ewig VS rune

You might be interested in ewig and immer by Juan Pedro Bolivar Puente:

https://github.com/arximboldi/ewig

https://github.com/arximboldi/immer

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:

https://m.youtube.com/watch?v=sPhpelUfu8Q

It’s backed by a “vector of vectors” data structure called a relaxed radix balanced tree:

https://infoscience.epfl.ch/record/169879/files/RMTrees.pdf

That original paper has seen lots of attention and attempts at performance improvements, such as:

https://hypirion.com/musings/thesis

https://github.com/hyPiRion/c-rrb

Ewig is an interesting implementation using immutable data structures. https://github.com/arximboldi/ewig Very proof of concept, tries to be a little vi like. Might be worth checking out.

For another approach: I built a didactic text editor to teach "value oriented design" and immutable data-structures in C++:

https://github.com/arximboldi/ewig

It's design is covered in these talks:

- Postmodern immutable data structures: https://www.youtube.com/watch?v=sPhpelUfu8Q

- The most valuable values: https://www.youtube.com/watch?v=_oBx_NbLghY

Two projects that may be of interest, related to this topic:

- Rune (https://github.com/CeleritasCelery/rune) - A re-implementation of Emacs but in Rust (like Remacs, but actively developed)

- Pimacs (https://github.com/federicotdn/pimacs) - Same, but using Go (created by me, but developed in a very slow pace)

[2] https://github.com/CeleritasCelery/rune/issues/17#issuecomme...

I second this ! I had trouble finding the github link, but here is is https://github.com/CeleritasCelery/rune

> How is anything rooted here? The lifetime changed from 'arena to 'root but I don't see a root being created.

In this example, the Vec has been rooted previously. So pushing an object into the Vec will make it "transitively" rooted (accessible from the root). You would root a struct with the root_struct![1] macro, which works very similar to the root! macro shown in the post.

However you made you realize one error; The rooted `Vec` in the example you pointed is a by value type, but in the implementation you can only get references to rooted structs, so that example needs to be updated.

> But later we see roots not obeying a LIFO order, under "Preventing escapes" where roots are dynamically created and destroyed in an arbitrary order.

Objects are just a copyable wrapper around a pointer, so they are not the part that has the LIFO semantics. inside the root! macro[2] there is a `StackRoot` type that is the actual "root". The object just borrows from that so that is has a 'root lifetime and is valid post gc. The actual root struct is not exposed outside of the macro.

I hope this makes the distinction between "roots" and "objects" clearer. Objects are just pointers to heap data. When we root an object we store the data it points to on the root stack and create a new `StackRoot`. Then we say this object is rooted. But the struct that "does the rooting" is inside the macro and not exposed. Rooting a struct works similarly.

[1] https://github.com/CeleritasCelery/rune/blob/5a616efbed763b9...

Hack on Rune