| Copyright | (C) 2011-2015 Edward Kmett |
|---|---|
| License | BSD-style (see the file LICENSE) |
| Maintainer | libraries@haskell.org |
| Stability | provisional |
| Portability | portable |
| Safe Haskell | Trustworthy |
| Language | Haskell2010 |
Data.Semigroup
Contents
Description
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.
The use of (<>) in this module conflicts with an operator with the same
name that is being exported by Data.Monoid. However, this package
re-exports (most of) the contents of Data.Monoid, so to use semigroups
and monoids in the same package just
import Data.Semigroup
Since: base-4.9.0.0
Synopsis
- class Semigroup a where
- stimesMonoid :: (Integral b, Monoid a) => b -> a -> a
- stimesIdempotent :: Integral b => b -> a -> a
- stimesIdempotentMonoid :: (Integral b, Monoid a) => b -> a -> a
- mtimesDefault :: (Integral b, Monoid a) => b -> a -> a
- newtype Min a = Min {
- getMin :: a
- newtype Max a = Max {
- getMax :: a
- newtype First a = First {
- getFirst :: a
- newtype Last a = Last {
- getLast :: a
- newtype WrappedMonoid m = WrapMonoid {
- unwrapMonoid :: m
- newtype Dual a = Dual {
- getDual :: a
- newtype Endo a = Endo {
- appEndo :: a -> a
- newtype All = All {}
- newtype Any = Any {}
- newtype Sum a = Sum {
- getSum :: a
- newtype Product a = Product {
- getProduct :: a
- newtype Option a = Option {}
- option :: b -> (a -> b) -> Option a -> b
- diff :: Semigroup m => m -> Endo m
- cycle1 :: Semigroup m => m -> m
- data Arg a b = Arg a b
- type ArgMin a b = Min (Arg a b)
- type ArgMax a b = Max (Arg a b)
Documentation
The class of semigroups (types with an associative binary operation).
Instances should satisfy the associativity law:
Since: base-4.9.0.0
Minimal complete definition
Methods
(<>) :: a -> a -> a infixr 6 #
An associative operation.
Reduce a non-empty list with <>
The default definition should be sufficient, but this can be overridden for efficiency.
stimes :: Integral b => b -> a -> a #
Repeat a value n times.
Given that this works on a Semigroup it is allowed to fail if
you request 0 or fewer repetitions, and the default definition
will do so.
By making this a member of the class, idempotent semigroups
and monoids can upgrade this to execute in O(1) by
picking stimes = or stimesIdempotentstimes =
respectively.stimesIdempotentMonoid
Instances
| Semigroup Ordering # | Since: base-4.9.0.0 |
| Semigroup () # | Since: base-4.9.0.0 |
| Semigroup Any # | Since: base-4.9.0.0 |
| Semigroup All # | Since: base-4.9.0.0 |
| Semigroup Lifetime # | Since: base-4.10.0.0 |
| Semigroup Event # | Since: base-4.10.0.0 |
| Semigroup Void # | Since: base-4.9.0.0 |
| Semigroup [a] # | Since: base-4.9.0.0 |
| Semigroup a => Semigroup (Maybe a) # | Since: base-4.9.0.0 |
| Semigroup a => Semigroup (IO a) # | Since: base-4.10.0.0 |
| Semigroup p => Semigroup (Par1 p) # | Since: base-4.12.0.0 |
| Semigroup (NonEmpty a) # | Since: base-4.9.0.0 |
| Semigroup a => Semigroup (Down a) # | Since: base-4.11.0.0 |
| Num a => Semigroup (Product a) # | Since: base-4.9.0.0 |
| Num a => Semigroup (Sum a) # | Since: base-4.9.0.0 |
| Semigroup (Endo a) # | Since: base-4.9.0.0 |
| Semigroup a => Semigroup (Dual a) # | Since: base-4.9.0.0 |
| Semigroup (Last a) # | Since: base-4.9.0.0 |
| Semigroup (First a) # | Since: base-4.9.0.0 |
| Semigroup a => Semigroup (Identity a) # | Since: base-4.9.0.0 |
| Semigroup a => Semigroup (Option a) # | Since: base-4.9.0.0 |
