The distributive package

[Tags:bsd3, library, test]

Haskell 98 Distributive functors -- Dual to Traversable

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Versions 0.1, 0.1.1, 0.1.2, 0.2.0,, 0.2.1, 0.2.2, 0.3, 0.3.1, 0.3.2, 0.4, 0.4.1, 0.4.2, 0.4.3,,, 0.4.4, 0.5,,, 0.5.1, 0.5.2
Change log CHANGELOG.markdown
Dependencies base (==4.*), transformers (>=0.2 && <0.4), transformers-compat (==0.1.*) [details]
License BSD3
Copyright Copyright (C) 2011 Edward A. Kmett
Author Edward A. Kmett
Maintainer Edward A. Kmett <>
Category Data Structures
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Source repository head: git clone git://
Uploaded Sun Jan 6 17:34:35 UTC 2013 by EdwardKmett
Distributions Arch:0.5.2, Debian:0.4.4, Fedora:0.5.2, FreeBSD:0.4.4, LTSHaskell:0.5.2, NixOS:0.5.2, Stackage:0.5.2, Tumbleweed:0.5.2
Downloads 140627 total (8344 in the last 30 days)
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Status Docs uploaded by user
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Readme for distributive

Readme for distributive-0.3


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This package provides the notion that is categorically dual to Traversable.

A Distributive Functor is one that you can push any functor inside of.

distribute :: (Functor f, Distributive g) => f (g a) -> g (f a)

Compare this with the corresponding Traversable notion, sequenceA.

sequenceA :: (Applicative f, Traversable g) => g (f a) -> f (g a)

This package includes instances for common types, and includes other methods similar to traverse which fuse the use of fmap.

We only require Functor rather than some dual notion to Applicative, because the latter cannot meaningfully exist in Haskell since all comonoids there are trivial.

Contact Information

Contributions and bug reports are welcome!

Please feel free to contact me through github or on the #haskell IRC channel on

-Edward Kmett