Negative nth index

Negative nth index

[Anand Tamariya]

[-- Attachment #1: Type: text/plain, Size: 71 bytes --]

Should negative index for nth be valid? e.g.
(nth -1 '(1 2)) returns 1

[-- Attachment #2: Type: text/html, Size: 137 bytes --]

Re: Negative nth index

[Eli Zaretskii]

> From: Anand Tamariya <atamariya@gmail.com>
> Date: Sun, 22 Dec 2024 11:13:18 +0530
> 
> Should negative index for nth be valid? e.g. 
> (nth -1 '(1 2)) returns 1

What does this do in other Lisps?

Re: Negative nth index

[Tassilo Horn]

Eli Zaretskii <eliz@gnu.org> writes:

>> Should negative index for nth be valid? e.g. 
>> (nth -1 '(1 2)) returns 1
>
> What does this do in other Lisps?

In CL, it errors (ditto for nthcdr with negative index).  Same for (nth
'(1 2 3) -1) in Clojure or (list-ref '(1 2 3) -1) in Scheme.

Bye,
Tassilo

Re: Negative nth index

[Andreas Schwab]

On Dez 22 2024, Anand Tamariya wrote:

> (nth -1 '(1 2)) returns 1

What would (nth -1 '#1=(1 2 . #1#)) return?

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."