrays, hashes, coderefs,&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/File_handle" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="File handle">file handles</a>&mdash;are represented in the interpreter by&nbsp;<a href="http://en.wikipedia.org/wiki/Struct_(C_programming_language)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Struct (C programming language)">C structs</a>. Operations on these structs are defined by a large collection of&nbsp;<a href="http://en.wikipedia.org/wiki/Macro_(computer_science)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Macro (computer science)">macros</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/Typedef" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Typedef">typedefs</a>, and functions; these constitute the Perl C&nbsp;<a href="http://en.wikipedia.org/wiki/Application_programming_interface" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Application programming interface">API</a>. The Perl API can be bewildering to the uninitiated, but its entry points follow a consistent&nbsp;<a href="http://en.wikipedia.org/wiki/Naming_scheme" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Naming scheme">naming scheme</a>, which provides guidance to those who use it.</p>

<p>The life of a Perl interpreter divides broadly into a compile phase and a run phase.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-67" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[67]</a>}&nbsp;In Perl, the&nbsp;<strong>phases</strong>&nbsp;are the major stages in the interpreter&#39;s life-cycle. Each interpreter goes through each phase only once, and the phases follow in a fixed sequence.</p>

<p>Most of what happens in Perl&#39;s compile phase is compilation, and most of what happens in Perl&#39;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&nbsp;<strong>compile time</strong>&nbsp;and&nbsp;<strong>run time</strong>. 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&nbsp;<code><a href="http://en.wikipedia.org/wiki/Eval" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Eval">eval</a></code>&nbsp;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&nbsp;<code>BEGIN</code>&nbsp;blocks executes at run time but in the compile phase.</p>

<p>At compile time, the interpreter parses Perl code into a&nbsp;<a href="http://en.wikipedia.org/wiki/Abstract_syntax_tree" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Abstract syntax tree">syntax tree</a>. At run time, it executes the program by&nbsp;<a href="http://en.wikipedia.org/wiki/Tree_traversal" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Tree traversal">walking the tree</a>. 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&nbsp;<a href="http://en.wikipedia.org/wiki/Constant_folding" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Constant folding">constant folding</a>&nbsp;and context propagation, but&nbsp;<a href="http://en.wikipedia.org/wiki/Peephole_optimization" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Peephole optimization">peephole optimization</a>&nbsp;is also performed.</p>

<p>Perl has a&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Turing-complete" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Turing-complete">Turing-complete</a>&nbsp;<a href="http://en.wikipedia.org/wiki/Formal_grammar" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Formal grammar">grammar</a>&nbsp;because parsing can be affected by run-time code executed during the compile phase.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-68" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[68]</a>}&nbsp;Therefore, Perl cannot be parsed by a straight&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Lex_programming_tool" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Lex programming tool">Lex</a>/<a href="http://en.wikipedia.org/wiki/Yacc" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Yacc">Yacc</a>&nbsp;<a href="http://en.wikipedia.org/wiki/Lexical_analysis" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Lexical analysis">lexer</a>/<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Parser" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Parser">parser</a>&nbsp;combination. Instead, the interpreter implements its own lexer, which coordinates with a modified&nbsp;<a href="http://en.wikipedia.org/wiki/GNU_bison" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="GNU bison">GNU bison</a>&nbsp;parser to resolve ambiguities in the language.</p>

<p>It is often said that &quot;Only perl can parse Perl&quot;,^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-69" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[69]</a>}&nbsp;meaning that only the Perl interpreter (<em><code>perl</code></em>) can parse the Perl language (<em>Perl</em>), 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&nbsp;<a href="http://en.wikipedia.org/wiki/Halting_problem" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Halting problem">halting problem</a>&nbsp;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.</p>

<p>Other programs that undertake to parse Perl, such as&nbsp;<a href="http://en.wikipedia.org/wiki/Static_program_analysis" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Static program analysis">source-code</a>&nbsp;analyzers and&nbsp;<a href="http://en.wikipedia.org/wiki/Indent_style" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Indent style">auto-indenters</a>, have to contend not only with ambiguous&nbsp;<a href="http://en.wikipedia.org/wiki/Language_construct" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Language construct">syntactic constructs</a>&nbsp;but also with the&nbsp;<a href="http://en.wikipedia.org/wiki/Recursive_language" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Recursive language">undecidability</a>&nbsp;of Perl parsing in the general case. Adam Kennedy&#39;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 &quot;parsing Perl suffers from the &#39;<a href="http://en.wikipedia.org/wiki/Halting_problem" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Halting problem">halting problem</a>&#39;&quot;,^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-70" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[70]</a>}&nbsp;which was later proved.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-71" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[71]</a>}</p>

<p>Perl is distributed with over 250,000&nbsp;<a href="http://en.wikipedia.org/wiki/Functional_testing" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Functional testing">functional tests</a>&nbsp;for core Perl language and over 250,000&nbsp;<a href="http://en.wikipedia.org/wiki/Functional_testing" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Functional testing">functional tests</a>&nbsp;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&nbsp;<a href="http://en.wikipedia.org/wiki/Software_bug" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Software bug">software bugs</a>; 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.</p>

