I've just realized that what I'm describing is called a rope data structure: https://en.wikipedia.org/wiki/Rope_(data_structure) https://en.wikipedia.org/wiki/R

I've just realized that what I'm describing is called a rope data structure: https://en.wikipedia.org/wiki/Rope_(data_structure) https://en.wikipedia.org/wiki/Rope_(data_structure) So, a difference list is a rope, but encoded with closures instead of explicit trees.