| Monoid m => Semigroup (WrappedMonoid m) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods (<>) :: WrappedMonoid m -> WrappedMonoid m -> WrappedMonoid m # sconcat :: NonEmpty (WrappedMonoid m) -> WrappedMonoid m # stimes :: Integral b => b -> WrappedMonoid m -> WrappedMonoid m # | |
| Semigroup (Last a) # | Since: base-4.9.0.0 |
| Semigroup (First a) # | Since: base-4.9.0.0 |
| Ord a => Semigroup (Max a) # | Since: base-4.9.0.0 |
| Ord a => Semigroup (Min a) # | Since: base-4.9.0.0 |
| Semigroup (Equivalence a) # | |
Defined in Data.Functor.Contravariant Methods (<>) :: Equivalence a -> Equivalence a -> Equivalence a # sconcat :: NonEmpty (Equivalence a) -> Equivalence a # stimes :: Integral b => b -> Equivalence a -> Equivalence a # | |
| Semigroup (Comparison a) # | |
Defined in Data.Functor.Contravariant Methods (<>) :: Comparison a -> Comparison a -> Comparison a # sconcat :: NonEmpty (Comparison a) -> Comparison a # stimes :: Integral b => b -> Comparison a -> Comparison a # | |
| Semigroup (Predicate a) # | |
| Semigroup b => Semigroup (a -> b) # | Since: base-4.9.0.0 |
| Semigroup (Either a b) # | Since: base-4.9.0.0 |
| Semigroup (V1 p) # | Since: base-4.12.0.0 |
| Semigroup (U1 p) # | Since: base-4.12.0.0 |
| (Semigroup a, Semigroup b) => Semigroup (a, b) # | Since: base-4.9.0.0 |
| Semigroup a => Semigroup (ST s a) # | Since: base-4.11.0.0 |
| Semigroup (Proxy s) # | Since: base-4.9.0.0 |
| Semigroup a => Semigroup (Op a b) # | |
| Semigroup (f p) => Semigroup (Rec1 f p) # | Since: base-4.12.0.0 |
| (Semigroup a, Semigroup b, Semigroup c) => Semigroup (a, b, c) # | Since: base-4.9.0.0 |
| Alternative f => Semigroup (Alt f a) # | Since: base-4.9.0.0 |
| (Applicative f, Semigroup a) => Semigroup (Ap f a) # | Since: base-4.12.0.0 |
| Semigroup a => Semigroup (Const a b) # | Since: base-4.9.0.0 |
| Semigroup c => Semigroup (K1 i c p) # | Since: base-4.12.0.0 |
| (Semigroup (f p), Semigroup (g p)) => Semigroup ((f :*: g) p) # | Since: base-4.12.0.0 |
| (Semigroup a, Semigroup b, Semigroup c, Semigroup d) => Semigroup (a, b, c, d) # | Since: base-4.9.0.0 |
| Semigroup (f p) => Semigroup (M1 i c f p) # | Since: base-4.12.0.0 |
| Semigroup (f (g p)) => Semigroup ((f :.: g) p) # | Since: base-4.12.0.0 |
| (Semigroup a, Semigroup b, Semigroup c, Semigroup d, Semigroup e) => Semigroup (a, b, c, d, e) # | Since: base-4.9.0.0 |
stimesMonoid :: (Integral b, Monoid a) => b -> a -> a #
stimesIdempotent :: Integral b => b -> a -> a #
stimesIdempotentMonoid :: (Integral b, Monoid a) => b -> a -> a #
mtimesDefault :: (Integral b, Monoid a) => b -> a -> a #
Semigroups
Instances
| Monad Min # | Since: base-4.9.0.0 |
| Functor Min # | Since: base-4.9.0.0 |
| MonadFix Min # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| Applicative Min # | Since: base-4.9.0.0 |
| Foldable Min # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods fold :: Monoid m => Min m -> m # foldMap :: Monoid m => (a -> m) -> Min a -> m # foldr :: (a -> b -> b) -> b -> Min a -> b # foldr' :: (a -> b -> b) -> b -> Min a -> b # foldl :: (b -> a -> b) -> b -> Min a -> b # foldl' :: (b -> a -> b) -> b -> Min a -> b # foldr1 :: (a -> a -> a) -> Min a -> a # foldl1 :: (a -> a -> a) -> Min a -> a # elem :: Eq a => a -> Min a -> Bool # maximum :: Ord a => Min a -> a # | |
| Traversable Min # | Since: base-4.9.0.0 |
| Bounded a => Bounded (Min a) # | Since: base-4.9.0.0 |
| Enum a => Enum (Min a) # | Since: base-4.9.0.0 |
| Eq a => Eq (Min a) # | Since: base-4.9.0.0 |
