Re: Drop $position callback…

The status quo is that we have a position argument in the fold-left/fold-right callback, and we don't have one in the scan-left/scan-right callback. That's just embarrassingly inconsistent and I think we absolutely need to fix it.

Could we please take a straw poll between three possible ways of resolving this:

(a) drop the position callback on fold-left/fold-right (without prejudice to decisions on any other functions)

(b) add the position callback to scan-left/scan-right

(c) drop the scan-left/scan-right functions entirely

Personally I would find any of these three an improvement on the status quo.

The main arguments in favour of the three proposals are:

(a) the position callback appears to compllicate the semantics of the fold functions (especially fold-right) a lot more than other functions: at the same time, it's not going to be used very often, and there's a reasonably easy workaround by creating a "numbered sequence" for the input.

(b) consistency with all other similar functions

(c) the use cases for the scan-left/scan-right functions are underwhelming.

Michael Kay
Saxonica



> On 10 Mar 2025, at 09:13, Norm Tovey-Walsh <norm@saxonica.com> wrote:
> 
> Hi folks,
> 
> We had a long discussion about PR #1735 last week. We seem to have several folks in favor of dropping the $position argument and several folks in favor of keeping it.
> 
> I’m going to put it on the agenda, but unless someone has a new argument that they think will be persuasive (one way or the other), I don’t think there’s much value in spending a lot more time discussing it.
> 
> Some languages provide position arguments, some don’t. We aren’t “copying JavaScript” if we keep them, nor are we “copying C#” if we drop them. Some people think they’re valuable and convenient, some think they’re complex and confusing.
> 
> I prefer it when discussions lead to unanimity or near unanimity, but with my chair’s hat pulled down firmly over my ears, I think the position we’re in is this: we have a status quo draft and this is a proposal to change the status quo. If there are still several members of the CG who are opposed to the change, then I think the PR will have to be abandoned in favor of the status quo.
> 
> If you have new, persuasive arguments, prepare to make them. (Better yet, make them now, in email, persuade your peers that you’re right, and we can resolve this quickly tomorrow, without acrimony.)
> 
>                                        Be seeing you,
>                                          norm
> 
> --
> Norm Tovey-Walsh
> Saxonica
>

Received on Monday, 10 March 2025 15:27:26 UTC