Thanks, I enjoyed that article. It gives a vivid picture of the gap between the array languages niche and mainstream programming culture.

I found this too, when I tried them both, first J then APL, perhaps because:

* APL uses () [] and {} in their pairs to parenthesize things, just like other languages, while J uses the 6 symbols as standalones, harder to read the code.

* All verbs in APL are single characters, whereas J symbols might be more than one.

* J, unlike APL, uses the concepts of rank, and forks and hooks, which are both difficult to grasp and don't seem to add much to the array processing idea.

life:{3=a-x*4=a:2{+(0+':x)+1_x,0}/x}

    0+':x  -> "sum each element with one to the left
               (0 left of the first)"
    1_x,0  -> "drop first, add zero at the end"
    
    (0+':x)+1_x,0 -> "sum each element with the one
                      to the left and the one to the
                      right (sum of previous expressions)"

    a:2{+...}/x -> "do that; transpose; do that; 
                    transpose again, and assign to a.
                    2{}/ means 'do twice'"

    4=a     -> "1 where a=4, 0 otherwise"
    x*4=a   -> "1 where x is 1 and a=4, 0 otherwise"
    a-x*4=a -> "decrease a from 4 to 3 if x=1 in the 
                that place"
    3=a-x*4=a -> "1 where one has 3 neighbours"

There is code golfing here; It would have been purely readable K code if it wasn't golfed. But it would also have been two to three times as long.