https://github.com/ekmett/distributive

Dual Traversable
https://github.com/ekmett/distributive

Last synced: 5 days ago
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Dual Traversable

• Host: GitHub
• URL: https://github.com/ekmett/distributive
• Owner: ekmett
• License: other
• Created: 2011-01-22T22:27:59.000Z (almost 14 years ago)
• Default Branch: main
• Last Pushed: 2023-05-16T21:28:22.000Z (over 1 year ago)
• Last Synced: 2024-05-08T16:03:47.180Z (6 months ago)
• Language: Haskell
• Homepage: http://hackage.haskell.org/package/distributive
• Size: 643 KB
• Stars: 41
• Watchers: 12
• Forks: 25
• Open Issues: 11
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE.md

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README

        
distributive

============

[![Hackage](https://img.shields.io/hackage/v/distributive.svg)](https://hackage.haskell.org/package/distributive) [![Build Status](https://github.com/ekmett/distributive/workflows/Haskell-CI/badge.svg)](https://github.com/ekmett/distributive/actions?query=workflow%3AHaskell-CI)

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

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

```haskell

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

```

Compare this with the corresponding Traversable notion, `sequenceA`.

```haskell

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 irc.freenode.net.

-Edward Kmett