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Perl
please note:
- the content below is remote from Wikipedia
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{{short description|Interpreted programming language first released in 1987}}{{other uses|Perl (disambiguation)}} {{distinguish|PEARL (programming language)}}- the content below is remote from Wikipedia
- it has been imported raw for GetWiki
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Name and logos
Perl was originally named “Pearl”. Wall wanted to give the language a short name with positive connotations. It is also a Christian reference to the Parable of the Pearl from the Gospel of Matthew.MAGAZINE, 2016-03-07, Scripting on the Lido Deck,www.wired.com/2000/10/cruise/, 2023-02-14, Wired,web.archive.org/web/20160307004219/https://www.wired.com/2000/10/cruise/, March 7, 2016, However, Wall discovered the existing PEARL programming language before Perl’s official release and changed the spelling of the name and dropped the “a” from the name.JOURNAL, Richardson, Marjorie, 1999-05-01, Larry Wall, the Guru of Perl,www.linuxjournal.com/article/3394, live, Linux Journal,www.linuxjournal.com/article/3394," title="web.archive.org/web/20130720013904www.linuxjournal.com/article/3394,">web.archive.org/web/20130720013904www.linuxjournal.com/article/3394, July 20, 2013, 2011-01-03, The name is occasionally expanded as a backronym: Practical Extraction and Report LanguageBOOK, Schwartz, Randal,archive.org/details/learningperl00schw_278, Learning Perl, foy, brian, Phoenix, Tom, June 16, 2011, O’Reilly Media, Inc., 978-1449313142, 4, Perl is sometimes called the “Practical Extraction and Report Language”, although it has also been called a “Pathologically Eclectic Rubbish Lister”, among other expansions. It’s actually a backronym, not an acronym, since Larry Wall, Perl’s creator, came up with the name first and the expansion later. That’s why ‘Perl’ isn’t in all caps. There’s no point in arguing that expansion is correct: Larry endorses both., Randal Schwartz, brian d foy, limited, and Wall’s own Pathologically Eclectic Rubbish Lister, which is in the manual page for perl.WEB, Wall, Larry, Larry Wall, perl - The Perl language interpreter,perldoc.perl.org/perl.html#BUGS, live,perldoc.perl.org/perl.html#BUGS," title="web.archive.org/web/20130701050810perldoc.perl.org/perl.html#BUGS,">web.archive.org/web/20130701050810perldoc.perl.org/perl.html#BUGS, July 1, 2013, 2011-01-26, Perl 5 version 12.2 documentation, Programming Perl, published by O’Reilly Media, features a picture of a dromedary camel on the cover and is commonly called the “Camel Book”.BOOK, Schwartz, Randal L, Randal L. Schwartz, Phoenix, Tom, Foy, Brian, Brian D Foy, Learning Perl, Third Edition, 978-0-596-00132-2, 2007-12-06, O’Reilly Media,archive.org/details/learningperl00schw, This image has become an unofficial symbol of Perl. O’Reilly owns the image as a trademark but licenses it for non-commercial use, requiring only an acknowledgement and a link to www.perl.com. Licensing for commercial use is decided on a case-by-case basis.WEB,archive.oreilly.com/pub/a/oreilly/perl/usage,archive.oreilly.com/pub/a/oreilly/perl/usage," title="web.archive.org/web/20180425080044archive.oreilly.com/pub/a/oreilly/perl/usage,">web.archive.org/web/20180425080044archive.oreilly.com/pub/a/oreilly/perl/usage, dead, 2018-04-25, The Perl Camel Usage and Trademark Information, 2011-01-09, O’Reilly Media, O’Reilly also provides “Programming Republic of Perl” logos for non-commercial sites and “Powered by Perl” buttons for any site that uses Perl.The Perl Foundation owns an alternative symbol, an onion, which it licenses to its subsidiaries, Perl Mongers, PerlMonks, Perl.org, and others.WEB,www.perlfoundation.org/perl_trademark, Perl Trademark, 2011-01-09, The Perl Foundation,www.perlfoundation.org/perl_trademark," title="web.archive.org/web/20110503211915www.perlfoundation.org/perl_trademark,">web.archive.org/web/20110503211915www.perlfoundation.org/perl_trademark, May 3, 2011, dead, mdy-all, The symbol is a visual pun on pearl onion.NEWS, Dan, Gillmore, Republic Of Perl, 1998-10-25,articles.chicagotribune.com/1998-10-25/news/9810250094_1_programmers-open-source-movement-programming-community, Chicago Tribune, 2011-01-10, April 30, 2011,articles.chicagotribune.com/1998-10-25/news/9810250094_1_programmers-open-source-movement-programming-community," title="web.archive.org/web/20110430031425articles.chicagotribune.com/1998-10-25/news/9810250094_1_programmers-open-source-movement-programming-community,">web.archive.org/web/20110430031425articles.chicagotribune.com/1998-10-25/news/9810250094_1_programmers-open-source-movement-programming-community, live, Sebastian Riedel, the creator of Mojolicious, created a logo depicting a raptor dinosaur, which is available under a CC-SA License, Version 4.0.WEB, Sebastian, Riedel, Perl 5 Raptor, 2012-01-18,github.com/kraih/perl-raptor, Sebastian Riedel, 2017-11-12, June 11, 2018,web.archive.org/web/20180611021629/https://github.com/kraih/perl-raptor, live, The analogue of the raptor comes from a series of talks given by Matt S Trout beginning in 2010.WEB, Matt, Trout, State of the Velociraptor - Phase two, 2005-06-16,shadow.cat/blog/matt-s-trout/sotv-vi/, Shadowcat Systems Limited, 2017-11-12, November 13, 2017,web.archive.org/web/20171113003519/https://shadow.cat/blog/matt-s-trout/sotv-vi/, live,History
Early versions
Larry Wall began work on Perl in 1987, while employed as a programmer at Unisys; he released version 1.0 on December 18, 1987.MAGAZINE, Long, Tony, Dec. 18, 1987: Perl Simplifies the Labyrinth That Is Programming Language, en-US, Wired,www.wired.com/2007/12/dec-18-1987-perl-simplifies-the-labyrinth-that-is-programming-language/, 2023-02-14, 1059-1028, Wall based early Perl on some methods existing languages used for text manipulation.Perl 2, released in June 1988,BOOK, Kalita, Jugal,books.google.com/books?id=aMuuTttVDcIC, On Perl: Perl for Students and Professionals, December 2003, Universal-Publishers, 978-1-58112-550-4, en, WEB, Perl Culture,docstore.mik.ua/orelly/perl/prog3/ch27_01.htm, 2023-03-16, docstore.mik.ua, en-US, featured a better regular expression engine. Perl 3, released in October 1989, added support for binary data streams.WEB, Holloway, Ruth, Perl turns 30 and its community continues to thrive {{!, Opensource.com |url=https://opensource.com/article/17/10/perl-turns-30 |access-date=2023-06-23 |website=opensource.com |language=en}}1990s
