my @numbers = (7, 12, 49, 44);
my @sorted =
    sort {
        print("Comparing $a with $b...\n");
        $a <=> $b
    }
    @numbers;


##</code><code>##

Comparing 7 with 12...
Comparing 49 with 44...
Comparing 7 with 44...
Comparing 44 with 12...