Interestingly, my article from a few years ago has a very similar motivation and initial figure. And it too ends up at append-only programming. But it does so i

Interestingly, my article from a few years ago has a very similar motivation and initial figure. And it too ends up at append-only programming. But it does so in a very different way: http://akkartik.name/post/wart-layers http://akkartik.name/post/wart-layers (I still program all my side projects in this way.)