KDB+ provides Q, which is implemented in terms of k4.

It should also be noted that the k4 implementation has evolved since Arthur left/sold to First Derivatives. Kdb 4.1 release touts some nice additions to q [1](syntactically I'm not sure if this cascades into underlying k... I don't have that depth of knowledge)

1 https://kx.com/blog/discover-kdb-4-1s-new-features/