Interesting to see the complaints on J. I've been playing with the Q language (basically K with some sugar) that is part of KDB+ and I think it solves all your problems in that it is a lot cleaner/simpler, very fast, support for dictionaries, strings, JSON, datetimes (it is a database too), very terse file IO...etc. The only drawback is it's a commercial product. Who knows though. Maybe they would give you a pretty cheap license if you agree to use it mostly like a calculator (not for large-scale financial analysis). The whole install was basically a single executable and a license file. Very elegant. The doc is finally pretty good too.

Edit: I tried using J and the install was pretty large iirc and the whole language is just too big and complicated. I know you can do cool stuff with it, but it just seemed to me that the cost was too high relative to benefit. Your mileage may vary.