Expressiveness of the Perl programming language
The collection of features in the Perl programming language is quite unique. Some of these features may seem surprising or even distasteful to people coming from other languages; yet their combination provides a fantastic toolbox for expressiveness in programming, where you can write not only effective, but also beautiful code.
True enough, expressivity can also be used for other purposes. Many years ago, a common entertainment game in the Perl community was the obfuscated Perl contest, where participants tried to exploit the most arcane parts of the language for producing illegible, yet working programs -- in the same spirit as today's brainrot videos! People were excited by the creativity potential of Perl. Other productions from that time also include Perl golf, Perl poetry and Perl haikus. But apart from fun, if your goals are conciseness, clarity of algorithms and long-term readability, you can use Perl too, with considerable benefits, because the code can be organized so that it closely reflects your thoughts. This is what I hope to show in this series.
Perl vs other languages : Compare facts, not opinions
Of course using the word "beautiful" in the title is opinionated ... but that is mainly to draw the reader's attention!
This series will try to focus on factual evidence, considering in turn various aspects of the Perl programming language and comparing those to similar or dissimilar constructs in other languages (mainly Python, Javascript and Java). This approach tries to stay away from the vast corpus of opinionated debates about Perl that can be found in many essays, posts or tweets. In most cases such discussions start with a general opinion and then use a few examples to illustrate the argument: under such conditions it is very unlikely that readers will be able to judge for themselves. A more profound comparison of languages requires time, requires details, and requires broad coverage; so here my intention is to go bottom-up, looking at many features of different granularity, so that you can decide for yourself if you find them indeed "beautiful".
What about Raku ?
Perl has a sister language now named Raku, formerly known as Perl6. Raku took a very long time to emerge, after a huge participative design effort that carefully discussed weaknesses of Perl and weighed the pros and cons of mechanisms to be incorporated into the new language. Since it was a fresh start, without backwards compatibility constraints, it was possible to freely choose what to keep and what to change.
The result is more than beautiful, it is awesome and brings Perl's spirit to another dimension ... but unfortunately Raku is still in a niche much smaller than Perl. Raku really deserves to get a larger audience, and has very qualified advocates for that; but that's not the purpose of the present series, which focuses on Perl5.
Technical notes about Perl fragments in the series
Upcoming posts will discuss various Perl features, in no particular order; some topics are small details, others are fundamental mechanisms.
Code fragments will be written in modern Perl, namely version 5.42.0, of course with pragmata strict, warnings and utf8 always activated (even if not repeated in every code fragment). Subroutine declarations will always use signatures. Object-oriented programming will mainly use core classes, or sometimes Moose when more sophisticated mechanisms are needed. Yes, this is Perl, there are several ways to do objects !
About the author
After 10 years in academia doing research in the field of theory of programming languages, I spent the rest of my career in public administration, using Perl for more than 25 years for a large number of tasks ranging from small, one-shot migration scripts to large enterprise applications or complex data analysis tools. The majority of these applications are still in use today, maintained by a team (contrary to the saying that "Perl code is write-only"), and so rich in features that their replacement by other technology will probably not happen for a while. I have also authored 36 modules published on the Comprehensive Perl Archive Network (CPAN).
My knowledge of Java and of Python is mostly theoretical, not consolidated by practical experience, so I apologize in advance if I write inaccurate statements about these languages -- please correct me if this is the case.
About the cover image
The picture shows the initial pages of Johann Sebastian Bach's motet Singet dem Herrn ein neues Lied. In the second half of the XVIIIth century, Bach's style went largely out of fashion because it was considered too complex, with an "excess of art that altered the beauty of the music". Common taste at that time preferred the galant style, with simpler melodies and reduced polyphony. Bach remained appreciated by a small circle of connoisseurs, though.
In 1789 when Mozart - already in his maturity - first heard the motet "Singet dem Herrn", he showed great enthusiasm, eagerly asking "what is this" and keen to study "something new at last from which he could learn". After this episode it took another 50 years before Bach's music started a slow revival, finally leading to his current recognition as one of the greatest composers of all times.
So Bach is here to remind us that notions of beauty and expressivity, and their relations with complexity or simplicity, may evolve over time!
Acknowledgements
Many thanks to Boyd Duffee, Matthew O. Persico and Marc Perry who took time to review this material before publication.
Cheers to Perl!
SOCIAL SHARE CARD GENERATOR