It’s not as easy to get information as other languages, but the mailing list is super helpful and all the questions I’ve asked have been replied to by paid Kx (the people that make Q) employees:
Not the person above, but I'd recommend learning APL first. Arthur Whitney (the author of k and q) got started programming by his father and Ken Iverson (the inventor of APL) being friends, and Iverson giving him live demos of APL. Iverson has a lot of amazing resources for learning J (APL's successor) and APL, and learning it will teach you how to be more productive in q, k, J, APL and more!
This is the arthurese micro APL implementation, which inspired the J implementation - although IIRC the design for J was already well on its way at the time (and indeed, Iverson did not consider J a new language, but rather an improved APL dialect, so you could say the design goes back to 1956...)
It likely also formed a draft for A/A+ which Arthur did at Morgan Stanley (open sourced at aplusdev.org, but unmaintained and rotting theese days) - which themselves led to the creation of K.
I thought so on first glance too, but from what I've heard from someone who worked there, it's working software and it makes a lot of money. That's the opposite of a pipe dream, even if far short of AGI.
My understanding is mostly the latter, but definitely also the former, but it's based off of "I worked there, but our customer list isn't public so I can't tell you who" type statements like you'll see elsewhere.
If I had to guess what it's been actually used for, I'd wager it's money laundering or counter-terrorism type stuff; it's fairly well suited to finding connections between people and entities given a large data-set, and unlike many ML models, it can tell you why it thinks someone is suspicious, which might be needed for justifying further investigation. This is a completely wild-ass guess though so take with a giant grain of salt.
