Edit: I just realized that you are the creator of https://beyondloom.com/tools/specialk.html and https://beyondloom.com/decker/index.html. I just want to say that your work is awesome! I've really enjoyed reading through your website many a time.
Edit: I just realized that you are the creator of https://beyondloom.com/tools/specialk.html and https://beyondloom.com/decker/index.html. I just want to say that your work is awesome! I've really enjoyed reading through your website many a time.
oK is a slow browser-based FOSS implementation of k6, with fun bells and whistles like "iKe", a visual livecoding environment. ngn/k and oK have diverged a bit, but are largely similar: https://github.com/JohnEarnest/ok
Q is a K-derived language built into kdb+; this is probably the most commercially viable dialect to learn, with the best educational materials (I recommend Nick Psaris' Q Tips), but it is proprietary, with (last I checked) free licenses available for personal use.
If you've seen Decker you may also have been exposed to Lil, which is similar in many ways to Q. It is more verbose and less expressive than Q or K, but I've generally heard people say they find it comparatively accessible: http://beyondloom.com/tools/trylil.html