Perl Weekly Challenge #208

First of all, a greeting. I posted an introduction with a notification of intent to take over a module on CPAN, but the maintainer responded to me. I'm Avery, I'm developing SeekMIDI, a small graphical MIDI sequencer. I started it in 2016 and I took a long break from programming entirely, and I've just restarted developing my programming skills again. For starters, I'm working on Perl Weekly Challenges and bug fixes to modules.

Without further ado, here are my solutions to the PWC #208. All solutions are about to be posted, but this could be a spoiler if you're trying to solve it too. I was very pleased this week that I got it down to about 15-25 minutes for each task, so I'm definitely getting more comfortable in Perl again.

First, task 1:

The first line of Perl_CGI script, env perl vs perl only, how different?

Hi ! Everyone there ! How are you ?

Until recently I runs all of my Perl scripts as well as Perl_CGI scripts by starting the folowing salutation,

#! /usr/bin/perl -w

The script with this beginning runs well at BASH shell at (/home/mkido/bin) LINUX such as Fedora, Ubuntu, Rocky (Alma-derivative). However, almost right now I noticed some of Perl example around has the different first line as below,

#! /usr/bin/env perl

And it doesn't seem to run at HOME BASH shell (/home/mkido/bin) by simple way of executing it by-itself by the command line. Will someone explain me about what is this [env perl] stuff? Thank you so much.

Mitsuru Kido

Perl Weekly Challenge 208: Minimum Index Sum and Duplicate and Missing

These are some answers to the Week 208 of the Perl Weekly Challenge organized by Mohammad S. Anwar.

Spoiler Alert: This weekly challenge deadline is due in a few days from now (on March 19, 2023 at 23:59). This blog post offers some solutions to this challenge. Please don’t read on if you intend to complete the challenge on your own.

Task 1: Minimum Index Sum

You are given two arrays of strings.

Write a script to find out all common strings in the given two arrays with minimum index sum. If no common strings found returns an empty list.

Example 1:

Template Toolkit’s DEFAULT is not too useful

Quoth the fine manual for Template Toolkit:

The DEFAULT directive is similar to SET but only updates variables that are currently undefined or have no "true" value (in the Perl sense).

Nice. Basically, where SET is like the = operator in Perl, DEFAULT is like the ||= operator. Quite useful! If it were, that is. Because the analogy is only superficially true.

Quiq - Weekly Travelling in CPAN

Destination: Quiq

Date of Latest Release: Feb 04, 2023
Distribution: Quiq
Module version: 1.207
Main Contributors: Frank Seitz(FSEITZ)
License: The Artistic License

Quiq is a "Perl class library for rapid development". The modules are "designed according to uniform principles" (translated from German).

Quiq contains 234 (Ooooops!!!) classes at the time this post is being written and their descriptions are mostly written in German.

It contains several text-based document/markup language code writers, namely Quiq::Tag (for XML), Quiq::Html::MODULES, Quiq::MediaWiki::Markup, Quiq::Css, Quiq::LaTex::MODULES; some network functionalities including Quiq::Http::MODULES, Quiq::Ssh and Quiq::Socket ; some tiny tools like Quiq::Color and Quiq::Stopwatch; some system tools like Quiq::Path, Quiq::TempFile and Quiq::Process; some modules for meta-development including Quiq::Hash and Quiq::Object; some modules for general use like Quiq::Converter, Quiq::Math and Quiq::Epoch. ...

For CSS, we have Quiq::Css :

ChatGPT for Perl Learning

How to learn Perl has been an eternal problem for the Perl community. Compared to many other languages that place an emphasis on teaching the basics and using education as a tool for evangelism we've had sporadic efforts along those lines. Given the size of our community and the fact that the best programmers are often in great demand, we have a hard time pumping out the needed docs and examples.

I've been using ChatGPT quite a lot lately and find that although it makes some mistakes it actually churns out pretty decent Perl if given good instructions. For example here's one I did this AM. We just had the dreaded hour shift here in the US and I'm just not up to thinking so I asked Chat GPT:

"write a perl subroutine that accepts two hashrefs and a list. For each item in the item merge the hashrefs by combining the values into an array ref. "

Here's what it pumped out:

This week in PSC (100)

All three of us met, and were joined by Pete Krawczyk who first wanted to discuss some TPRF-related issues.

Following on from this we discussed:

  • Zefram's request to back out the strict-vs-VERSION changes. There's some merit here, he sent a PR to undo the whole thing. We feel there's two different issues that need looking at separately. Paul will explain some thoughts in more detail.

  • Yves's request to reöpen discussions about "deprecated::" warning categories. There may be benefit here too. Paul will write a followup response.

Call for Papers. TPRC 2023

Call For Papers is now open! You can submit your talk Ideas at Talk submission deadline is March 31 Midnight UTC. Talks must be given live and in-person. If you are looking for any talk ideas, try out the conference wiki.

Visit the TPRC 2023 website at
Follow us on Twitter: @PerlConferences
Like us on Facebook: The Perl Foundation (@tpf.perl)
Subscribe to the mailing list:
Post a message to us at

Regexp::Assemble - Weekly Travelling in CPAN

It has been on my mind quite a while. Originally it was suggested on Twitter, by Mohammad Anwar, the maintainer of "The Weekly Challenge", that the community should re-publish the CPAN Weekly, which existed before I joined the hacker community. Our plan was having the newsletter began in December 2022. Actually that collided with the Advent Calendar, so, not a good time. Anyway, after many twists and turns, I was busy in late 2022 and early 2023 for job hunting (settled now). Now I try to act as a tour guide and visit some CPAN modules (or distributions) with you in a causal manner.