Originally, the only documentation for Perl was a single lengthy man page. In 1991, Programming Perl, known to many Perl programmers as the “Camel Book” because of its cover, was published and became the de facto reference for the language.WEB, Programming Perl, 3rd Edition [Book],www.oreilly.com/library/view/programming-perl-3rd/0596000278/, 2023-04-11, www.oreilly.com, en, 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.WEB, perlhist - the Perl history records - Perldoc Browser,perldoc.perl.org/perlhist, 2023-07-28, perldoc.perl.org, Perl 4 was released in March 1991.Perl 4 went through a series of maintenance releases, culminating in Perl 4.036 in 1993, whereupon Wall abandoned Perl 4 to begin work on Perl 5. Initial design of Perl 5 continued into 1994. The perl5-porters mailing list was established in May 1994 to coordinate work on porting Perl 5 to different platforms. It remains the primary forum for development, maintenance, and porting of Perl 5.WEB,www.nntp.perl.org/group/perl.perl5.porters/, perl.perl5.porters archive, 2011-01-13, perl.org, May 1, 2011,www.nntp.perl.org/group/perl.perl5.porters/," title="web.archive.org/web/20110501081803www.nntp.perl.org/group/perl.perl5.porters/,">web.archive.org/web/20110501081803www.nntp.perl.org/group/perl.perl5.porters/, live, Perl 5.000 was released on October 17, 1994.WEB,perldoc.perl.org/perlhist.html, perlhist — the Perl history records, 2011-01-21, Perl 5 version 12.2 documentation, perldoc.perl.org, January 13, 2011,perldoc.perl.org/perlhist.html," title="web.archive.org/web/20110113030100perldoc.perl.org/perlhist.html,">web.archive.org/web/20110113030100perldoc.perl.org/perlhist.html, live, It was a nearly complete rewrite of the interpreter, and it added many new features to the language, including objects, references, lexical (my) variables, and modules. Importantly, modules provided a mechanism for extending the language without modifying the interpreter. This allowed the core interpreter to stabilize, even as it enabled ordinary Perl programmers to add new language features. Perl 5 has been in active development since then.Perl 5.001 was released on March 13, 1995. Perl 5.002 was released on February 29, 1996 with the new prototypes feature. This allowed module authors to make subroutines that behaved like Perl builtins. Perl 5.003 was released June 25, 1996, as a security release.WEB, Perl {{!, Definition, History, & Facts {{!}} Britannica |url=https://www.britannica.com/technology/Perl |access-date=2022-06-15 |website=www.britannica.com |language=en}}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 Comprehensive Perl Archive Network (CPAN) was established as a repository for the Perl language and Perl modules; {{as of|December 2022|lc=y}}, it carries over 211,850 modules in 43,865 distributions, written by more than 14,324 authors, and is mirrored worldwide at more than 245 locations.WEB,www.cpan.org/, CPAN, 2022-12-19, CPAN, October 3, 2019,web.archive.org/web/20191003040107/https://www.cpan.org/, live, Perl 5.004 was released on May 15, 1997, and included, among other things, the UNIVERSAL package, giving Perl a base object from which all classes were automatically derived and the ability to require versions of modules. Another significant development was the inclusion of the CGI.pm module,WEB,perldoc.perl.org/perl5004delta.html, perl5004delta — what’s new for perl5.004, 2011-01-08, Perl 5 version 12.2 documentation, perldoc.perl.org, February 27, 2011,perldoc.perl.org/perl5004delta.html," title="web.archive.org/web/20110227200616perldoc.perl.org/perl5004delta.html,">web.archive.org/web/20110227200616perldoc.perl.org/perl5004delta.html, live, which contributed to Perl’s popularity as a CGI scripting language.BOOK, Patwardhan, Nathan, Siever, Ellen, Spainhour, Stephen, Perl in a Nutshell, Second Edition, O’Reilly Media, 2002, 978-0-596-00241-1,archive.org/details/perlinnutshell00patw, Perl 5.004 added support for Microsoft Windows, Plan 9, QNX, and AmigaOS.Perl 5.005 was released on July 22, 1998. This release included several enhancements to the regex engine, new hooks into the backend through the B::* modules, the q regex quote operator, a large selection of other new core modules, and added support for several more operating systems, including BeOS.WEB, http:perldoc.perl.org/perl5005delta.html, perl5005delta - what’s new for perl5.005, 2011-01-21, Perl 5 version 12.2 documentation, perldoc.perl.org, February 3, 2011,perldoc.perl.org/perl5005delta.html," title="web.archive.org/web/20110203100249perldoc.perl.org/perl5005delta.html,">web.archive.org/web/20110203100249perldoc.perl.org/perl5005delta.html, live,2000–2020{| class“wikitable floatright”
Perl 6 and Raku
thumb|Camelia, the logo for the Perl 6 projectWEB,perl6.org/, Perl 6, 2011-02-27, The Perl 6 Project, February 21, 2011,perl6.org/," title="web.archive.org/web/20110221094526perl6.org/,">web.archive.org/web/20110221094526perl6.org/, live, At the 2000 Perl Conference, Jon Orwant made a case for a major new language-initiative.WEB,www.nntp.perl.org/group/perl.perl6.meta/2000/10/msg424.html, Transcription of Larry’s talk, 2011-01-25, Torkington, Nathan, nntp.perl.org, May 1, 2011,www.nntp.perl.org/group/perl.perl6.meta/2000/10/msg424.html," title="web.archive.org/web/20110501081806www.nntp.perl.org/group/perl.perl6.meta/2000/10/msg424.html,">web.archive.org/web/20110501081806www.nntp.perl.org/group/perl.perl6.meta/2000/10/msg424.html, live, This led to a decision to begin work on a redesign of the language, to be called Perl 6. Proposals for new language features were solicited from the Perl community at large, which submitted more than 300 RFCs.WEB, Perl6 - The future of Perl,www.java-samples.com/showtutorial.php?tutorialid=1443, 2021-05-18, www.java-samples.com, Wall spent the next few years digesting the RFCs and synthesizing them into a coherent framework for Perl 6. He presented his design for Perl 6 in a series of documents called “apocalypses“{{snd}}numbered to correspond to chapters in Programming Perl. {{as of|2011|January}}, the developing specification of Perl 6 was encapsulated in design documents called Synopses{{snd}}numbered to correspond to Apocalypses.WEB,perlcabal.org/syn/, Official Perl 6 Documentation, 2011-01-25, The Perl 6 Project,perlcabal.org/syn/," title="web.archive.org/web/20090831103918perlcabal.org/syn/,">web.archive.org/web/20090831103918perlcabal.org/syn/, August 31, 2009, dead, Thesis work by Bradley M. Kuhn, overseen by Wall, considered the possible use of the Java virtual machine as a runtime for Perl.THESIS, Kuhn, Bradley M., Bradley M. Kuhn, Considerations on Porting Perl to the Java Virtual Machine, MS thesis, University of Cincinnati, January 2001,www.ebb.org/bkuhn/writings/technical/thesis/, 2008-06-28, March 21, 2008,ebb.org/bkuhn/writings/technical/thesis/," title="web.archive.org/web/20080321164747ebb.org/bkuhn/writings/technical/thesis/,">web.archive.org/web/20080321164747ebb.org/bkuhn/writings/technical/thesis/, live, Kuhn’s thesis showed this approach to be problematic. In 2001, it was decided that Perl 6 would run on a cross-language virtual machine called Parrot.In 2005, Audrey Tang created the Pugs project, an implementation of Perl 6 in Haskell. This acted as, and continues to act as, a test platform for the Perl 6 language (separate from the development of the actual implementation){{snd}}allowing the language designers to explore. The Pugs project spawned an active Perl/Haskell cross-language community centered around the Libera Chat #raku IRC channel. Many functional programming influences were absorbed by the Perl 6 design team.BOOK, Chromatic,books.google.com/books?id=JUjmsgEACAAJ, Modern Perl, 2015, Pragmatic Bookshelf, 978-1-68050-088-2, en, In 2012, Perl 6 development was centered primarily on two compilers:WEB,perl6.org/compilers/features, Feature comparison of Perl 6 compilers, March 28, 2012,web.archive.org/web/20170811073233/https://perl6.org/compilers/features, August 11, 2017, dead,- Rakudo, an implementation running on the Parrot virtual machine and the Java virtual machine.WEB, Worthington, Jonathan, Rakudo JVM News: More tests, plus Thread and Promise prototypes,6guts.wordpress.com/2013/07/15/rakudo-jvm-news-more-tests-plus-thread-and-promise-prototypes/, 6guts, July 15, 2013, July 24, 2013, October 5, 2013,6guts.wordpress.com/2013/07/15/rakudo-jvm-news-more-tests-plus-thread-and-promise-prototypes/," title="web.archive.org/web/201310050555596guts.wordpress.com/2013/07/15/rakudo-jvm-news-more-tests-plus-thread-and-promise-prototypes/,">web.archive.org/web/201310050555596guts.wordpress.com/2013/07/15/rakudo-jvm-news-more-tests-plus-thread-and-promise-prototypes/, live,
- Niecza, which targets the Common Language Runtime.
