As others have stated, it is unclear what you want here. Your title and text seem to have no relationship to each other. Please read the guidelines in "How do I post a question effectively?" and follow them before posting again.

My best guess at what you're after:

#!/usr/bin/env perl -l

use strict;
use warnings;

my @x = qw{X A B};
my $x = shift @x;
my @y = map { [ $_ ] } @x;
push @$_, $x for @y;
print join ',' => map { "@$_" } @y;
[download]

Output:

A X,B X
[download]