Mostly. Mona is k2/k3 (described in this post). K4/Q is much much cleaner - so it is easier and preferable in my opinion. You can get a free(gratis) 32-bit interpreter of that to play with; but if you insist on free(libre), kona is acceptable to dabble in. There's also J, which I think prefers purity and mathematical aesthetics to practicality, that you may like.
(J is a different language; both J and K can be traced back to the origin of A, a 20 C line implementation of an APL dialect)
https://github.com/kevinlawler/kona