I've been reading about effectful systems that would remove the pain points around transformers all the way back to 2016, or earlier. Yet there still doesn't seem to be any to overtake the library ecosystem.
Of course this is where the "write your own custom monad"/free monad interpreter might come into play in practice.
[1] https://github.com/ElementsProject/simplicity/blob/35627fc49...
https://github.com/jasonincanada/kattis/blob/master/src/Pivo...
This tests each element of a list to see if it's a pivot, meaning it's between the maximum to the left and the minimum to the right. In a single logical traversal it shouldn't be able to see the minimum yet, since it hasn't visited those elements. With reverse state you pretend you can anyway and let Haskell figure out the dependencies during execution