Exactly! OCaml is the language I like to solve problems in, and I'm excited to solve problems in, so that's why Terrateam uses OCaml (I'm the CTO). You can do a lot (but not all) of this in Go, or TypeScript, but I don't get excited about those languages. Certainly I'll use them if I have to (our UI is written in Svelte) but building your own company is a grind, and using OCaml makes the grind just a bit more exciting, and that's an edge.

Industry is just starting to come around to it, but I've never been more happy programming than when using a strongly-typed language with sum types. What most people fail to understand is that fighting the type checker is almost always a feature, not a bug. It is training you to write code in a way that it understands, which forces your thinking to be less sloppy, even on non-happy paths.

Sum types enable much higher levels of expressivity of what valid states are while still being statically analyzable. Any new PL lacking them, IMO, is making a huge unforced error. They don't apply for every situation, but they do handle a large amount of day-to-day programming concerns.

Side note: OO is oft-maligned in OCaml, but I really appreciate that they included it anyway. I much prefer languages that give you a set of tools to use in whatever situation you find yourself in.

I've used a lot of Rust and Haskell over the past few years (I consider OCaml to be similar), and I think the benefits go beyond just user preference. But I think it's something that requires experience with "must not fail" systems failing in production, and then seeing how these languages make that failure impossible. The level of freedom and confidence that brings is amazing. And yes, that also makes them more fun to use.