The distributive package

[Tags: bsd3, library]

Distributive functors -- Dual to Traversable

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Versions0.1, 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
Change logCHANGELOG.markdown
Dependenciesbase (==4.*), ghc-prim, tagged (>=0.7 && <1), transformers (>=0.2 && <0.5), transformers-compat (>=0.3 && <1) [details]
CopyrightCopyright (C) 2011-2014 Edward A. Kmett
AuthorEdward A. Kmett
MaintainerEdward A. Kmett <>
CategoryData Structures
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Source repositoryhead: git clone git://
UploadedMon May 5 20:51:17 UTC 2014 by EdwardKmett
DistributionsDebian:0.4.4, Fedora:0.4.4, FreeBSD:0.4.4, LTSHaskell:0.4.4, NixOS:0.4.4, Stackage:0.4.4
Downloads121333 total (78 in last 30 days)
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StatusDocs available [build log]
Successful builds reported [all 1 reports]





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Readme for distributive-0.4.4


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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