[crntaylor]

I used K (well, actually the combination of Q and kdb+) in my previous job at an investment bank, and I've used it (to a lesser degree) in my current job at a hedge fund (disclaimer: I have a PhD...).

K/Q is a beautiful language - it's uncompromisingly terse, extremely powerful, and very fast. The interop with kbd+ (a lightning fast, column-oriented, in-memory database) is gorgeous.

It has an unfortunate reputation for obscurity, stemming mainly from the people who think it's fun to write your entire program as a K one-liner and remove all the whitespace. You can write perfectly clear code in Q - super modular, concise, and well documented. It's just that a lot of Q programmers don't bother.