I had thought of making programmable coercion before, but never realized the connection between functional position and coercing the object to a fn.
Great job. I think it should be added to the master version, since you still have defcall and in theory nothings "changed" except an increase in performance and conceptual simplicity.
I have actually merged both rntz.coerce.0 and rntz.defcall.0 into arc3.master; I forgot to mention that in my original post. Unless you were asking about merging this into the arc2-based master branch, which I haven't done - I didn't really think about it; I've switched over entirely to arc3 at this point.