| 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
Description
A type a is a Semigroup if it provides an associative function (<>) that lets you combine any two values of type a into one. Where being associative means that the following must always hold:
(a <> b) <> c == a <> (b <> c)
Examples
The Min Semigroup instance for Int is defined to always pick the smaller number: >>> Min 1 <> Min 2 <> Min 3 <> Min 4 :: Min Int Min {getMin = 1}
If we need to combine multiple values we can use the sconcat function to do so. We need to ensure however that we have at least one value to operate on, since otherwise our result would be undefined. It is for this reason that sconcat uses Data.List.NonEmpty.NonEmpty - a list that can never be empty:
>>>(1 :| [])1 :| [] -- equivalent to [1] but guaranteed to be non-empty.
>>>(1 :| [2, 3, 4])1 :| [2,3,4] -- equivalent to [1,2,3,4] but guaranteed to be non-empty.
Equipped with this guaranteed to be non-empty data structure, we can combine values using sconcat and a Semigroup of our choosing. We can try the Min and Max instances of Int which pick the smallest, or largest number respectively:
>>>sconcat (1 :| [2, 3, 4]) :: Min IntMin {getMin = 1}>>>sconcat (1 :| [2, 3, 4]) :: Max IntMax {getMax = 4}
String concatenation is another example of a Semigroup instance:
>>>"foo" <> "bar""foobar"
A Semigroup is a generalization of a Monoid. Yet unlike the Semigroup, the Monoid requires the presence of a neutral element (mempty) in addition to the associative operator. The requirement for a neutral element prevents many types from being a full Monoid, like Data.List.NonEmpty.NonEmpty.
Note that 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
- 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
class Semigroup a where Source #
The class of semigroups (types with an associative binary operation).
Instances should satisfy the following:
You can alternatively define sconcat instead of (<>), in which case the laws are:
Since: base-4.9.0.0
Methods
(<>) :: a -> a -> a infixr 6 Source #
An associative operation.
>>>[1,2,3] <> [4,5,6][1,2,3,4,5,6]
sconcat :: NonEmpty a -> a Source #
Reduce a non-empty list with <>
The default definition should be sufficient, but this can be overridden for efficiency.
>>>import Data.List.NonEmpty (NonEmpty (..))>>>sconcat $ "Hello" :| [" ", "Haskell", "!"]"Hello Haskell!"
stimes :: Integral b => b -> a -> a Source #
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 \(\mathcal{O}(1)\) by picking stimes = or stimesIdempotentstimes = respectively.stimesIdempotentMonoid
>>>stimes 4 [1][1,1,1,1]
Instances
| Semigroup ByteArray Source # | Since: base-4.17.0.0 |
| Semigroup All Source # | Since: base-4.9.0.0 |
| Semigroup Any Source # | Since: base-4.9.0.0 |
| Semigroup Void Source # | Since: base-4.9.0.0 |
| Semigroup Event Source # | Since: base-4.10.0.0 |
| Semigroup Lifetime Source # | Since: base-4.10.0.0 |
| Semigroup Ordering Source # | Since: base-4.9.0.0 |
| Semigroup () Source # | Since: base-4.9.0.0 |
| Bits a => Semigroup (And a) Source # | Since: base-4.16 |
| FiniteBits a => Semigroup (Iff a) Source # | This constraint is arguably too strong. However, as some types (such as Since: base-4.16 |
| Bits a => Semigroup (Ior a) Source # | Since: base-4.16 |
| Bits a => Semigroup (Xor a) Source # | Since: base-4.16 |
| Semigroup (Comparison a) Source # |
(<>) :: Comparison a -> Comparison a -> Comparison a Comparison cmp <> Comparison cmp' = Comparison a a' -> cmp a a' <> cmp a a' |
Defined in Data.Functor.Contravariant Methods (<>) :: Comparison a -> Comparison a -> Comparison a Source # sconcat :: NonEmpty (Comparison a) -> Comparison a Source # stimes :: Integral b => b -> Comparison a -> Comparison a Source # | |
| Semigroup (Equivalence a) Source # |
(<>) :: Equivalence a -> Equivalence a -> Equivalence a Equivalence equiv <> Equivalence equiv' = Equivalence a b -> equiv a b && equiv' a b |
Defined in Data.Functor.Contravariant Methods (<>) :: Equivalence a -> Equivalence a -> Equivalence a Source # sconcat :: NonEmpty (Equivalence a) -> Equivalence a Source # stimes :: Integral b => b -> Equivalence a -> Equivalence a Source # | |