| Data a => Data (Min a) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Min a -> c (Min a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Min a) # dataTypeOf :: Min a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Min a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Min a)) # gmapT :: (forall b. Data b => b -> b) -> Min a -> Min a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Min a -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Min a -> r # gmapQ :: (forall d. Data d => d -> u) -> Min a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Min a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Min a -> m (Min a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Min a -> m (Min a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Min a -> m (Min a) # | |
| Num a => Num (Min a) # | Since: base-4.9.0.0 |
| Ord a => Ord (Min a) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| Read a => Read (Min a) # | Since: base-4.9.0.0 |
| Show a => Show (Min a) # | Since: base-4.9.0.0 |
| Generic (Min a) # | |
| Ord a => Semigroup (Min a) # | Since: base-4.9.0.0 |
| (Ord a, Bounded a) => Monoid (Min a) # | Since: base-4.9.0.0 |
| Generic1 Min # | |
| type Rep (Min a) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| type Rep1 Min # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
Instances
| Monad Max # | Since: base-4.9.0.0 |
| Functor Max # | Since: base-4.9.0.0 |
| MonadFix Max # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| Applicative Max # | Since: base-4.9.0.0 |
| Foldable Max # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods fold :: Monoid m => Max m -> m # foldMap :: Monoid m => (a -> m) -> Max a -> m # foldr :: (a -> b -> b) -> b -> Max a -> b # foldr' :: (a -> b -> b) -> b -> Max a -> b # foldl :: (b -> a -> b) -> b -> Max a -> b # foldl' :: (b -> a -> b) -> b -> Max a -> b # foldr1 :: (a -> a -> a) -> Max a -> a # foldl1 :: (a -> a -> a) -> Max a -> a # elem :: Eq a => a -> Max a -> Bool # maximum :: Ord a => Max a -> a # | |
| Traversable Max # | Since: base-4.9.0.0 |
| Bounded a => Bounded (Max a) # | Since: base-4.9.0.0 |
| Enum a => Enum (Max a) # | Since: base-4.9.0.0 |
| Eq a => Eq (Max a) # | Since: base-4.9.0.0 |
| Data a => Data (Max a) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Max a -> c (Max a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Max a) # dataTypeOf :: Max a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Max a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Max a)) # gmapT :: (forall b. Data b => b -> b) -> Max a -> Max a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Max a -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Max a -> r # gmapQ :: (forall d. Data d => d -> u) -> Max a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Max a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Max a -> m (Max a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Max a -> m (Max a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Max a -> m (Max a) # | |
| Num a => Num (Max a) # | Since: base-4.9.0.0 |
| Ord a => Ord (Max a) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| Read a => Read (Max a) # | Since: base-4.9.0.0 |
| Show a => Show (Max a) # | Since: base-4.9.0.0 |
| Generic (Max a) # | |
| Ord a => Semigroup (Max a) # | Since: base-4.9.0.0 |
| (Ord a, Bounded a) => Monoid (Max a) # | Since: base-4.9.0.0 |
| Generic1 Max # | |
| type Rep (Max a) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| type Rep1 Max # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
Use to get the behavior of
Option (First a)First from Data.Monoid.
