I don't have experience with Redux so I cannot comment on that, but I do believe my rewrite is equivalent to the ReasonML example (it should express the same thing and still be typesafe).

While I'm sure the author did not intentionally try to make TypeScript look bad, (imo) they didn't put enough effort to make it look good either. There's a lot more to TypeScript that this post fails to mention. ReasonML is a good language (I think OCaml was just fine though), but TypeScript is good too.

The author says "ReasonML is everything TypeScript tries to be (and a bit more) without all that JavaScript weirdness.", but I strongly disagree. Embracing "all that JS weirdness" is the whole point of TypeScript, and what makes it so successful. Unlike most typed languages, TypeScript (for better or for worse) adapts its type system to the developer's code, not the other way around. This is why its type system is much more expressive than many other type systems including ReasonML's.