Bookmarked Wikipedia: AppleScript update by Mark GardnerMark Gardner (Wikipedia)
Update infobox: remove unused & invalid values, update current AppleScript version & official website after updating Wikidata; still need to verify earliest macOS release that included this version & update Script Editor page as well

Made my first Wikipedia edit in five years, this time to update some basic info on AppleScript. In the process I learned how to update the AppleScript entry on Wikidata, Wikimedia’s data­base for pop­u­lat­ing such things.

This week’s Perl and Raku Conference 2022 in Houston was packed with great pre­sen­ta­tions, and I humbly added to them with a five-​ish minute light­ning talk on two of Perl’s more mis­un­der­stood func­tions: map and grep.

Sorry about the um”s and ah”s…

I’ve writ­ten much about list pro­cess­ing in Perl, and this talk was based on the fol­low­ing blog posts:

Overall I loved attend­ing the con­fer­ence, and it real­ly invig­o­rat­ed my par­tic­i­pa­tion in the Perl com­mu­ni­ty. Stay tuned as I resume reg­u­lar posting!

Update for Raku

On Twitter I nudged promi­nent Raku hack­er (and recov­ered Perl hack­er) Elizabeth Mattijsen to write about the Raku pro­gram­ming language’s map and grep func­tion­al­i­ty. Check out her five-​part series on DEV.to.

IKEA BLÅHAJ shark toys

IKEA’s toy BLÅHAJ shark has become a beloved Internet icon over the past sev­er­al years. I thought it might be cute to write a lit­tle Perl to get info about it and even dis­play a cud­dly pic­ture right in the ter­mi­nal where I’m run­ning the code. Maybe this will give you some ideas for your own quick web clients. Of course, you could accom­plish all of these things using a pipeline of indi­vid­ual command-​line util­i­ties like curl, jq, and GNU core­uti­lsbase64. These exam­ples focus on Perl as the glue, though.

Warning: dodgy API ahead

I haven’t found a publicly-​documented and ‑sup­port­ed offi­cial API for query­ing IKEA prod­uct infor­ma­tion but oth­ers have decon­struct­ed the company’s web site AJAX requests so we can use that instead. The alter­na­tive would be to scrape the IKEA web site direct­ly which, although pos­si­ble, would be more tedious and prone to fail­ure should their design change. An unof­fi­cial API is also unre­li­able but the sim­pler client code is eas­i­er to change should any errors surface.

Enter the Mojolicious

My orig­i­nal goal was to do this in a sin­gle line issued to the perl com­mand, and luck­i­ly the Mojolicious framework’s ojo mod­ule is tailor-​made for such things. By adding a -Mojo switch to the perl com­mand, you get over a dozen quick single-​character func­tions for spin­ning up a quick web appli­ca­tion or, in our case, mak­ing and inter­pret­ing web requests with­out a lot of cer­e­mo­ny. Here’s the start of my one-​line request to the IKEA API for infor­ma­tion on their BLÅHAJ prod­uct, using ojo’s g func­tion to per­form an HTTP GET and dis­play­ing the JSON from the response body to the terminal.

$ perl -Mojo -E 'say g("https://sik.search.blue.cdtapps.com/us/en/search-result-page", form => {types => "PRODUCT", q => "BLÅHAJ"})->body'

This cur­rent­ly returns over 2,400 lines of data, so after read­ing it over I’ll con­vert the response body JSON to a Perl data struc­ture and dump only the main prod­uct infor­ma­tion using ojo’s r func­tion:

$ perl -Mojo -E 'say r g("https://sik.search.blue.cdtapps.com/us/en/search-result-page", form => {types => "PRODUCT", q => "BLÅHAJ"})->json->{searchResultPage}{products}{main}{items}[0]{product}'
{
  "availability" => [],
  "breathTaking" => bless( do{\(my $o = 0)}, 'JSON::PP::Boolean' ),
  "colors" => [
    {
      "hex" => "0058a3",
      "id" => 10007,
      "name" => "blue"
    },
    {
      "hex" => "ffffff",
      "id" => 10156,
      "name" => "white"
    }
  ],
  "contextualImageUrl" => "https://www.ikea.com/us/en/images/products/blahaj-soft-toy-shark__0877371_pe633608_s5.jpg",
  "currencyCode" => "USD",
  "discount" => "",
  "features" => [],
  "gprDescription" => {
    "numberOfVariants" => 0,
    "variants" => []
  },
  "id" => 90373590,
  "itemMeasureReferenceText" => "39 \x{bc} \"",
  "itemNo" => 90373590,
  "itemNoGlobal" => 30373588,
  "itemType" => "ART",
  "lastChance" => $VAR1->{"breathTaking"},
  "mainImageAlt" => "BL\x{c5}HAJ Soft toy, shark, 39 \x{bc} \"",
  "mainImageUrl" => "https://www.ikea.com/us/en/images/products/blahaj-soft-toy-shark__0710175_pe727378_s5.jpg",
  "name" => "BL\x{c5}HAJ",
  "onlineSellable" => bless( do{\(my $o = 1)}, 'JSON::PP::Boolean' ),
  "pipUrl" => "https://www.ikea.com/us/en/p/blahaj-soft-toy-shark-90373590/",
  "price" => {
    "decimals" => 99,
    "isRegularCurrency" => $VAR1->{"breathTaking"},
    "prefix" => "\$",
    "separator" => ".",
    "suffix" => "",
    "wholeNumber" => 19
  },
  "priceNumeral" => "19.99",
  "quickFacts" => [],
  "tag" => "NONE",
  "typeName" => "Soft toy"
}

