I think that, having used both of them, Rust is going to feel a lot lower level than OCaml. The single biggest thing is that it's pretty hard (slash near impossible) to write Rust code without thinking about memory allocation, which adds non-trivial mental overhead to the work. That isn't to put down Rust - I think they are the first language that actually has a static, type-checkable story about memory allocation, and that's phenomenal, _but_, the reason for this is to be able to write soft-realtime code (for example, browser engines, games, etc). Web code, at least in the early stages, probably usually has lower performance requirements, and most people would probably trade some performance (and I don't mean to say that OCaml is slow, anymore than Go is slow, etc) for not having to even think about that stuff.