Perl 7
In June 2020, Perl 7 was announced as the successor to Perl 5.WEB,news.perlfoundation.org/post/perl_7_announced_sawyerx_conference, Perl 7 announced at Perl Conference in the Cloud, perlfoundation.org, 2020-06-24, 2020-06-24, June 26, 2020,web.archive.org/web/20200626213418/https://news.perlfoundation.org/post/perl_7_announced_sawyerx_conference, live, Perl 7 was to initially be based on Perl 5.32 with a release expected in first half of 2021, and release candidates sooner.WEB,www.perl.com/article/announcing-perl-7/, Announcing Perl 7, perl.com, 2020-06-24, 2020-06-24, June 24, 2020,web.archive.org/web/20200624160531/https://www.perl.com/article/announcing-perl-7/, live, This plan was revised in May 2021, without any release timeframe or version of Perl 5 for use as a baseline specified.WEB, Steering Council meeting #019 2021-05-06,www.nntp.perl.org/group/perl.perl5.porters/2021/05/msg260050.html, The plan remains that there will be a Perl 7 bump, but not immediately after 5.34.0 is released.{{nbsp, ... We don’t think that we can deliver on [Perl 7] in 12 months.|author=Nicholas Clark|date=2021-05-09|access-date=2021-05-17|website=www.nntp.perl.org|archive-date=2021-05-18|archive-url=https://web.archive.org/web/20210518015233www.nntp.perl.org/group/perl.perl5.porters/2021/05/msg260050.html|url-status=live}} When Perl 7 would be released, Perl 5 would have gone into long term maintenance. Supported Perl 5 versions however would continue to get important security and bug fixes.BOOK,leanpub.com/preparing_for_perl7, Preparing for Perl 7d, leanpub.com, 2020-06-24, 2020-06-24, June 25, 2020,web.archive.org/web/20200625004047/https://leanpub.com/preparing_for_perl7, live, Perl 7 was announced on 24 June 2020 at “The Perl Conference in the Cloud” as the successor to Perl 5. Based on Perl 5.32, Perl 7 was planned to be backward compatible with modern Perl 5 code; Perl 5 code, without boilerplate (pragma) header needs adding use compat::perl5; to stay compatible, but modern code can drop some of the boilerplate. The plan to go to Perl 7 brought up more discussion, however, and the Perl Steering Committee canceled it to avoid issues with backward compatibility for scripts that were not written to the pragmas and modules that would become the default in Perl 7. Perl 7 will only come out when the developers add enough features to warrant a major release upgrade.WEB, Perl Steering Council, What happened to Perl 7?,blogs.perl.org/users/psc/2022/05/what-happened-to-perl-7.html, blogs.perl.org, 7 July 2022,Design
Philosophy
According to Wall, Perl has two slogans. The first is “There’s more than one way to do it,” commonly known as TMTOWTDI, (pronounced Tim Toady). As proponents of this motto argue, this philosophy makes it easy to write concise statements.WEB, Richardson, Marjorie, Larry Wall, the Guru of Perl {{!, Linux Journal |url=https://www.linuxjournal.com/article/3394 |website=www.linuxjournal.com |publisher=Linux Journal |access-date=16 January 2023}}JOURNAL, Schwartz, Alan, December 1998, Tutorial: Perl, a psychologically efficient reformatting language, Behavior Research Methods, Instruments, & Computers, en, 30, 4, 605–609, 10.3758/BF03209477, 61028367, 0743-3808, free, JOURNAL, Gilbert, James G. R., March 2002, How to become a programming tadpole,www.nature.com/articles/nbt0302-221, Nature Biotechnology, en, 20, 3, 221, 10.1038/nbt0302-221, 38728402, 1087-0156, The second slogan is “Easy things should be easy and hard things should be possible”.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 compiler technology. Many earlier computer languages, such as Fortran and C, aimed to make efficient use of expensive computer hardware. In contrast, Perl was designed so that computer programmers could write programs more quickly and easily.WEB, February 13, 2014, The Fall Of Perl, The Web’s Most Promising Language,www.fastcompany.com/3026446/the-fall-of-perl-the-webs-most-promising-language, FastCompany, Perl has many features that ease the task of the programmer at the expense of greater CPU and memory requirements. These include automatic memory management; dynamic typing; strings, lists, and hashes; regular expressions; introspection; and an eval() function. Perl follows the theory of “no built-in limits”, an idea similar to the Zero One Infinity rule.Wall was trained as a linguist, and the design of Perl is very much informed by linguistic principles. Examples include Huffman coding (common constructions should be short), good end-weighting (the important information should come first), and a large collection of language primitives. Perl favors language constructs that are concise and natural for humans to write, even where they complicate the Perl interpreter.WEB, Wall, Larry, perl - The Perl 5 language interpreter - Perldoc Browser,perldoc.perl.org/perl, 2021-06-24, perldoc.perl.org, Perl’s syntax reflects the idea that “things that are different should look different.“JOURNAL,www.linuxjournal.com/article/2070, Wherefore Art, Thou?, 2011-03-13, Wall, Larry, 1997-03-01, Linux Journal, December 9, 2010,www.linuxjournal.com/article/2070," title="web.archive.org/web/20101209021107www.linuxjournal.com/article/2070,">web.archive.org/web/20101209021107www.linuxjournal.com/article/2070, live, 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.There is a broad practical bent to both the Perl language and the community and culture that surround it. The preface to Programming Perl begins: “Perl is a language for getting your job done.” One consequence of this is that Perl is not a tidy language. It includes many features, tolerates exceptions to its rules, and employs heuristics to resolve syntactical ambiguities. Because of the forgiving nature of the compiler, bugs can sometimes be hard to find. Perl’s function documentation remarks on the variant behavior of built-in functions in list and scalar contexts by saying, “In general, they do what you want, unless you want consistency.“WEB,perldoc.perl.org/perlfunc.html, perlfunc - Perl builtin functions, 2011-01-10, Perl 5 version 12.2 documentation, perldoc.perl.org, January 6, 2011,perldoc.perl.org/perlfunc.html," title="web.archive.org/web/20110106003034perldoc.perl.org/perlfunc.html,">web.archive.org/web/20110106003034perldoc.perl.org/perlfunc.html, live,Features
The overall structure of Perl derives broadly from C. Perl is procedural in nature, with variables, expressions, assignment statements, brace-delimited blocks, control structures, and subroutines.BOOK, Nagpal, D.P., Web Design Technology, S. Chand, 2010, 978-8121927635, India, 700, English, Perl also takes features from shell programming. All variables are marked with leading sigils, which allow variables to be interpolated directly into strings. However, unlike the shell, Perl uses sigils on all accesses to variables, and unlike most other programming languages that use sigils, the sigil doesn’t denote the type of the variable but the type of the expression. So for example, while an array is denoted by the sigil “@” (for example @arrayname), an individual member of the array is denoted by the scalar sigil “$” (for example $arrayname[3]). Perl also has many built-in functions that provide tools often used in shell programming (although many of these tools are implemented by programs external to the shell) such as sorting, and calling operating system facilities.{{cn|date=December 2020}}Perl takes hashes (“associative arrays“) from AWK and regular expressions from sed. These simplify many parsing, text-handling, and data-management tasks. Shared with Lisp is the implicit return of the last value in a block, and all statements are also expressions which can be used in larger expressions themselves.