Perl was developed byLarry Wall in 1987[10] as a general-purposeUnixscripting language to make report processing easier.[11][10][12] Since then, it has undergone many changes and revisions. Perl originally was not capitalized and the name was changed to being capitalized by the time Perl 4 was released.[12] The latest release is Perl 5, first released in 1994. From 2000 to October 2019 a sixth version of Perl was in development; the sixth version's name was changed toRaku.[13][14] Both languages continue to be developed independently by different development teams which liberally borrow ideas from each other.
Perl borrows features from other programming languages includingC,sh,AWK, andsed.[1] It provides text processing facilities without the arbitrary data-length limits of many contemporaryUnix command line tools.[15] Perl is a highlyexpressive programming language: source code for a given algorithm can be short and highly compressible.[16][17]
Perl was originally named "Pearl". Wall wanted to give the language a short name with positive connotations. It is also a Christian reference to theParable of the Pearl from the Gospel of Matthew.[10][24] However, Wall discovered the existingPEARL language before Perl's official release and dropped the "a" from the name.[25][10]
The name is occasionally expanded as abackronym:Practical Extraction and Report Language[26] and Wall's ownPathologically Eclectic Rubbish Lister, which is in themanual page for perl.[27]
Programming Perl, published byO'Reilly Media, features a picture of adromedary camel on the cover and is commonly called the "Camel Book".[28] This image has become an unofficial symbol of Perl. O'Reilly owns the image as atrademark but licenses it fornon-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.[29] O'Reilly also provides "Programming Republic of Perl" logos for non-commercial sites and "Powered by Perl" buttons for any site that uses Perl.[29]
In 2024, a new camel logo for the language was published[32] under aCreative Commons license by a small group of developers. While not an official logo, it is intended to represent both the language and the community and draws on Perl's longtime association with the camel from the O'Reilly book.
Larry Wall began work on Perl in 1987, while employed as a programmer atUnisys;[15] he released version 1.0 on December 18, 1987.[1][10] Wall based earlyPerl on some methods existing languages used for text manipulation.[10]
Perl 2, released in June 1988,[33][34] featured a better regular expression engine. Perl 3, released in October 1989,[33] added support forbinary data streams.[35]
Originally, the only documentation for Perl was a single lengthyman page. In 1991,Programming Perl, known to many Perl programmers as the "Camel Book" because of its cover, was published and became thede facto reference for the language.[36] 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.[37] Perl 4 was released in March 1991.[33]
Perl 4 went through a series ofmaintenance 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. Theperl5-portersmailing 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.[38]
Perl 5.000 was released on October 17, 1994.[39] It was a nearly complete rewrite of theinterpreter, and it added many new features to the language, includingobjects,references,lexical (my) variables, andmodules. 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 makesubroutines that behaved like Perlbuiltins. Perl 5.003 was released June 25, 1996, as a security release.[40]
One of the most important events in Perl 5 history took place outside of the language proper and was a consequence of its module support. On October 26, 1995, theComprehensive Perl Archive Network (CPAN) was established as arepository for the Perl language andPerl modules; as of December 2022[update], 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.[41]
Perl 5.004 was released on May 15, 1997, and included, among other things, the UNIVERSAL package, giving Perl a base object from which allclasses were automatically derived and the ability to require versions of modules. Another significant development was the inclusion of theCGI.pm module,[42] which contributed to Perl's popularity as aCGI scripting language.[43]
Perl 5.005 was released on July 22, 1998. This release included several enhancements to theregex engine, new hooks into the backend through theB::* modules, theqr// regex quote operator, a large selection of other new core modules, and added support for several more operating systems, includingBeOS.[44]
Perl 5.6 was released on March 22, 2000. Major changes included64-bit support,Unicode string representation, support for files over 2 GiB, and the "our" keyword.[46][47] When developing Perl 5.6, the decision was made to switch theversioning 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.[48]
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,[49] work began on the "Apocalypses" for Perl 6, a series of documents meant to summarize the change requests and present the design of the next generation of Perl. They were presented as a digest of the RFCs, rather than a formal document. At this time, Perl 6 existed only as a description of a language.[citation needed]
Perl 5.8 was first released on July 18, 2002, and further 5.X versions have been released approximately yearly 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.[50] As of 2013, this version was still the most popular Perl version and was used byRed HatLinux 5,SUSE Linux 10,Solaris 10,HP-UX 11.31, andAIX 5.
