GTK4 Hello world in Perl

hello-gtk4.pl

#!/usr/bin/env perl
use strict;
use warnings;
use utf8;
use v5.38;
use Glib::Object::Introspection;
Glib::Object::Introspection->setup(
  basename => 'Gio',
  version => '2.0',
  package => 'Gio');
Glib::Object::Introspection->setup(
  basename => 'Gtk',
  version => '4.0',
  package => 'Gtk');
Glib::Object::Introspection->setup(
  basename => 'Gdk',
  version => '4.0',
  package => 'Gdk');
Glib::Object::Introspection->setup(
  basename => 'Gsk',
  version => '4.0',
  package => 'Gsk');

my $app = Gtk::Application->new('org.gtk.HelloApp', 'flags-none');

# When the application is launched

$app->signal_connect(activate => sub {
  # create a new window 
  my $win = Gtk::ApplicationWindow->new($app);
  # with a button in it 
  my $btn = Gtk::Button->new_with_label('Hello World!');
  # which closes the window when clicked
  $btn->signal_connect(clicked => sub { $win->close(); });
  $win->set_child($btn);
  $win->present();
});

# Run the application
$app->run();