#!/usr/bin/env perl
#
#   pm_1155868_first_grep_large_file_2.pl [no modules]
#

use strict;
use warnings;
use autodie;

open my $lines_fh, '<', input_filename();
while (<$lines_fh>) {
    next unless is_a_match($_);
    process_match($_) and last;
}

sub input_filename { 'pm_1155868_input.txt' }
sub get_strings { [qw{rst uvw xyz}] }
BEGIN {
    my $re = '(?:' . join('|', @{get_strings()}) . ')';
    sub is_a_match { $_[0] =~ /$re/ }
}
sub process_match { print "Match: $_[0]" }

##</code><code>##

$ pm_1155868_first_grep_large_file_2.pl
Match: dddddddxyzdddd