In 2004, work began on the "Synopses" – documents that originally summarized the Apocalypses, but which became the specification for the Perl 6 language. In February 2005,Audrey Tang began work onPugs, a Perl 6 interpreter written inHaskell.[51] This was the first concerted effort toward making Perl 6 a reality. This effort stalled in 2006.[52]
The Perl On New Internal Engine (PONIE) project existed from 2003 until 2006. It was to be a bridge between Perl 5 and 6, and an effort to rewrite the Perl 5 interpreter to run on the Perl 6Parrot virtual machine. The goal was to ensure the future of the millions of lines of Perl 5 code at thousands of companies around the world.[53] The PONIE project ended in 2006 and is no longer being actively developed. Some of the improvements made to the Perl 5 interpreter as part of PONIE were folded into that project.[54]
On December 18, 2007, the 20th anniversary of Perl 1.0, Perl 5.10.0 was released. Perl 5.10.0 included notable new features, which brought it closer to Perl 6. These included aswitch statement (called "given"/"when"), regular expressions updates, and thesmart match operator (~~).[55][56]Around this same time, development began in earnest on another implementation of Perl 6 known asRakudo Perl, developed in tandem with theParrot virtual machine. As of November 2009, Rakudo Perl has had regular monthly releases and now is the most complete implementation of Perl 6.
A major change in the development process of Perl 5 occurred with Perl 5.11; the development community has switched to a monthly release cycle of development releases, with a yearly schedule of stable releases. By that plan, bugfix point releases will follow the stable releases every three months.[citation needed]
On April 12, 2010, Perl 5.12.0 was released. Notable core enhancements include newpackage NAME VERSION syntax, theyada yada operator (intended to mark placeholder code that is not yet implemented), implicit strictures, fullY2038 compliance, regex conversion overloading,DTrace support, andUnicode 5.2.[57]
On May 14, 2011, Perl 5.14 was released withJSON support built-in.[58]
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.[59][failed verification] Perl 5.16 also updates the core to supportUnicode 6.1.[59]
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.[60]
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, and a rand() function using a consistent random number generator.[61]
Some observers credit the release of Perl 5.10 with the start of the Modern Perl movement.[62] 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.[63] While the bookModern Perl[64] may be the most visible standard-bearer of this idea, other groups such as the Enlightened Perl Organization[65] have taken up the cause.
In late 2012 and 2013, several projects for alternative implementations for Perl 5 started: Perl5 inPerl6 by the Rakudo Perl team,[66]moe by Stevan Little and friends,[67]p2[68] by the Perl11 team under Reini Urban,gperl by goccy,[69] andrperl, a Kickstarter project led by Will Braswell and affiliated with the Perl11 project.[70]
At the 2000Perl Conference, Jon Orwant made a case for a major new language initiative.[72] 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 300RFCs.[73]
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" – numbered to correspond to chapters inProgramming Perl. As of January 2011[update], the developing specification of Perl 6 was encapsulated in design documents called Synopses – numbered to correspond to Apocalypses.[74]
Thesis work byBradley M. Kuhn, overseen by Wall, considered the possible use of theJava virtual machine as a runtime for Perl.[75] Kuhn's thesis showed this approach to be problematic. In 2001, it was decided that Perl 6 would run on a cross-languagevirtual machine calledParrot.
In 2005,Audrey Tang created thePugs project, an implementation of Perl 6 inHaskell. This acted 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 theLibera Chat #raku IRC channel. Manyfunctional programming influences were absorbed by the Perl 6 design team.[76]
In 2012, Perl 6 development was centered primarily on two compilers:[77]
Rakudo, an implementation running on the Parrot virtual machine and the Java virtual machine.[78]
As of 2017[update] only the Rakudo implementation and MoarVM are under active development, and other virtual machines, such as the Java Virtual Machine andJavaScript, are supported.[81]
In June 2020, Perl 7 was announced as the successor to Perl 5.[82] Perl 7 was to initially be based on Perl 5.32 with a release expected in first half of 2021, and release candidates sooner.[83]
This plan was revised in May 2021, without any release timeframe or version of Perl 5 for use as a baseline specified.[84] 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.[85]
Perl 7 was announced on 24 June 2020 at "The Perl Conference in the Cloud" as the successor to Perl 5.[83][82] Based on Perl 5.32, Perl 7 was planned to bebackward compatible with modern Perl 5 code; Perl 5 code, withoutboilerplate (pragma) header needs addinguse 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.[86]
According to Wall, Perl has two slogans. The first is "There's more than one way to do it," commonly known as TMTOWTDI, (pronouncedTim Toady). As proponents of this motto argue, this philosophy makes it easy to write concise statements.[87][88][89]
The second slogan is "Easy things should be easy and hard things should be possible".[15]
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 incompiler technology. Many earlier computer languages, such asFortran 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.[90]
Perl has many features that ease the task of the programmer at the expense of greaterCPU and memory requirements. These include automatic memory management;dynamic typing; strings, lists, and hashes; regular expressions;introspection; and aneval() function. Perl follows the theory of "no built-in limits",[28] an idea similar to theZero One Infinity rule.
