Well, that was in the context of the claim that "Rust is very much ML". We weren't talking about (say) BitC here. I've got nearly two decades worth of ML code

Well, that was in the context of the claim that "Rust is very much ML". We weren't talking about (say) BitC here. I've got nearly two decades worth of ML code lying around (mostly OCaml, some SML and F#) and for most of it rewriting it in Rust would require significant redesign for the reasons I mentioned. This starts with even very simple things like List.rev.