<p>Perl is&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Dual_licensed" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Dual licensed">dual licensed</a>&nbsp;under both the&nbsp;<a href="http://en.wikipedia.org/wiki/Artistic_License" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Artistic License">Artistic License</a>&nbsp;and the&nbsp;<a href="http://en.wikipedia.org/wiki/GNU_General_Public_License" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="GNU General Public License">GNU General Public License</a>. Distributions are available for most&nbsp;<a href="http://en.wikipedia.org/wiki/Operating_system" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Operating system">operating systems</a>. It is particularly prevalent on<a href="http://en.wikipedia.org/wiki/Unix" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Unix">Unix</a>&nbsp;and&nbsp;<a href="http://en.wikipedia.org/wiki/Unix-like" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Unix-like">Unix-like</a>&nbsp;systems, but it has been ported to most modern (and many obsolete) platforms. With only six reported exceptions, Perl can be compiled from&nbsp;<a href="http://en.wikipedia.org/wiki/Source_code" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Source code">source code</a>&nbsp;on all&nbsp;<a href="http://en.wikipedia.org/wiki/POSIX" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="POSIX">POSIX</a>-compliant, or otherwise-Unix-compatible platforms.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-cpanports-72" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[72]</a>}</p>

<p>Because of unusual changes required for the&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Mac_OS_history" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Mac OS history">Mac OS Classic</a>&nbsp;environment, a special port called MacPerl was shipped independently.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-macperl-73" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[73]</a>}</p>

<p>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); background: none;" title="CPAN">Comprehensive Perl Archive Network</a>&nbsp;carries a complete list of supported platforms with links to the distributions available on each.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-74" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[74]</a>}&nbsp;CPAN is also the source for publicly available Perl modules that are not part of the core Perl distribution.</p>

<h4>Windows<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=14" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Edit section: Windows">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h4>

<p>Users of&nbsp;<a href="http://en.wikipedia.org/wiki/Microsoft_Windows" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Microsoft Windows">Microsoft Windows</a>&nbsp;typically install one of the native binary distributions of Perl for Win32, most commonly&nbsp;<a href="http://en.wikipedia.org/wiki/Strawberry_Perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Strawberry Perl">Strawberry Perl</a>&nbsp;or&nbsp;<a href="http://en.wikipedia.org/wiki/ActivePerl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="ActivePerl">ActivePerl</a>. Compiling Perl from<a href="http://en.wikipedia.org/wiki/Source_code" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Source code">source code</a>&nbsp;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.</p>

<p><a href="http://en.wikipedia.org/wiki/ActivePerl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="ActivePerl">ActivePerl</a>&nbsp;is a closed source distribution from&nbsp;<a href="http://en.wikipedia.org/wiki/ActiveState" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="ActiveState">ActiveState</a>&nbsp;that has regular releases that track the core Perl releases.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-activestate-75" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[75]</a>}&nbsp;The distribution also includes the&nbsp;<a href="http://en.wikipedia.org/wiki/Perl_package_manager" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Perl package manager">Perl package manager</a>&nbsp;(PPM),^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-activestateppm-76" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[76]</a>}&nbsp;a popular tool for installing, removing, upgrading, and managing the use of common Perl modules. Included also is&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/PerlScript" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="PerlScript">PerlScript</a>, a&nbsp;<a href="http://en.wikipedia.org/wiki/Windows_Script_Host" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Windows Script Host">Windows Script Host</a>(WSH) engine implementing the Perl language.&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Visual_Perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Visual Perl">Visual Perl</a>&nbsp;is an ActiveState tool that adds Perl to the Visual Studio .NET development suite.</p>

<p><a href="http://en.wikipedia.org/wiki/Strawberry_Perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Strawberry Perl">Strawberry Perl</a>&nbsp;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.</p>

<p>The&nbsp;<a href="http://en.wikipedia.org/wiki/Cygwin" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Cygwin">Cygwin</a>&nbsp;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&nbsp;<a href="http://en.wikipedia.org/wiki/GNU_Compiler_Collection" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="GNU Compiler Collection">gcc</a>, compiling Perl from source is also possible.</p>

<p>Implementations of Perl come with the&nbsp;<a href="http://en.wikipedia.org/wiki/MKS_Toolkit" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="MKS Toolkit">MKS Toolkit</a>&nbsp;and&nbsp;<a href="http://en.wikipedia.org/wiki/UWIN" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="UWIN">UWIN</a>.</p>

<h2>Database interfaces<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=15" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Edit section: Database interfaces">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h2>

