APL could be interesting, but the last time I checked everyone wanted real money for APL that you could run on modern hardware. Maybe some golfed Perl 5 could be used instead.
There are definitely some options today:
There's a GNU APL implementation (https://www.gnu.org/software/apl/). And Dyalog APL has gratis licenses for personal and educational use (https://www.dyalog.com/prices-and-licences.htm#educational).
J is available under the GPLv3 as well as commercial licenses (http://jsoftware.com/source.htm).
There are options for getting gratis licenses of KDB+ for non-commercial use (https://kx.com/connect-with-us/licenses/).