Spoiler Alert: This weekly challenge deadline is due in a few days from now (on September 1, 2024, at 23:59). This blog post provides some solutions to this challenge. Please don’t read on if you intend to complete the challenge on your own.
Task 1: Lucky Integer
You are given an array of integers, @ints.
Write a script to find the lucky integer if found otherwise return -1. If there are more than one then return the largest.
A lucky integer is an integer that has a frequency in the array equal to its value.
Chapter 3 of Higher Order Perl describes various approaches to memoization of an expensive function: private cache and the Memoize module. The book was written in 2005 (Perl was at version 5.8 back then) , so it does not include another way for function caching that is now available : caching through state variables (introduced in Perl 5.10). The Fibonacci example considered in HOP also requires the ability to initialize state hash variables (available since Perl 5.28). The code below contrasts the implementation with a state variable v.s. the memoize module:
We merged HTTP-Tiny#6, and then discussed a number of topics:
some improvements on the process for releasing blead-upstream dual-life modules are needed
the instructions for releasing a new Perl are difficult to follow and partly redundant, the process takes longer than it should, and more of it could be automated
the pumpkin permission list has grown over time, and probably needs to be trimmed
more talk about Markdown documentation
thoughts on how to strike a better balance with the verbosity/brevity of meeting minutes
In the week 270, the second task was really interesting and difficult. Here’s a slightly reformulated version:
We’re given an array of positive integers @ints and two additional integers, $x and $y. We can apply any sequence of the following two operations: 1. Increment one element of @ints. 2. Increment two elements of @ints. The cost of each application of operation 1 is $x, the cost of operation 2 is $y. What’s the minimal cost of a sequence of operations that makes all the elements of @ints equal?
Why do I say it was difficult? I compared all the Perl and Raku solutions I could find in the GitHub repository and none of them gave the same results as mine. It took me several days to find an algorithm that would answer the tricky inputs I generated with a pen and paper, and one more day to optimise it to find the solutions in a reasonable time.
Spoiler Alert: This blog post provides some solutions to this challenge. Please don’t read on if you intend to complete the challenge on your own.
Task 2: Digit Count Value
You are given an array of positive integers, @ints.
Write a script to return true if for every index i in the range 0 <= i < size of array, the digit i occurs exactly the $ints[$i] times in the given array otherwise return false.
Last year at the Perl Toolchain Summit (PTS) in Lyon, I left three draft pull requests: one about the class declaration introduced in Perl 5.37, one about the PAUSE on docker, and one about multifactor authentication. I wanted to brush them up and ask Andreas König to merge some, but which should I prioritize this year?
Following up on my previous post (MariaDB 10 and Perl DBIx::Class::Schema::Loader), I wanted to try the 'deploy' feature to create database tables from Schema/Result classes.
I was surprised that I could not create a table in the database when a timestamp field had a default of current_time(). The problem was that the generated CREATE TABLE entry placed quotes around 'current_timestamp()' causing an error and rejected entry.
As mentioned in a previous post, I had created file SQL/Translator/Producer/MariDB.pm as part of the effort to get MariaDB 10 clients to work correctly with DBIx::Class::Schema::Loader. Initially it was a clone of the MySQL.pm file with name substitutions. To correct the current_timestamp problem I added a search/replace in the existing create_field subroutine in the MariaDB.pm file to remove the quotes.
revived the “HTTPS out-of-the-box” project: the CPAN Security Group committed to help us select a workable solution, with a goal of implementing it in time for Perl 5.42
Spoiler Alert: This weekly challenge deadline is due in a few days from now (on August 25, 2024, at 23:59). This blog post provides some solutions to this challenge. Please don’t read on if you intend to complete the challenge on your own.
Task 1: Unique Number
You are given an array of integers, @ints, where every element appears more than once except one element.
`
Write a script to find the one element that appears exactly one time.
We're happy to confirm the venue and date of this year's London Perl & Raku Workshop.
When: Saturday 26th October 2024 Where: The Trampery, 239 Old Street, London EC1V 9EY
This year's workshop will be held at The Trampery, at Old Street. A dedicated modern event space in central London. We have hired both The Ballroom and The Library; allowing us to run a main track for up to 160 attendees, and second smaller track for up to 35 attendees.
The Trampery in Old Street is located a two minute walk from the Northern Line's Old Street tube station in central London. The Northern Line has stops at most of the major train stations in London, or trivial links to others, so we recommend taking the tube to get to the venue.
If you haven't already, please signup and submit talks using the official workshop site: https://act.yapc.eu/lpw2024/
Thanks to this year's sponsors, without whom LPW would not happen:
The paella must be possibly the worst national dish ever created, I thought to myself as I looked at the charred remains in my pan. It is as if the mind of some ancient Spanish conquistador, returned from his conquests abroad feeling hungry and unfulfilled, dreamt
of bringing byriani to Spain, but in the midst of pillaging had forgotten to take culinary notes.