| Semigroup (Predicate a) Source # |
(<>) :: Predicate a -> Predicate a -> Predicate a Predicate pred <> Predicate pred' = Predicate a -> pred a && pred' a |
| Semigroup a => Semigroup (Identity a) Source # | Since: base-4.9.0.0 |
| Semigroup (First a) Source # | Since: base-4.9.0.0 |
| Semigroup (Last a) Source # | Since: base-4.9.0.0 |
| Semigroup a => Semigroup (Down a) Source # | Since: base-4.11.0.0 |
| Semigroup (First a) Source # | Since: base-4.9.0.0 |
| Semigroup (Last a) Source # | Since: base-4.9.0.0 |
| Ord a => Semigroup (Max a) Source # | Since: base-4.9.0.0 |
| Ord a => Semigroup (Min a) Source # | Since: base-4.9.0.0 |
| Monoid m => Semigroup (WrappedMonoid m) Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods (<>) :: WrappedMonoid m -> WrappedMonoid m -> WrappedMonoid m Source # sconcat :: NonEmpty (WrappedMonoid m) -> WrappedMonoid m Source # stimes :: Integral b => b -> WrappedMonoid m -> WrappedMonoid m Source # | |
| Semigroup a => Semigroup (Dual a) Source # | Since: base-4.9.0.0 |
| Semigroup (Endo a) Source # | Since: base-4.9.0.0 |
| Num a => Semigroup (Product a) Source # | Since: base-4.9.0.0 |
| Num a => Semigroup (Sum a) Source # | Since: base-4.9.0.0 |
| Semigroup (NonEmpty a) Source # | Since: base-4.9.0.0 |
| Semigroup a => Semigroup (STM a) Source # | Since: base-4.17.0.0 |
| (Generic a, Semigroup (Rep a ())) => Semigroup (Generically a) Source # | Since: base-4.17.0.0 |
Defined in GHC.Generics Methods (<>) :: Generically a -> Generically a -> Generically a Source # sconcat :: NonEmpty (Generically a) -> Generically a Source # stimes :: Integral b => b -> Generically a -> Generically a Source # | |
| Semigroup p => Semigroup (Par1 p) Source # | Since: base-4.12.0.0 |
| Semigroup a => Semigroup (IO a) Source # | Since: base-4.10.0.0 |
| Semigroup a => Semigroup (Maybe a) Source # | Since: base-4.9.0.0 |
| Semigroup a => Semigroup (a) Source # | Since: base-4.15 |
| Semigroup [a] Source # | Since: base-4.9.0.0 |
| Semigroup (Either a b) Source # | Since: base-4.9.0.0 |
| Semigroup a => Semigroup (Op a b) Source # |
(<>) :: Op a b -> Op a b -> Op a b Op f <> Op g = Op a -> f a <> g a |
| Semigroup (Proxy s) Source # | Since: base-4.9.0.0 |
| Semigroup (U1 p) Source # | Since: base-4.12.0.0 |
| Semigroup (V1 p) Source # | Since: base-4.12.0.0 |
| Semigroup a => Semigroup (ST s a) Source # | Since: base-4.11.0.0 |
| (Semigroup a, Semigroup b) => Semigroup (a, b) Source # | Since: base-4.9.0.0 |
| Semigroup b => Semigroup (a -> b) Source # | Since: base-4.9.0.0 |
| Semigroup a => Semigroup (Const a b) Source # | Since: base-4.9.0.0 |
| (Applicative f, Semigroup a) => Semigroup (Ap f a) Source # | Since: base-4.12.0.0 |
| Alternative f => Semigroup (Alt f a) Source # | Since: base-4.9.0.0 |
| Semigroup (f p) => Semigroup (Rec1 f p) Source # | Since: base-4.12.0.0 |
| (Semigroup a, Semigroup b, Semigroup c) => Semigroup (a, b, c) Source # | Since: base-4.9.0.0 |
| (Semigroup (f a), Semigroup (g a)) => Semigroup (Product f g a) Source # | Since: base-4.16.0.0 |
| (Semigroup (f p), Semigroup (g p)) => Semigroup ((f :*: g) p) Source # | Since: base-4.12.0.0 |
| Semigroup c => Semigroup (K1 i c p) Source # | Since: base-4.12.0.0 |
| (Semigroup a, Semigroup b, Semigroup c, Semigroup d) => Semigroup (a, b, c, d) Source # | Since: base-4.9.0.0 |
| Semigroup (f (g a)) => Semigroup (Compose f g a) Source # | Since: base-4.16.0.0 |
| Semigroup (f (g p)) => Semigroup ((f :.: g) p) Source # | Since: base-4.12.0.0 |
| Semigroup (f p) => Semigroup (M1 i c f p) Source # | Since: base-4.12.0.0 |
| (Semigroup a, Semigroup b, Semigroup c, Semigroup d, Semigroup e) => Semigroup (a, b, c, d, e) Source # | Since: base-4.9.0.0 |
stimesMonoid :: (Integral b, Monoid a) => b -> a -> a Source #
stimesIdempotent :: Integral b => b -> a -> a Source #
stimesIdempotentMonoid :: (Integral b, Monoid a) => b -> a -> a Source #
mtimesDefault :: (Integral b, Monoid a) => b -> a -> a Source #
Repeat a value n times.
