So I've been writing a JIT runtime for a Lisp dialect [0] for a while and got into the habit of feeling jealous of other languages with array primitives, especially after I learned what you can do with arrays or opaque lists (see V8 element kinds [1] for an example). And then I discovered this article (or complaint?) by Xah Lee.

Aesthetically speaking, I quite like conses, in that it is powerful and flexible enough to hold both trees and lists. But performance-wise, I guess it's always the simplest things that are hard to optimize, and cons-style linked lists can't really compete with arrays [2], if you are aiming to get on par with V8.

However, I still believe that, with a JIT runtime, it is possible to have some Lisp lists backed by arrays and am working on it [3]. Currently, =setcdr= causes most trouble for me and I don't know if the additional checks are going to ruin the performance improvement brought by arrays. But if things go well, we might get to see what conses could have cost us.

[0] Emacs Lisp, in Java, with Graal Truffle

[1] https://v8.dev/blog/elements-kinds

[2] https://en.wikichip.org/wiki/pointer_chasing

[3] I am not aware of other Lisps doing this. Cdr-coding is the closest, but it is still a linked list (implicitly).