Which languages are on-topic?
All APL dialects or only Dyalog APL?
How about J?
This will also affect the design and logo of the site.
[APL](https://aplwiki.com) and APL-like languages (e.g. [J](https://aplwiki.com/wiki/J), [K](https://en.wikipedia.org/wiki/K_(programming_language)) and [Q](https://en.wikipedia.org/wiki/Q_(programming_language_from_Kx_Systems))), along with [array programming](https://en.wikipedia.org/wiki/Array_programming) in any language (e.g. [NumPy](https://en.wikipedia.org/wiki/NumPy), [Julia](https://en.wikipedia.org/wiki/Julia_(programming_language)), and [MatLab](https://en.wikipedia.org/wiki/MATLAB)) (especially if in comparison to APLs).
# APL only
In line with [APL Wiki](https://aplwiki.com/wiki/APL_Wiki:Content_guidelines#What_is_APL.3F) only APLs are addressed directly, with related topics being relegated to content about them in the context of main-line APL.
This disallows things like J, K, and NumPy.
While this might lead to less content being included, it'll probable lessen the noise ratio, as non-APL content isn't generally *useful* the the APLer, though it might be interesting.
It also makes UI choices regard syntax colouring, the custom language bar, and the default TIO language easier.
There are [only 227](https://stackoverflow.com/questions/tagged/apl) questions tagged `apl` on SO. There are also (https://stackoverflow.com/questions/tagged/j) tagged `j` and (https://stackoverflow.com/questions/tagged/k) tagged `k`.
That being so, it would be good to err on the side of wider scope. From what I can tell, although the syntax looks very different in each case, both [J](https://en.wikipedia.org/wiki/J_(programming_language))[^1] and [K](https://en.wikipedia.org/wiki/K_(programming_language))[^2] are closely related to APL. Likewise Q and LYaPAS though those look like they may be very niche.
The real question, which I can't answer myself, is whether expertise and interest in APL is likely to denote expertise and interest of some degree in the other areas. If that is the case I hope you'll include them in scope.
[^1]: > The J programming language, developed in the early 1990s by Kenneth E. Iverson and Roger Hui, is an array programming language ***based primarily on APL*** (also by Iverson).
[^2]: > K is a proprietary array processing programming language developed by Arthur Whitney and commercialized by Kx Systems. The language serves as the foundation for kdb+, an in-memory, column-based database, and other related financial products. The language, originally developed in 1993, ***is a variant of APL*** and contains elements of Scheme. Advocates of the language emphasize its speed, facility in handling arrays, and expressive syntax.
# Dyalog only
The benefit of this is that there'll be no confusion as to what code works where, and it'll be very easy to make design choices for the site, language bar, and TIO language.
The downside is that there'll be less content.
A possibility is to include close Dyalog "clones", like ngn/apl and dzaima/APL.