The four noisy horsemen of Perl hate

I pub­lish Perl sto­ries on this blog once a week, and it seems every time there’s at least one response on social media that amounts to, ​“ I hate Perl because of its weird syn­tax.” Or, ​“ It looks like line noise.” (Perl seems to have out­last­ed that one — when’s the last time you used an acoustic modem?) Or the quote attrib­uted to Keith Bostic: ​“ The only lan­guage that looks the same before and after RSA encryption.”

So let’s address, con­front, and demys­ti­fy this hate. What are these objec­tion­able syn­tac­ti­cal, noisy, pos­si­bly encrypt­ed bits? And why does Perl have them?

Regular expres­sions, or reg­ex­ps, are not unique to Perl. JavaScript has them. Java has them. Python has them as well as anoth­er mod­ule that adds even more fea­tures. It’s hard to find a lan­guage that does­n’t have them, either native­ly or through the use of a library. It’s com­mon to want to search text using some kind of pat­tern, and reg­ex­ps pro­vide a fair­ly stan­dard­ized if terse mini-​language for doing so. There’s even a C‑based library called PCRE, or ​“ Perl Compatible Regular Expressions,” enabling many oth­er pieces of soft­ware to embed a reg­exp engine that’s inspired by (though not quite com­pat­i­ble) with Perl’s syntax.

Being itself inspired by Unix tools like grep, sed, and awk, Perl incor­po­rat­ed reg­u­lar expres­sions into the lan­guage as few oth­er lan­guages have, with bind­ing oper­a­tors of =~ and !~ enabling easy match­ing and sub­sti­tu­tions against expres­sions, and pre-​compilation of reg­ex­ps into their own type of val­ue. Perl then added the abil­i­ty to sep­a­rate reg­ex­ps by white­space to improve read­abil­i­ty, use dif­fer­ent delim­iters to avoid the leaning-​toothpick syn­drome of escap­ing slash (/) char­ac­ters with back­slash­es (\), and name your cap­ture groups and back­ref­er­ences when sub­sti­tut­ing or extract­ing strings.

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