Been doing k for a bit (under a year). A single glance is optimistic, but probably only took me a few seconds. Almost certainly faster than any equivalent code in any other language. It's even easier if you give it a nice name, like "fib".
Unfortunately it's closed source so I can't share much about the world of application and library development with q/k. If you want to learn more about how it's used though, I'd recommend checking out KX and kdb+.