Have you tried using (clojure.reflect/reflect Mat) to see all the available methods and their signatures? That might point you in the right direction.

Reflect confirms what I read in the source. The MatType is an enum, and turns out MatType/CV_64F is an Int32.

(let [x (Size. 4 5)
      y MatType/CV_64F]
    (Mat.   x  (MatType. y)))

And this form works.

Hi! We ported our Clojure product to ClojureScript, and want to do the same with ClojureCLR. Is there an equivalent of the ClojureScript differences page (https://clojurescript.org/about/differences) for ClojureCLR? Mostly interested in what is not supported (like one biggy for cljs was the macro compilation differences)