If you want polished tooling, support and documentation, learn Dyalog. The company freely distributes great learning materials and trial licenses. Apart from th

If you want polished tooling, support and documentation, learn Dyalog. The company freely distributes great learning materials and trial licenses. Apart from the fact that you will have to (eventually) learn a new keyboard layout, it's a pretty beginner-friendly choice. If you want to get a job working with a vector language, learn Q. It's very popular in finance these days. If you live in the right cities and you have a strong grasp of KDB+ you can practically name your price. If you want something simple and beautiful: Learn K. It's the most aggressively compact (in terms of scope of language features as well as concrete on-disk-size) in the APL family. The whole language fits in your head easily. There are deep similarities between the dfns dialect of Dyalog and K. (It's also my personal favorite.) If you want to see features you haven't been exposed to before, learn J. It's probably the most alien-looking of these four (Dyalog's special symbols notwithstanding), but it's overflowing with curious and interesting ideas. Rich support for tacit programming. An elaborate numeric tower. A primitive for expressing arbitrary state machines. Much, much more.