If I just want the price I can do:

$ perl -Mojo -E 'say g("https://sik.search.blue.cdtapps.com/us/en/search-result-page", form => {types => "PRODUCT", q => "BLÅHAJ"})->json->{searchResultPage}{products}{main}{items}[0]{product}->@{qw(currencyCode priceNumeral)}'
USD19.99

That ->@{qw(currencyCode priceNumeral)} towards the end uses the post­fix ref­er­ence slic­ing syn­tax intro­duced exper­i­men­tal­ly in Perl v5.20 and made offi­cial in v5.24. If you’re using an old­er perl, you’d say:

$ perl -Mojo -E 'say @{g("https://sik.search.blue.cdtapps.com/us/en/search-result-page", form => {types => "PRODUCT", q => "BLÅHAJ"})->json->{searchResultPage}{products}{main}{items}[0]{product}}{qw(currencyCode priceNumeral)}'
USD19.99

I pre­fer the for­mer, though, because it’s eas­i­er to read left-to-right.

But I’m not in the United States! Where’s my native currency?

You can either replace the us/en” in the URL above or use the core I18N::LangTags::Detect mod­ule added in Perl v5.8.5 if you’re real­ly deter­mined to be portable across dif­fer­ent users’ locales. This is real­ly stretch­ing the def­i­n­i­tion of one-​liner,” though.

$ LANG=de_DE.UTF-8 perl -Mojo -MI18N::LangTags::Detect -E 'my @lang = (split /-/, I18N::LangTags::Detect::detect)[1,0]; say g("https://sik.search.blue.cdtapps.com/" . join("/", @lang == 2 ? @lang : ("us", "en")) . "/search-result-page", form => {types => "PRODUCT", q => "BLÅHAJ"})->json->{searchResultPage}{products}{main}{items}[0]{product}->@{qw(currencyCode priceNumeral)}'
EUR27.99

Window dressing

It’s hard to envi­sion cud­dling a num­ber, but luck­i­ly the prod­uct infor­ma­tion returned above links to a JPEG file in the mainImageUrl key. My favorite ter­mi­nal app iTerm2 can dis­play images inline from either a file or Base64 encod­ed data, so adding an extra HTTP request and encod­ing from the core MIME::Base64 mod­ule yields:

$ perl -Mojo -MMIME::Base64 -E 'say "\c[]1337;File=inline=1;width=100%:", encode_base64(g(g("https://sik.search.blue.cdtapps.com/us/en/search-result-page", form => {types => "PRODUCT", q => "BLÅHAJ"})->json->{searchResultPage}{products}{main}{items}[0]{product}{mainImageUrl})->body), "\cG"'

(You could just send the image URL to iTerm2’s bun­dled imgcat util­i­ty, but where’s the fun in that?)

$ imgcat --url `perl -Mojo -E 'print g("https://sik.search.blue.cdtapps.com/us/en/search-result-page", form => {types => "PRODUCT", q => "BLÅHAJ"})->json->{searchResultPage}{products}{main}{items}[0]{product}{mainImageUrl}'`

But I don’t have iTerm2 or a Mac!

I got you. At the expense of a num­ber of oth­er depen­den­cies, here’s a ver­sion that will work on any ter­mi­nal that sup­ports 256-​color mode with ANSI codes using Image::Term256Color from CPAN and a Unicode font with block char­ac­ters. I’ll also use Term::ReadKey to size the image for the width of your win­dow. (Again, this stretch­es the def­i­n­i­tion of one-​liner.”)

$ perl -Mojo -MImage::Term256Color -MTerm::ReadKey -E 'say for Image::Term256Color::convert(g(g("https://sik.search.blue.cdtapps.com/us/en/search-result-page", form => {types => "PRODUCT", q => "BLÅHAJ"})->json->{searchResultPage}{products}{main}{items}[0]{product}{mainImageUrl})->body, {scale_x => (GetTerminalSize)[0], utf8 => 1})'

I hate Mojolicious! Can’t you just use core modules?

