I kinda liked J but my gripe with it is that I have to learn it almost from scratch every time I try to use it.

The tacit syntax is too idiosyncratic (I always forget the different types of verb trains) and I'm not entirely convinced it actually helped me as a "tool of thought" (but it might just be me not sticking with it long enough to be able to decode The Matrix).

I wish multidimensional arrays were a first-class citizen in my main languages though.

> "tool of thought"

I felt compelled to make a comment about that last week[1]; I stopped thinking of it like "APL is a tool for thought [and nothing else is]" and started thinking of it like the Sapir-Whorf idea; all programming languages and mathematical notations are tools for thought and we don't normally talk about them like that. Their designs promote/encourage/ease some ways of thinking about problems and reveal some patterns in the data and the algorithms, and on the flip side by making design choices they necessarily demote/discourage/frustrate other ways of thinking and obscure some patterns.

It's not just that Go has Goroutines in it as a technical feature, it's that having a first class way to express that feature encourages Go developers to think about solving problems in terms of Goroutines. A bit like "if the only tool you have is a hammer, every problem starts to looks like a nail". But we still go down the direction of making a kitchen-sink language which has a bodge of half-implemented mismatched features from different areas wedged awkwardly into its syntax, and then saying "this company only does Java" or "only uses C++" instead of making smaller simpler tools that fit particular problems and working on ways to learn about them and integrate them.

> "I wish multidimensional arrays were a first-class citizen in my main languages though."

It has not helped you but you wish you had access to it because it's changed the way you think? Same; it has changed the way I think about bulk-transforming arrays of data, and using intermediate array structures, and thinking it's good to have an interpreter layer which transforms a whole array using SIMD/vector extensions instead of a loop which does individual non-SIMD tests on items so it can exit part way through the array to "save time".

[1] https://news.ycombinator.com/item?id=46183808

You're probably aware of it, but if not: Uiua is much easier to understand in this regard.

> I'm not entirely convinced it actually helped me as a "tool of thought"

This is so real. I had the same issue and was only able to break through by collabing with professional APLers. It's very non-ideal for the curious autodidacts.

I'd love to share, hone, and flesh out what the Tool of Thought looks like in practice with interested others. For anyone here to whom that sounds fun, feel free to reach out. Contact info is in my profile.