Rust is not fast by design. OCaml is kind of but still not as fast as Ruby for me at least. I spent a lot of time learning Haskell and Scala and I'm still lea

Rust is not fast by design. OCaml is kind of but still not as fast as Ruby for me at least. I spent a lot of time learning Haskell and Scala and I'm still learning. And they never caught up with ruby on rails in terms of velocity for me. One big thing is about the feedback loop. Typesafe so what? Type is type, it's not either value or business invariant. I'm not convinced as long as you're not writing proofs in dependent-type languages like Idris. So, I still prefer REPL that I can sure about in no time, and watching tests every 0.1s after I change the code. One can say interpreted languages are optimized for developing because when you change the code, it can be just run once -- there's no point of compiling it because in the next second you'll be changing it. And compiled languages are optimized for the runtime, because it's compiled it's ready to be run many times. Of course, there are JIT for interpreted languages and interpreted static-typed languages, but Haskell REPL is still pretty slow compared to Slime. And for Rails, you can actually touch anything runtime entity in the console.