Fine. Here’s retriev­ing the prod­uct price using HTTP::Tiny and the pure-​Perl JSON pars­er JSON::PP, which were added to core in ver­sion 5.14.

$ perl -MHTTP::Tiny -MJSON::PP -E 'say @{decode_json(HTTP::Tiny->new->get("https://sik.search.blue.cdtapps.com/us/en/search-result-page?types=PRODUCT&q=BLÅHAJ")->{content})->{searchResultPage}{products}{main}{items}[0]{product}}{qw(currencyCode priceNumeral)}'
USD19.99

Fetching and dis­play­ing a pic­ture of the hug­gable shark using MIME::Base64 or Image::Term256Color as above is left as an exer­cise to the reader.

plate of eggs and hash browns

This month I start­ed a new job at Alert Logic, a cyber­se­cu­ri­ty provider with Perl (among many oth­er things) at its beat­ing heart. I’ve been learn­ing a lot, and part of the process has been under­stand­ing the APIs in the code base. To that end, I’ve been writ­ing small test scripts to tease apart data struc­tures, using Perl array-​processing, list-​processing, and hash- (i.e., asso­cia­tive array)-processing func­tions.

I’ve cov­ered map, grep, and friends a cou­ple times before. Most recent­ly, I described using List::Util’s any func­tion to check if a con­di­tion is true for any item in a list. In the sim­plest case, you can use it to check to see if a giv­en val­ue is in the list at all:

use feature 'say';
use List::Util 'any';
my @colors =
  qw(red orange yellow green blue indigo violet);
say 'matched' if any { /^red$/ } @colors;

However, if you’re going to be doing this a lot with arbi­trary strings, Perl FAQ sec­tion 4 advis­es turn­ing the array into the keys of a hash and then check­ing for mem­ber­ship there. For exam­ple, here’s a sim­ple script to check if the col­ors input (either from the key­board or from files passed as argu­ments) are in the rainbow:

#!/usr/bin/env perl

use v5.22; # introduced <<>> for safe opening of arguments
use warnings;
 
my %in_colors = map {$_ => 1}
  qw(red orange yellow green blue indigo violet);

while (<<>>) {
  chomp;
  say "$_ is in the rainbow" if $in_colors{$_};
}

List::Util has a bunch of func­tions for pro­cess­ing lists of pairs that I’ve found use­ful when paw­ing through hash­es. pairgrep, for exam­ple, acts just like grep but instead assigns $a and $b to each key and val­ue passed in and returns the result­ing pairs that match. I’ve used it as a quick way to search for hash entries match­ing cer­tain val­ue conditions:

use List::Util 'pairgrep';
my %numbers = (zero => 0, one => 1, two => 2, three => 3);
my %odds = pairgrep {$b % 2} %numbers;

Sure, you could do this by invok­ing a mix of plain grep, keys, and a hash slice, but it’s nois­i­er and more repetitive:

use v5.20; # for key/value hash slice 
my %odds = %numbers{grep {$numbers{$_} % 2} keys %numbers};

pairgreps com­piled C‑based XS code can also be faster, as evi­denced by this Benchmark script that works through a hash made of the Unix words file (479,828 entries on my machine):

#!/usr/bin/env perl

use v5.20;
use warnings;
use List::Util 'pairgrep';
use Benchmark 'cmpthese';

my (%words, $count);
open my $fh, '<', '/usr/share/dict/words'
  or die "can't open words: $!";
while (<$fh>) {
  chomp;
  $words{$_} = $count++;
}
close $fh;

cmpthese(100, {
  grep => sub {
    my %odds = %words{grep {$words{$_} % 2} keys %words};
  },
  pairgrep => sub {
    my %odds = pairgrep {$b % 2} %words;
  },
} );

Benchmark out­put:

           Rate     grep pairgrep
grep     1.47/s       --     -20%
pairgrep 1.84/s      25%       --

In gen­er­al, I urge you to work through the Perl doc­u­men­ta­tions tuto­ri­als on ref­er­ences, lists of lists, the data struc­tures cook­book, and the FAQs on array and hash manip­u­la­tion. Then dip into the var­i­ous list-​processing mod­ules (espe­cial­ly the includ­ed List::Util and CPAN’s List::SomeUtils) for ready-​made func­tions for com­mon oper­a­tions. You’ll find a wealth of tech­niques for cre­at­ing, man­ag­ing, and pro­cess­ing the data struc­tures that your pro­grams need.