{{cn|date=December 2020}}Perl 5 added features that support complex data structures, first-class functions (that is, closures as values), and an object-oriented programming model. These include references, packages, class-based method dispatch, and lexically scoped variables, along with compiler directives (for example, the strict pragma). A major additional feature introduced with Perl 5 was the ability to package code as reusable modules. Wall later stated that “The whole intent of Perl 5’s module system was to encourage the growth of Perl culture rather than the Perl core.“NEWSGROUP, title unknown, 1997-05-10, 199705101952.MAA00756@wall.org, {{Dead link|date=November 2014}}All versions of Perl do automatic data-typing and automatic memory management. The interpreter knows the type and storage requirements of every data object in the program; it allocates and frees storage for them as necessary using reference counting (so it cannot deallocate circular data structures without manual intervention). Legal type conversions — for example, conversions from number to string — are done automatically at run time; illegal type conversions are fatal errors.{{cn|date=December 2020}}Syntax
Perl has been referred to as “(wikt:line noise|line noise)” and a write-only language by its critics. The earliest such mention was in the first edition of the book Learning Perl, a Perl 4 tutorial book written by Randal L. Schwartz,JOURNAL, Developer Update, 2, Dr. Dobb’s Developer Update, Miller-Freeman, 1995, in the first chapter of which he states: “Yes, sometimes Perl looks like line noise to the uninitiated, but to the seasoned Perl programmer, it looks like checksummed line noise with a mission in life.“BOOK, Learning Perl, Schwartz, Randal L., Randal L. Schwartz, O’Reilly & Associates, 1993, Learning Perl, 1993lepe.book.....S, He also stated that the accusation that Perl is a write-only language could be avoided by coding with “proper care”. The Perl overview document {{Proper name|perlintro}} states that the names of built-in “magic” scalar variables “look like punctuation or line noise”.WEB,perldoc.perl.org/perlintro.html, perlintro, Perl 5 version 18.0 documentation, Perl 5 Porters and perldoc.perl.org, 2013-06-30,perldoc.perl.org/perlintro.html," title="web.archive.org/web/20110109121845perldoc.perl.org/perlintro.html,">web.archive.org/web/20110109121845perldoc.perl.org/perlintro.html, January 9, 2011, dead, However, the English module provides both long and short English alternatives. {{Proper name|perlstyle}} document states that line noise in regular expressions could be mitigated using the /x modifier to add whitespace.WEB,perldoc.perl.org/perlstyle.html, perlstyle, Perl 5 version 18.0 documentation, Perl 5 Porters and perldoc.perl.org, 2013-06-30,perldoc.perl.org/perlstyle.html," title="web.archive.org/web/20130626010707perldoc.perl.org/perlstyle.html,">web.archive.org/web/20130626010707perldoc.perl.org/perlstyle.html, June 26, 2013, dead, According to the Perl 6 FAQ, Perl 6 was designed to mitigate “the usual suspects” that elicit the “line noise” claim from Perl 5 critics, including the removal of “the majority of the punctuation variables” and the sanitization of the regex syntax.WEB,www.perl6.org/archive/faq.html, Perl 6 FAQ, Perl 6 Project, 2013-06-30, July 1, 2013,www.perl6.org/archive/faq.html," title="web.archive.org/web/20130701183900www.perl6.org/archive/faq.html,">web.archive.org/web/20130701183900www.perl6.org/archive/faq.html, dead, The Perl 6 FAQ also states that what is sometimes referred to as Perl’s line noise is “the actual syntax of the language” just as gerunds and prepositions are a part of the English language. In a December 2012 blog posting, despite claiming that “Rakudo Perl 6 has failed and will continue to fail unless it gets some adult supervision”, chromatic stated that the design of Perl 6 has a “well-defined grammar” as well as an “improved type system, a unified object system with an intelligent metamodel, metaoperators, and a clearer system of context that provides for such niceties as pervasive laziness”.WEB,www.modernperlbooks.com/mt/2012/12/the-implementation-of-perl-5-versus-perl-6.html, The Implementation of Perl 5 versus Perl 6, chromatic, chromatic (programmer), 2012-12-31, 2013-06-30, July 29, 2013,www.modernperlbooks.com/mt/2012/12/the-implementation-of-perl-5-versus-perl-6.html," title="web.archive.org/web/20130729214209www.modernperlbooks.com/mt/2012/12/the-implementation-of-perl-5-versus-perl-6.html,">web.archive.org/web/20130729214209www.modernperlbooks.com/mt/2012/12/the-implementation-of-perl-5-versus-perl-6.html, live, He also stated that “Perl 6 has a coherence and a consistency that Perl 5 lacks.“In Perl, one could write the “Hello, World!” program as:print “Hello, World!n”;Here is a more complex Perl program, that counts down seconds from a given starting value:- !/usr/bin/perl
printf ( “Remaining %s/%s r”, $remaining--, $total );
sleep 1;
}print “n”;The Perl interpreter can also be used for one-off scripts on the command line. The following example (as invoked from an sh-compatible shell, such as Bash) translates the string “Bob” in all files ending with .txt in the current directory to “Robert”:$ perl -i.bak -lp -e ‘s/Bob/Robert/g’ *.txtsleep 1;
Implementation
No written specification or standard for the Perl language exists for Perl versions through Perl 5, and there are no plans to create one for the current version of Perl. There has been only one implementation of the interpreter, and the language has evolved along with it. That interpreter, together with its functional tests, stands as a de facto specification of the language. Perl 6, however, started with a specification,WEB,www.perl6.org/specification, Perl 6 Specification, 2011-01-27, The Perl 6 Project, December 2, 2009,www.perl6.org/specification/," title="web.archive.org/web/20091202073507www.perl6.org/specification/,">web.archive.org/web/20091202073507www.perl6.org/specification/, live, and several projectsWEB,www.perl6.org/compilers/, Perl 6 Compilers, 2011-01-27, The Perl 6 Project, December 2, 2009,www.perl6.org/compilers/," title="web.archive.org/web/20091202073302www.perl6.org/compilers/,">web.archive.org/web/20091202073302www.perl6.org/compilers/, live, aim to implement some or all of the specification.{{cn|date=December 2020}}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 interpreter is 150,000 lines of C code and compiles to a 1 MB executable on typical machine architectures. Alternatively, the interpreter can be compiled to a link library and embedded in other programs. There are nearly 500 modules in the distribution, comprising 200,000 lines of Perl and an additional 350,000 lines of C code (much of the C code in the modules consists of character encoding tables).{{cn|date=December 2020}}The interpreter has an object-oriented architecture. All of the elements of the Perl language—scalars, arrays, hashes, coderefs, file handles—are represented in the interpreter by C structs. Operations on these structs are defined by a large collection of macros, typedefs, and functions; these constitute the Perl C API. The Perl API can be bewildering to the uninitiated, but its entry points follow a consistent naming scheme, which provides guidance to those who use it.