my @values = (
    { name => 'fred', index => 2 },
    { name => 'bob', index => 1 },
    { name => 'john', index => 4 },
    { name => 'peter', index => 3 },
);

my @sorted_values = sort { $a->{index} <=> $b->{index} } @values;

##</code><code>##

my @sorted_indices = sort { $array_b[$a] <=> $array_b[$b] } 0 .. $#array_b;

@array_a = @array_a[@sorted_indices];
@array_b = @array_b[@sorted_indices];