People interested in this stuff might also want to take a look at the rope in https://github.com/google/xi-editor https://github.com/google/xi-editor. It's not

People interested in this stuff might also want to take a look at the rope in https://github.com/google/xi-editor https://github.com/google/xi-editor. It's not a finger tree, rather it's based on a B-tree, which is simpler but doesn't have quite as good asymptotic guarantees for operations at the beginning and end of the sequence. Also, Rust.