[JulianMorrison]

Kona, a K implementation that's open source. https://github.com/kevinlawler/kona

Useful for reading K-tradition C programming style, too.

[ColanR]

I've been puzzled about Kona for a while, since I don't really see a purpose for it. K/Q is specifically intended as a very high-efficiency language, and Kona doesn't say anything about benchmarks.

[bakul]

The original reason may have been that k3 was not open source and the free version was limited. But in general people write these things for all sorts of reasons. Just as there are dozens of Scheme interpreters.