How do I call mmap() in Haskell?

[William Lee Irwin III]

I've been wondering how to do mmap() in Haskell since I don't know how
to get things to interact with the runtime system etc.

Actually, similar questions apply to asynchronous IO.

The foreign function interface is nice and all, but modelling the
result with types and interoperating with the runtime system is the
real question here.


-- wli