Most folks on HN who are interested in PLs, including me, are familiar with transducers at a high level. Composable, performant, yada yada ya. What we (or maybe just I) do not have is a nontrivial example of advantage.

Your comment sharpened that for me. I don't want FizzBuzz; I want someone taking a reasonable toy problem, such as a trad+photon+quadtree raytracer and demonstrating advantage by applying the concept.