distributive

Distributive functors -- Dual to Traversable http://github.com/ekmett/distributive/

Version on this page:	0.6
LTS Haskell 13.7:	0.6
Stackage Nightly 2019-02-17:	0.6
Latest on Hackage:	0.6

See all snapshots distributive appears in

BSD-3-Clause licensed by Edward A. Kmett

Maintained by Edward A. Kmett

Module documentation for 0.6

Data
- Data.Distributive
  - Data.Distributive.Generic

distributive

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 irc.freenode.net.

-Edward Kmett

Changes

0.6 [2018.07.02]

Remove fmapCollect. (See here for an explanation of why it was removed.)
Avoid incurring some dependencies when using recent GHCs.

0.5.3

Support doctest-0.12

0.5.2

Revamp Setup.hs to use cabal-doctest. This makes distributive build with Cabal-1.25, and makes the doctests work with cabal new-build and sandboxes.
Fix bugs in Data.Distributive.Generic that cause generic Distributive instances not to work properly for datatypes with recursive types
Add genericCollect to Data.Distributive.Generic, and switch the underlying machinery in that module to work on a collect-like method instead of a distribute-like one
Add a test suite for regression-testing Data.Distributive.Generic

0.5.1

Add Distributive instances for datatypes from Data.Semigroup and GHC.Generics
Add MINIMAL pragma for Distributive

0.5.0.2

A more elegant fix for builds on GHC 7.2

0.5.0.1

Fix builds on GHC 7.2

0.5

Added flags for removing some dependencies.
Support doctests when building to non-standard locations (such as when using stack.)
Support base-orphans

0.4.4

transformers 0.4 compatibility

0.4.3.1

Fixed builds with older versions of GHC

0.4.2

Added Data.Distributive.Generic.

0.4.1

Control.Monad.Instances is deprecated in GHC 7.8. Don’t import it there.

0.4

Added support for Data.Tagged and Data.Proxy.

0.3.1

Minor documentation fix

0.3

Added instances for Control.Applicative.Backwards and Data.Functor.Reverse from transformers 0.3, taking them from transformers-compat if necessary for transformers 0.2

Depends on 4 packages:

base, base-orphans, tagged, transformers