# The kan-extensions package

Kan extensions, Kan lifts, various forms of the Yoneda lemma, and (co)density (co)monads

## Modules

[Index]

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#### Maintainer's Corner

For package maintainers and hackage trustees

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# kan-extensions

This package provides tools for working with various Kan extensions and Kan lifts in Haskell.

Among the interesting bits included are:

• Right and left Kan extensions (Ran and Lan)
• Right and left Kan lifts (Rift and Lift)
• Multiple forms of the Yoneda lemma (Yoneda)
• The Codensity monad, which can be used to improve the asymptotic complexity of code over free monads (Codensity, Density)
• A "comonad to monad-transformer transformer" that is a special case of a right Kan lift. (CoT, Co)

## 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