CppCon
5 HN recommenders · recommended in 11 months, 2017–2025
1:06:00 · 31K views · Oct 27, 2017
Juan Pedro Bolivar Puente explains immutable and persistent data structures in C++ and how they support value semantics. He presents the Immer library, rrb-trees, and a prototype text editor that opens a huge file instantly.
HN people point to it for rrb-trees, text editor data structures and bringing Clojure-style persistent structures to C++.
13 comments from Hacker News
Hey. Check out Juan Pedro Bolivar Puente's talks om value oriented design. He worked on Ableton which is a large application. He specifically speaks to Undo. He describes a much better pattern than the Command Pattern. He also released his source for Value Oriented Data structures Juan Pedro is a next level programmer who I think has pushed the craft forward through his work on bringing Value Oriented Design into the C++ world. Talk I this video Talk II [LINK] Data Structures: [LINK] Application Structure: [LINK] Text Editor: [LINK] Good luck.
> [...] which is a must for anything performance oriented. But that's also not really true. Using functional data structures it is possible to write highly performant software. Check out for example "CppCon 2017: Juan Pedro Bolivar Puente - Postmodern immutable data structures"[1], an impressive talk, in which someone shows their developed editor that can edit huge text files without lag faster than any mainstream editor today. This is enabled by functional data structures. Usage of functional data structures throughout a project also ensures, that parts can be trivially parallelized, which is not true for traditional algorithms, and therefore can easily scale with number of CPUs available. For more on that subject, you might want to watch a few Joe Armstrong talks. Rust achieves type safety by introducing more language concepts like ownership, borrowing, and lifetimes, to formalize, who has access when and how. It also creates things as immutable by default, unless you make use of `mut`. Unfortunately, Rust's philosophy is shared memory and making shared memory access safe, rather than message passing, which is at odds with FP. [1]: this video
You might be interested in ewig and immer by Juan Pedro Bolivar Puente: [LINK] [LINK] See the author instantly opening a ~1GB text file with async loading, paging through, copying/pasting, and undoing/redoing in their prototype “ewig” text editor about 27 minutes into their talk here: this video It’s backed by a “vector of vectors” data structure called a relaxed radix balanced tree: [LINK] That original paper has seen lots of attention and attempts at performance improvements, such as: [LINK] [LINK]
In case anyone hasn't seen it this CppCon talk this video talks about rrb-trees and how they're a great data structure for writing a text editor that can handle unlimited sized documents without locking up, and allows for editing while saving and opening, and an easy way to support an undo command. Most text editors today do not support such functionality. With lockless data structures like an rrb-tree it becomes easy. It really is an ideal way to do write a text editor.
Mmm tasty. If anyone wants a backstory building up to this data structure checkout this talk: this video He builds an rrb-tree which uses the same underlying concepts ALEX uses, just without the ML-enhancement.