Please, get rid off the primes example, as it is horrible inefficient (in the sense of, "Ok, let's find the first n primes by a simple well-known algorithm, like the Sieve of Eratosthenes") and a simple (non-pure) array-based approach will kick its ass.
Such a toy-example just contributes to the wrong belief that Haskell is just useful in academics or teaching. Some time ago I did implement the sieve in several languages and I also considered Haskell but set for an unpure approach (IOUArray) and it was extremely fast (getting close to C/C++ and outperforming Go, Java, etc.). Obviously such an example is not good to present Haskell's novel ideas but this toy example is worse then no example.
edit: Sorry, did not want to appear nit-picky, I like the language and the new design.