Array Notation Discussion

[Morten|Dyalog]

This topic has been created for discussions regarding the proposed Array Notation, which Dyalog hopes to implement in a future version of Dyalog APL. The proposal can be found on the APL Wiki. The page on the Wiki, and the associated design considerations page will be updated to contain a record of significant feedback received via this forum or any widely used array language media.

[paulmansour]

Unless I'm missing something, the proposal seems somewhat lacking in examples (it has...1) and explanations. Is there a single PDF somewhere that lays out the formal proposal, an informal explanation of it, and lots of examples? I'd rather not wade through a discussion of how we got where we are. ( I think I asked for this years ago).

[Morten|Dyalog]

This is a good point, thanks! One of the risks of working on a proposal for such a long time, perhaps: there have been lots of examples in presentations over the years (you can find links to the presentations at the bottom of the main Wiki page), but you are right that we should collect more of them a place "right next to" the proposal. We will get this done within a few days. We will also consider extracting the Specification (which is the section in the middle of the page) and the examples into a separate document.

[Phil Last]

Thanks Morten for starting this and for your explanation in Peter's recent wide ranging topic that started solely about "Deserialise".

But to put a spanner in the works can I point out that Paul's point above will soon get lost, even were others to contribute more in the same vein, when other aspects of the notation come under scrutiny. It seems to me that a single topic is too narrow a place for these discussions. I can already envisage at least five almost unrelated topics all of which could come simultaneously under "Array Notation Discussion" and be totally impossible to follow.

Given that there are already twenty separate forums I should not advocate for a separate forum for this. So I suggest to post any new point not directly related to any previous as a new topic within this "Language" forum. Perhaps prefixing the subject with "Array Notation:".

[Morten|Dyalog]

Several threads sounds fine to me. We will endeavour to bring it all together in a single place. If the APL wiki turns out not to be the right place to host, we will maintain the updated proposal with readable comments somewhere else and let everyone know. I envisage that this process may take several months, the very earliest we can imagine implementing anything in the interpreter would be v20, released in 2024.

[paulmansour]

I just watched Adám's webinar at the BAA meeting, which was excellent, but there seems to be some reluctance to the suggestion that Dyalog should produce a document with Dyalog's plans.

I understand the desire to make this more than about Dyalog, and the APL wiki is fine for that.

But the bottom line is that Dyalog is planning to implement something with significant long-term implications, and wants comments on it. Dyalog should have a self-contained document that explains exactly what it is considering to implement, why, the formal spec, with lots of examples and use cases for simple folk like me who thinks Backus-Naur is an evil character from the Marvel Universe, what the implications are, etc. (Like Dyalog did for ⎕CSV, ⎕DT, etc.) This doc should be comprehensive, and I don't even see how Dyalog can proceed with implementation without having this doc internally. This document may change of course as feedback is processed. This is what I want to look at and comment on, not pages on the wiki and collections of videos, as useful as they may be.

This document can of course have footnotes that point to the wiki if someone is interested in the history of how it all came about, who-said-what-when over the last 10 years, or how many hobby implementations there are, or how k and J do things.

[Morten|Dyalog]

Agreed. We opened this discussion topic a bit too early, due to the way the "Deserialisation" discussion evolved. Our plan was/is to produce the type of document that you are looking for after Dyalog'22, and circulate it widely. Most Dyalog folks will be running round like headless chickens for the next 2-3 weeks, preparing and participating in the User Meeting. I suggest we take a break and resume when we have the document ready for circulation.

[Adam|Dyalog]

Our plan was/is to produce the type of document that you are looking for after Dyalog'22, and circulate it widely. (…) I suggest we take a break and resume when we have the document ready for circulation.

The document is now ready: Download.

[ray]

Feedback from the Formal Proposal

I believe that all official Dyalog documentation now uses ⎕IO←1 and ⎕ML←1 by default.

On page 7 in the paragraph "Namespaces", is the note:

Note that for Dyalog APL, ⊃ is Mix using ⎕ML←3 for read‐
ability outside the Dyalog community.

I am very happy with the use (for readability) of "⊃" as mix.
However should this note itself, actually appear before the first use of "⊃" in the examples earlier on page 7?

[ray]

Will the proposed extensions work in a workspace (as against within a function or script).

I am thinking around the problem relating to "Extended Multiline Input".

And will one be able to edit the array directly in the session?