This is an interesting talk. If you already know about functional datastructures and B+-Trees, you can safely skip to the second half of the talk.
Here is the project he is talking about: https://github.com/datacrypt-project/hitchhiker-tree
I found it very interesting.
Possible to share some links for learning(/getting started) about functional data structures?
Check out Erik Demaine’s 6.851 material from his course on advanced data structures.