Up until around 2 months ago the project actually built with stable Rust. But as I had to get the project ready for release it became a recurring annoyance to write shims for things I needed (e.g. `maybe_uninit_fill` to conveniently fill the return value of my arena allocator). My breaking point was the aforementioned `LinkedList` API and its lack of cursors in stable Rust. I know it's silly, but this, combined with the time pressure, and combined with the lack of `allocator_api` in stable, just kind of broke me. I deleted all my shims the same day (or sometime around it at least), switched to nightly Rust and called it a day.

It definitely helped me with my development speed, because I had a much larger breadth of APIs available to me all at once. Now that the project is released, I'll probably stay with the nightly version for another few months until after `let_chains` is out in stable, because I genuinely love that quality-of-life feature so much and just don't want to live without it anymore. Afterward, I'll make sure it builds in stable Rust. There's not really any genuine reason it needs nightly, except for... time.

Apropos custom helpers, I think it may be worth optimizing `Vec::splice`. I wrote myself a custom splice function to reduce the binary size: https://github.com/microsoft/edit/blob/e8d40f6e7a95a6e19765f...

The differences can be quite significant: https://godbolt.org/z/GeoEnf5M7