You could add a parameter that gives the length of the first array like this:

&d(scalar(@a),@a, @b);

sub d{
  my ($len,@c)= @_;
  my @d= splice(@c,$len);
  ...
[download]

But you really need a good reason to do that, this is 2/3 of a bad hack. Use references (and strict and warnings, by the way)

UPDATE: Typo in the script corrected. Thanks go to CountZero for finding it