<p>Perl&#39;s text-handling capabilities can be used for generating&nbsp;<a href="http://en.wikipedia.org/wiki/SQL" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="SQL">SQL</a>&nbsp;queries; arrays, hashes, and automatic memory management make it easy to collect and process the returned data. For example, in Tim Bunce&#39;s&nbsp;<a href="http://en.wikipedia.org/wiki/Perl_DBI" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Perl DBI">Perl DBI</a>&nbsp;<a href="http://en.wikipedia.org/wiki/Application_programming_interface" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Application programming interface">application programming interface</a>&nbsp;(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&nbsp;<a href="http://en.wikipedia.org/wiki/Web_page" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Web page">Web page</a>&nbsp;using&nbsp;<a href="http://en.wikipedia.org/wiki/HTML" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="HTML">HTML</a>,&nbsp;<a href="http://en.wikipedia.org/wiki/JavaScript" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="JavaScript">JavaScript</a>, and SQL in a&nbsp;<a href="http://en.wikipedia.org/wiki/Here_document" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Here document">here document</a>). The use of Perl&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Variable_interpolation" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Variable interpolation">variable interpolation</a>&nbsp;to programmatically customize each of the SQL queries, and the specification of Perl arrays or hashes as the structures to programmatically hold the resulting<a href="http://en.wikipedia.org/wiki/Data_set" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Data set">data sets</a>&nbsp;from each SQL query, allows a high-level mechanism for handling large amounts of data for post-processing by a Perl subprogram.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-77" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[77]</a>}&nbsp;In early versions of Perl, database interfaces were created by relinking the interpreter with a&nbsp;<a href="http://en.wikipedia.org/wiki/Client-side" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Client-side">client-side</a>&nbsp;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&nbsp;<code>perl</code>&nbsp;executable to using just one database interface at a time.</p>

<p>In Perl 5, database interfaces are implemented by&nbsp;<a href="http://en.wikipedia.org/wiki/Perl_DBI" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Perl DBI">Perl DBI</a>&nbsp;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&nbsp;<a href="http://en.wikipedia.org/wiki/American_National_Standards_Institute" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="American National Standards Institute">ANSI</a>&nbsp;<a href="http://en.wikipedia.org/wiki/SQL" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="SQL">SQL</a>&nbsp;databases.</p>

<p>DBI provides caching for database handles and queries, which can greatly improve performance in long-lived execution environments such as&nbsp;<a href="http://en.wikipedia.org/wiki/Mod_perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Mod perl">mod perl</a>,^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-78" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[78]</a>}&nbsp;helping high-volume systems avert load spikes as in the&nbsp;<a href="http://en.wikipedia.org/wiki/Slashdot_effect" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Slashdot effect">Slashdot effect</a>.</p>

<p>In modern Perl applications, especially those written using&nbsp;<a href="http://en.wikipedia.org/wiki/Web_application_framework" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Web application framework">Web application frameworks</a>&nbsp;such as&nbsp;<a href="http://en.wikipedia.org/wiki/Catalyst_(software)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Catalyst (software)">Catalyst</a>, the DBI module is often used indirectly via&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Object-relational_mapper" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Object-relational mapper">object-relational mappers</a>&nbsp;such as&nbsp;<a href="http://en.wikipedia.org/wiki/DBIx::Class" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="DBIx::Class">DBIx::Class</a>,&nbsp;<a class="new" href="http://en.wikipedia.org/w/index.php?title=Class::DBI&amp;action=edit&amp;redlink=1" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(165, 88, 88); background: none;" title="Class::DBI (page does not exist)">Class::DBI</a>&nbsp;or&nbsp;<a class="new" href="http://en.wikipedia.org/w/index.php?title=Rose::DB::Object&amp;action=edit&amp;redlink=1" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(165, 88, 88); background: none;" title="Rose::DB::Object (page does not exist)">Rose::DB::Object</a>&nbsp;that generate SQL queries and handle data transparently to the application author.</p>

<h2>Comparative performance<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=16" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Edit section: Comparative performance">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h2>

<p>The Computer Language Benchmarks Game, a project hosted by&nbsp;<a href="http://en.wikipedia.org/wiki/Alioth_(Debian)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Alioth (Debian)">Alioth</a>, compares the performance of implementations of typical programming problems in several programming languages.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-79" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[79]</a>}&nbsp;The submitted Perl implementations typically perform toward the high end of the memory-usage spectrum and give varied speed results. Perl&#39;s performance in the benchmarks game is typical for interpreted languages.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-80" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[80]</a>}</p>

<p>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&nbsp;<a href="http://en.wikipedia.org/wiki/Yet_Another_Perl_Conference" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Yet Another Perl Conference">YAPC::Europe 2005</a>&nbsp;conference and subsequent article &quot;A Timely Start&quot;, 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.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-81" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[81]</a>}&nbsp;Unlike Java, Python, and Ruby, Perl has only experimental support for pre-compiling.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-82" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[82]</a>}Therefore Perl programs pay this overhead penalty on every execution. The run phase of typical programs is long enough that&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Amortized" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Amortized">amortized</a>&nbsp;startup time is not substantial, but benchmarks that measure very short execution times are likely to be skewed due to this overhead.</p>

