Since print operates on a list you could dispense with the

for my $line (
    map { ... }
    sort {
    ...
    }
    map {
    ...
    }
    <DATA>) {
    print $line;
}
[download]

and just do

print
    map { ... }
    sort {
    ...
    }
    map {
    ...
    }
    <DATA>;
[download]

without the need to assign each line before printing it. It looks a little easier to my eye.

Cheers,

JohnGG