Instances
| Monad First # | Since: base-4.9.0.0 |
| Functor First # | Since: base-4.9.0.0 |
| MonadFix First # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| Applicative First # | Since: base-4.9.0.0 |
| Foldable First # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods fold :: Monoid m => First m -> m # foldMap :: Monoid m => (a -> m) -> First a -> m # foldr :: (a -> b -> b) -> b -> First a -> b # foldr' :: (a -> b -> b) -> b -> First a -> b # foldl :: (b -> a -> b) -> b -> First a -> b # foldl' :: (b -> a -> b) -> b -> First a -> b # foldr1 :: (a -> a -> a) -> First a -> a # foldl1 :: (a -> a -> a) -> First a -> a # elem :: Eq a => a -> First a -> Bool # maximum :: Ord a => First a -> a # minimum :: Ord a => First a -> a # | |
| Traversable First # | Since: base-4.9.0.0 |
| Bounded a => Bounded (First a) # | Since: base-4.9.0.0 |
| Enum a => Enum (First a) # | Since: base-4.9.0.0 |
| Eq a => Eq (First a) # | Since: base-4.9.0.0 |
| Data a => Data (First a) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> First a -> c (First a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (First a) # toConstr :: First a -> Constr # dataTypeOf :: First a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (First a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (First a)) # gmapT :: (forall b. Data b => b -> b) -> First a -> First a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> First a -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> First a -> r # gmapQ :: (forall d. Data d => d -> u) -> First a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> First a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> First a -> m (First a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> First a -> m (First a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> First a -> m (First a) # | |
| Ord a => Ord (First a) # | Since: base-4.9.0.0 |
| Read a => Read (First a) # | Since: base-4.9.0.0 |
| Show a => Show (First a) # | Since: base-4.9.0.0 |
| Generic (First a) # | |
| Semigroup (First a) # | Since: base-4.9.0.0 |
| Generic1 First # | |
| type Rep (First a) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| type Rep1 First # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
Use to get the behavior of
Option (Last a)Last from Data.Monoid
Instances
| Monad Last # | Since: base-4.9.0.0 |
| Functor Last # | Since: base-4.9.0.0 |
| MonadFix Last # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| Applicative Last # | Since: base-4.9.0.0 |
| Foldable Last # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods fold :: Monoid m => Last m -> m # foldMap :: Monoid m => (a -> m) -> Last a -> m # foldr :: (a -> b -> b) -> b -> Last a -> b # foldr' :: (a -> b -> b) -> b -> Last a -> b # foldl :: (b -> a -> b) -> b -> Last a -> b # foldl' :: (b -> a -> b) -> b -> Last a -> b # foldr1 :: (a -> a -> a) -> Last a -> a # foldl1 :: (a -> a -> a) -> Last a -> a # elem :: Eq a => a -> Last a -> Bool # maximum :: Ord a => Last a -> a # | |
| Traversable Last # | Since: base-4.9.0.0 |
| Bounded a => Bounded (Last a) # | Since: base-4.9.0.0 |
| Enum a => Enum (Last a) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| Eq a => Eq (Last a) # | Since: base-4.9.0.0 |
| Data a => Data (Last a) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Last a -> c (Last a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Last a) # toConstr :: Last a -> Constr # dataTypeOf :: Last a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Last a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Last a)) # gmapT :: (forall b. Data b => b -> b) -> Last a -> Last a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Last a -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Last a -> r # gmapQ :: (forall d. Data d => d -> u) -> Last a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Last a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Last a -> m (Last a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Last a -> m (Last a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Last a -> m (Last a) # | |
| Ord a => Ord (Last a) # | Since: base-4.9.0.0 |
| Read a => Read (Last a) # | Since: base-4.9.0.0 |
| Show a => Show (Last a) # | Since: base-4.9.0.0 |
| Generic (Last a) # | |
| Semigroup (Last a) # | Since: base-4.9.0.0 |
| Generic1 Last # | |
| type Rep (Last a) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| type Rep1 Last # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
newtype WrappedMonoid m #
Provide a Semigroup for an arbitrary Monoid.
NOTE: This is not needed anymore since Semigroup became a superclass of
Monoid in base-4.11 and this newtype be deprecated at some point in the future.
Constructors
| WrapMonoid | |
Fields
| |
Instances
Re-exported monoids from Data.Monoid
The dual of a Monoid, obtained by swapping the arguments of mappend.
