I don't think any ML languages are going to be able to qualify for best language for fast development. They are a paradigm shift for too many developers, which

I don't think any ML languages are going to be able to qualify for best language for fast development. They are a paradigm shift for too many developers, which means you're going to pay a price getting up to speed. Compilation time is generally not the bounding factor for development speed these days. Theoretically, compile time is zero for scripting languages so that's at least one point against weighing compile time heavily. I think the key benefit of OCaml and other ML langauges over Rust right now is actually higher kinded types, dependent types, and things in that realm of abstraction -- which you're probably not going to be using unless they're built into some library you're making use of, so the benefit is kinda moot there. Feels like the best power/weight for abstractions in codebases is the typeclass (or Traits in rust), most of the stuff above that is not great for fast development unless it's already in place. And if we're talking about ML languages, I'm firmly in the Haskell camp because I think it has a better ecosystem (more than any research language should), an incredibly good runtime system (they've got the best native+green thread implementation I've ever seen), and fantastic abstractions for working with shared memory (when you need that). The whole "if it compiles, it works" is generally true. No need for a holy war, but if OCaml is in the race for fast development (which means that ML is in the race), then I'd pick Haskell over it to start on ecosystem/adoption, production readiness and features -- if you can manage to keep your developers from climbing the ladder of research-level abstraction.