My version. What can I say, I like the ? : operator :)

Usage: &print_with_ands(\@array);

sub print_with_ands {
  my $x=0;
  my $a=shift;
  printf "$a->[$x-1]%s",
    defined $a->[$x+1] ? ", " : 
    ! defined $a->[$x] ? "\n" : 
    $x==1 ? " and " : ", and " 
    while defined $a->[$x++];
}
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