Log Message:
Import hs-regions-0.4 as wip/hs-regions.

This package provides the region monad transformer. Scarce resources
like files, memory pointers or USB devices for example can be opened
in a region. When the region terminates, all opened resources will be
automatically closed. The main advantage of regions is that the opened
resources can not be returned from the region which ensures no I/O
with closed resources is possible.

The primary technique used in this package is called "Lightweight
monadic regions" which was invented by Oleg Kiselyov and Chung-chieh
Shan. See:

http://okmij.org/ftp/Haskell/regions.html#light-weight

Also see the regions-monadsfd and regions-monadstf packages which
provide instances for the classes in the respected monads packages.

For an example on how to use this library see the safer-file-handles,
usb-safe or regional-pointers packages.

Note that if you want to open your type of scarce resource in a
region, the only thing you have to do is define an instance for the
Resource class (which you can find in: Control.Resource).