Wall was trained as a linguist, and the design of Perl is very much informed bylinguistic principles. Examples includeHuffman coding (common constructions should be short), good end-weighting (the important information should come first), and a large collection oflanguage primitives. Perl favors language constructs that are concise and natural for humans to write, even where they complicate the Perl interpreter.[91]
Perl'ssyntax reflects the idea that "things that are different should look different."[92] 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 toProgramming Perl begins: "Perl is a language for getting your job done."[15] One consequence of this is that Perl is not a tidy language. It includes many features, tolerates exceptions to its rules, and employsheuristics 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."[93]
Perl also takes features from shell programming. All variables are marked with leadingsigils, which allow variables to beinterpolated directly intostrings. 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 assorting, and callingoperating system facilities.[citation needed]
Perl takeshashes ("associative arrays") fromAWK andregular expressions fromsed. These simplify many parsing, text-handling, and data-management tasks. Shared withLisp is the implicitreturn of the last value in a block, and all statements are also expressions which can be used in larger expressions themselves.[citation needed]
Perl 5 added features that support complexdata structures,first-class functions (that is,closures as values), and an object-oriented programming model. These includereferences, packages, class-basedmethod dispatch, andlexically scoped variables, along withcompiler directives (for example, thestrictpragma). 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."[95]
All versions of Perl do automaticdata-typing and automaticmemory management. The interpreter knows the type andstorage requirements of every data object in the program; it allocates and frees storage for them as necessary usingreference counting (so it cannot deallocatecircular data structures without manual intervention). Legaltype conversions – for example, conversions from number to string – are done automatically atrun time; illegal type conversions are fatal errors.[citation needed]
Perl has been referred to as "line noise" and a "write-only language" by its critics.Randal L. Schwartz in the first edition of the bookLearning Perl,[96] in the first chapter states: "Yes, sometimes Perl looks like line noise to the uninitiated, but to the seasoned Perl programmer, it looks likechecksummed line noise with a mission in life."[97] He also stated that the accusation that Perl is awrite-only language could be avoided by coding with "proper care".[97] The Perl overview documentperlintro states that the names of built-in "magic" scalarvariables "look like punctuation or line noise".[98] However, the English module provides both long and short English alternatives.perlstyle document states that line noise inregular expressions could be mitigated using the/x modifier to add whitespace.[99]
According to thePerl 6 FAQ,[100] 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. ThePerl 6 FAQ also states that what is sometimes referred to as Perl's line noise is "the actual syntax of the language" just asgerunds andprepositions are a part of theEnglish language.[100] 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", an "improved type system, a unified object system with an intelligentmetamodel, metaoperators, and a clearer system of context that provides for such niceties as pervasive laziness."[101] He also stated that "Perl 6 has a coherence and a consistency that Perl 5 lacks."[101]
To run the code above, store it in a file namedcounter.pl, and then execute it.
$perlcounter.pl42
The Perl interpreter can also be used forone-off scripts on thecommand line. The following example (as invoked from an sh-compatible shell, such asBash) translates the string "Bob" in all files ending with .txt in the current directory to "Robert":
No writtenspecification 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 ade facto specification of the language. Perl 6, however, started with a specification,[102] and several projects[103] aim to implement some or all of the specification.[citation needed]
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[update], 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 ofcharacter encoding tables).[citation needed]
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 byC structs. Operations on these structs are defined by a large collection ofmacros,typedefs, and functions; these constitute the Perl CAPI. The Perl API can be bewildering to the uninitiated, but its entry points follow a consistentnaming scheme, which provides guidance to those who use it.[citation needed]
The life of a Perl interpreter divides broadly into a compile phase and a run phase.[104] According to Aluín et al., "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."[105]
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 arecompile time andrun 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 theeval 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 inBEGIN blocks executes at run time but in the compile phase.
