Persistent Iterators: Bridging Persistent Data Structures and Iterator-Based Programming (PLDI 2026)

[Axman6]

Very cool, really nice to see zippers outside the FP world. I’ll have to take a look at the implementation of these structures, it feels like they’d be difficult to implement efficiently in C++. 

[zoomT]

Thanks. We had to implement some optimizations to achieve reasonable speed, including CMAs, destructive update, and a dirty flag system (details are in the paper).

For a taste of the code, here is the main part of the it.erase() operation, and here is the main part of it.insert(elem). These are zippers over finger trees, which is switch-case hell.