blogs.perl.org

These are some answers to the Week 164 of the Perl Weekly Challenge organized by Mohammad S. Anwar.

Spoiler Alert: This weekly challenge deadline is due in a few of days from now (on May 15, 2022 at 24:00). 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: Prime Palindromes

Write a script to find all prime numbers less than 1000, which are also palindromes in base 10. Palindromic numbers are numbers whose digits are the same in reverse. For example, 313 is a palindromic prime, but 337 is not, even though 733 (337 reversed) is also prime.

Prime Palindromes in Raku

We use a data pipeline (chained method invocations) with two grep statements, one to keep palindromes and one to keep prime numbers. This leads to a fairly concise one-line solution:

say (1..^1000).grep({ $_ == .flip }).grep({.is-prime});

If you're using XS and C in your Perl module, you might have to worry about memory errors. There are tools like valgrind or memory sanitizer which you can use of course:

valgrind perl -I blib/lib -I blib/arch ./mytestscript

or if your problems are even more serious ones like segmentation fault errors you can run Perl under a debugger like gdb:

gdb perl
% run -I blib/lib -I blib/arch ./mytestscript

However, it might be worth noting some "easy" ways to catch memory errors which actually catch a lot of things.

The first thing is setting the variable to 0 after freeing:

 free (result);
 result = 0;

This prevents you from using the variable again accidentally after freeing, although free (0) is actually not an error, so it doesn't prevent you freeing it twice.

Twenty years ago today I released my first CPAN module: Fork::Queue.

Then there was a group of people supervising module names, and they advised me to move it under the Proc namespace and so it became Proc::Queue.

A couple of weeks before, a bug on one of my scripts had fork-bombed a production box. I barely remember the details now... just that my manager had a serious conversation with me about the incident.

Anyway, that forced me to write the module.

Something I remember for sure is the proud I was of it. How I had been able to replace several Perl builtins playing with the CORE::GLOBAL namespace in a (IMO) clever way!

Here are solutions to this weeks challenges from the Perl Weekly Challenge.

You can find my full code on Github

Task 1: Chinese zodiac

You are given a year $year.

The animal cycle: Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog, Pig.

The element cycle: Wood, Fire, Earth, Metal, Water.

Additionally there is a two year cycle between Yin & Yang

This challenge is a relatively simple challenge - and one perl is well suited:

sub year_name {
  return join q( ),
    qw( Yang   Yin                             )[  $_[0]    %  2 ],
    qw( Metal  Water   Wood   Fire  Earth      )[ ($_[0]/2) %  5 ],
    qw( Monkey Rooster Dog    Pig   Rat   Ox
        Tiger  Rabbit  Dragon Snake Horse Goat )[  $_[0]    % 12 ];
}

These are some answers to the Week 163 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 May 8, 2022 at 24:00). 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: Sum Bitwise Operator

You are given list positive numbers, @n.

Write script to calculate the sum of bitwise & operator for all unique pairs.

Example 1:

Input: @n = (1, 2, 3)
Output: 3

Since (1 & 2) + (2 & 3) + (1 & 3) => 0 + 2 + 1 =>  3.

Example 2:

I got this email from PAUSE just now:

Failed: PAUSE indexer report BKB/Go-Tokenize-0.01.tar.gz

     module : switch

It looks like it doesn't like this line of code containing Go keywords:

chan         else         goto         package      switch

Folk's in the world of Perl have been making amazing efforts to blog more and even to produce video content. That's awesome! Keep it up!

Risking sounding like a mandatory training video from HR, I want to remind budding authors of some high level criteria you should review before completing a post:

• Does it welcome new people to Perl?
• Does it welcome people back to Perl?
• Does it lift, encourage and praise them?
• Is it respectful to people who's use case, experiences and journey with Perl is different to yours?
• Is it respectful of peoples lifestyle, politics, background, and differing lived experiences?
• Does it grow the Perl community and celebrate our diversity?
• Does it teach people something new about Perl?

The answer in all cases should be yes.

Here are some examples that aren't inspired by any specific post but are based on content or comments I have read.

Using system perl is stupid, it's not real perl

Back to school ...

Apology for the delay in monthly report, usually I get it released on first day of the month.

Last month was the shortest month of the year as you all know, so getting things done became relatively harder.

What is in store this time?

Well, there were two things that took away all the attentions.

500th edition of Perl Weekly newsletter

I have been a regular reader of the weekly newsletter for many years now. If you want regular dose of Perl news directly in your inbox every Monday then please do subscribe the newsletter. I joined the elite group of editors in May 2018, thanks to Gabor Szabo for giving me the opportunity. I had the honour to edit the 500th edition of the Perl Weekly newsletter. It feels nice and gives me sense of achievments.

These are some answers to the Week 162 of the Perl Weekly Challenge organized by Mohammad S. Anwar.

Spoiler Alert: This weekly challenge deadline is due in a couple of days from now (on May 1st, 2022 at 24:00). 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: ISBN-13

Write a script to generate the check digit of given ISBN-13 code. Please refer wikipedia for more information.

Example

ISBN-13 check digit for '978-0-306-40615-7' is 7.

This how Wikipedia describes the calculation of the ISBN-13 check digit:

Too fanboy/girl-ish, perhaps?

Yes, I'm well on-trend, by a couple of months. As you see, lockdown has made a hot mess of my blogging schedule. I count myself very fortunate that is the worst effect it's had on me, alongside the gaining of some mass.

