The Haskell Cabal
The Common Architecture for Building Applications and Libraries.
http://www.haskell.org/cabal

IMPORTANT INFORMATION:

See both the README file and the changelog for important interface
changes and installation instructions.

DOWNLOAD:

The Haskell Cabal has reached stable version 1.4.0.2

Download the Cabal library here (source tarballs available):
http://www.haskell.org/cabal/download.html

BUGS:

Please report bugs and wish-list items at:
http://hackage.haskell.org/trac/hackage
or send an email to libraries@haskell.org.

ABOUT:

The Haskell Cabal is meant to be a part of a larger infrastructure for
distributing, organizing, and cataloging Haskell Libraries and
Tools. It is an effort to provide a framework for developers to more
effectively contribute their software to the Haskell community.

Specifically, the Cabal describes what a Haskell package is, how these
packages interact with the language, and what Haskell implementations
must to do to support packages. The Cabal also specifies some
infrastructure (code) that makes it easy for tool authors to build and
distribute conforming packages.

The Cabal is only one contribution to the larger goal. In particular,
the Cabal says nothing about more global issues such as how authors
decide where in the module name space their library should live; how
users can find a package they want; how orphan packages find new
owners; and so on.

MORE INFORMATION:

Please see the web site for the source code, interfaces, and user guide:
http://www.haskell.org/cabal/

There is some more information available on the development wiki:
http://hackage.haskell.org/trac/hackage/wiki