I just spent the last few days implementing a better version of an "persistent list" data structure (heavily modelled on Clojure's vector) for a new programming language that I'm working on.<p>I did a quick survey of existing implementations in multiple languages and found all of them lacking. They are either overly complex, slow, or both. Even Clojure's vector, while being simple and very performant, is only usable as a stack, not as a queue, and therefore IMO inadequate as a "generic random-access array-like data structure" (akin to Python's list, i.e. "just use it don't worry about performance").<p>My version is about as fast as Clojure's vector, while implementing a "deque"-like interface. It's a bit more complex, but still significantly simpler than Scala's vectors (both Scala 2 and Scala 3). Cyclops (a Java-only persistent collection library) is so slow I didn't even bother finishing the benchmarks. I also compared my code to Rust's `im` (way more complex), C++'s `immer` (stack, not deque) and `immutable.js` (slower than ClojureScript).<p>I'll clean up the code and post it here.