Almost five years ago, Saoirse “boats” wrote “Notes on a smaller Rust”, and a year after that, revisited the idea.
The basic idea is a language that is highly inspired by Rust but doesn’t have the strict constraint of being a “systems” language in the vein of C and C++; in particular, it can have a nontrivial (or “thick”) runtime and doesn’t need to limit itself to “zero-cost” abstractions.
What languages are being designed that fit this description? I’ve seen a few scripting languages written in Rust on GitHub, but none of them have been very active. I also recently learned about Hylo, which does have some ideas that I think are promising, but it seems too syntactically alien to really be a “smaller Rust.”
Edit to add: I think Graydon Hoare’s post about language design choices he would have preferred for Rust also sheds some light on the kind of things a hypothetical “Rust-like but not Rust” language could do differently: https://graydon2.dreamwidth.org/307291.html
Although I’m fully in camp functional, I doubt that. There are problems that are inherently stateful and rely on mutability. Modelling that in Haskell often results in unnecessary abstractions. I think Rust hits a sweet spot here (when you’re that experienced to write idiomatic Rust, whatever that exactly is). Also being lazy by default has its own (performance) implications, strict + lazy iterators (like Rust) is a good default IMO.