The Perl Foundation has released Perl 5.10, the first major upgrade to the programming language in over five years. This version builds on the 5.8.x series by adding new language features and improving the Perl interpreter. The Perl development team has taken features from the Perl 6 project, as well as from academic languages and blended them with Perl.
The most exciting change is the new smart match operator. It implements a new kind of comparison, the specifics of which are contextual based on the inputs to the operator. For example, to find if scalar $needle is in array @haystack, simply use the new ~~ operator:
if ( $needle ~~ @haystack ) ...
Building on the smart-match operator, Perl finally gets a switch statement, and it goes far beyond the kind of traditional switch statement found in languages like C, C++, and Java.
Regular expressions are now far more powerful. Programmers can now use named captures in regular expressions, rather than counting parentheses for positional captures. Perl 5.10 also supports recursive patterns, making many useful constructs, especially in parsing, now possible. Even with these new features, the regular expression engine has been tweaked, tuned, and sped up in many cases.
Other improvements include state variables that allow variables to persist between calls to subroutines; user-defined pragmata that lets users write modules to influence the way Perl behaves; a defined-or operator; field hashes for inside-out objects, and better error messages.
The Perl interpreter is faster with a smaller memory footprint, and has several UTF-8 and threading improvements. The Perl installation is now relocatable, a blessing for systems administrators and operating system packagers. The source code is more portable, and many small bugs have been fixed along the way.
For a list of all changes in Perl 5.10, see Perl 5.10's perldelta document included with the source distribution. Users who don't want to wait for their operating system vendor to release a package can dig into Perl 5.10 by downloading it from CPAN, the Comprehensive Perl Archive Network, or from the Perl home page.
Windows users can also take advantage of the power of Perl by compiling a source distribution from CPAN, or downloading one of two easily installed binary distributions. Strawberry Perl is a community-built binary distribution for Windows, and ActiveState's distribution is free but commercially maintained.