<p>A number of tools have been introduced to improve this situation. The first such tool was Apache&#39;s&nbsp;<a href="http://en.wikipedia.org/wiki/Mod_perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Mod perl">mod perl</a>, which sought to address one of the most-common reasons that small Perl programs were invoked rapidly:&nbsp;<a href="http://en.wikipedia.org/wiki/Common_Gateway_Interface" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Common Gateway Interface">CGI</a>&nbsp;<a href="http://en.wikipedia.org/wiki/World_Wide_Web" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="World Wide Web">Web</a>&nbsp;development.&nbsp;<a href="http://en.wikipedia.org/wiki/ActiveState" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="ActiveState">ActivePerl</a>, via Microsoft&nbsp;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/ISAPI" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="ISAPI">ISAPI</a>, provides similar performance improvements.</p>

<p>Once Perl code is compiled, there is additional overhead during the execution phase that typically isn&#39;t present for programs written in compiled languages such as C or C++. Examples of such overhead include&nbsp;<a href="http://en.wikipedia.org/wiki/Bytecode" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Bytecode">bytecode</a>&nbsp;interpretation, reference-counting memory management, and dynamic type-checking.</p>

<h3>Optimizing<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=17" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Edit section: Optimizing">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h3>

<p>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&nbsp;<a href="http://en.wikipedia.org/wiki/C_(programming_language)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="C (programming language)">C</a>, which can be connected to Perl via simple Inline modules or the more complex but flexible&nbsp;<a href="http://en.wikipedia.org/wiki/XS_(Perl)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="XS (Perl)">XS</a>&nbsp;mechanism.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-83" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[83]</a>}</p>

<h2>Perl 6<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=18" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Edit section: Perl 6">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h2>

<div class="hatnote relarticle mainarticle" style="font-stylesize: italic; padding-left: 1.6em14px; margin-bottom: 0.5em; font-family: sans-serif; color: rgb(37, 37, 37); font-familystyle: sans-serifitalic; fontpadding-sizeleft: 14px1.6em; line-height: 17.9200000762939px;17px">Main article:&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); background: none;" title="Perl 6">Perl 6</a></div>

<div class="thumb tright" style="clearfont-size: right14px; floatfont-family: rightsans-serif; marginwidth: 0.5em 0px 1.3em 1.4emauto; widthfloat: autoright; color: rgb(37, 37, 37); font-familyclear: sans-serifright; font-sizemargin: 14px0.5em 0px 1.3em 1.4em; line-height: 17.9200000762939px;17px"><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: 202px; min-width: 100px; border-bottom: 1px solid rgb(204, 204, 204)1px solid; padding-bottom: 3px; fonttext-align: center; padding-sizetop: 13.1600008010864px3px; textpadding-alignleft: center3px; overflowborder-left: hiddenrgb(204,204,204) 1px solid; widthpadding-right: 202px3px; background-color: rgb(249, 249, 249);"><a class="image" href="http://en.wikipedia.org/wiki/File:Camelia.svg" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;"><img alt="" class="thumbimage" src="http://upload.wikimedia.org/wikipedia/commons/thumb/8/85/Camelia.svg/200px-Camelia.svg.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:146px; vertical-align:middle; width:200px" /></a>

<div class="thumbcaption" style="font-size: 12px; border-top: medium none; border-right: medium none; lineborder-heightbottom: 1.4emmedium none; padding-bottom: 3px; fonttext-align: left; padding-sizetop: 12.370400428772px3px; textpadding-alignleft: 3px; border-left: medium none; line-height: 1.4em;padding-right: 3px"><div class="magnify" style="float: right; margin-left: 3px; margin-right: 0px;">&nbsp;</div><em>Camelia</em>, the logo for the Perl 6 project.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-84" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[84]</a>}</div>

<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); background: none;" 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); background: none;" title="Jon Orwant (page does not exist)">Jon Orwant</a>&nbsp;made a case for a major new language-initiative.^{<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); white-space: nowrap; background: none;">[85]</a>}&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); background: none;" title="Request for Comments">RFCs</a>.</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.^{<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); white-space: nowrap; background: none;">[86]</a>}</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.^{<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); white-space: nowrap; background: none;">[87]</a>}</p>

<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); background: none;" 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); background: none;" title="Java virtual machine">Java virtual machine</a>&nbsp;as a runtime for Perl.^{<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); white-space: nowrap; background: none;">[88]</a>}&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); background: none;" 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); background: none;" 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); background: none;" title="CPAN">CPAN</a>, allowing some level of cross-language development.</p>

<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); background: none;" 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); background: none;" 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); background: none;" 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); background: none;" title="Freenode">freenode</a>&nbsp;#perl6 IRC channel.</p>

<p>As of 2012, Perl 6 development centers primarily around two compilers:^{<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); white-space: nowrap; background: none;">[89]</a>}</p>

