What are hyperfunctions in the context of computer science?

Question

In Arrows: A General Interface to Computation I found this brief remark on hyperfunctions:

The weird datatype

newtype Hyper b c = H (Hyper c b -> c)

can be shown to be an arrow [KLP01].

but the link to the paper is broken.

There is also hyperfunctions package on Hackage.

Neither provides any explanation of what they are and what are their properties.

So what are hyperfunctions, how are they useful and what are their properties?

---

^{Apparently the same name is used for something completely different in the context of holomorphic functions}

^{As I know almost nothing about the concept, I just guessed the tags from my current references coming from Haskell/FP, feel free to correct them.}

Answer 1

I could find something here: http://www.citeulike.org/user/Benja/author/Launchbury:J

Abstract
Hyperfunctions from A to B are elements of the infinitely nested function type

[A; B] = (((...) -> A) -> B) -> A) -> B: ...