why $ is need to access array [negative index]?

[Patrick Schluter]

On Friday, 18 September 2020 at 20:56:30 UTC, mw wrote:
> On Friday, 18 September 2020 at 20:48:47 UTC, bachmeier wrote:
>> I'm inclined to say typing a single character is not a 
>> hardship in exchange for extreme clarity of the code. Keep in 
>> mind that
>
> It not about saving "typing a single character".
>
> In the example I showed,
>
> signs[sign] = ...;  // the sign can be -1, 0, 1
>
> in D, to write the same code, you have to test the sign and 
> branch:
>
> if (sign >= 0) {
>   signs[  sign] = ...;
> } else {
>   signs[$+sign] = ...;  // remember + here
> }

signs[1+sign]