<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); background: none;" 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); background: none;" 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); background: none;" title="Java virtual machine">Java virtual machine</a>.^{<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); white-space: nowrap; background: none;">[90]</a>}&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); background: none;" title="MoarVM">MoarVM</a>, a C language-based virtual machine designed specifically for Rakudo.^{<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); white-space: nowrap; background: none;">[91]</a>}</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); background: none;" 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); background: none;" title="Common Language Runtime">Common Language Runtime</a>.</li>

<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); background: none;" title="Edit section: Future of Perl 5">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h2>

<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.,^{<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); white-space: nowrap; background: none;">[33]</a>}^{<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); white-space: nowrap; background: none;">[92]</a>}&nbsp;followed by Perl 5.14.1 (released on June 17, 2011), Perl 5.16.1 (released on August 9, 2012.^{<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); white-space: nowrap; background: none;">[93]</a>}), 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.^{<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); white-space: nowrap; background: none;">[94]</a>}</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); background: none;" title="Meta-object protocol">Meta-object protocol</a>&nbsp;in core.^{<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); white-space: nowrap; background: none;">[95]</a>}</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.^{<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); white-space: nowrap; background: none;">[96]</a>}</p>

<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); background: none;" title="Edit section: Perl community">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h2>

<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); background: none;" 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.^{<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); white-space: nowrap; background: none;">[97]</a>}</p>

<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); background: none;" title="Edit section: State of the Onion">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h3>

<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); background: none;" 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); background: none;" title="Christian">Christian</a>&nbsp;background.^{<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); white-space: nowrap; background: none;">[98]</a>}</p>

<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); background: none;" title="Edit section: Perl pastimes">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h3>

<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); background: none;" 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); background: none;" title="Randal L. Schwartz">Randal L. Schwartz</a>, one of the earliest professional Perl trainers.^{<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); white-space: nowrap; background: none;">[99]</a>}&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); background: none;" 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.^{<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); white-space: nowrap; background: none;">[100]</a>}</p>

<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); background: none;" title="Golf">golf</a>&nbsp;players seek to take as few shots as possible in a round. The phrase&#39;s first use^{<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); white-space: nowrap; background: none;">[101]</a>}&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); background: none;" 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); background: none;" 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); background: none;" title="RSA (algorithm)">RSA</a>&nbsp;encryption prompted a widespread and practical interest in this pastime.^{<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); white-space: nowrap; background: none;">[102]</a>}&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); background: none;" title="Code golf">code golf</a>&quot; has been applied to the pastime in other languages.^{<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); white-space: nowrap; background: none;">[103]</a>}&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); background: none;" title="Perl Golf Apocalypse">Perl Golf Apocalypse</a>&nbsp;was held at Perl Conference 4.0 in Monterey, California in July 2000.</p>

<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); background: none;" 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); background: none;" 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); background: none;" 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); background: none;" title="Signature block">signature block</a>.^{<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); white-space: nowrap; background: none;">[104]</a>}</p>

<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); background: none;" 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); background: none;" title="PerlMonks">PerlMonks</a>.^{<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); white-space: nowrap; background: none;">[105]</a>}</p>

<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); background: none;" title="Edit section: Perl on IRC">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h3>

<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); background: none;" title="Internet Relay Chat">IRC</a>&nbsp;channels that offer support for the language and some modules.</p>

<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:17.9200000762939px17px; margin:1em 0px">

<th style="text-align: center; background-color:rgb(242, 242, 242); border-color:rgb(170, 170, 170); text-align:center">IRC Network</th> <th style="text-align: center; background-color:rgb(242, 242, 242); border-color:rgb(170, 170, 170); text-align:center">Channels</th>

<td style="border-color:rgb(170, 170, 170)">irc.freenode.net</td> <td style="border-color:rgb(170, 170, 170)">#perl #perl6 #cbstream #perlcafe #poe</td>

<td style="border-color:rgb(170, 170, 170)">irc.perl.org</td> <td style="border-color:rgb(170, 170, 170)">#moose #poe #catalyst #dbix-class #perl-help #distzilla #epo #corehackers #sdl #win32 #toolchain #padre #dancer</td>

<td style="border-color:rgb(170, 170, 170)">irc.slashnet.org</td> <td style="border-color:rgb(170, 170, 170)">#perlmonks</td>

<td style="border-color:rgb(170, 170, 170)">irc.oftc.net</td> <td style="border-color:rgb(170, 170, 170)">#perl</td>

<td style="border-color:rgb(170, 170, 170)">irc.efnet.net</td> <td style="border-color:rgb(170, 170, 170)">#perlhelp</td>

<td style="border-color:rgb(170, 170, 170)">irc.rizon.net</td> <td style="border-color:rgb(170, 170, 170)">#perl</td>

<td style="border-color:rgb(170, 170, 170)">irc.debian.org</td> <td style="border-color:rgb(170, 170, 170)">#debian-perl</td>

<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); background: none;" title="Edit section: CPAN Acme">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h3>

