my $before = [qw(1 2 3 4 5 6 7 8 9 10)];
my $after  = [qw(2 3 4 5 1 6 7 8 9 10)];

##</code><code>##

my $element = splice(@$after, 0, 1); #remove element 0;
splice(@$after, 4, 0, $element);     #insert element at offset 4