arrow communication direction display

When I first start­ed writ­ing Perl in my ear­ly 20’s, I tend­ed to fol­low a lot of the struc­tured pro­gram­ming con­ven­tions I had learned in school through Pascal, espe­cial­ly the notion that every func­tion has a sin­gle point of exit. For example:

sub double_even_number {
    # not using signatures, this is mid-1990's code
    my $number = shift;

    if (not $number % 2) {
        $number *= 2;
    }

    return $number; 
}

This could get pret­ty con­vo­lut­ed, espe­cial­ly if I was doing some­thing like val­i­dat­ing mul­ti­ple argu­ments. And at the time I didn’t yet grok how to han­dle excep­tions with eval and die, so I’d end up with code like:

sub print_postal_address {
    # too many arguments, I know
    my ($name, $street1, $street2, $city, $state, $zip) = @_;
    # also this notion of addresses is naive and US-centric

    my $error;

    if (!$name) {
        $error = 'no name';
    }
    else {
        print "$name\n";

        if (!$street1) {
            $error = 'no street';
        }
        else {
            print "$street1\n";

            if ($street2) {
                print "$street2\n";
            }

            if (!$city) {
                $error = 'no city';
            }
            else {
                print "$city, ";

                if (!$state) {
                    $error = 'no state';
                }
                else {
                    print "$state ";

                    if (!$zip) {
                        $error = 'no ZIP code';
                    }
                    else {
                        print "$zip\n";
                    }
                }
            }
        }
    }

    return $error;
}

What a mess. Want to count all those braces to make sure they’re bal­anced? This is some­times called the arrow anti-​pattern, with the arrowhead(s) being the most nest­ed state­ment. The default ProhibitDeepNests perlcritic pol­i­cy is meant to keep you from doing that.

The way out (lit­er­al­ly) is guard claus­es: check­ing ear­ly if some­thing is valid and bail­ing out quick­ly if not. The above exam­ple could be written:

sub print_postal_address {
    my ($name, $street1, $street2, $city, $state, $zip) = @_;

    if (!$name) {
        return 'no name';
    }
    if (!$street1) {
        return 'no street1';
    }
    if (!$city) {
        return 'no city';
    }
    if (!$state) {
        return 'no state';
    }
    if (!$zip) {
        return 'no zip';
    }

    print join "\n",
      $name,
      $street1,
      $street2 ? $street2 : (),
      "$city, $state $zip\n";

    return;
}

With Perl’s state­ment mod­i­fiers (some­times called post­fix con­trols) we can do even better:

    ...

    return 'no name'    if !$name;
    return 'no street1' if !$street1;
    return 'no city'    if !$city;
    return 'no state'   if !$state;
    return 'no zip'     if !$zip;

    ...

(Why if instead of unless? Because the lat­ter can be con­fus­ing with double-​negatives.)

Guard claus­es aren’t lim­it­ed to the begin­nings of func­tions or even exit­ing func­tions entire­ly. Often you’ll want to skip or even exit ear­ly con­di­tions in a loop, like this exam­ple that process­es files from stan­dard input or the com­mand line:

while (<>) {
    next if /^SKIP THIS LINE: /;
    last if /^END THINGS HERE$/;

    ...
}

Of course, if you are val­i­dat­ing func­tion argu­ments, you should con­sid­er using actu­al sub­rou­tine sig­na­tures if you have a Perl new­er than v5.20 (released in 2014), or one of the oth­er type val­i­da­tion solu­tions if not. Today I would write that postal func­tion like this, using Type::Params for val­i­da­tion and named arguments:

use feature qw(say state); 
use Types::Standard 'Str';
use Type::Params 'compile_named';

sub print_postal_address {
    state $check = compile_named(
        name    => Str,
        street1 => Str,
        street2 => Str, {optional => 1},
        city    => Str,
        state   => Str,
        zip     => Str,
    );
    my $arg = $check->(@_);

    say join "\n",
      $arg->{name},
      $arg->{street1},
      $arg->{street2} ? $arg->{street2} : (),
      "$arg->{city}, $arg->{state} $arg->{zip}";

    return;
}

print_postal_address(
    name    => 'J. Random Hacker',
    street1 => '123 Any Street',
    city    => 'Somewhereville',
    state   => 'TX',
    zip     => 12345,
);

Note that was this part of a larg­er pro­gram, I’d wrap that print_postal_address call in a try block and catch excep­tions such as those thrown by the code ref­er­ence $check gen­er­at­ed by compile_named. This high­lights one con­cern of guard claus­es and oth­er return ear­ly” pat­terns: depend­ing on how much has already occurred in your pro­gram, you may have to per­form some resource cleanup either in a catch block or some­thing like Syntax::Keyword::Try’s finally block if you need to tidy up after both suc­cess and failure.