<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); background: none;" 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); background: none;" title="Latin">Latin</a>.^{<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); white-space: nowrap; background: none;">[106]</a>}&nbsp;Upon execution of such a program, the module translates its source code into regular Perl and runs it.</p>

<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); background: none;" 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,^{<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); white-space: nowrap; background: none;">[107]</a>}&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>

<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); background: none;" title="Edit section: Example code">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h2>

<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); background: none;" title="Hello World">Hello World</a>&nbsp;program as:</p>

<div class="mw-geshi mw-code mw-content-ltr" dir="ltr" style="directionfont-size: 14px; border-top: ltrrgb(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; fontpadding-sizeright: 14px1em; background-color: rgb(249, 249, 249);"><div class="perl source-perl" style="font-family: monospace, monospace; line-height: normal; tab-size: 4; font-family: monospace, monospace;">

<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>

<div class="mw-geshi mw-code mw-content-ltr" dir="ltr" style="directionfont-size: 14px; border-top: ltrrgb(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; fontpadding-sizeright: 14px1em; background-color: rgb(249, 249, 249);"><div class="perl source-perl" style="font-family: monospace, monospace; line-height: normal; tab-size: 4; font-family: monospace, monospace;">

<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>

<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); background: none;" title="Directive (programming)">pragmas</a>, leading into something like:</p>

<div class="mw-geshi mw-code mw-content-ltr" dir="ltr" style="directionfont-size: 14px; border-top: ltrrgb(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; fontpadding-sizeright: 14px1em; background-color: rgb(249, 249, 249);"><div class="perl source-perl" style="font-family: monospace, monospace; line-height: normal; tab-size: 4; font-family: monospace, monospace;">

<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)">&quot;Hello World!<strong>\n</strong>&quot;</span><span style="color:rgb(51, 153, 51)">;</span>

<div class="mw-geshi mw-code mw-content-ltr" dir="ltr" style="directionfont-size: 14px; border-top: ltrrgb(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; fontpadding-sizeright: 14px1em; background-color: rgb(249, 249, 249);"><div class="perl source-perl" style="font-family: monospace, monospace; line-height: normal; tab-size: 4; font-family: monospace, monospace;">

<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)">-&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 style="color:rgb(177, 177, 0)">while</span> <span style="color:rgb(0, 153, 0)">(</span> <span style="color:rgb(0, 0, 255)">$remaining</span> <span style="color:rgb(0, 153, 0)">)</span> <span style="color:rgb(0, 153, 0)">{</span> <span style="color:rgb(0, 0, 102)">printf</span> <span style="color:rgb(0, 153, 0)">(</span> <span style="color:rgb(255, 0, 0)">&quot;Remaining %s/%s <strong>\r</strong>&quot;</span><span style="color:rgb(51, 153, 51)">,</span> <span style="color:rgb(0, 0, 255)">$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 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)">&quot;<strong>\n</strong>&quot;</span><span style="color:rgb(51, 153, 51)">;</span>

<div class="mw-geshi mw-code mw-content-ltr" dir="ltr" style="directionfont-size: 14px; border-top: ltrrgb(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; fontpadding-sizeright: 14px1em; background-color: rgb(249, 249, 249);"><div class="bash source-bash" style="font-family: monospace, monospace; line-height: normal; tab-size: 4; font-family: monospace, monospace;">

$ <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

<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); background: none;" title="Edit section: Criticism">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h2>

<p>Perl has been referred to as &quot;<a class="mw-redirect" href="http://en.wikipedia.org/wiki/Line_noise" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Line noise">line noise</a>&quot; by some programmers who claim its syntax makes it a&nbsp;<a href="http://en.wikipedia.org/wiki/Write-only_language" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Write-only language">write-only language</a>. The earliest such mention was in the first edition of the book&nbsp;<em><a href="http://en.wikipedia.org/wiki/Learning_Perl" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Learning Perl">Learning Perl</a></em>, a Perl 5 tutorial book written 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); background: none;" title="Randal L. Schwartz">Randal L. Schwartz</a>,^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-108" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[108]</a>}&nbsp;in the first chapter of which he states: &quot;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.&quot;^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-LP-109" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[109]</a>}&nbsp;He also stated that the accusation that Perl is a write-only language could be avoided by coding with &quot;proper care&quot;.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-LP-109" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[109]</a>}&nbsp;The Perl overview document&nbsp;<em>perlintro</em>&nbsp;states that the names of built-in &quot;magic&quot; scalar&nbsp;<a href="http://en.wikipedia.org/wiki/Variable_(computer_science)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Variable (computer science)">variables</a>&nbsp;&quot;look like punctuation or line noise&quot;.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-110" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[110]</a>}&nbsp;The&nbsp;<em>perlstyle</em>&nbsp;document states that line noise in regular expressions could be mitigated using the&nbsp;<code>/x</code>&nbsp;modifier to add whitespace.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-111" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[111]</a>}</p>

