use strict;
use warnings;
use Roman ();

my @unsorted = qw(8 11 9 4 3);
*f = \&Roman::roman;

my @sorted =
   map  { $_->[0] }
   sort { $a->[1] cmp $b->[1] } # or <=>, or $b before $a
   map  { [$_, f($_)] }
   @unsorted;

print "@sorted\n";

__END__ # output shown below
3 4 9 8 11