The changes to the IR data structures in this release are really neat- whole trees and graphs fit in a small fixed number of flat arrays. This saves on allocations, saves on total memory usage, and makes them trivial to serialize because there are no pointers.

I recently arrived at a similar design for manipulating NFAs as adjacency matrices, as a replacement for more pointer-y adjacency lists, by way of sparse matrix data structures. Rather than Zig's performance angle, I found that it made whole-graph operations much easier to implement and reuse.

I've also seen similar approaches from array languages like APL, for example this project for running this kind of stuff on GPUs: https://github.com/Co-dfns/Co-dfns

And, I've seen it in Rust as a "workaround" for the borrow checker, where that framing tends to make it feel like cheating or settling, which IMO is unfortunate since when people arrive at it for other reasons it seems to have a lot of other benefits!

There are probably more contexts I'm not familiar with- anyone have any good examples from domains they've worked in?