regions: Provides the region monad for safely opening and working with scarce resources.

[ bsd3, control, library, monadic-regions ] [ Propose Tags ]

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:

This package provides two modules:

  • Control.Monad.Trans.Region.Unsafe should only be used by library authors wishing to allow their users to open their type of resources in a region. It should not be used by end-users directly!

  • Control.Monad.Trans.Region provides the public and safe interface to regions which can be used by end-users.

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

For an example of how to use this library see the safer-file-handles or usb-safe packages.


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Versions [RSS] 0.1,, 0.2, 0.3, 0.4, 0.5, 0.6,, 0.7,, 0.8, 0.8.1, 0.9, 0.10, 0.11
Dependencies base (>=4 && <4.3), base-unicode-symbols (>=0.1.1 && <0.2), MonadCatchIO-transformers (>=0.0.2 && <0.0.3), transformers (>=0.1.4 && <0.2) [details]
License BSD-3-Clause
Copyright 2009 Bas van Dijk
Author Bas van Dijk
Maintainer Bas van Dijk <>
Category Control, Monadic Regions
Source repo head: darcs get
Uploaded by BasVanDijk at 2010-01-07T14:14:15Z
Distributions NixOS:0.11
Downloads 11805 total (24 in the last 30 days)
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Status Docs uploaded by user
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