Perl is a programming language that will always live deep into my heart. It was the first programming language I can say I mastered. But it’s sad that not even God uses this programming language anymore. It’s a great programming language, it has evolved in the latest years, so much that it even looks like a modern programming language. Some of the stupid design of perl has been fixed.

It is known by everyone that the perl Syntax sucks. It makes 0 sense, at least for learners. Experimented perl programmers no longer fear anything.

For comments or questions on this post, email me at sukamu at riseup dot net.

Function prototypes

Perl always lacked function signatures (prototypes), the way you passed arguments to a function in perl was horrible, it is like functions in bash:

1: sub sum() {
2:      my ($x, $y) = @_;
3:      return $x + $y;
4: }
6: print sum(3, 4); # Prints 7

You define the function parameters inside the function, just like in bash. This is, in my opinion, horrible, but since perl 5.36, you can have function signatures, to use perl’s new features, you have to specify the version of perl you want to use, to do this just use the use keyword.

1: use v5.36;
3: sub sum($x, $y) {
4:      return $x + $y;
5: }
6: say sum(4, 5); # prints 9, and adds a newline.

The function signature feature was added in Perl v5.20, but it started to be considered stable at v5.36. There is also this new “say” function that is just like print but adds a newline at the end of the line, like python’s print or C’s puts(). These features were inhereted from Raku.


Perl added an experimental Try/Catch blocks in v5.34. These are still considered experimental as of v5.36. But you can still use them. The try/catch (also finally if you’re using v5.36) works like any other programming language that has try/catch blocks. As this feature is still experimental and should not be used seriously, you have to specify that you want to use the experimental feature 'try':

 1: use v5.36;
 2: use strict;
 3: use warnings;
 5: use experimental 'try';
 7: sub attempt() {
 8:      say "I'm doing something!";
 9:      die "Goodbye cruel world";
10:      return 42;
11: }
13: try {
14:      my $x = attempt();
15: } catch($e) {
16:      say "Exception: $e";
17: } finally {
18:      say "Finished";
19: }

And the thing does exactly that, the script dies inside the try block, so it’s passed to the catch block as an exception. And finally, the finally block is executed.

the isa operator

The isa operator tests whether an object has a instance of a certain class, in non-object programming slang, it just checks the type of a variable. The isa operator was introdouced as an experimental feature in perl v5.34.0 and was no longer considered experimental in the current v5.36.0.

 1: #!/usr/bin/perl
 3: use v5.36;
 4: use LWP::UserAgent;
 5: my $ua = LWP::UserAgent->new;
 8: if ($ua isa LWP::UserAgent ) {
 9:      say "LWP::UserAgent object instanced successfully";
10: } else {
11:      die "something that should not have happened happened.";
12: }

Before this operator, you had to use the ref function and string checker to accomplish the same thing, like this;

1: use LWP::UserAgent;
2: my $ua = LWP::UserAgent->new;
4: if(ref($ua) eq "LWP::UserAgent") {
5:      # Do stuff...
6: } else {
7:      # Do stuff when failed.
8: }

Which clearly makes a difference at the moment of reading and writing new code.

The defer block

This is a feature that others programming languages have, C++ calls it RAII, there are plans to add it to the next version of the C programming language, also golang has the defer block. Thing is that in perl it works like this:

 1: #!/usr/bin/perl
 3: use v5.36;
 5: use experimental 'defer';
 6: my $x = 0;
 7: {
 8:      $x = (2^31)-1;
 9:      defer {
10:           say "The block has finished it's execution";
11:           $x = 0;
12:      };
13:      say "Let's pretend i'm doing stuff...";
14:      say "x value: $x";
15: }
16: say "x value: $x";

Simillary to try/catch, this function is experimental and should not be used in production. Or use it if you want. But don’t blame the perl devs if something breaks (which, honestly, I doubt that your system will break because of an experimental feature. Just don’t abuse it or use it in very weird ways and you’ll be fine).

builtin values

builtin is a new core module that shipts with perl v5.36. This package are plains function and behave like user defined cuntions. They do not provide any special thing you have never seen in perl before. But they’re still good to have, as they help to make the code more easy to write and read. These functions are also experimental so be careful at the moment of using them.

 1: use v5.36;
 2: use experimental 'builtin';
 3: use builtin qw(true false is_bool trim
 4:                               reftype created_as_string
 5:                               created_as_number); # There are more builtin functions...
 6: my $bool_value = true;
 8: if ($bool_value) {
 9:      say "The value is true";
10: } else {
11:      say "The value is false";
12: }
14: say is_bool($bool_value);       # Will print "true";
16: my $str = "\t\n\r   Hello world\t\r\n";
17: $str = trim($str);    # This trim() function will remove all the whitespace
18: #characteres defined by unicode (
20: print $str; # Will print "Hello world", without newlines, tabs, or
21:             # carriage returns.

These new functions are not the greatest or most useful thing ever, but they are still helpful.


Perl’s not dead. At least that’s what I kept telling myself because I don’t want to see this programming language dying in my lifespan. But it’s pretty cool that they still add new features to Perl 5. Despite everything you could say, perl is still alive, but no one uses it, but well, no one uses Haskell either. :^)