0.20 [2021.11.15]
* Support hashable-1.4. The Hashable1 instances added in 0.19.2 are removed
for all types except NonEmpty, in accordance with the corresponding
changes from hashable-1.4.
0.19.2 [2021.08.30]
* Backport Hashable1 instances for NonEmpty, Min, Max, First, Last,
WrappedMonoid, and Option.
0.19.1 [2019.08.27]
* Add GenericSemigroupMonoid, an adapter newtype suitable for
DerivingVia, to Data.Semigroup.Generic.
* Work around a bug related to the backported Generic(1) instances in
this package (that could only be triggered on GHC 7.2 or 7.4) in
which the hand-written Datatype, Constructor, and Selector instances
for internal data types could overlap with GHC-generated instances.
0.19 [2019.05.10]
* The (<>) method of the backported Semigroup class no longer has a
default implementation in terms of mappend. This mirrors the
Data.Semigroup API that was introduced in base-4.9. This is a
breaking change for any Semigroup instances that are defined in
tandem with versions of base older than 4.9.
* Make the backported Hashable Arg instance reflect its respective
variants in the hashable package. In hashable-1.3, the Hashable Arg
instance only hashes the first argument, lest equal values have
different hashes.
* Backport the Lift (NonEmpty a) instance introduced in
template-haskell-2.15.0.0.
* Data.List.NonEmpty is now unconditionally Trustworthy.
0.18.5 [2018.07.02]
* Use a more efficient sconcat for the Semigroup instances for strict
and lazy ByteString.
0.18.4 [2018.01.29]
* Backport Semigroup instances for Data.Ord.Down and strict ST, which
were added in base-4.11.
0.18.3
* Add Semigroup instance for IO, as well as for Event and Lifetime
from GHC.Event
* Add Eq1, Ord1, Read1, and Show1 instances for NonEmpty
* Define Generic and Generic1 instances back to GHC 7.2, and expose
the Data.Semigroup.Generic module on GHC 7.2
0.18.2
* Depend on the bytestring-builder package to ensure Semigroup
instances for bytestring Builder and ShortByteString are always
defined
* Allow building with binary-0.8.3 and later
0.18.1
* Add the missing instance for Data.Binary.Builder.Builder.
0.18.0.1
* Added support for base-4.9
0.18
* Removed the partial functions words, unwords, lines, unlines
0.17.0.1
* Fixed the @since annotations
0.17
* Added groupWith, groupAllWith, groupWith1, groupAllWith1
* Renamed sortOn to sortWith to match the "Comprehensive
comprehensions" paper and TransformListComp extension.
* Add Semigroup instances for Alt, Void, Proxy and Tagged
* Add Num instances for Min and Max
* Removed times1p in favor of stimes.
0.16.2.2
* Cleaned up imports to remove warnings on GHC 7.10.
0.16.2.1
* Restored the ability to build on GHC < 7.6. (Generic1 deriving was only added in GHC 7.6)
0.16.2
* Added genericMappend and supporting GSemigroup class for generically
deriving Semigroup instances.
* Added Arg a b which only compares for equality/order on its first
argument, which can be used to compute argmin and argmax.
* Add Bifunctor Arg instance to avoid orphans for GHC 7.10+.
* Added missing Data.Monoid.Generic module to source control.
0.16.1
* Added Semigroup instances for various Builder constructions in text
and bytestring where available.
* Added MonadFix and MonadPlus instances for NonEmpty.
0.16.0.1
* Bumped deepseq version bound for GHC 7.10 compatibility.
0.16
* times1p and timesN are now reduced to accepting only a Natural
argument. Whole doesn't exist in GHC 7.10's Numeric.Natural, and
nats version 1 has removed support for the class.
0.15.4
* Use Data.Coerce.coerce on GHC 7.8+ to reduce the number of
eta-expansions in the resulting core.
* Avoid conflict with pending Foldable.length in base.
packaged for wip by pho.
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.