>>>getDual (mappend (Dual "Hello") (Dual "World"))"WorldHello"
Instances
| Monad Dual # | Since: base-4.8.0.0 |
| Functor Dual # | Since: base-4.8.0.0 |
| MonadFix Dual # | Since: base-4.8.0.0 |
Defined in Control.Monad.Fix | |
| Applicative Dual # | Since: base-4.8.0.0 |
| Foldable Dual # | Since: base-4.8.0.0 |
Defined in Data.Foldable Methods fold :: Monoid m => Dual m -> m # foldMap :: Monoid m => (a -> m) -> Dual a -> m # foldr :: (a -> b -> b) -> b -> Dual a -> b # foldr' :: (a -> b -> b) -> b -> Dual a -> b # foldl :: (b -> a -> b) -> b -> Dual a -> b # foldl' :: (b -> a -> b) -> b -> Dual a -> b # foldr1 :: (a -> a -> a) -> Dual a -> a # foldl1 :: (a -> a -> a) -> Dual a -> a # elem :: Eq a => a -> Dual a -> Bool # maximum :: Ord a => Dual a -> a # | |
| Traversable Dual # | Since: base-4.8.0.0 |
| MonadZip Dual # | Since: base-4.8.0.0 |
| Bounded a => Bounded (Dual a) # | Since: base-2.1 |
| Eq a => Eq (Dual a) # | Since: base-2.1 |
| Data a => Data (Dual a) # | 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) -> Dual a -> c (Dual a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Dual a) # toConstr :: Dual a -> Constr # dataTypeOf :: Dual a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Dual a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Dual a)) # gmapT :: (forall b. Data b => b -> b) -> Dual a -> Dual a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Dual a -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Dual a -> r # gmapQ :: (forall d. Data d => d -> u) -> Dual a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Dual a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Dual a -> m (Dual a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Dual a -> m (Dual a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Dual a -> m (Dual a) # | |
| Ord a => Ord (Dual a) # | Since: base-2.1 |
| Read a => Read (Dual a) # | Since: base-2.1 |
| Show a => Show (Dual a) # | Since: base-2.1 |
| Generic (Dual a) # | |
| Semigroup a => Semigroup (Dual a) # | Since: base-4.9.0.0 |
| Monoid a => Monoid (Dual a) # | Since: base-2.1 |
| Generic1 Dual # | |
| type Rep (Dual a) # | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
| type Rep1 Dual # | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
The monoid of endomorphisms under composition.
>>>let computation = Endo ("Hello, " ++) <> Endo (++ "!")>>>appEndo computation "Haskell""Hello, Haskell!"
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 :: (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 # | |
| Semigroup All # | Since: base-4.9.0.0 |
| Monoid All # | Since: base-2.1 |
| type Rep All # | Since: base-4.7.0.0 |
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 :: (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 # | |
| Semigroup Any # | Since: base-4.9.0.0 |
| Monoid Any # | Since: base-2.1 |
| type Rep Any # | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
Monoid under addition.
>>>getSum (Sum 1 <> Sum 2 <> mempty)3
Instances
| Monad Sum # | Since: base-4.8.0.0 |
| Functor Sum # | Since: base-4.8.0.0 |
| MonadFix Sum # | Since: base-4.8.0.0 |
Defined in Control.Monad.Fix | |
| Applicative Sum # | Since: base-4.8.0.0 |
| Foldable Sum # | Since: base-4.8.0.0 |
Defined in Data.Foldable Methods fold :: Monoid m => Sum m -> m # foldMap :: Monoid m => (a -> m) -> Sum a -> m # foldr :: (a -> b -> b) -> b -> Sum a -> b # foldr' :: (a -> b -> b) -> b -> Sum a -> b # foldl :: (b -> a -> b) -> b -> Sum a -> b # foldl' :: (b -> a -> b) -> b -> Sum a -> b # foldr1 :: (a -> a -> a) -> Sum a -> a # foldl1 :: (a -> a -> a) -> Sum a -> a # elem :: Eq a => a -> Sum a -> Bool # maximum :: Ord a => Sum a -> a # | |
| Traversable Sum # | Since: base-4.8.0.0 |
| MonadZip Sum # | Since: base-4.8.0.0 |
| Bounded a => Bounded (Sum a) # | Since: base-2.1 |
| Eq a => Eq (Sum a) # | Since: base-2.1 |
| Data a => Data (Sum a) # | 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) -> Sum a -> c (Sum a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Sum a) # dataTypeOf :: Sum a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Sum a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Sum a)) # gmapT :: (forall b. Data b => b -> b) -> Sum a -> Sum a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Sum a -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Sum a -> r # gmapQ :: (forall d. Data d => d -> u) -> Sum a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Sum a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Sum a -> m (Sum a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Sum a -> m (Sum a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Sum a -> m (Sum a) # | |
| Num a => Num (Sum a) # | Since: base-4.7.0.0 |
| Ord a => Ord (Sum a) # | Since: base-2.1 |
Defined in Data.Semigroup.Internal | |
| Read a => Read (Sum a) # | Since: base-2.1 |
| Show a => Show (Sum a) # | Since: base-2.1 |
| Generic (Sum a) # | |
| Num a => Semigroup (Sum a) # | Since: base-4.9.0.0 |
| Num a => Monoid (Sum a) # | Since: base-2.1 |
| Generic1 Sum # | |
| type Rep (Sum a) # | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
| type Rep1 Sum # | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
Monoid under multiplication.
