Perl, also called the Programming Extraction and Reporting Language, is a family of two high-level, interpreted, general-purpose, dynamic programming languages. The “Perl” language refers to Perl 5 but is also related to its redesigned “sister language” Perl 6, until it was officially renamed Raku in 2019.
It was first developed by American computer programmer Larry Wall in 1987 as a general-purpose programming language (GPL) for the Unix scripting language to make report processing more optimized. From that point, Perl had many improvements and revisions. Its sister language, Raku, evolved as a separate language and has similar ideas to its original language.
Perl 5 was notable in the 1990s as a CGI scripting language due to its powerful regular expression and string parsing abilities. It is now used in various fields, like network programming, system administration, bioinformatics, finance, and GUIs.
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The majority of the structure of Perl is broadly derived from C. It’s procedural, with assignment statements, variables, expressions, control structures, subroutines, and brace-delimited blocks.
Perl also has features of shell programming. All variables are marked with leading sigils ($), which allows variables to be interpolated directly into strings. But, compared to the Shell and other programming languages that use sigils, Perl utilizes sigils on all accesses to variables and denotes the type of the expression.
It also has many built-in functions often used in shell programming, like sorting and calling operating system facilities. Its features support complex data structures, first-class functions, and an object-oriented programming model. Perl 5 also could package code as reusable modules.
All versions of Perl had automatic memory management and automated data typing features. The interpreter knows the kind and data storage requirements of every data object in the program via reference counting. Legal-type conversions are also automatically executed at run time.
The Perl 5 language has various applications; it’s notably used in CGI scripts and large projects, such as TWiki, RT, Slash, Bugzilla, cPanel, and Movable Type. It’s also being used in high-traffic web pages, like Craigslist, Priceline.com, LiveJournal, IMDb, Ticketmaster, DuckDuckGo, and Slashdot.
Perl is an alternative component of the popular LAMP (Linux, Apache, MySQL, PHP/Perl/Python) technology stack for web development. It’s widely used as a system programming language in the Debian Linux distribution.
The Perl language is dual-licensed under the Artistic License 1.0 and the GNU General Public License. Distributions are available for most operating systems, including Unix and other Unix-like systems. Perl can also be compiled from source code on all POSIX (Portable Operating System Interface)-compliant and Unix-compatible platforms.
The CPAN (Comprehensive Perl Archive Network) contains a complete list of supported platforms with links to each distribution available.
Perl 7 was announced in 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 the modern Perl 5 code.
The plan to go to Perl 7 was brought to discussion. Still, it was quickly canceled by the Perl Steering Committee to avoid issues with backward compatibility for scripts that weren’t written to modules and pragmas that would become the default in Perl 7.