"You go into your toolchest and you select, I don't know, that sad excuse for a Scala effect system, for instance, because you're trying to tell the world that you take yourself too seriously to care about monad tutorials or abstract category-theory. [...] And you're also blithely unaware that in 2013, Andrej Bauer demonstrated a collection of effects in Eff, which helped pioneer the idea of using in-language handlers, using Pitts’ theory of minimal invariant relations to prove its core calculus adequate to the task. And then I think it was HOPE, which for years continued to push for non-MTL-based systems of effects. And then handlers started showing up in the effect systems of eight different designers. And then it filtered down, through Ocaml, into the .NET languages and finally over into some tragic open source clearance bin. It's sort of comical how you think that you've made a choice that exempts you from category theory, when in fact you are using the effect system that was selected for you."