APL was designed to be written on a chalkboard (if I remember the story right). It is quite dense, and programs are quite small. Reading is slow and requires you to ponder about what was written. You can hold a lot of content in a small amount of 'ink'.

Now, an idea: HN is always complaining that an ipad (or any other tablet) is a consumption device, as it is not designed to be used with keyboard/mouse. Do any of you know if there is an app where you can write APL with a stylus, and has the ability to evaluate expression on the fly, similar to a repl? That would be an awesome thing to do.

I presented the same idea[0] and some people had already built something similar.

[0] https://news.ycombinator.com/threads?id=JaumeGreen#46718221

List of links:

[NKoP]: https://mlajtos.mu/posts/new-kind-of-paper [MathNotes]: https://mlajtos.mu/posts/new-kind-of-paper-5 [Fluent]: https://news.ycombinator.com/item?id=46649223 [Demo]: https://youtu.be/y5Tpp_y2TBk

https://mlajtos.mu/posts/new-kind-of-paper

On-screen tablet/phone keyboards seem perfect for apl to me.

There’s an iOS port of J but it’s no longer available on the App Store.

Here's a demonstration where APL is written on a typewriter thing: https://www.youtube.com/watch?v=_DTpQ4Kk2wA&t=208