Pugs (compiler)

<h2 id="overview">Overview</h2>
<p>The Pugs project aimed to <a href="/facts/Bootstrapping_(compilers)/uvQscbU5">bootstrap</a> Perl 6 by implementing the full Perl 6 specification, as detailed in the <a href="https://web.archive.org/web/20050222013737/http://dev.perl.org/perl6/synopsis/">Synopses</a>. It is written in <a href="/facts/Haskell/ydEsHuGy">Haskell</a>, specifically targeting the <a href="/facts/Glasgow_Haskell_Compiler/4msB3KFN">Glasgow Haskell Compiler</a>.
</p><p>Pugs includes two main executables:
</p>
<ul><li><i>Pugs</i> is the interpreter with an interactive shell.</li>
<li><i>Pugscc</i> can compile Perl 6 programs into Haskell code, Perl 5, <a href="/facts/JavaScript/XhhIIEsl">JavaScript</a>, or <a href="/facts/Parrot_virtual_machine/tlcl5jAM">Parrot virtual machine</a>'s <a href="/facts/Parrot_intermediate_representation/Idmrdajt">Parrot intermediate representation</a> (PIR) <a href="/facts/Assembly_language/7XuV0cla">assembly language</a>.</li></ul>
<p>Pugs is <a href="/facts/Free_and_open-source_software/1cHtjLCB">free and open-source software</a>, distributable under the terms of either the <a href="/facts/GNU_General_Public_License/S75KhLSX">GNU General Public License</a> or the <a href="/facts/Artistic_License/9vHBm47P">Artistic License</a>.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> These are the same terms as Perl.
</p>
<h2 id="version-numbering">Version numbering</h2>
<p>The major/minor version numbers of Pugs converge to 2π (being reminiscent of <a href="/facts/TeX/HDrl3Yvd">TeX</a> and <a href="/facts/Metafont/j7vCXw8s">Metafont</a>, which use a similar scheme); each significant digit in the minor version represents a successfully completed milestone. The third digit is incremented for each release. The current milestones are:
</p>
<ul><li>6.0: Initial release</li>
<li>6.2: Basic IO and control flow elements; mutable variables; assignment</li>
<li>6.28: Classes and traits</li>
<li>6.283: Rules and Grammars</li>
<li>6.2831: Type system and linking</li>
<li>6.28318: Macros</li>
<li>6.283185: Port Pugs to Perl 6, if needed</li></ul>
<h2 id="perl-5-compatibility">Perl 5 compatibility</h2>
<p>As of version 6.2.6, Pugs also has the ability to embed Perl 5 and use <a href="/facts/CPAN/MB7Iv662">CPAN</a> modules installed on the system. The example below demonstrates the use of the popular <a href="/facts/Perl_DBI/U3fAzmXB">Perl DBI</a> module to manage a database:
</p>
#!/usr/bin/pugs
use v6;
use perl5:DBI;

my $dbh = DBI.connect('dbi:SQLite:dbname=test.db');
$dbh.do("CREATE TABLE Test (Project, Pumpking)");

my $sth = $dbh.prepare("INSERT INTO Test VALUES (?, ?)");
$sth.execute(<PGE Patrick>);
$sth.execute(<Pugs Audrey>);
$sth.execute(<Parrot Leo>);

my $res = $dbh.selectall_hashref('SELECT * FROM Test', 'Pumpking');
# Just another Pugs hacker
say "Just another $res<Audrey><Project> hacker";

<h2 id="development-model">Development model</h2>
<p>Several factors have been suggested as reasons for Pugs's progress:
</p>
<ul><li>Haskell's <a href="/facts/Static_typing/Tz0bAMS9">static typing</a> can make it easier for program bugs to be detected at compile time. Haskell code is also often thought to be concise. The Parsec library <a href="https://web.archive.org/web/20060807052639/http://www.cs.uu.nl/~daan/parsec.html">[1]</a>, a <a href="/facts/Monad_(functional_programming)/kYazRoF1">monadic</a> <a href="/facts/Combinatorial/k14xUoKT">combinatorial</a> parser written fully in Haskell, simplifies parsing. Because Haskell is a <a href="/facts/Purely_functional_programming/am3DcNAd">purely functional programming</a> language, making the functional code interact with the real world (<a href="/facts/Input%2foutput/WQTE8Jas">input/output</a> and time-driven environment) requires thought. To achieve this, Pugs makes extensive use of <a href="/facts/Monad_(functional_programming)/kYazRoF1">monads</a>.</li>
<li>Pugs's use of <a href="/facts/Test-driven_development/fDCzXkt1">test-driven development</a> methodology (a tenet of <a href="/facts/Extreme_Programming/UCeJIvhQ">Extreme Programming</a>). This methodology dictates that every module should have test code, even before the modules are implemented. Advocates of this methodology argue that it improves <a href="/facts/Software_quality/7yoRvIuz">software quality</a>. However, the project often silenced failed regression tests before releases, removing much of the benefit of test-driven development.</li>
<li>Tang's liberal granting of the <a href="/facts/Commit_bit/kU6oKu1Y">commit bit</a>. Pugs development is currently based around a <a href="/facts/Apache_Subversion/b5j9wAbt">Subversion</a> repository, and access is freely given, especially to people wishing to write tests. Because of this, a huge library of tests has accumulated. Other Perl 6 implementations rely on many tests developed for Pugs as an executable specification for Perl 6.</li>
<li>Tang's communication style; her journal (linked below) attracted many people to the project.</li></ul>
<p>Despite these factors, progress on the Haskell implementation stalled in late 2006, as personal issues kept Audrey from devoting as much time to the project as she had in 2005.
</p><p>Many Pugs contributors have since moved on to implement Perl6-inspired systems as CPAN modules on Perl 5, such as the <a href="/facts/Moose_(Perl)/Um2JSQc9">Moose</a> project.
</p>

<h2 id="external-links">External links</h2>
<ul><li><a href="https://web.archive.org/web/20050221223310/http://www.pugscode.org/">pugscode.org: Pugs</a></li>
<li><a href="http://pugs.blogs.com">Pugs Journal</a></li>
<li><a href="http://www.onlamp.com/pub/wlg/7996">Ofun: Optimizing for Fun</a> <a href="https://web.archive.org/web/20141221232712/http://www.onlamp.com/pub/wlg/7996">Archived</a> 2014-12-21 at the <a href="/facts/Wayback_Machine/nmQ3a6JC">Wayback Machine</a></li>
<li><a href="https://metacpan.org/module/Perl6::Pugs">Perl6::Pugs on CPAN</a></li>
<li><a href="http://www.nntp.perl.org/group/perl.perl6.language/19263">Kudos from Perl 6 Design Team</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Tang, Audrey (21 April 2010). "How to Implement Perl 6 in '10". Pugs Blogs. <a href="/wiki/Audrey_Tang" target="_blank">/wiki/Audrey_Tang</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>"Pugs Apocryphon 1". Archived from the original on 5 March 2007. Retrieved 9 March 2007. <a href="https://web.archive.org/web/20070305173601/http://svn.pugscode.org/pugs/docs/01Overview.html" target="_blank">https://web.archive.org/web/20070305173601/http://svn.pugscode.org/pugs/docs/01Overview.html</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
</ol>

Pugs (compiler) open-in-new

Pugs (compiler)