perl -e 'open my $outfh, ">", "sample.txt"; while ($i++ < 50_000_000) {print $outfh "abcdefghijklmnopqrstuvwxyz0123456789\n";}'

##</code><code>##

perl -E 'open my $infh, "<", "sample.txt"; while(<$infh>) {$i++} say $i;'

##</code><code>##

my %dispatch = (
    sample =>  sub {my $capture = shift; # do something with $capture},
    good   =>  sub {my $capture = shift; # do something with $capture},
);

while(<FILE>) {
    if (/^(sample|good)\s+(\S+)/) {
        $dispatch{$1}->($2);
    }
}