{{cn|date=December 2020}}The life of a Perl interpreter divides broadly into a compile phase and a run phase.A description of the Perl 5 interpreter can be found in Programming Perl, 3rd Ed., chapter 18. See particularly page 467, which carefully distinguishes run phase and compile phase from run time and compile time. Perl “time” and “phase” are often confused. In Perl, the phases are the major stages in the interpreter’s life-cycle. Each interpreter goes through each phase only once, and the phases follow in a fixed sequence.{{cn|date=December 2020}}Most of what happens in Perl’s compile phase is compilation, and most of what happens in Perl’s run phase is execution, but there are significant exceptions. Perl makes important use of its capability to execute Perl code during the compile phase. Perl will also delay compilation into the run phase. The terms that indicate the kind of processing that is actually occurring at any moment are compile time and run time. Perl is in compile time at most points during the compile phase, but compile time may also be entered during the run phase. The compile time for code in a string argument passed to the eval built-in occurs during the run phase. Perl is often in run time during the compile phase and spends most of the run phase in run time. Code in BEGIN blocks executes at run time but in the compile phase.At compile time, the interpreter parses Perl code into a syntax tree. At run time, it executes the program by walking the tree. Text is parsed only once, and the syntax tree is subject to optimization before it is executed, so that execution is relatively efficient. Compile-time optimizations on the syntax tree include constant folding and context propagation, but peephole optimization is also performed.WEB, perlguts - Introduction to the Perl API - Perldoc Browser,perldoc.perl.org/perlguts#Compile-pass-3:-peephole-optimization, 2022-01-24, perldoc.perl.org, Perl has a Turing-complete grammar because parsing can be affected by run-time code executed during the compile phase.WEB, Schwartz, Randal, Randal L. Schwartz, On Parsing Perl,www.perlmonks.org/index.pl?node_id=44722, 2007-01-03, September 27, 2007,www.perlmonks.org/index.pl?node_id=44722," title="web.archive.org/web/20070927000827www.perlmonks.org/index.pl?node_id=44722,">web.archive.org/web/20070927000827www.perlmonks.org/index.pl?node_id=44722, live, Therefore, Perl cannot be parsed by a straight Lex/Yacc lexer/parser combination. Instead, the interpreter implements its own lexer, which coordinates with a modified GNU bison parser to resolve ambiguities in the language.{{cn|date=December 2020}}It is often said that “Only perl can parse Perl”,WEB,ftp.ora.com/pub/labs/tpj/tpj2.pdf, The Perl Journal #19/9.26, 2011-02-04, O’Reilly Media, meaning that only the Perl interpreter (perl) can parse the Perl language (Perl), but even this is not, in general, true. Because the Perl interpreter can simulate a Turing machine during its compile phase, it would need to decide the halting problem in order to complete parsing in every case. It is a longstanding 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.WEB,blogs.perl.org/users/jeffrey_kegler/2011/10/perl-and-parsing-11-are-all-perl-programs-parseable.html
, Perl and Parsing 11: Are all Perl programs parseable?, Kegler, Jeffrey, October 7, 2011, October 25, 2022
, ... we seem to be giving up absolutely nothing. Nobody has ever been able to show a practical downside,
Other programs that undertake to parse Perl, such as source-code analyzers and auto-indenters, have to contend not only with ambiguous syntactic constructs but also with the undecidability of Perl parsing in the general case. Adam Kennedy’s PPI project focused on parsing Perl code as a document (retaining its integrity as a document), instead of parsing Perl as executable code (that not even Perl itself can always do). It was Kennedy who first conjectured that “parsing Perl suffers from the ‘halting problem’,“WEB,metacpan.org/module/PPI, PPI—Parse, Analyze and Manipulate Perl (without perl), Kennedy, Adam, 2006, CPAN, September 16, 2013, September 3, 2013,web.archive.org/web/20130903091241/https://metacpan.org/module/PPI, live, which was later proved.JOURNAL, Rice’s Theorem, The Perl Review, 4, 3, 23–29, Summer 2008, and JOURNAL, Perl is Undecidable, The Perl Review, 5, 7–11, Fall 2008, , available online at WEB,www.jeffreykegler.com/Home/perl-and-undecidability, Perl and Undecidability, Kegler, Jeffrey, January 4, 2009, August 17, 2009,www.jeffreykegler.com/Home/perl-and-undecidability," title="web.archive.org/web/20090817183115www.jeffreykegler.com/Home/perl-and-undecidability,">web.archive.org/web/20090817183115www.jeffreykegler.com/Home/perl-and-undecidability, live, Perl is distributed with over 250,000 functional tests for core Perl language and over 250,000 functional tests for core modules. These run as part of the normal build process and extensively exercise the interpreter and its core modules. Perl developers rely on the functional tests to ensure that changes to the interpreter do not introduce software bugs; additionally, Perl users who see that the interpreter passes its functional tests on their system can have a high degree of confidence that it is working properly.{{cn|date=December 2020}}, Perl and Parsing 11: Are all Perl programs parseable?, Kegler, Jeffrey, October 7, 2011, October 25, 2022
, ... we seem to be giving up absolutely nothing. Nobody has ever been able to show a practical downside,
Ports
Perl is dual licensed under both the Artistic License 1.0WEB,dev.perl.org/licenses/artistic.html, The “Artistic License” - dev.perl.org, dev.perl.org, June 24, 2016, July 24, 2018,dev.perl.org/licenses/artistic.html," title="web.archive.org/web/20180724213601dev.perl.org/licenses/artistic.html,">web.archive.org/web/20180724213601dev.perl.org/licenses/artistic.html, live, Artistic {{Webarchive|url=https://web.archive.org/web/20180725033309perl5.git.perl.org/perl.git/blob/HEAD:/Artistic |date=July 25, 2018 }} - file on the Perl 5 git repository and the GNU General Public License.WEB,dev.perl.org/licenses, Perl Licensing, 2011-01-08, dev.perl.org, January 22, 2011,dev.perl.org/licenses/," title="web.archive.org/web/20110122175123dev.perl.org/licenses/,">web.archive.org/web/20110122175123dev.perl.org/licenses/, live, Distributions are available for most operating systems. It is particularly prevalent on Unix and Unix-like systems, but it has been ported to most modern (and many obsolete) platforms. With only six{{citation needed|date=November 2017}} reported exceptions, Perl can be compiled from source code on all POSIX-compliant, or otherwise-Unix-compatible, platforms.WEB,www.cpan.org/ports/, Perl Ports (Binary Distributions), CPAN.org, Hietaniemi, Jarkko, 1998, April 16, 2006, April 18, 2006,www.cpan.org/ports/," title="web.archive.org/web/20060418115903www.cpan.org/ports/,">web.archive.org/web/20060418115903www.cpan.org/ports/, live, Because of unusual changes required for the classic Mac OS environment, a special port called MacPerl was shipped independently.WEB,www.macperl.com/, The MacPerl Pages, 1997, Prime Time Freeware, January 18, 2006, January 18, 2006,www.macperl.com/," title="web.archive.org/web/20060118125208www.macperl.com/,">web.archive.org/web/20060118125208www.macperl.com/, live, The Comprehensive Perl Archive Network carries a complete list of supported platforms with links to the distributions available on each.WEB,www.cpan.org/ports/, Perl Ports (Binary Distributions), 2011-01-27, CPAN, April 18, 2006,www.cpan.org/ports/," title="web.archive.org/web/20060418115903www.cpan.org/ports/,">web.archive.org/web/20060418115903www.cpan.org/ports/, live, CPAN is also the source for publicly available Perl modules that are not part of the core Perl distribution.