mtimesDefault n a = a <> a <> ... <> a -- using <> (n-1) times
In many cases, `stimes 0 a` for a Monoid will produce mempty. However, there are situations when it cannot do so. In particular, the following situation is fairly common:
data T a = ... class Constraint1 a class Constraint1 a => Constraint2 a
instance Constraint1 a => Semigroup (T a) instance Constraint2 a => Monoid (T a) @
Since Constraint1 is insufficient to implement mempty, stimes for T a cannot do so.
When working with such a type, or when working polymorphically with Semigroup instances, mtimesDefault should be used when the multiplier might be zero. It is implemented using stimes when the multiplier is nonzero and mempty when it is zero.
Semigroups
Instances
| MonadFix Min Source # | Since: base-4.9.0.0 |
| Foldable Min Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods fold :: Monoid m => Min m -> m Source # foldMap :: Monoid m => (a -> m) -> Min a -> m Source # foldMap' :: Monoid m => (a -> m) -> Min a -> m Source # foldr :: (a -> b -> b) -> b -> Min a -> b Source # foldr' :: (a -> b -> b) -> b -> Min a -> b Source # foldl :: (b -> a -> b) -> b -> Min a -> b Source # foldl' :: (b -> a -> b) -> b -> Min a -> b Source # foldr1 :: (a -> a -> a) -> Min a -> a Source # foldl1 :: (a -> a -> a) -> Min a -> a Source # toList :: Min a -> [a] Source # null :: Min a -> Bool Source # length :: Min a -> Int Source # elem :: Eq a => a -> Min a -> Bool Source # maximum :: Ord a => Min a -> a Source # minimum :: Ord a => Min a -> a Source # | |
| Foldable1 Min Source # | |
Defined in Data.Foldable1 Methods fold1 :: Semigroup m => Min m -> m Source # foldMap1 :: Semigroup m => (a -> m) -> Min a -> m Source # foldMap1' :: Semigroup m => (a -> m) -> Min a -> m Source # toNonEmpty :: Min a -> NonEmpty a Source # maximum :: Ord a => Min a -> a Source # minimum :: Ord a => Min a -> a Source # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Min a -> b Source # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Min a -> b Source # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Min a -> b Source # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Min a -> b Source # | |
| Traversable Min Source # | Since: base-4.9.0.0 |
| Applicative Min Source # | Since: base-4.9.0.0 |
| Functor Min Source # | Since: base-4.9.0.0 |
| Monad Min Source # | Since: base-4.9.0.0 |
| Generic1 Min Source # | |
| Data a => Data (Min a) Source # | 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) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Min a) Source # toConstr :: Min a -> Constr Source # dataTypeOf :: Min a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Min a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Min a)) Source # gmapT :: (forall b. Data b => b -> b) -> Min a -> Min a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Min a -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Min a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Min a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Min a -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Min a -> m (Min a) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Min a -> m (Min a) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Min a -> m (Min a) Source # | |
| (Ord a, Bounded a) => Monoid (Min a) Source # | Since: base-4.9.0.0 |
| Ord a => Semigroup (Min a) Source # | Since: base-4.9.0.0 |
| Bounded a => Bounded (Min a) Source # | Since: base-4.9.0.0 |
| Enum a => Enum (Min a) Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods succ :: Min a -> Min a Source # pred :: Min a -> Min a Source # toEnum :: Int -> Min a Source # fromEnum :: Min a -> Int Source # enumFrom :: Min a -> [Min a] Source # enumFromThen :: Min a -> Min a -> [Min a] Source # enumFromTo :: Min a -> Min a -> [Min a] Source # enumFromThenTo :: Min a -> Min a -> Min a -> [Min a] Source # | |
| Generic (Min a) Source # | |
| Num a => Num (Min a) Source # | Since: base-4.9.0.0 |
| Read a => Read (Min a) Source # | Since: base-4.9.0.0 |
| Show a => Show (Min a) Source # | Since: base-4.9.0.0 |
| Eq a => Eq (Min a) Source # | Since: base-4.9.0.0 |