>>>getProduct (Product 3 <> Product 4 <> mempty)12
Constructors
| Product | |
Fields
| |
Instances
| Monad Product # | Since: base-4.8.0.0 |
| Functor Product # | Since: base-4.8.0.0 |
| MonadFix Product # | Since: base-4.8.0.0 |
Defined in Control.Monad.Fix | |
| Applicative Product # | Since: base-4.8.0.0 |
| Foldable Product # | Since: base-4.8.0.0 |
Defined in Data.Foldable Methods fold :: Monoid m => Product m -> m # foldMap :: Monoid m => (a -> m) -> Product a -> m # foldr :: (a -> b -> b) -> b -> Product a -> b # foldr' :: (a -> b -> b) -> b -> Product a -> b # foldl :: (b -> a -> b) -> b -> Product a -> b # foldl' :: (b -> a -> b) -> b -> Product a -> b # foldr1 :: (a -> a -> a) -> Product a -> a # foldl1 :: (a -> a -> a) -> Product a -> a # elem :: Eq a => a -> Product a -> Bool # maximum :: Ord a => Product a -> a # minimum :: Ord a => Product a -> a # | |
| Traversable Product # | Since: base-4.8.0.0 |
| MonadZip Product # | Since: base-4.8.0.0 |
| Bounded a => Bounded (Product a) # | Since: base-2.1 |
| Eq a => Eq (Product a) # | Since: base-2.1 |
| Data a => Data (Product a) # | 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) -> Product a -> c (Product a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Product a) # toConstr :: Product a -> Constr # dataTypeOf :: Product a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Product a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Product a)) # gmapT :: (forall b. Data b => b -> b) -> Product a -> Product a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Product a -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Product a -> r # gmapQ :: (forall d. Data d => d -> u) -> Product a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Product a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Product a -> m (Product a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Product a -> m (Product a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Product a -> m (Product a) # | |
| Num a => Num (Product a) # | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
| Ord a => Ord (Product a) # | Since: base-2.1 |
Defined in Data.Semigroup.Internal | |
| Read a => Read (Product a) # | Since: base-2.1 |
| Show a => Show (Product a) # | Since: base-2.1 |
| Generic (Product a) # | |
| Num a => Semigroup (Product a) # | Since: base-4.9.0.0 |
| Num a => Monoid (Product a) # | Since: base-2.1 |
| Generic1 Product # | |
| type Rep (Product a) # | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
| type Rep1 Product # | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
A better monoid for Maybe
Option is effectively Maybe with a better instance of
Monoid, built off of an underlying Semigroup instead of an
underlying Monoid.
Ideally, this type would not exist at all and we would just fix the
Monoid instance of Maybe.
In GHC 8.4 and higher, the Monoid instance for Maybe has been
corrected to lift a Semigroup instance instead of a Monoid
instance. Consequently, this type is no longer useful. It will be
marked deprecated in GHC 8.8 and removed in GHC 8.10.
Instances
| Monad Option # | Since: base-4.9.0.0 |
| Functor Option # | Since: base-4.9.0.0 |
| MonadFix Option # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| Applicative Option # | Since: base-4.9.0.0 |
| Foldable Option # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods fold :: Monoid m => Option m -> m # foldMap :: Monoid m => (a -> m) -> Option a -> m # foldr :: (a -> b -> b) -> b -> Option a -> b # foldr' :: (a -> b -> b) -> b -> Option a -> b # foldl :: (b -> a -> b) -> b -> Option a -> b # foldl' :: (b -> a -> b) -> b -> Option a -> b # foldr1 :: (a -> a -> a) -> Option a -> a # foldl1 :: (a -> a -> a) -> Option a -> a # elem :: Eq a => a -> Option a -> Bool # maximum :: Ord a => Option a -> a # minimum :: Ord a => Option a -> a # | |
| Traversable Option # | Since: base-4.9.0.0 |
| MonadPlus Option # | Since: base-4.9.0.0 |
| Alternative Option # | Since: base-4.9.0.0 |
| Eq a => Eq (Option a) # | Since: base-4.9.0.0 |
| Data a => Data (Option a) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Option a -> c (Option a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Option a) # toConstr :: Option a -> Constr # dataTypeOf :: Option a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Option a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Option a)) # gmapT :: (forall b. Data b => b -> b) -> Option a -> Option a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Option a -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Option a -> r # gmapQ :: (forall d. Data d => d -> u) -> Option a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Option a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Option a -> m (Option a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Option a -> m (Option a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Option a -> m (Option a) # | |
| Ord a => Ord (Option a) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| Read a => Read (Option a) # | Since: base-4.9.0.0 |
| Show a => Show (Option a) # | Since: base-4.9.0.0 |
| Generic (Option a) # | |
| Semigroup a => Semigroup (Option a) # | Since: base-4.9.0.0 |
| Semigroup a => Monoid (Option a) # | Since: base-4.9.0.0 |
| Generic1 Option # | |
| type Rep (Option a) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| type Rep1 Option # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
Difference lists of a semigroup
ArgMin, ArgMax
Arg isn't itself a Semigroup in its own right, but it can be
placed inside Min and Max to compute an arg min or arg max.