{{cn|date=December 2020}}ActivePerl is a closed-source distribution from ActiveState that has regular releases that track the core Perl releases.WEB,www.activestate.com/activeperl, ActivePerl is Perl for Windows, Mac, Linux, AIX, HP-UX & Solaris, 2011-01-09, ActiveState, ActiveState Software,www.activestate.com/activeperl," title="web.archive.org/web/20160331201814www.activestate.com/activeperl,">web.archive.org/web/20160331201814www.activestate.com/activeperl, March 31, 2016, dead, The distribution previously included the Perl package manager (PPM),WEB,docs.activestate.com/activeperl/5.12/faq/ActivePerl-faq2.html, Using PPM, 2011-01-09, ActiveState, ActiveState Software, August 27, 2010,docs.activestate.com/activeperl/5.12/faq/ActivePerl-faq2.html," title="web.archive.org/web/20100827110749docs.activestate.com/activeperl/5.12/faq/ActivePerl-faq2.html,">web.archive.org/web/20100827110749docs.activestate.com/activeperl/5.12/faq/ActivePerl-faq2.html, live, a popular tool for installing, removing, upgrading, and managing the use of common Perl modules; however, this tool was discontinued as of ActivePerl 5.28.WEB,www.activestate.com/blog/goodbye-ppm-hello-state-tool/, Goodbye PPM, Hello State Tool, activestate.com, July 23, 2019, April 16, 2020, July 28, 2020,web.archive.org/web/20200728080612/https://www.activestate.com/blog/goodbye-ppm-hello-state-tool/, live, Included also is PerlScript, a Windows Script Host (WSH) engine implementing the Perl language. Visual Perl is an ActiveState tool that adds Perl to the Visual Studio .NET development suite. A VBScript-to-Perl converter, as well as a Perl compiler for Windows, and converters of awk and sed to Perl have also been produced by this company and included on the ActiveState CD for Windows, which includes all of their distributions plus the Komodo IDE and all but the first on the Unix/Linux/Posix variant thereof in 2002 and subsequently.readme.txtPerformance
The Computer Language Benchmarks Game compares the performance of implementations of typical programming problems in several programming languages.WEB,alioth.debian.org/projects/benchmarksgame/, Alioth: The Computer Language Benchmarks Game: Project Info, 2011-01-13, Alioth,web.archive.org/web/20130325192723/https://alioth.debian.org/projects/benchmarksgame/, March 25, 2013, dead, mdy-all, The submitted Perl implementations typically perform toward the high end of the memory-usage spectrum and give varied speed results. Perl’s performance in the benchmarks game is typical for interpreted languages.WEB,benchmarksgame.alioth.debian.org/u32/which-programs-are-fastest.php?v8=on&lua=on&jruby=on&php=on&python3=on&yarv=on&perl=on,benchmarksgame.alioth.debian.org/u32/which-programs-are-fastest.php?v8=on&lua=on&jruby=on&php=on&python3=on&yarv=on&perl=on," title="web.archive.org/web/20130517145336benchmarksgame.alioth.debian.org/u32/which-programs-are-fastest.php?v8=on&lua=on&jruby=on&php=on&python3=on&yarv=on&perl=on,">web.archive.org/web/20130517145336benchmarksgame.alioth.debian.org/u32/which-programs-are-fastest.php?v8=on&lua=on&jruby=on&php=on&python3=on&yarv=on&perl=on, dead, 2013-05-17, Which programs are fastest?, 2011-01-13, Computer Language Benchmarks Game, Alioth, 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 (Yet Another Perl Conference|YAPC::Europe 2005) conference and subsequent article “A Timely Start”, Jean-Louis Leroy found that his Perl programs took much longer to run than expected because the perl interpreter spent significant time finding modules within his over-large include path.WEB,www.perl.com/pub/a/2005/12/21/a_timely_start.html, A Timely Start, Leroy, Jean-Louis, 2005-12-01, O’Reilly, May 22, 2006, June 13, 2006,www.perl.com/pub/a/2005/12/21/a_timely_start.html," title="web.archive.org/web/20060613025623www.perl.com/pub/a/2005/12/21/a_timely_start.html,">web.archive.org/web/20060613025623www.perl.com/pub/a/2005/12/21/a_timely_start.html, live, Unlike Java, Python, and Ruby, Perl has only experimental support for pre-compiling.WEB,metacpan.org/module/NWCLARK/perl-5.8.8/ext/B/B/Bytecode.pm#KNOWN-BUGS, B::Bytecode Perl compiler’s bytecode backend, Beattie, Malcolm, Enache Adrian, amp, 2003, CPAN, September 16, 2013, March 30, 2021,web.archive.org/web/20210330011632/https://metacpan.org/pod/release/NWCLARK/perl-5.8.8/ext/B/B/Bytecode.pm#KNOWN-BUGS, dead, Therefore, Perl programs pay this overhead penalty on every execution. The run phase of typical programs is long enough that amortized startup time is not substantial, but benchmarks that measure very short execution times are likely to be skewed due to this overhead.BOOK, Schwartz, Randal,books.google.com/books?id=va1PSgaO4xIC&q=Therefore,+Perl+programs+pay+this+overhead+penalty+on+every+execution.+The+run+phase+of+typical+programs+is+long+enough+that+amortized+startup+time+is+not+substantial,+but+benchmarks+that+measure+very+short+execution+times+are+likely+to+be+skewed+due+to+this+overhead., Learning Perl, foy, brian, Phoenix, Tom, 2011-06-23, “O’Reilly Media, Inc.”, 978-1-4493-0358-7, en, A number of tools have been introduced to improve this situation. The first such tool was Apache’s mod_perl, which sought to address one of the most-common reasons that small Perl programs were invoked rapidly: CGI Web development. ActivePerl, via Microsoft ISAPI, provides similar performance improvements.BOOK, Stein, Lincoln,books.google.com/books?id=qyzTI_eAeHUC&q=A+number+of+tools+have+been+introduced+to+improve+this+situation.+The+first+such+tool+was+Apache’s+mod+perl,+which+sought+to+address+one+of+the+most-common+reasons+that+small+Perl+programs+were+invoked+rapidly:+CGI+Web+development.+ActivePerl,+via+Microsoft+ISAPI,+provides+similar+performance+improvements., Writing Apache Modules with Perl and C: The Apache API and Mod_perl, MacEachern, Doug, 1999, “O’Reilly Media, Inc.”, 978-1-56592-567-0, en, Once Perl code is compiled, there is additional overhead during the execution phase that typically isn’t present for programs written in compiled languages such as C or C++. Examples of such overhead include bytecode interpretation, reference-counting memory management, and dynamic type-checking.BOOK, Bekman, Stas,books.google.com/books?id=UDabAgAAQBAJ&q=Once+Perl+code+is+compiled,+there+is+additional+overhead+during+the+execution+phase+that+typically+isn’t+present+for+programs+written+in+compiled+languages+such+as+C+or+C++.+Examples+of+such+overhead+include+bytecode+interpretation,+reference-counting+memory+management,+and+dynamic+type-checking., Practical Mod_perl, Cholet, Eric, 2003, “O’Reilly Media, Inc.”, 978-0-596-00227-5, en, The most critical routines can be written in other languages (such as C), which can be connected to Perl via simple Inline modules or the more complex, but flexible, XS mechanism.WEB,metacpan.org/module/Inline, Inline - metacpan.org, 2011-01-26, Ingerson, Brian, CPAN, dead,web.archive.org/web/20130613163723/https://metacpan.org/module/Inline, June 13, 2013,Applications
