#!/usr/bin/env perl

open (my $data, "<", "test.txt") or die "There was a problem opening: $!";
my @primers = <$data>;
close $data;
chomp @primers;
use strict; use warnings;
use Algorithm::Combinatorics qw(combinations);
my $strings = \@primers;
my $iter = combinations($strings, 2);
while (my $c = $iter->next) {
    print "@$c\n";
}