free: Monads for free

[ bsd3, control, library, monads ] [ Propose Tags ]

Free monads are useful for many tree-like structures and domain specific languages.

If f is a Functor then the free Monad on f is the type of trees whose nodes are labeled with the constructors of f. The word "free" is used in the sense of "unrestricted" rather than "zero-cost": Free f makes no constraining assumptions beyond those given by f and the definition of Monad. As used here it is a standard term from the mathematical theory of adjoint functors.

Cofree comonads are dual to free monads. They provide convenient ways to talk about branching streams and rose-trees, and can be used to annotate syntax trees. The cofree comonad can be seen as a stream parameterized by a Functor that controls its branching factor.

More information on free monads, including examples, can be found in the following blog posts: http://comonad.com/reader/2008/monads-for-free/ http://comonad.com/reader/2011/free-monads-for-less/


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Versions 0.1.0, 0.1.1, 0.2.0, 0.2.1, 0.2.2, 0.2.3, 1.8.0, 1.8.0.1, 1.8.0.3, 1.8.0.4, 2.0, 2.0.1, 2.0.1.1, 2.0.2, 2.0.3, 2.1, 2.1.1, 2.1.1.1, 2.2, 3.0, 3.1, 3.1.1, 3.2, 3.3, 3.3.0.1, 3.3.0.2, 3.3.1, 3.4, 3.4.1, 3.4.2, 4.0, 4.1, 4.2, 4.4, 4.5, 4.6, 4.6.1, 4.7, 4.7.1, 4.8, 4.8.0.1, 4.9, 4.10.0.1, 4.11, 4.12, 4.12.1, 4.12.2, 4.12.3, 4.12.4, 5, 5.0.1, 5.0.2
Change log CHANGELOG.markdown
Dependencies base (>=4 && <4.8), bifunctors (==4.*), comonad (==4.*), distributive (>=0.2.1), mtl (>=2.0.1.0 && <2.2), prelude-extras (>=0.4 && <1), profunctors (==4.*), semigroupoids (==4.*), semigroups (>=0.8.3.1 && <1), template-haskell (>=2.7.0.0 && <3), transformers (>=0.2.0 && <0.4) [details]
License BSD-3-Clause
Copyright Copyright (C) 2008-2013 Edward A. Kmett
Author Edward A. Kmett
Maintainer Edward A. Kmett <ekmett@gmail.com>
Revised Revision 1 made by HerbertValerioRiedel at Tue Dec 2 10:55:14 UTC 2014
Category Control, Monads
Home page http://github.com/ekmett/free/
Bug tracker http://github.com/ekmett/free/issues
Source repo head: git clone git://github.com/ekmett/free.git
Uploaded by EdwardKmett at Sun Apr 20 00:30:56 UTC 2014
Distributions Arch:5.0.2, Debian:4.12.1, Fedora:4.12.4, FreeBSD:4.12.1, LTSHaskell:5.0.2, NixOS:5.0.2, Stackage:5.0.2, openSUSE:5.0.2
Downloads 159540 total (576 in the last 30 days)
Rating 2.5 (votes: 3) [estimated by rule of succession]
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Status Docs available [build log]
Successful builds reported [all 1 reports]
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free

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This package provides a common definitions for working with free monads, free applicatives, and cofree comonads in Haskell.

Contact Information

Contributions and bug reports are welcome!

Please feel free to contact me through github or on the #haskell IRC channel on irc.freenode.net.

-Edward Kmett