gistfile1.pl

#!/usr/bin/env perl
use Mojo;

my $ua = Mojo::UserAgent->new;
$ua->max_redirects(5);

my $base_url ='http://api.powerhousemuseum.com/api/v1/category/xml/';
my $api_key = 'xxx';

my $base_rest_url = Mojo::URL->new($base_url)->query({ api_key => $api_key});

my @names = $ua->get($base_rest_url)->res->dom->find('name')
    ->map(sub { $_->text })->each;

print join ',', @names;