Constructors
| Arg a b |
Instances
| Bifunctor Arg # | Since: base-4.9.0.0 |
| Bifoldable Arg # | Since: base-4.10.0.0 |
| Bitraversable Arg # | Since: base-4.10.0.0 |
Defined in Data.Semigroup Methods bitraverse :: Applicative f => (a -> f c) -> (b -> f d) -> Arg a b -> f (Arg c d) # | |
| Functor (Arg a) # | Since: base-4.9.0.0 |
| Foldable (Arg a) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods fold :: Monoid m => Arg a m -> m # foldMap :: Monoid m => (a0 -> m) -> Arg a a0 -> m # foldr :: (a0 -> b -> b) -> b -> Arg a a0 -> b # foldr' :: (a0 -> b -> b) -> b -> Arg a a0 -> b # foldl :: (b -> a0 -> b) -> b -> Arg a a0 -> b # foldl' :: (b -> a0 -> b) -> b -> Arg a a0 -> b # foldr1 :: (a0 -> a0 -> a0) -> Arg a a0 -> a0 # foldl1 :: (a0 -> a0 -> a0) -> Arg a a0 -> a0 # elem :: Eq a0 => a0 -> Arg a a0 -> Bool # maximum :: Ord a0 => Arg a a0 -> a0 # minimum :: Ord a0 => Arg a a0 -> a0 # | |
| Traversable (Arg a) # | Since: base-4.9.0.0 |
| Generic1 (Arg a :: Type -> Type) # | |
| Eq a => Eq (Arg a b) # | Since: base-4.9.0.0 |
| (Data a, Data b) => Data (Arg a b) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods gfoldl :: (forall d b0. Data d => c (d -> b0) -> d -> c b0) -> (forall g. g -> c g) -> Arg a b -> c (Arg a b) # gunfold :: (forall b0 r. Data b0 => c (b0 -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Arg a b) # toConstr :: Arg a b -> Constr # dataTypeOf :: Arg a b -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Arg a b)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Arg a b)) # gmapT :: (forall b0. Data b0 => b0 -> b0) -> Arg a b -> Arg a b # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Arg a b -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Arg a b -> r # gmapQ :: (forall d. Data d => d -> u) -> Arg a b -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Arg a b -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Arg a b -> m (Arg a b) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Arg a b -> m (Arg a b) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Arg a b -> m (Arg a b) # | |
| Ord a => Ord (Arg a b) # | Since: base-4.9.0.0 |
| (Read a, Read b) => Read (Arg a b) # | Since: base-4.9.0.0 |
| (Show a, Show b) => Show (Arg a b) # | Since: base-4.9.0.0 |
| Generic (Arg a b) # | |
| type Rep1 (Arg a :: Type -> Type) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup type Rep1 (Arg a :: Type -> Type) = D1 (MetaData "Arg" "Data.Semigroup" "base" False) (C1 (MetaCons "Arg" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 a) :*: S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) Par1)) | |
| type Rep (Arg a b) # | Since: base-4.9.0.0 |
Defined in Data.Semigroup type Rep (Arg a b) = D1 (MetaData "Arg" "Data.Semigroup" "base" False) (C1 (MetaCons "Arg" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 a) :*: S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 b))) | |