tluyben2 comments on “Papers from the Lost Culture of Array Languages (2011)”
It is still there and open source  and I guess you can say k (not kdb or q!) are it’s successors in some ways. Definitely in the way they are all very much APLs, with or without the glyphs. If you read the APL book by Iverson and then go to implementations of APL, A+, J, K, you’ll notice differences, but there are all identical enough to pick them up fast once you are proficient at one of them. kdb+/q are different beasts and that is were the issues start (and the big bucks are to be found); debugging (performance) issues related to critical software written on top of k.
Go to Link: https://news.ycombinator.com/item?id=16849735