WfH WARNING! Watch out for those caramel waffles! A single Stroopwaffle has enough calories to feed a hungry village for a day and are not a sustainable treatment for anxiety. Two kWh per packet, not a word of a lie.

Here are solutions to this weeks challenges from the Perl Weekly Challenge.

You can find my full code on Github

Task 1: Rare Numbers

You are given a positive integer $N. Write a script to generate all Rare numbers of size $N if exists. Please checkout the page for more information about it.

Examples:

• 2 digits: 65
• 6 digits: 621,770
• 9 digits: 281,089,082

The solution

There is a very naive solution to this problem.

Following on from the Gzip::Libdeflate I mentioned before, I also made this: Gzip::Zopfli

It is based on the Zopfli gzip compression library from Google Research.

Both Zopfli and libdeflate seem to excel at compressing JSON files compared to the ordinary zlib compression, sometimes with an improvement of up to 30%. Zopfli usually wins by a small margin over libdeflate. Here are some results of this script on random JSON files:

These are some answers to the Week 161 of the Perl Weekly Challenge organized by Mohammad S. Anwar.

Spoiler Alert: This weekly challenge deadline is due in a couple of days from now (on April 24, 2022 at 24:00). 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: Abecedarian Words

An abecedarian word is a word whose letters are arranged in alphabetical order. For example, “knotty” is an abecedarian word, but “knots” is not. Output or return a list of all abecedarian words in the dictionary, sorted in decreasing order of length.

Optionally, using only abecedarian words, leave a short comment in your code to make your reviewer smile.

Abecedarian Words in Raku

Despite rt.cpan.org still displaying the sunset message, it is in fact not going away forever on the 1st of March, but will have an 'extended downtime' while it is moved elsewhere. In future it'd be nice if communications of such things, and even allowing others to have a say on the matter, could be handled better.

• https://www.nntp.perl.org/group/perl.perl5.porters/2021/02/msg259168.html
• https://news.perlfoundation.org/post/rt-cpan-org-future
• https://blogs.perl.org/users/martin_mcgrath/2021/01/regarding-the-closure-of-rtcpan.html

Hi all,

I started the Inline::F2003 project in 2017 because I have a strong interest in modern Fortran and Perl programming.

The project features the Perl module Inline::F2003. This module allows modern Fortran source to be inlined and called from a Perl program. The module compiles the Fortran source and builds an executable shared library that is loaded into the Perl system.

Inline::F2003 is usually invoked at compile-time. The source fragment below shows typical use of the module.

It's often (for work or for personal projects) that I need to create a real-time feature for a website. This can range from a simple notification whenever an event happens on the server of an existing website, to implementing a real-time multiplayer game or adding a feature inspired from social media websites.

Unfortunately the increase in complexity in code (Perl & JS) and architecture involved in setting up a reliable solution, very often made me forego the opportunity to use WebSockets for many of these projects, and instead resorted to http polling to keep the solution simple for the others to maintain.

So I started looking for a library with a client & server component, that would make life easier. The library would hopefully have to have the following features:

These are some answers to the Week 160 of the Perl Weekly Challenge organized by Mohammad S. Anwar.

Spoiler Alert: This weekly challenge deadline is due in a couple of days from now (on April 17, 2022 at 24:00). 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: Four is Magic

You are given a positive number, $n < 10.

Write a script to generate English text sequence starting with the English cardinal representation of the given number, the word ‘is’ and then the English cardinal representation of the count of characters that made up the first word, followed by a comma. Continue until you reach four.

Example 1:

Input: $n = 5
Output: Five is four, four is magic.

Example 2:

Input: $n = 7
Output: Seven is five, five is four, four is magic.

Here are solutions to this weeks challenges from the Perl Weekly Challenge.

You can find my full code on Github

Task 1: Pack a Spiral

Your task is to pack that array into an MxN matrix spirally counterclockwise, as tightly as possible.

‘Tightly’ means the absolute value |M-N| of the difference has to be as small as possible.

I've turned the libdeflate compression library into a CPAN module:

Gzip::Libdeflate

This is the gzip compression method, but updated.

It's supposed to be much faster and better than libz (the original gzip library).

Sometimes I am getting compression of as much as 30% better on some files.

So far I haven't tested whether or not it is faster.

See the module above for links to the original library and so on.

Since this is an early release, it's very likely indeed that bugs in the module are my fault rather than any problem with libdeflate, so please report them to me.

I've released berrybrew version 1.33. This version has significant enhancements, along with some bug fixes and handling of some uncaught exceptions. The changes reflect versions 1.30 to 1.33.

Major changes include:

UI:

• Allows you to install, switch to, remove and use Strawberry Perls directly
• Can now spawn a CLI window for any Perl you have installed
• Allows you to spawn a CLI window for the currently active Perl
• Provides access to modify several of the core configuration options (debug, file association etc)
• Allows you to disable all berrybrew Perls and restore to system default

Installer:

• Performs an upgrade on any previous berrybrew install
• Adds any new configuration options, while preserving the values of any previously set existing ones
• Provides facility to install the most recent version of Strawberry Perl
• Allows you to have berrybrew manage the .pl file association
• Allows you to have the UI run at system startup
• Aborts if trying to install the same version that's already installed

Functionality:

• You can now leave off the 32/64 bit prefix on a Perl name, and we'll default to _64
• All execution paths return a proper exit code
• Added new berrybrew hidden command, lists all, well, hidden commands

For all other changes, please refer to the Changes file.

Cheers!

-stevieb