At compile time, the interpreter parses Perl code into asyntax tree. At run time, it executes the program bywalking 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 includeconstant folding and context propagation, butpeephole optimization is also performed.[106]
Perl has aTuring-completegrammar because parsing can be affected by run-time code executed during the compile phase.[107] The code cannot be parsed by a straightLex/Yacclexer/parser. To resolve ambiguities in the language the interpreter must implement its own lexer to coordinate with a modifiedGNU bison parser.[108]
It is often said that "Only perl can parse Perl",[109] 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 thehalting 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.[110]
Other programs that undertake to parse Perl, such assource-code analyzers andauto-indenters, have to contend not only with ambiguoussyntactic constructs but also with theundecidability 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',"[111] which was later proved.[112]
Perl is distributed with over 250,000functional 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 introducesoftware bugs; further, 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.[citation needed]
Because of unusual changes required for theclassic Mac OS environment, a special port called MacPerl was shipped independently.[114]
TheComprehensive Perl Archive Network carries a complete list of supported platforms with links to the distributions available on each.[115] CPAN is also the source for publicly available Perl modules that are not part of the core Perl distribution.[citation needed]
ActivePerl is a closed-source distribution fromActiveState that has regular releases that track the core Perl releases.[116] The distribution previously included thePerl package manager (PPM),[117] 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.[118] Included also isPerlScript, aWindows Script Host (WSH) engine implementing the Perl language.Visual Perl is an ActiveState tool that adds Perl to theVisual Studio.NET development suite. AVBScript-to-Perl converter, a Perl compiler for Windows, and converters ofAWK andsed to Perl have also been produced by this company and included on theActiveState CD for Windows, which includes all of their distributions plus theKomodo IDE and all but the first on the Unix–Linux–POSIX variant thereof in 2002 and afterward.[citation needed]
The Computer Language Benchmarks Game compares the performance of implementations of typical programming problems in several programming languages.[119] 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.[120]
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 theYAPC::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.[121] Unlike Java, Python, and Ruby, Perl has only experimental support for pre-compiling.[122] Therefore, Perl programs pay this overhead penalty on every execution. The run phase of typical programs is long enough thatamortized startup time is not substantial, but benchmarks that measure very short execution times are likely to be skewed due to this overhead.[123]
A number of tools have been introduced to improve this situation. The first such tool was Apache'smod_perl, which sought to address one of the most-common reasons that small Perl programs were invoked rapidly:CGIWeb development.ActivePerl, via MicrosoftISAPI, provides similar performance improvements.[124]
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 includebytecode interpretation, reference-counting memory management, and dynamic type-checking.[125]
The most critical routines can be written in other languages (such asC), which can be connected to Perl via simple Inline modules or the more complex, but flexible,XS mechanism.[126]
Perl is often used as aglue language, tying together systems and interfaces that were not specifically designed to interoperate, and for "data munging",[132] that is, converting or processing large amounts of data for tasks such as creating reports. These strengths are linked intimately. The combination makes Perl a popular all-purpose language forsystem administrators, particularly because short programs, often called "one-liner programs", can be entered and run on a singlecommand line.[citation needed]
Perl code can be made portable acrossWindows and Unix; such code is often used by suppliers of software (bothcommercial off-the-shelf (COTS) and bespoke) to simplify packaging and maintenance of software build- and deployment-scripts.[citation needed]
Perl's text-handling capabilities can be used for generatingSQL queries; arrays, hashes, and automatic memory management make it easy to collect and process the returned data. For example, in Tim Bunce'sPerl DBIapplication 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 aWeb page usingHTML,JavaScript, and SQL in ahere document). The use of Perlvariable interpolation to programmatically customize each of the SQL queries, and the specification of Perl arrays or hashes as the structures to programmatically hold the resultingdata sets from each SQL query, allows a high-level mechanism for handling large amounts of data for post-processing by a Perl subprogram.[133]In early versions of Perl, database interfaces were created by relinking the interpreter with aclient-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 resultingperl executable to using just one database interface at a time.[134]
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 mostANSISQL databases.[135]
DBI provides caching for database handles and queries, which can greatly improve performance in long-lived execution environments such asmod_perl,[136] helping high-volume systems avert load spikes as in theSlashdot effect.[137]
In modern Perl applications, especially those written usingweb frameworks such asCatalyst, the DBI module is often used indirectly viaobject-relational mappers such asDBIx::Class, Class::DBI[138] or Rose::DB::Object[139] that generate SQL queries and handle data transparently to the application author.[140]
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.[141]
State of the Onion is the name for Wall's yearlykeynote-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.[142] 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 byRandal L. Schwartz, one of the earliest professional Perl trainers.[143] 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, [sic]". 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.[144]
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 thatgolf players seek to take as few shots as possible in a round. The phrase's first use[145] 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 languageAPL in previous decades. The use of Perl to write a program that performedRSA encryption prompted a widespread and practical interest in this pastime.[146] In subsequent years, the term "code golf" has been applied to the pastime in other languages.[147] 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. TheObfuscated Perl Contest was a competition held byThe 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 Usenetsignature block.[148]
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 atPerlMonks.[149]
^"About Perl". perl.org.Archived from the original on November 6, 2015. RetrievedApril 20, 2013."Perl" is a family of languages, "Perl 6" is part of the family, but it is a separate language that has its own development team. Its existence has no significant impact on the continuing development of "Perl 5".