"How difficult can it be, Jose?" the weary warrior muses,
"Yeah, yeah, its just rice and meat, innit", says his Catalan colleague coming from the Spanish equivalent of Birmingham.
"We could use something flavourless, amorphous and chewy, like mussels, instead of meat",
"Whoaaah, nice,",
"And langoustines...",
"langa-what?",
"I know, right? Just throw them all in, don't bother shelling them",
"Raphael has some tomatoes he doesn't need for pelting passing pedestrians",
"Ahh...the flavours", fanning the flames as the smell of their concoction cooking brings back fond memories of far-away burning villages.
Spoiler Alert: This weekly challenge deadline is due in a few days from now (on August 18, 2024, at 23:59). This blog post provides some solutions to this challenge. Please don’t read on if you intend to complete the challenge on your own.
Task 2: Changing Keys
You are given an alphabetic string, $str, as typed by user.
Write a script to find the number of times user had to change the key to type the given string. Changing key is defined as using a key different from the last used key. The shift and caps lock keys won’t be counted.
Fixing DBIx::Class::Schema::Loader For Use With MariaDB 10 Client Software
I recently set up a virtual Server Running Rocky Linux 9 as a client from which to query a remote MariaDB database. I used perlbrew to install Perl 5.38.2. I installed client related RPMs for MariaDB 10.5, I installed DBIx::Class as a relational mapper that can create Perl Schema Result Classes for each table in the database. If you are new to DBIx::Class, you can review its purpose and features in DBIx::Class::Manual::Intro. The Result Classes used by Perl to query the database are stored on the client server in a schema directory. They are created with the DBIx::Class::Schema::Loader module.
The new Carp::Object module is an object-oriented replacement for Carp or Carp::Clan. What is the point ? Well, here is some motivation.
The Carp module and its croak function have been around since perl 5.000. Errors can then be reported from the perspective of where the module was called, instead of the line where the error is raised. This excellent example from Mastering Perl explains why this is useful :
1 package Local::Math {
2 use Carp qw(croak);
3 sub divide {
4 my( $class, $numerator, $denominator ) = @_;
5 croak q(Can't divide by zero!) if $denominator == 0;
6 $numerator / $denominator;
7 }
8 }
Sometimes life catches up with you. I've felt that way for the last few years and I'm probably not alone.
During that time the cpancover project has basically just been plodding along, pretty much just working. As new modules were uploaded to CPAN, cpancover would pick them up, calculate the test coverage, and make the results available to be displayed on metacpan, along with detailed output on cpancover.com.
A little while ago I decided it was probably about time that I should update the OS and perl version and libraries and stuff.
Spoiler Alert: This weekly challenge deadline is due in a few days from now (on August 18, 2024, at 23:59). This blog post provides some solutions to this challenge. Please don’t read on if you intend to complete the challenge on your own.
Task 1: Good Integer
You are given a positive integer, $int, having 3 or more digits.
Write a script to return the Good Integer in the given integer or -1 if none found.
A good integer is exactly three consecutive matching digits.
We talked about HTTPS in core, and some ideas about it, while the CPAN
Security Group is preparing some proposals. Today was the deadline for
releasing 5.41.1, but we don’t have volunteers yet, so Graham said he
would do it sometime soon.
We also noted that we’ll need some volunteers for the next 10 or so
development releases.
Tried posting this on Reddit instead, but there seem to be some issues with code insert there, so here it is properly: Although Benchmark::DKbench is a good overall indicator for generic CPU performance for comparing different systems (especially when it comes to Perl software), the best benchmark is always your own code. Hence, the module now lets you incorporate your own custom benchmarks. You can either have them run together with the default benchmarks, or run only your own set, just taking advantage of the framework (reports, multi-threading, monotonic precision timing, configurable repeats with averages/stdev, calculation of thread scaling etc). Here's an example where I run a couple of custom benchmarks on their own with Benchmark::DKbench:
I just got back from the Perl Toolchain Summit 2024 in Lisbon Portugal!
Thank you to Grant Street Group for sponsoring my attendance at the event! Grant Street Group is an amazing place to work, and GSG is hiring! Contact me on irc.perl.org (Exodist) if you would like a referral.
This year I took a little side trip before the PTS to explore Lisbon with my wife. It is an amazing city, with a lot of history. I highly recommend visiting it and exploring the castles, palaces, and archaeological sights!
My goal for the PTS was to polish up Yath 2.0 and get it out the door. Spoiler alert: I did not achieve this goal, though I did make good progress. Instead several other things occurred that were even better as far as achieving things that require collaboration go!