<p>According to the&nbsp;<em>Perl 6 FAQ</em>, Perl 6 was designed to mitigate &quot;the usual suspects&quot; that elicit the &quot;line noise&quot; claim from Perl 5 critics, including the removal of &quot;the majority of the punctuation variables&quot; and the sanitization of the regex syntax.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-P6FAQ-112" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[112]</a>}&nbsp;The&nbsp;<em>Perl 6 FAQ</em>&nbsp;also states that what is sometimes referred to as Perl&#39;s line noise is &quot;the actual syntax of the language&quot; just as&nbsp;<a href="http://en.wikipedia.org/wiki/Gerund" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Gerund">gerunds</a>&nbsp;and&nbsp;<a href="http://en.wikipedia.org/wiki/Preposition_and_postposition" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Preposition and postposition">prepositions</a>&nbsp;are a part of the&nbsp;<a href="http://en.wikipedia.org/wiki/English_language" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="English language">English language</a>.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-P6FAQ-112" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[112]</a>}&nbsp;In a December 2012 blog posting, despite claiming that &quot;Rakudo Perl 6 has failed and will continue to fail unless it gets some adult supervision&quot;,&nbsp;<a href="http://en.wikipedia.org/wiki/Chromatic_(programmer)" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Chromatic (programmer)">chromatic</a>&nbsp;stated that the design of Perl 6 has a &quot;well-defined grammar&quot; as well as an &quot;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&quot;.^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-chromatic-blog-113" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[113]</a>}&nbsp;He also stated that &quot;Perl 6 has a coherence and a consistency that Perl 5 lacks.&quot;^{<a href="http://en.wikipedia.org/wiki/Perl#cite_note-chromatic-blog-113" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; white-space: nowrap; color: rgb(11, 0, 128); white-space: nowrap; background: none;">[113]</a>}</p>

<h2>References<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=27" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; color: rgb(11, 0, 128); background: none;" title="Edit section: References">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h2>