^"Path to Raku". GitHub.Archived from the original on November 12, 2020. RetrievedJanuary 14, 2021.This document describes the steps to be taken to effectuate a rename of Perl 6 to Raku
^"Language Evaluations".Archived from the original on March 10, 2015. RetrievedJanuary 30, 2015.Perl's strongest point is its extremely powerful built-in facilities for pattern-directed processing of textual, line-oriented data formats; it is unsurpassed at this.
^"You Used Perl to Write WHAT?!". January 24, 2008.Archived from the original on February 4, 2015. RetrievedFebruary 4, 2015.perl has always been the go-to language for any task that involves pattern-matching input
^Schwartz, Randal;foy, brian; Phoenix, Tom (June 16, 2011).Learning Perl. O'Reilly Media, Inc. p. 4.ISBN978-1449313142.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.
^ab"Announcing Perl 7". perl.com. June 24, 2020.Archived from the original on June 24, 2020. RetrievedJune 24, 2020.
^Clark, Nicholas (May 9, 2021)."Steering Council meeting #019 2021-05-06".www.nntp.perl.org.Archived from the original on May 18, 2021. RetrievedMay 17, 2021.The plan remains that there will be a Perl 7 bump, but not immediately after 5.34.0 is released.... We don't think that we can deliver on [Perl 7] in 12 months.
^"perlintro".Perl 5 version 18.0 documentation. Perl 5 Porters and perldoc.perl.org. Archived fromthe original on January 9, 2011. RetrievedJune 30, 2013.
^"perlstyle".Perl 5 version 18.0 documentation. Perl 5 Porters and perldoc.perl.org. Archived fromthe original on June 26, 2013. RetrievedJune 30, 2013.
^"Perl 6 Compilers". The Perl 6 Project.Archived from the original on December 2, 2009. RetrievedJanuary 27, 2011.
^A description of the Perl 5 interpreter can be found inProgramming Perl, 3rd Ed., chapter 18. See particularly page 467, which carefully distinguishes run phase and compile phase fromrun time andcompile time. Perl "time" and "phase" are often confused.
^Abuin, Jose M.; Pichel, Juan C.; Pena, Tomas F.; Gamallo, Pablo; Garcia, Marcos (2014). "Perldoop: Efficient execution of Perl scripts on Hadoop clusters".2014 IEEE International Conference on Big Data (Big Data). IEEE. pp. 766–771.doi:10.1109/BigData.2014.7004303.ISBN978-1-4799-5666-1.
^Abuin, Jose M.; Pichel, Juan C.; Pena, Tomas F.; Gamallo, Pablo; Garcia, Marcos (2014). "Perldoop: Efficient execution of Perl scripts on Hadoop clusters".2014 IEEE International Conference on Big Data (Big Data). IEEE. pp. 766–771.doi:10.1109/BigData.2014.7004303.ISBN978-1-4799-5666-1.
^"Rice's Theorem".The Perl Review.4 (3):23–29. Summer 2008. and"Perl is Undecidable".The Perl Review.5:7–11. Fall 2008., available online atKegler, Jeffrey."Perl and Undecidability".Archived from the original on August 17, 2009. RetrievedJanuary 4, 2009.
^"Perl FAQ".Archived from the original on August 6, 2019. RetrievedAugust 6, 2019.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).
^Gallo, Felix (2003)."The Zeroth Obfuscated Perl Contest"(PDF). In Jon Orwant (ed.).Games, diversions, and Perl culture: best of the Perl journal. O'Reilly Media. Archived fromthe original(PDF) on November 22, 2009. RetrievedJanuary 12, 2011.
