Oh My God.. I tried to learn APL for about two days some years ago and all I gorked was just basic stuff. Then I found out J and recommended that to our APL loving Prof. who converted from his about $2000 expensive prorietary APL symbolic minfu to the free J alternative. I could write much more with J, but Julia still feels more natural.

I've not made any speed comparisons, but maybe you can give APL, J, Julia and SAC a bench? That would be neat! A simple hello world like example, for example using the same FFT algorithm, or "addition" loop would be enough.