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semigroupoids: Semigroupoids: Category sans id

[ bsd2, comonads, control, library ] [ Propose Tags ] [ Report a vulnerability ]

Provides a wide array of (semi)groupoids and operations for working with them.

A Semigroupoid is a Category without the requirement of identity arrows for every object in the category.

A Category is any Semigroupoid for which the Yoneda lemma holds.

When working with comonads you often have the <*> portion of an Applicative, but not the pure. This was captured in Uustalu and Vene's "Essence of Dataflow Programming" in the form of the ComonadZip class in the days before Applicative. Apply provides a weaker invariant, but for the comonads used for data flow programming (found in the streams package), this invariant is preserved. Applicative function composition forms a semigroupoid.

Similarly many structures are nearly a comonad, but not quite, for instance lists provide a reasonable extend operation in the form of tails, but do not always contain a value.

Ideally the following relationships would hold:

Foldable ----> Traversable <--- Functor ------> Alt ---------> Plus Semigroupoid | | | | | v v v v v Foldable1 ---> Traversable1 Apply --------> Applicative -> Alternative Category | | | | v v v v Bind ---------> Monad -------> MonadPlus Arrow

Apply, Bind, and Extend (not shown) give rise the Static, Kleisli and Cokleisli semigroupoids respectively.

This lets us remove many of the restrictions from various monad transformers as in many cases the binding operation or <*> operation does not require them.

Finally, to work with these weaker structures it is beneficial to have containers that can provide stronger guarantees about their contents, so versions of Traversable and Foldable that can be folded with just a Semigroup are added.

Flags

Manual Flags

NameDescriptionDefault
containers

You can disable the use of the containers package using `-f-containers`.

Disabing this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.

Enabled
contravariant

You can disable the use of the contravariant package using `-f-contravariant`.

Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.

If disabled we will not supply instances of Contravariant

Enabled
distributive

You can disable the use of the distributive package using `-f-distributive`.

Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.

If disabled we will not supply instances of Distributive

Enabled
doctests

You can disable testing with doctests using `-f-doctests`.

Enabled
comonad

You can disable the use of the comonad package using `-f-comonad`.

Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.

If disabled we will not supply instances of Comonad

Enabled

Use -f <flag> to enable a flag, or -f -<flag> to disable that flag. More info

Downloads

Note: This package has metadata revisions in the cabal description newer than included in the tarball. To unpack the package including the revisions, use 'cabal get'.

Maintainer's Corner

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For package maintainers and hackage trustees

Candidates

Versions [RSS] 1.0.0, 1.1.0, 1.1.1, 1.1.2, 1.1.3, 1.2.0, 1.2.1, 1.2.2, 1.2.2.1, 1.2.2.2, 1.2.2.3, 1.2.2.4, 1.2.4, 1.2.5, 1.2.6, 1.2.6.1, 1.2.6.2, 1.3, 1.3.1, 1.3.1.1, 1.3.1.2, 1.3.2, 1.3.2.1, 1.3.3, 1.3.4, 3.0, 3.0.0.1, 3.0.0.2, 3.0.1, 3.0.2, 3.0.3, 3.1, 4.0, 4.0.1, 4.0.2, 4.0.2.1, 4.0.3, 4.0.4, 4.2, 4.3, 4.5, 5, 5.0.0.1, 5.0.0.2, 5.0.0.3, 5.0.0.4, 5.0.1, 5.1, 5.2, 5.2.1, 5.2.2, 5.3, 5.3.1, 5.3.2, 5.3.3, 5.3.4, 5.3.5, 5.3.6, 5.3.7, 6, 6.0.0.1, 6.0.1 (info)
Dependencies base (>=4 && <4.4 || >=4.5 && <5), base-orphans (==0), comonad (>=4 && <5), containers (>=0.3 && <0.6), contravariant (>=0.2.0.1 && <2), distributive (>=0.2.2 && <0.5), semigroups (>=0.8.3.1 && <1), transformers (>=0.2 && <0.6), transformers-compat (>=0.3 && <0.5) [details]
License BSD-3-Clause
Copyright Copyright (C) 2011-2013 Edward A. Kmett
Author Edward A. Kmett
Maintainer Edward A. Kmett <ekmett@gmail.com>
Revised Revision 3 made by HerbertValerioRiedel at 2018-08-29T10:00:26Z
Category Control, Comonads
Home page http://github.com/ekmett/semigroupoids
Bug tracker http://github.com/ekmett/semigroupoids/issues
Source repo head: git clone git://github.com/ekmett/semigroupoids.git
Uploaded by EdwardKmett at 2015-02-13T18:48:18Z
Distributions Arch:6.0.1, Debian:5.3.4, Fedora:6.0.1, FreeBSD:5.0.0.3, LTSHaskell:6.0.1, NixOS:6.0.1, Stackage:6.0.1, openSUSE:6.0.1
Reverse Dependencies 215 direct, 8994 indirect [details]
Downloads 308845 total (231 in the last 30 days)
Rating 2.5 (votes: 9) [estimated by Bayesian average]
Your Rating
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Status Docs available [build log]
Last success reported on 2015-02-13 [all 1 reports]