| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Distribution.Compat.Semigroup
Description
Compatibility layer for Data.Semigroup
Synopsis
- class Semigroup a where
- (<>) :: a -> a -> a
- class Semigroup a => Monoid a where
- newtype All = All {}
- newtype Any = Any {}
- newtype First' a = First' {
- getFirst' :: a
- newtype Last' a = Last' {
- getLast' :: a
- newtype Option' a = Option' {
- getOption' :: Maybe a
- gmappend :: (Generic a, GSemigroup (Rep a)) => a -> a -> a
- gmempty :: (Generic a, GMonoid (Rep a)) => a
Documentation
The class of semigroups (types with an associative binary operation).
Instances should satisfy the following:
Since: base-4.9.0.0
Instances
class Semigroup a => Monoid a where #
The class of monoids (types with an associative binary operation that has an identity). Instances should satisfy the following:
- Right identity
x<>mempty= x- Left identity
mempty<>x = x- Associativity
x(<>(y<>z) = (x<>y)<>zSemigrouplaw)- Concatenation
mconcat=foldr(<>)mempty
The method names refer to the monoid of lists under concatenation, but there are many other instances.
Some types can be viewed as a monoid in more than one way,
e.g. both addition and multiplication on numbers.
In such cases we often define newtypes and make those instances
of Monoid, e.g. Sum and Product.
NOTE: Semigroup is a superclass of Monoid since base-4.11.0.0.
Minimal complete definition
Methods
Identity of mappend
>>>"Hello world" <> mempty"Hello world"
An associative operation
NOTE: This method is redundant and has the default
implementation mappend = (<>)mappend is a synonym for
(<>), it is expected that the two functions are defined the same
way. In a future GHC release mappend will be removed from Monoid.
Fold a list using the monoid.
For most types, the default definition for mconcat will be
used, but the function is included in the class definition so
that an optimized version can be provided for specific types.
>>>mconcat ["Hello", " ", "Haskell", "!"]"Hello Haskell!"
Instances
Boolean monoid under conjunction (&&).
>>>getAll (All True <> mempty <> All False)False
>>>getAll (mconcat (map (\x -> All (even x)) [2,4,6,7,8]))False
Instances
| Bounded All | Since: base-2.1 |
| Eq All | Since: base-2.1 |
| Data All | Since: base-4.8.0.0 |
Defined in Data.Data Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> All -> c All # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c All # dataTypeOf :: All -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c All) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c All) # gmapT :: (forall b. Data b => b -> b) -> All -> All # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> All -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> All -> r # gmapQ :: (forall d. Data d => d -> u) -> All -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> All -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> All -> m All # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> All -> m All # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> All -> m All # | |
| Ord All | Since: base-2.1 |
| Read All | Since: base-2.1 |
| Show All | Since: base-2.1 |
| Generic All | Since: base-4.7.0.0 |
| Semigroup All | Since: base-4.9.0.0 |
| Monoid All | Since: base-2.1 |
| Binary All | Since: binary-0.8.4.0 |
| NFData All | Since: deepseq-1.4.0.0 |
Defined in Control.DeepSeq | |
| type Rep All | |
Defined in Data.Semigroup.Internal | |
Boolean monoid under disjunction (||).
>>>getAny (Any True <> mempty <> Any False)True
>>>getAny (mconcat (map (\x -> Any (even x)) [2,4,6,7,8]))True
Instances
| Bounded Any | Since: base-2.1 |
| Eq Any | Since: base-2.1 |
| Data Any | Since: base-4.8.0.0 |
Defined in Data.Data Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Any -> c Any # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Any # dataTypeOf :: Any -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Any) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Any) # gmapT :: (forall b. Data b => b -> b) -> Any -> Any # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Any -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Any -> r # gmapQ :: (forall d. Data d => d -> u) -> Any -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Any -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Any -> m Any # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Any -> m Any # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Any -> m Any # | |
| Ord Any | Since: base-2.1 |
| Read Any | Since: base-2.1 |
| Show Any | Since: base-2.1 |
| Generic Any | Since: base-4.7.0.0 |
| Semigroup Any | Since: base-4.9.0.0 |
| Monoid Any | Since: base-2.1 |
| Binary Any | Since: binary-0.8.4.0 |
| NFData Any | Since: deepseq-1.4.0.0 |
Defined in Control.DeepSeq | |
| type Rep Any | |
Defined in Data.Semigroup.Internal | |
A copy of First.
A copy of Last.
Instances
| Functor Last' Source # | |
| Eq a => Eq (Last' a) Source # | |
| Ord a => Ord (Last' a) Source # | |
Defined in Distribution.Compat.Semigroup | |
| Read a => Read (Last' a) Source # | |
| Show a => Show (Last' a) Source # | |
| Generic (Last' a) Source # | |
| Semigroup (Last' a) Source # | |
| Binary a => Binary (Last' a) Source # | |
| Structured a => Structured (Last' a) Source # | |
Defined in Distribution.Compat.Semigroup | |
| type Rep (Last' a) Source # | |
Defined in Distribution.Compat.Semigroup | |
A wrapper around Maybe, providing the Semigroup and Monoid instances
implemented for Maybe since base-4.11.
Constructors
| Option' | |
Fields
| |
Instances
| Functor Option' Source # | |
| Eq a => Eq (Option' a) Source # | |
| Ord a => Ord (Option' a) Source # | |
| Read a => Read (Option' a) Source # | |
| Show a => Show (Option' a) Source # | |
| Generic (Option' a) Source # | |
| Semigroup a => Semigroup (Option' a) Source # | |
| Semigroup a => Monoid (Option' a) Source # | |
| Binary a => Binary (Option' a) Source # | |
| Structured a => Structured (Option' a) Source # | |
Defined in Distribution.Compat.Semigroup | |
| type Rep (Option' a) Source # | |
Defined in Distribution.Compat.Semigroup | |