I want to sort on the numeric part using $a <=> $b

Here's my guess:

use strict;
use warnings;

my @data = qw(a-2 a-10 a-9 a-8 a-0 a-1 a-3 a-6 a-5 a-4 a-7);
my @sorted = map {'a-' . $_} sort {$b <=> $a} map {substr($_, 2, lengt
+h($_) -2) } @data;
print "@sorted\n";

__END__

Outputs:
a-10 a-9 a-8 a-7 a-6 a-5 a-4 a-3 a-2 a-1 a-0
[download]

If you want them to appear in the reverse order, instead do:

my @sorted = map {'a-' . $_} sort {$a <=> $b} map {substr($_, 2, lengt
+h($_) -2) } @data;
[download]

Cheers,
Rob