<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; background: linear-gradient6th Edition (transparent, transparent2011) 100% 50% no-repeat, url(data:image/svg+xml,%3C%3Fxml%20version%3D%221O&#39;Reilly.0%22%20encoding%3D%22UTFBeginner-8%22%3F%3E%3Csvg%20xmlns%3D%22http%3A%2F%2Fwwwlevel introduction to Perl.w3.org%2F2000%2Fsvg%22%20width%3D%2210%22%20height%3D%2210%22%3E%3Cg%20transform%3D%22translate%28-826</li> <li><a class="external text" href="http://ofps.429%20-698oreilly.791%29%22%3E%3Crect%20width%3D%225com/titles/9781118013847/index.982%22%20heighthtml" rel="nofollow" style="text-decoration: none; background: none transparent scroll repeat 0%3D0%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; color: rgb(102,51,102); padding-right: 13px">Beginning Perl</a>&nbsp;1st Edition (2012), Wrox.194%20698A beginner&#39;s tutorial for those new to programming or just new to Perl.791h5.234v5.391l-1</li> <li><a class="external text" href="http://onyxneon.571%201.545com/books/modern_perl/" rel="nofollow" style="text-1.31-1.31-2.725decoration: none; background: none transparent scroll repeat 0%202.725-2.689-2.6890%202.808; color: rgb(102,51,102); padding-2right: 13px">Modern Perl</a>&nbsp;2nd Edition (2012), Onyx Neon.808-1.311-1Describes&nbsp;<a class="new" href="http://en.wikipedia.311z%22%20fill%3D%22%2306f%22%2F%3E%3Cpath%20d%3D%22M835org/w/index.424%20699.795l.022%204.885-1.817-php?title=Modern_Perl&amp;action=edit&amp;redlink=1.817" style="text-2.881decoration: none; background: none transparent scroll repeat 0%202.881-1.228-1.2280%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%;; color: rgb(165,88,88)" title=">Learning Modern Perl (page does not exist)">Modern Perl</a>&nbsp;6th Edition (2011), O&#39;Reillyprogramming techniques. Beginner-level introduction to Perl.</</li> <li><a class="external text" href="http://ofpsshop.oreilly.com/titlesproduct/9781118013847/index9780596004927.htmldo" 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; background: linear-gradient4th Edition (transparent, transparent2012) 100% 50% no-repeat, url(data:imageO&#39;Reilly. The definitive Perl reference.</svg+xml,%3C%3Fxml%20version%3D%221.0%22%20encoding%3D%22UTF-8%22%3F%3E%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3li> <li><a class="external text" href="http://www.org%2F2000%2Fsvg%22%20width%3D%2210%22%20height%3D%2210%22%3E%3Cg%20transform%3D%22translate%28-826pearsonhighered.429%20com/educator/product/Effective-Perl-Programming-Ways-698to-Write-Better-More-Idiomatic-Perl-2E/9780321496942.791page" rel="nofollow" style="text-decoration: none; background: none transparent scroll repeat 0%290%22%3E%3Crect%20width%3D%225.982%22%20height%3D%225.982%22%20x%3D%22826; color: rgb(102,51,102); padding-right: 13px">Effective Perl Programming</a>&nbsp;2nd Edition (2010), Addison-Wesley.929%22%20y%3D%22702Intermediate- to advanced-level guide to writing idiomatic Perl.309%22%20fill%3D%22%23fff%22%20stroke%3D%22%2306c%22%2F%3E%3Cg%3E%3Cpath%20d%3D%22M831</li> <li><em><a href="http://en.194%20698wikipedia.791h5.234v5.391lorg/wiki/Perl_Cookbook" style="text-1.571decoration: none; background: none transparent scroll repeat 0% 0%201.545-1.31-1.31-2.725%202.725-2.689-2.689%202.808; color: rgb(11,0,128)" title="Perl Cookbook">Perl Cookbook</a></em>,&nbsp;<a class="internal mw-2.808magiclink-1isbn" href="http://en.311-1wikipedia.311z%22%20fill%3D%22%2306forg/wiki/Special:BookSources/0596003137" style="text-decoration: none; background: none transparent scroll repeat 0%220%2F%3E%3Cpath%20d%3D%22M835.424%20699.795l.022%204.885; color: rgb(11,0,128)">ISBN 0-1.817596-1.81700313-2.881%2027</a>.881-1Practical Perl programming examples.228-1.228%202.881-2.881-1</li> <li>Dominus, Mark Jason (2005).851-1.851z%22%20fill%3D%22%23fff%22%2F%3E%3C%2Fg%3E%3C%2Fg%3E%3C%2Fsvg%3E) 100% 50%;&nbsp;<a class="external text" href=">Beginning Perl<http://a>&nbsp;1st Edition (2012), Wroxhop.perl.plover. A beginner&#39;s tutorial for those new to programming or just new to Perl.</li> <li><a classcom/book/" rel="external text" href="http://onyxneon.com/books/modern_perl/" rel="nofollownofollow" style="text-decoration: none; colorbackground: rgbnone transparent scroll repeat 0% 0%; color: rgb(102, 51, 102); padding-right: 13px; background: linear-gradient(transparent, transparent) 100% 50% no-repeat, url(data:image"><em>Higher Order Perl</em></svg+xml,%3C%3Fxml%20version%3D%221a>. Morgan Kaufmann.0%22%20encoding%3D%22UTF-8%22%3F%3E%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww&nbsp;<a href="http://en.w3wikipedia.org/wiki/International_Standard_Book_Number" style="text-decoration: none; background: none transparent scroll repeat 0%2F20000%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 class="new" href="http://en.wikipedia.org/w/index.php?title=Modern_Perl&amp;action=edit&amp;redlink=1" style="text-decoration: none; color: rgb(165, 88, 88); background: none;" title="Modern Perl (page does not exist)">Modern Perl</a>&nbsp;programming techniques.</li> <li><a class="external text" href="http://shop.oreilly.com/product/9780596004927.do" rel="nofollow" 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&#39;Reilly. The definitive Perl reference.</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; 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><em><a href="http://en.wikipedia.org/wiki/Perl_Cookbook" style="text-decoration: none; color: rgb(11, 0, 128); background: none;" 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; color: rgb(11, 0, 128); background: none;">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; 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%;"><em>Higher Order Perl</em></a>. Morgan Kaufmann.&nbsp;<a href="http://en.wikipedia.org/wiki/International_Standard_Book_Number" style="text-decoration: none; color: rgb(11, 0, 128); background: none;" title="International Standard Book Number">ISBN</a>&nbsp;<a href="http://en.wikipedia.org/wiki/Special:BookSources/1-55860-701-3" style="text-decoration: none; color: rgb(11, 0, 128); background: none;" title="Special:BookSources/color: rgb(11,0,128)" title="International Standard Book Number">ISBN</a>&nbsp;1-55860-701-3">1-55860-701-3</a>.&nbsp;Functional programming techniques in Perl.</li>

<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); background: none;" title="Edit section: See also">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h2>

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<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); background: none;" title="Outline of Perl">Outline of Perl</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); background: none;" title="Perl Data Language">Perl Data Language</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); background: none;" 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); background: none;" title="Plain Old Documentation">Plain Old Documentation</a></li>

<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); background: none;" title="Edit section: External links">edit</a><span style="color:rgb(85, 85, 85)">]</span></span></h2>

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<li><a class="external text" href="https://www.perl.org/" rel="nofollow" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; 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%;">Official website</a>&nbsp;Perl.org</li> <li><a class="external text" href="https://metacpan.org/" rel="nofollow" style="text-decoration: none; background: none transparent scroll repeat 0% 0%; 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%;">MetaCPAN</a>&nbsp;the new Comprehensive Perl Archive Network Web interface</li> <li><a class="external text" href="http://www.cpan.org/" rel="nofollow" style="text-decoration: none; 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background: none transparent scroll repeat 0% 0%; 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%;">The Perl Foundation</a></li> <li><a class="external text" href="http://www.perlmonks.org/" rel="nofollow" style="text-decoration: none; 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