Raku: Perl отбасынан туындаған бағдарламалау тілі

Programming language derived from Perl

Raku is a member of the Perl family of programming languages. Formerly known as Perl 6, it was renamed in October 2019. Raku introduces elements of many modern and historical languages. Compatibility with Perl was not a goal, though a compatibility mode is part of the specification. The design process for Raku began in 2000.

The Raku design process was first announced on 19 July 2000, on the fourth day of that year's Perl Conference, by Larry Wall in his State of the Onion 2000 talk. At that time, the primary goals were to remove "historical warts" from the language; "easy things should stay easy, hard things should get easier, and impossible things should get hard"; a general cleanup of the internal design and APIs. The process began with a series of requests for comments or "RFCs". This process was open to all contributors, and left no aspect of the language closed to change. Once the RFC process was complete, Wall reviewed and classified each of the 361 requests received. He then began the process of writing several "Apocalypses", using the original meaning of the term, "revealing". While the original goal was to write one Apocalypse for each chapter of Programming Perl, it became obvious that, as each Apocalypse was written, previous Apocalypses were being invalidated by later changes. For this reason, a set of Synopses were published, each one relating the contents of an Apocalypse, but with any subsequent changes reflected in updates. Today, the Raku specification is managed through the "roast" testing suite, while the Synopses are kept as a historical reference. There are also a series of Exegeses written by Damian Conway that explain the content of each Apocalypse in terms of practical usage. Each Exegesis consists of code examples along with discussion of the usage and implications of the examples. There are three primary methods of communication used in the development of Raku today. The first is the raku IRC channel on Libera Chat. The second is a set of mailing lists. The third is the Git source code repository hosted at GitHub.

The major goal Wall suggested in his initial speech was the removal of historical warts. These included the confusion surrounding sigil usage for containers, the ambiguity between the select functions, and the syntactic impact of bareword filehandles. There were many other problems that Perl programmers had discussed fixing for years that were explicitly addressed by Wall in his speech. An implication of these goals was that Perl 6 would not have backward compatibility with the existing Perl codebase. This meant that some code which was correctly interpreted by a Perl 5 compiler would not be accepted by a Perl 6 compiler. Since backward compatibility is a common goal when enhancing software, the breaking changes in Perl 6 had to be stated explicitly. The distinction between Perl 5 and Perl 6 became so large that eventually Perl 6 was renamed Raku.

The language's mascot is "Camelia, the Raku bug". Her name is a nod to the camel mascot associated with Perl, and her form, in the pun loving tradition of the Perl community, is a play on "software bug". Spiral designs embedded in her butterfly like wings resemble the characters "P6", the favored nickname for Perl 6, and off center eye placement is an intentional pun on "Wall eyed". One of the goals behind the lively and colorful design of the logo was to discourage misogyny in the community and for it to be an opportunity for those of "masculine persuasion" to show their sensitive side.

as of 2017, only the Rakudo implementation is under active development. No implementation will be designated as the official Raku implementation; rather, "Raku is anything that passes the official test suite." targets a number of virtual machines, such as MoarVM, the Java Virtual Machine, and JavaScript. MoarVM is a virtual machine built especially for Rakudo and the NQP Compiler Toolchain. There is a layer between Raku and the virtual machines called Not Quite Perl 6, or NQP, which implements Raku rules for parsing Raku, as well as an abstract syntax tree and backend specific code generation. Large portions of Rakudo are written in Raku itself, or in its subset NQP. Rakudo is not a completely self hosting implementation, nor are there concrete plans at this point to make Rakudo a bootstrapping compiler.

Pugs was an initial implementation of Perl 6 written in Haskell. Pugs used to be the most advanced implementation of Perl 6, but since mid 2007 it is mostly dormant (with updates made only to track the current version of GHC). As of November 2014 Pugs was not being actively maintained. In 2007, v6 MiniPerl6 ("mp6") and its reimplementation, v6 KindaPerl6 ("kp6") were written as a means to bootstrap the Perl 6.0.0 STD, using Perl 5. The STD is a full grammar for Perl 6 and is written in Perl 6. In theory, anything capable of parsing the STD and generating executable code is a suitable bootstrapping system for Perl 6. kp6 is currently compiled by mp6 and can work with multiple backends. mp6 and kp6 are not full Perl 6 implementations and are designed only to implement the minimum featureset required to bootstrap a full Perl 6 compiler. Yapsi was a Perl 6 compiler and runtime written in Perl 6 itself. As a result, it required an existing Perl 6 interpreter, such as one of the Rakudo Star releases, in order to run. Niecza, another major Perl 6 implementation effort, focused on optimization and efficient implementation research. It targets the Common Language Infrastructure.

The Raku specification requests that modules be identified by name, version, and authority. It is possible to load only a specific version of a module, or even two modules of the same name that differ in version or authority. As a convenience, aliasing to a short name is provided. CPAN, the Perl module distribution system, does not yet handle Raku modules. Instead a prototype module system is in use.

Perl and Raku differ fundamentally, though in general the intent has been to "keep Raku Perl", so that Raku is clearly "a Perl programming language". Most of the changes are intended to normalize the language, to make it easier for novice and expert programmers alike to understand, and to make "easy things easier and hard things more possible".

A major non technical difference between Perl and Raku is that Raku began as a specification. This means that Raku can be re implemented if needed, and it also means that programmers do not have to read the source code for the ultimate authority on any given feature. In contrast, in Perl, the official documentation is not considered authoritative and only describes the behavior of the actual Perl interpreter informally. Any discrepancies found between the documentation and the implementation may lead to either being changed to reflect the other, a dynamic which drives the continuing development and refinement of the Perl releases.

Perl's regular expression and string processing support has always been one of its defining features. Since Perl's pattern matching constructs have exceeded the capabilities of regular language expressions for some time, Raku documentation exclusively refers to them as regexes, distancing the term from the formal definition. Raku provides a superset of Perl features with respect to regexes, folding them into a larger framework called "rules" which provide the capabilities of context sensitive parsing formalisms (such as the syntactic predicates of parsing expression grammars and ANTLR), as well as acting as a closure with respect to their lexical scope. Rules are introduced with the rule keyword which has a usage quite similar to subroutine definition. Anonymous rules can also be introduced with the regex (or rx) keyword, or they can simply be used inline as regexps were in Perl via the m (matching) or s (substitute) operators. In Apocalypse 5, Larry Wall enumerated 20 problems with "current regex culture". Among these were that Perl's regexes were "too compact and 'cute'", had "too much reliance on too few metacharacters", "little support for named captures", "little support for grammars", and "poor integration with 'real' language".

Some Perl constructs have been changed in Raku, optimized for different syntactic cues for the most common cases. For example, the parentheses (round brackets) required in control flow constructs in Perl are now optional:
@integers = 0 Inf; # integers from 0 to infinity
The code above will not crash by attempting to assign a list of infinite size to the array @integers, nor will it hang indefinitely in attempting to expand the list if a limited number of slots are searched. This simplifies many common tasks in Raku including input/output operations, list transformations, and parameter passing.

In Perl, identifier names can use the ASCII alphanumerics and underscores also available in other languages. In Raku, the alphanumerics can include most Unicode characters. In addition, hyphens and apostrophes can be used (with certain restrictions, such as not being followed by a digit). Using hyphens instead of underscores to separate words in a name leads to a style of naming called "kebab case".

Also, a book dedicated to one of the first Perl 6 virtual machines, Parrot, was published in 2009.