[yiyus]

There is something I call "the whiteboard test". I work in research, and I spend a good part of my time working with formulas in whiteboards and discussing about them with my colleagues. I am constantly confronted with the irregularities and limitations of standard mathematical notation and see APL as a huge improvement, I would really like to use it more, and I have even taught some basics to colleagues so we can use +/ for sum and ×/ for prod, or ⌈ and ⌊ for max and min, for example.

Iverson solved some remaining inconsistencies in J, and it includes some elegant concepts as tacit programming (+/ % # for the arithmetic average is beautiful) that were not in the original APL, but I do not see myself writing J in the whiteboard or a notebook.

But ASCII may not be the main problem. Curiously, I find that K performs much better in my whiteboard test than J, perhaps because the set of symbols is much smaller. And if you think it may be a matter of getting used to it, I have worked with APL far less than with J and still find the APL symbols more appealing.

There are many things I like about J, and I do not have a very rational explanation to give you, but I agree with those that say that APL is a better tool of thought.