`$` refers to the length of the array, so `d[$]` is an array-bounds error. `d[$-1]` is needed for the last element, but you can’t do that blindly, you have to check that the length is nonzero or you’ll get unsigned underflow to ulong.max

Which will also cause an array-bounds error. So you're covered!

perl have $d[$#d] represent the index of last element.

$my_properly_named_array[$#my_properly_named_array] doesn't look like QoL.

Yeah, but $#list is better used for writing loops:

  foreach my $i (0..$#list) {
    say "$i: $list[$i]";
  }

For getting the last element from a list you can just use -1 (and of course further negative numbers work like you would expect, -2 is second to last and so on):

  my @last_three = @items[-1, -2, -3];

yes, I forgot perl have negative index!