> The idea of UI being a pure function of the model seems so obviously incorrect, and leads to such a plethora of problems, that it is a bit puzzling how one could come up with it in the first place, and certainly how one would stick with it in face of the avalanche of problems that just keeps coming. A part of this is certainly the current unthinking infatuation with functional programming ideas. These ideas are broadly good, but not nearly as widely or universally applicable as some of their more starry-eyed proponents propose (I hesitate to use the word "think" in this context).