semigroups: Anything that associates

[ algebra, bsd3, data, data-structures, library, math ] [ Propose Tags ]

In mathematics, a semigroup is an algebraic structure consisting of a set together with an associative binary operation. A semigroup generalizes a monoid in that there might not exist an identity element. It also (originally) generalized a group (a monoid with all inverses) to a type where every element did not have to have an inverse, thus the name semigroup.

[Skip to Readme]

Versions	0.1.0, 0.2.0, 0.3.0, 0.3.1, 0.3.2, 0.3.3, 0.3.4, 0.3.4.1, 0.3.4.2, 0.4.0, 0.5.0, 0.5.0.1, 0.5.0.2, 0.6, 0.6.1, 0.7.0, 0.7.1, 0.7.1.1, 0.7.1.2, 0.8, 0.8.0.1, 0.8.2, 0.8.3, 0.8.3.1, 0.8.3.2, 0.8.4, 0.8.4.1, 0.8.5, 0.9, 0.9.1, 0.9.2, 0.10, 0.11, 0.12, 0.12.0.1, 0.12.1, 0.12.2, 0.13, 0.13.0.1, 0.14, 0.15, 0.15.1, 0.15.2, 0.15.3, 0.15.4, 0.16, 0.16.0.1, 0.16.1, 0.16.2, 0.16.2.1, 0.16.2.2, 0.17, 0.17.0.1, 0.18, 0.18.0.1, 0.18.1, 0.18.2, 0.18.3, 0.18.4, 0.18.5
Change log	CHANGELOG.markdown
Dependencies	base (>=2 && <5), binary, bytestring (>=0.9 && <1), bytestring-builder (>=0.10.4 && <1), containers (>=0.3 && <0.7), deepseq (>=1.1 && <1.5), ghc-prim, hashable (>=1.1 && <1.3), nats (>=0.1 && <2), tagged (>=0.4.4 && <1), text (>=0.10 && <2), transformers (>=0.2 && <0.6), transformers-compat (>=0.5 && <1), unordered-containers (==0.2.*) [details]
License	BSD-3-Clause
Copyright	Copyright (C) 2011-2015 Edward A. Kmett
Author	Edward A. Kmett
Maintainer	Edward A. Kmett <ekmett@gmail.com>
Category	Algebra, Data, Data Structures, Math
Home page	http://github.com/ekmett/semigroups/
Bug tracker	http://github.com/ekmett/semigroups/issues
Source repo	head: git clone git://github.com/ekmett/semigroups.git
Uploaded	by ryanglscott at Mon Jul 2 22:09:56 UTC 2018
Distributions	Debian:0.18.0.1, Fedora:0.18.3, FreeBSD:0.16.2.2, LTSHaskell:0.18.5, NixOS:0.18.5, Stackage:0.18.5, openSUSE:0.18.5
Downloads	385135 total (424 in the last 30 days)
Rating	2.75 (votes: 8) [estimated by rule of succession]
Your Rating	λ λ λ
Status	Docs available [build log] Last success reported on 2018-07-02 [all 1 reports] Hackage Matrix CI

Modules

[Index]

Data
- List
  - Data.List.NonEmpty
- Data.Semigroup
  - Data.Semigroup.Generic

Flags

Name	Description	Default	Type
hashable	You can disable the use of the `hashable` package using `-f-hashable`. 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 `Hashable` Note: `-f-hashable` implies `-f-unordered-containers`, as we are necessarily not able to supply those instances as well.	Enabled	Manual
binary	You can disable the use of the `binary` package using `-f-binary`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.	Enabled	Manual
bytestring	You can disable the use of the `bytestring` package using `-f-bytestring`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.	Enabled	Manual
bytestring-builder	Decides whether to use an older version of bytestring along with bytestring-builder or just a newer version of bytestring. This flag normally toggles automatically but you can use `-fbytestring-builder` or `-f-bytestring-builder` to explicitly change it.	Disabled	Automatic
containers	You can disable the use of the `containers` package using `-f-containers`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.	Enabled	Manual
deepseq	You can disable the use of the `deepseq` package using `-f-deepseq`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.	Enabled	Manual
tagged	You can disable the use of the `tagged` package using `-f-tagged`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.	Enabled	Manual
text	You can disable the use of the `text` package using `-f-text`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.	Enabled	Manual
transformers	You can disable the use of the `transformers` and `transformers-compat` packages using `-f-transformers`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.	Enabled	Manual
unordered-containers	You can disable the use of the `unordered-containers` package using `-f-unordered-containers`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.	Enabled	Manual

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

Downloads

semigroups-0.18.5.tar.gz [browse] (Cabal source package)
Package description (as included in the package)

Maintainer's Corner

For package maintainers and hackage trustees

edit package information

Readme for semigroups-0.18.5

[back to package description]

semigroups

Haskellers are usually familiar with monoids. A monoid has an appending operation <> or mappend and an identity element mempty. A Semigroup has an append <>, but does not require an mempty element. A Monoid can be made a Semigroup with just instance Semigroup MyMonoid

More formally, a semigroup is an algebraic structure consisting of a set together with an associative binary operation. A semigroup generalizes a monoid in that there might not exist an identity element. It also (originally) generalized a group (a monoid with all inverses) to a type where every element did not have to have an inverse, thus the name semigroup.

Data.Semigroup and Data.List.NonEmpty were added to base as of 4.9.0.0. This package now offers a backwards-compatible API and some tools for deriving semigroups with generics.

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