Perl has many and varied applications, compounded by the availability of many standard and third-party modules.Perl has chiefly been used to write CGI scripts: large projects written in Perl include cPanel, Slash, Bugzilla, RT, TWiki, and Movable Type; high-traffic websites that use Perl extensively include Priceline.com, Craigslist,BOOK, Gilmore, W. J., Beginning PHP and MySQL: From Novice to Professional, Fourth Edition, 2010,archive.org/details/beginningphpmysq00gilm_240, limited, Apress, 484, 978-1-4302-3114-1, IMDb,WEB, IMDb Helpdesk: What software/hardware are you using to run the site?, Internet Movie Database,www.imdb.com/help/search?domain=helpdesk_faq&index=1&file=techinfo, 2011-02-12, March 9, 2017,www.imdb.com/help/search?domain=helpdesk_faq&index=1&file=techinfo," title="web.archive.org/web/20170309083513www.imdb.com/help/search?domain=helpdesk_faq&index=1&file=techinfo,">web.archive.org/web/20170309083513www.imdb.com/help/search?domain=helpdesk_faq&index=1&file=techinfo, live, LiveJournal, DuckDuckGo,DuckDuckGo handles a large amount of search queries at 4.5 million queries per day .duckduckgo.com/traffic.html {{Webarchive|url=http://webarchive.loc.gov/all/20120215210604duckduckgo.com/traffic.html |date=February 15, 2012 }}DuckDuckGo uses Perlwww.gabrielweinberg.com/blog/2009/03/duck-duck-go-architecture.html" title="web.archive.org/web/20101231135106www.gabrielweinberg.com/blog/2009/03/duck-duck-go-architecture.html">web.archive.org/web/20101231135106www.gabrielweinberg.com/blog/2009/03/duck-duck-go-architecture.html Slashdot and Ticketmaster. It is also an optional component of the popular LAMP technology stack for Web development, in lieu of PHP or Python. Perl is used extensively as a system programming language in the Debian Linux distribution.WEB,wiki.debian.org/PerlFAQ, Perl FAQ, Perl is used quite extensively in Debian. Not only are some core functions written in Perl, but there are over 700 packages in unstable that have perl in their name (Mar 2004)., August 6, 2019, August 6, 2019,web.archive.org/web/20190806111259/https://wiki.debian.org/PerlFAQ, live, Perl is often used as a glue language, tying together systems and interfaces that were not specifically designed to interoperate, and for “data munging”,WEB,books.perl.org/book/95, Perl Books - Book: Data Munging with Perl, Perl.org, December 30, 2010, September 7, 2011,books.perl.org/book/95," title="web.archive.org/web/20110907020511books.perl.org/book/95,">web.archive.org/web/20110907020511books.perl.org/book/95, live, that is, converting or processing large amounts of data for tasks such as creating reports. In fact, these strengths are intimately linked. The combination makes Perl a popular all-purpose language for system administrators, particularly because short programs, often called “one-liner programs”, can be entered and run on a single command line.{{cn|date=December 2020}}Perl code can be made portable across Windows and Unix; such code is often used by suppliers of software (both COTS and bespoke) to simplify packaging and maintenance of software build- and deployment-scripts.{{cn|date=December 2020}}Perl/Tk and wxPerl are commonly used to add graphical user interfaces to Perl scripts.Perl’s text-handling capabilities can be used for generating SQL queries; arrays, hashes, and automatic memory management make it easy to collect and process the returned data. For example, in Tim Bunce’s Perl DBI application programming interface (API), the arguments to the API can be the text of SQL queries; thus it is possible to program in multiple languages at the same time (e.g., for generating a Web page using HTML, JavaScript, and SQL in a here document). The use of Perl variable interpolation to programmatically customize each of the SQL queries, and the specification of Perl arrays or hashes as the structures to programmatically hold the resulting data sets from each SQL query, allows a high-level mechanism for handling large amounts of data for post-processing by a Perl subprogram.BOOK, Descartes, Alligator, Programming the Perl DBI : [database programming with Perl], 2000, O’Reilly, Beijing [u.a.], 978-1-56592-699-8, 1, Bunce, Tim,archive.org/details/programmingperld00desc, In early versions of Perl, database interfaces were created by relinking the interpreter with a client-side database library. This was sufficiently difficult that it was done for only a few of the most-important and most widely used databases, and it restricted the resulting perl executable to using just one database interface at a time.WEB, Perl Programming - Principles of Programming Languages,sites.google.com/a/principlesofprogram.com/www/perl, 2021-05-18, sites.google.com, October 8, 2020,web.archive.org/web/20201008130113/https://sites.google.com/a/principlesofprogram.com/www/perl, dead, In Perl 5, database interfaces are implemented by Perl DBI modules. The DBI (Database Interface) module presents a single, database-independent interface to Perl applications, while the DBD (Database Driver) modules handle the details of accessing some 50 different databases; there are DBD drivers for most ANSI SQL databases.BOOK, Bunce, Tim,books.google.com/books?id=WfoOrfuwcb8C&q=The+DBI+(Database+Interface)+module+presents+a+single,+database-independent+interface+to+Perl+applications,+while+the+DBD+(Database+Driver)+modules+handle+the+details+of+accessing+some+50+different+databases;+there+are+DBD+drivers+for+most+ANSI+SQL+databases, Programming the Perl DBI: Database programming with Perl, Descartes, Alligator, 2000-02-04, “O’Reilly Media, Inc.”, 978-1-4493-1536-8, en, DBI provides caching for database handles and queries, which can greatly improve performance in long-lived execution environments such as mod_perl,WEB, Bekman, Stas, Efficient Work with Databases under mod_perl,perl.apache.org/docs/1.0/guide/performance.html#Efficient_Work_with_Databases_under_mod_perl, 2007-09-01, August 22, 2007,perl.apache.org/docs/1.0/guide/performance.html#Efficient_Work_with_Databases_under_mod_perl," title="web.archive.org/web/20070822162513perl.apache.org/docs/1.0/guide/performance.html#Efficient_Work_with_Databases_under_mod_perl,">web.archive.org/web/20070822162513perl.apache.org/docs/1.0/guide/performance.html#Efficient_Work_with_Databases_under_mod_perl, live, helping high-volume systems avert load spikes as in the Slashdot effect.BOOK, Pachev, Sasha,books.google.com/books?id=vz6PcTdo8VUC&q=DBI+provides+caching+for+database+handles+and+queries,+which+can+greatly+improve+performance+in+long-lived+execution+environments+such+as+mod+perl,%5B100%5D+helping+high-volume+systems+avert+load+spikes+as+in+the+Slashdot+effect, Understanding MySQL Internals: Discovering and Improving a Great Database, 2007-04-10, “O’Reilly Media, Inc.”, 978-0-596-55280-0, en, In modern Perl applications, especially those written using web frameworks such as Catalyst, the DBI module is often used indirectly via object-relational mappers such as (DBIx::Class), Class::DBIWEB,metacpan.org/pod/Class::DBI, Class::DBI - Simple Database Abstraction - metacpan.org, metacpan.org, 2020-04-08, August 6, 2020,web.archive.org/web/20200806100410/https://metacpan.org/pod/Class::DBI, live, or Rose::DB::ObjectWEB,metacpan.org/pod/Rose::DB::Object, Rose::DB::Object - Extensible, high performance object-relational mapper (ORM). - metacpan.org, metacpan.org, 2020-04-08, August 6, 2020,web.archive.org/web/20200806085143/https://metacpan.org/pod/Rose::DB::Object, live, that generate SQL queries and handle data transparently to the application author.WEB, T sql querying developer reference,pdfpremiumfree.com/download/t-sql-querying-developer-reference-pdf/, 2021-05-18, pdfpremiumfree.com, en,Community