Destination: Regexp::Assemble

Date of Latest Release: Jun 20, 2017
Distribution: Regexp-Assemble
Module version: 0.38
Main Contributors: David Landgren and Ron Savage(RSAVAGE)

Regexp::Assemble is used for combining regular expressions.

my $ra = Regexp::Assemble->new;
$ra->add('cat', 'rat');
say $ra->re;
say $ra->as_string;
# (?^:[cr]at)
# [cr]at

The two methods of the module you will probably use most frequently, as_string and re , have subtle differences:

Perl Weekly Challenge 207: Keyboard Word and H-Index

These are some answers to the Week 207 of the Perl Weekly Challenge organized by Mohammad S. Anwar.

Spoiler Alert: This weekly challenge deadline is due in a few days from now (on March 12, 2023 at 23:59). This blog post offers some solutions to this challenge. Please don’t read on if you intend to complete the challenge on your own.

Task 1: Keyboard Word

You are given an array of words.

Write a script to print all the words in the given array that can be types using alphabet on only one row of the keyboard.

Let us assume the keys are arranged as below:

Row 1: qwertyuiop
Row 2: asdfghjkl
Row 3: zxcvbnm

Example 1

Input: @words = ("Hello","Alaska","Dad","Peace")
Output: ("Alaska","Dad")

Example 2

This week in PSC (099)

After missing last week, all three of us attended.

  • Recapped the missing weeks from absences
  • Smartmatch deprecation seems to be causing some BBC failures due to new warnings, but that’s to be expected; Philippe to submit patches upstream
  • Refined the questions surrounding SSL-in-core; Paul to send a follow-up email
  • RFC0013 needs some core changes to how overload works; best deferred for 5.39 now
  • Agreed to rename “RFC” to “PPC” (”Proposed Perl Change”)

TWC 205: Exclusive Third Or First

In which we ponder the highest bit, and find a much faster Max_XOR.

Ordering Your Tests

By default, the test actions of both ExtUtils::MakeMaker and Module::Build test t/*.t in lexicographic order (a.k.a. ASCIIbetical order). Under this default, some Perl module authors who want tests performed in a given order have resorted to numbering tests: t/01_basic.t, t/10_functional.t, and so on.

My personal preference is to take the lexicographic ordering into consideration when naming test files: t/basic.t through t/whole_thing.t. But the price of this choice is a certain number of contrived test names, and even the occasional thesaurus lookup.

But there is a better way. Both ExtUtils::MakeMaker and Module::Build allow you to specify tests explicitly.

Under ExtUtils::MakeMaker version 6.76 or above, you call WriteMakeFile() thus:

Perl and Raku Merch from Freewear

Freewear now has Perl and Raku merch featuring Camelia, The Onion Logo and a Camel Shadow. A donation is made to TPRF for each sale.


The above plus more colors and shirt styles are also available!

Buy now at:

Assert Your Environment


In the category of "scratching my itch".

I was doing some data pipelining and dockerising my creation. And - as always - when testing and devving I forgot to set the right environment variables. And when container image gets passed around, the information about the required env settings will certainly get lost.

Here is something of a solution to that:

How to ensure you have the environment variables and values you need?

Here is a common sight:

$ PLAEC='Stockholm'
$ if [[ "$PLACE" == '' ]]; then echo "Normal OK"; fi

... And the program fails with no errors!

Not quite what we want!

Another example, from a docker container image I created lately:

Using Type::Params Effectively

One of the modules bundled with Type::Tiny is Type::Params, a module that allows you to validate subroutine signatures using type constraints. It's one of the more popular parts of the suite.

This article provides a few hints for using it effectively.

ChatGPT suggests new keywords for Perl

I asked ChatGPT to suggest some new keywords that might make Perl more desirable. Here's the dialog:

JOHN: suggest some new keywords that Perl could add to its core syntax that would make the language more desirable to modern programmers

CHATGPT: Perl is a mature language that has undergone significant development since its inception. Despite this, there are always new features that can be added to a language to improve its appeal to modern programmers. Here are some suggestions for new keywords that Perl could add to its core syntax:

async and await: Asynchronous programming has become an increasingly important aspect of modern programming. Adding support for async and await keywords in Perl would enable developers to write non-blocking code that can take full advantage of modern hardware.

let: The let keyword is commonly used in languages like JavaScript and Rust to create variables with a limited scope. Adding let to Perl would make it easier to write clean and concise code.

Outstanding GitHub Items

Recently I received a bump on a GitHub pull request. This surprised me, because I was unaware of anything outstanding. I was even more surprised when I discovered that the distribution in question also had two open issues, one dating back about three months.

I have no idea why I was oblivious to these, but it made me want to audit myself to see if any other distributions had the same problem. GitHub has these nice links at the top of the page, Pull requests and Issues, but these show pull requests and issues that I initiated. I found no obvious way to display pull requests or issues filed against my repositories.

Inevitable Improbabilities

Guys anything can happen. There is literally no way of avoiding something that you haven’t prepared for. So in the face of mounting anxiety over the huge number of unexpected scenarios that may be around the corner, what can you do? You can contemplate insulating yourself, try and minimise the hazards, control your environment to a fine level of detail so that the surprises are infrequent and hazards are mitigated. At work I am drowned in Health and Safety Guidance, IT security protocols, Fire Safety Training. This means that work is to a large extent a somewhat boringly protected environment for me, my colleagues and my patients. Yet, even this can not avoid surprises. So what about your home, sitting in front of your computer. All the protection provided by protocols here are more vague, less policed, seen more as guidelines rather than mandatory.

The worst enemy

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