| Ord a => Ord (Min a) Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| type Rep1 Min Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| type Rep (Min a) Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
Instances
| MonadFix Max Source # | Since: base-4.9.0.0 |
| Foldable Max Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods fold :: Monoid m => Max m -> m Source # foldMap :: Monoid m => (a -> m) -> Max a -> m Source # foldMap' :: Monoid m => (a -> m) -> Max a -> m Source # foldr :: (a -> b -> b) -> b -> Max a -> b Source # foldr' :: (a -> b -> b) -> b -> Max a -> b Source # foldl :: (b -> a -> b) -> b -> Max a -> b Source # foldl' :: (b -> a -> b) -> b -> Max a -> b Source # foldr1 :: (a -> a -> a) -> Max a -> a Source # foldl1 :: (a -> a -> a) -> Max a -> a Source # toList :: Max a -> [a] Source # null :: Max a -> Bool Source # length :: Max a -> Int Source # elem :: Eq a => a -> Max a -> Bool Source # maximum :: Ord a => Max a -> a Source # minimum :: Ord a => Max a -> a Source # | |
| Foldable1 Max Source # | |
Defined in Data.Foldable1 Methods fold1 :: Semigroup m => Max m -> m Source # foldMap1 :: Semigroup m => (a -> m) -> Max a -> m Source # foldMap1' :: Semigroup m => (a -> m) -> Max a -> m Source # toNonEmpty :: Max a -> NonEmpty a Source # maximum :: Ord a => Max a -> a Source # minimum :: Ord a => Max a -> a Source # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Max a -> b Source # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Max a -> b Source # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Max a -> b Source # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Max a -> b Source # | |
| Traversable Max Source # | Since: base-4.9.0.0 |
| Applicative Max Source # | Since: base-4.9.0.0 |
| Functor Max Source # | Since: base-4.9.0.0 |
| Monad Max Source # | Since: base-4.9.0.0 |
| Generic1 Max Source # | |
| Data a => Data (Max a) Source # | 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) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Max a) Source # toConstr :: Max a -> Constr Source # dataTypeOf :: Max a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Max a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Max a)) Source # gmapT :: (forall b. Data b => b -> b) -> Max a -> Max a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Max a -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Max a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Max a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Max a -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Max a -> m (Max a) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Max a -> m (Max a) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Max a -> m (Max a) Source # | |
| (Ord a, Bounded a) => Monoid (Max a) Source # | Since: base-4.9.0.0 |
| Ord a => Semigroup (Max a) Source # | Since: base-4.9.0.0 |
| Bounded a => Bounded (Max a) Source # | Since: base-4.9.0.0 |
| Enum a => Enum (Max a) Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods succ :: Max a -> Max a Source # pred :: Max a -> Max a Source # toEnum :: Int -> Max a Source # fromEnum :: Max a -> Int Source # enumFrom :: Max a -> [Max a] Source # enumFromThen :: Max a -> Max a -> [Max a] Source # enumFromTo :: Max a -> Max a -> [Max a] Source # enumFromThenTo :: Max a -> Max a -> Max a -> [Max a] Source # | |
| Generic (Max a) Source # | |
| Num a => Num (Max a) Source # | Since: base-4.9.0.0 |
| Read a => Read (Max a) Source # | Since: base-4.9.0.0 |
| Show a => Show (Max a) Source # | Since: base-4.9.0.0 |
| Eq a => Eq (Max a) Source # | Since: base-4.9.0.0 |
| Ord a => Ord (Max a) Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| type Rep1 Max Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| type Rep (Max a) Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
Beware that Data.Semigroup.First is different from Data.Monoid.First. The former simply returns the first value, so Data.Semigroup.First Nothing <> x = Data.Semigroup.First Nothing. The latter returns the first non-Nothing, thus Data.Monoid.First Nothing <> x = x.
