FWIW, I'm leaning toward something that just creates a Clojure map, converts it to js (hopefully via clj->js), then leaves it to Vega to evaluate it

like gyptis does (https://github.com/dvdt/gyptis)

Not a bad option 🙂

I guess it depends how much you plan to use it. If it's more than a little, it's not too bad usually to write a thin cljs wrapper over a js lib.

That's the approach I took with the Mathbox lib, which is another JS graphics lib. If you want to get an idea of what's involved, take a look at https://github.com/eggsyntax/cljs-mathbox

The actual wrappers (which was most of the work) are in https://github.com/eggsyntax/cljs-mathbox/tree/master/src/cljs_mathbox

A lot of it's stuff like this:

(defn bezier [mb-instance opts-map]
  (. mb-instance bezier (clj->js opts-map)))

that looks interesting

& if you have to do a bunch of them, you could write a fn-to-js-method macro or something...

my JS fu is not as good as I'd like it to be, so I favor something simple until I get a chunk of time to read up on all the frontend stuff I don't currently know

Totally.