Static typing is also a nice way to communicate design intentions. But for this to work, the annotations have to be very expressive.

I don’t know the first thing about OCaml, but I have worked professionally with Haskell and static typing is a joy when it adds clarity and makes the contracts of functions instantly readable.

Contrast this with Scala, which I have also worked with professionally and the difference is stark. Scala type annotations are much harder to read, and the mechanism of implicits can make for extremely mysterious code that looks like it shouldn’t compile and only once you track down some distant implicit that’s somehow in scope, can you make sense of the way types are flowing through some function contract.