Perl’s culture and community has developed alongside the language itself. Usenet was the first public venue in which Perl was introduced, but over the course of its evolution, Perl’s community was shaped by the growth of broadening Internet-based services including the introduction of the World Wide Web. The community that surrounds Perl was, in fact, the topic of Wall’s first “State of the Onion” talk.WEB,grnlight.net/index.php/programming-articles/100-perl-culture, Perl Culture (AKA the first State of the Onion), Larry, Wall, Larry Wall, 2014-05-22, May 22, 2014, May 22, 2014,grnlight.net/index.php/programming-articles/100-perl-culture," title="web.archive.org/web/20140522141559grnlight.net/index.php/programming-articles/100-perl-culture,">web.archive.org/web/20140522141559grnlight.net/index.php/programming-articles/100-perl-culture, live, State of the Onion is the name for Wall’s yearly keynote-style summaries on the progress of Perl and its community. They are characterized by his hallmark humor, employing references to Perl’s culture, the wider hacker culture, Wall’s linguistic background, sometimes his family life, and occasionally even his Christian background.WEB, 2nd State of the Onion, Larry Wall,www.wall.org/~larry/onion/onion.html, 2012-10-12, July 17, 2012,www.wall.org/~larry/onion/onion.html," title="web.archive.org/web/20120717014443www.wall.org/~larry/onion/onion.html,">web.archive.org/web/20120717014443www.wall.org/~larry/onion/onion.html, live, (Search for ‘church’) Each talk is first given at various Perl conferences and is eventually also published online.In email, Usenet, and message board postings, “Just another Perl hacker” (JAPH) programs are a common trend, originated by Randal L. Schwartz, one of the earliest professional Perl trainers.NEWSGROUP, Randal L. Schwartz, Who is Just another Perl hacker?, m1hfpvh2jq.fsf@halfdome.holdit.com, comp.lang.perl.misc, 1999-05-02,groups.google.com/forum/#!msg/comp.lang.perl.misc/nK-lswsaMec/DBL87v4FxOwJ, December 5, 2014, July 8, 2012,groups.google.com/group/comp.sys.acorn.programmer/browse_thread/thread/b5fd3717bda6a8d0/d4d3e151a783dffa?lnk=gst&q=ioc%23d4d3e151a783dffa#!msg/comp.lang.perl.misc/nK-lswsaMec/DBL87v4FxOwJ," title="archive.today/20120708165748groups.google.com/group/comp.sys.acorn.programmer/browse_thread/thread/b5fd3717bda6a8d0/d4d3e151a783dffa?lnk=gst&q=ioc%23d4d3e151a783dffa#!msg/comp.lang.perl.misc/nK-lswsaMec/DBL87v4FxOwJ,">archive.today/20120708165748groups.google.com/group/comp.sys.acorn.programmer/browse_thread/thread/b5fd3717bda6a8d0/d4d3e151a783dffa?lnk=gst&q=ioc%23d4d3e151a783dffa#!msg/comp.lang.perl.misc/nK-lswsaMec/DBL87v4FxOwJ, live, In the parlance of Perl culture, Perl programmers are known as Perl hackers, and from this derives the practice of writing short programs to print out the phrase “Just another Perl hacker”. In the spirit of the original concept, these programs are moderately obfuscated and short enough to fit into the signature of an email or Usenet message. The “canonical” JAPH as developed by Schwartz includes the comma at the end, although this is often omitted.WEB,www.perlmonks.org/bare/?node_id=443856, Canonical JAPH, 2011-05-16, Schwartz, Randal, Randal L. Schwartz, 2005-03-31, PerlMonks, July 22, 2011,www.perlmonks.org/bare/?node_id=443856," title="web.archive.org/web/20110722055125www.perlmonks.org/bare/?node_id=443856,">web.archive.org/web/20110722055125www.perlmonks.org/bare/?node_id=443856, live, {{Anchor|Perl golf}}Perl “golf” is the pastime of reducing the number of characters (key “strokes“) used in a Perl program to the bare minimum, much in the same way that golf players seek to take as few shots as possible in a round. The phrase’s first useNEWSGROUP, Greg Bacon, Re: Incrementing a value in a slice, 7imnti$mjh$1@info2.uah.edu, comp.lang.perl.misc, 1999-05-28,groups.google.com/group/comp.lang.perl.misc/msg/7b97c434492c8d20, 2011-07-12, July 7, 2011,groups.google.com/group/comp.lang.perl.misc/msg/7b97c434492c8d20," title="web.archive.org/web/20110707134412groups.google.com/group/comp.lang.perl.misc/msg/7b97c434492c8d20,">web.archive.org/web/20110707134412groups.google.com/group/comp.lang.perl.misc/msg/7b97c434492c8d20, live, emphasized the difference between pedestrian code meant to teach a newcomer and terse hacks likely to amuse experienced Perl programmers, an example of the latter being JAPHs that were already used in signatures in Usenet postings and elsewhere. Similar stunts had been an unnamed pastime in the language APL in previous decades. The use of Perl to write a program that performed RSA encryption prompted a widespread and practical interest in this pastime.WEB,www.cypherspace.org/rsa/pureperl.html, RSA in 5 lines of perl, 2011-01-10, Back, Adam, January 19, 2011,www.cypherspace.org/rsa/pureperl.html," title="web.archive.org/web/20110119154503www.cypherspace.org/rsa/pureperl.html,">web.archive.org/web/20110119154503www.cypherspace.org/rsa/pureperl.html, live, In subsequent years, the term “code golf” has been applied to the pastime in other languages.WEB,codegolf.com/, Code Golf: What is Code Golf?, 29degrees, 2007, November 26, 2018,codegolf.com/," title="web.archive.org/web/20120113152453codegolf.com/,">web.archive.org/web/20120113152453codegolf.com/, January 13, 2012, dead, mdy-all, A Perl Golf Apocalypse was held at Perl Conference 4.0 in Monterey, California in July 2000.As with C, obfuscated code competitions were a well known pastime in the late 1990s. The Obfuscated Perl Contest was a competition held by The Perl Journal from 1996 to 2000 that made an arch virtue of Perl’s syntactic flexibility. Awards were given for categories such as “most powerful“—programs that made efficient use of space—and “best four-line signature” for programs that fit into four lines of 76 characters in the style of a Usenet signature block.BOOK, Gallo, Felix, Games, diversions, and Perl culture: best of the Perl journal, The Zeroth Obfuscated Perl Contest, Jon Orwant, O’Reilly Media, 2003,oreilly.com/catalog/tpj3/chapter/ch43.pdf, 2011-01-12, dead,oreilly.com/catalog/tpj3/chapter/ch43.pdf," title="web.archive.org/web/20091122114544oreilly.com/catalog/tpj3/chapter/ch43.pdf,">web.archive.org/web/20091122114544oreilly.com/catalog/tpj3/chapter/ch43.pdf, November 22, 2009, mdy-all, Perl poetry is the practice of writing poems that can be compiled as legal Perl code, for example the piece known as Black Perl. Perl poetry is made possible by the large number of English words that are used in the Perl language. New poems are regularly submitted to the community at PerlMonks.WEB,www.perlmonks.org/?node_id=1590, Perl Poetry, 2011-01-27, PerlMonks, September 27, 2007,www.perlmonks.org/?node_id=1590," title="web.archive.org/web/20070927000904www.perlmonks.org/?node_id=1590,">web.archive.org/web/20070927000904www.perlmonks.org/?node_id=1590, live,See also
References
{{reflist}}Further reading
- Learning Perl 6th Edition (2011), O’Reilly. Beginner-level introduction to Perl.
- Beginning Perl 1st Edition (2012), Wrox. A beginner’s tutorial for those new to programming or just new to Perl.
- Modern Perl {{Webarchive|url=https://web.archive.org/web/20111222045417onyxneon.com/books/modern_perl/ |date=December 22, 2011 }} 2nd Edition (2012), Onyx Neon. Describes Modern Perl programming techniques.
- Programming Perl 4th Edition (2012), O’Reilly. The definitive Perl reference.
- Effective Perl Programming 2nd Edition (2010), Addison-Wesley. Intermediate- to advanced-level guide to writing idiomatic Perl.
- Perl Cookbook, {{ISBN|0-596-00313-7}}. Practical Perl programming examples.
- BOOK, Dominus, Mark Jason, Higher Order Perl,hop.perl.plover.com/book/, 2005, Morgan Kaufmann, 978-1-55860-701-9, Functional programming techniques in Perl.
External links
{{Sister project links|commons=Category:Perl (programming language)|v=Topic:Perl|n=no|q=Perl|s=no|b=Perl Programming}}- {{Official website}}
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