But Swift has had a more specific target platform, where it wouldn't make sense to produce excessively high level generic abstractions.

Whereas a language like Haskell is happy to try some absurdly abstract concepts in the interest of promoting computer science.

If you don't use complicated compiler extensions (which, to be fair, many people do), then Haskell's complexity is more compositional. There are not a lot of fundamental concepts you need to understand; it's just their combination that creates the complexity (such as typeclasses like Monad).

Swift's complexity feels much less compositional. There are still a lot of situations where I won't really know how certain features interact (especially when it comes to generics, associated types, etc.). Also, the documentation on some edge-cases is basically non-existant.

I would Swift is more complex than Haskell, though much more familiar to many programmers. Pure Haskell is pretty simple, all in all. Maybe using it isn’t, given the ecosystem ;-)

Swift and Rust are definitely similar in complexity, but Rust actually merits most of its complexity imo. It gives strong guarantees and a strong foundation for the future; I don’t believe that Swift has that. Swift adds a lot of features for the sake of having them, and I think that will catch up with the language quickly (see C++.)