Instances
| MonadFix First Source # | Since: base-4.9.0.0 |
| Foldable First Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods fold :: Monoid m => First m -> m Source # foldMap :: Monoid m => (a -> m) -> First a -> m Source # foldMap' :: Monoid m => (a -> m) -> First a -> m Source # foldr :: (a -> b -> b) -> b -> First a -> b Source # foldr' :: (a -> b -> b) -> b -> First a -> b Source # foldl :: (b -> a -> b) -> b -> First a -> b Source # foldl' :: (b -> a -> b) -> b -> First a -> b Source # foldr1 :: (a -> a -> a) -> First a -> a Source # foldl1 :: (a -> a -> a) -> First a -> a Source # toList :: First a -> [a] Source # null :: First a -> Bool Source # length :: First a -> Int Source # elem :: Eq a => a -> First a -> Bool Source # maximum :: Ord a => First a -> a Source # minimum :: Ord a => First a -> a Source # | |
| Foldable1 First Source # | |
Defined in Data.Foldable1 Methods fold1 :: Semigroup m => First m -> m Source # foldMap1 :: Semigroup m => (a -> m) -> First a -> m Source # foldMap1' :: Semigroup m => (a -> m) -> First a -> m Source # toNonEmpty :: First a -> NonEmpty a Source # maximum :: Ord a => First a -> a Source # minimum :: Ord a => First a -> a Source # foldrMap1 :: (a -> b) -> (a -> b -> b) -> First a -> b Source # foldlMap1' :: (a -> b) -> (b -> a -> b) -> First a -> b Source # foldlMap1 :: (a -> b) -> (b -> a -> b) -> First a -> b Source # foldrMap1' :: (a -> b) -> (a -> b -> b) -> First a -> b Source # | |
| Traversable First Source # | Since: base-4.9.0.0 |
| Applicative First Source # | Since: base-4.9.0.0 |
| Functor First Source # | Since: base-4.9.0.0 |
| Monad First Source # | Since: base-4.9.0.0 |
| Generic1 First Source # | |
| Data a => Data (First a) Source # | 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) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (First a) Source # toConstr :: First a -> Constr Source # dataTypeOf :: First a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (First a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (First a)) Source # gmapT :: (forall b. Data b => b -> b) -> First a -> First a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> First a -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> First a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> First a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> First a -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> First a -> m (First a) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> First a -> m (First a) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> First a -> m (First a) Source # | |
| Semigroup (First a) Source # | Since: base-4.9.0.0 |
| Bounded a => Bounded (First a) Source # | Since: base-4.9.0.0 |
| Enum a => Enum (First a) Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods succ :: First a -> First a Source # pred :: First a -> First a Source # toEnum :: Int -> First a Source # fromEnum :: First a -> Int Source # enumFrom :: First a -> [First a] Source # enumFromThen :: First a -> First a -> [First a] Source # enumFromTo :: First a -> First a -> [First a] Source # enumFromThenTo :: First a -> First a -> First a -> [First a] Source # | |
| Generic (First a) Source # | |
| Read a => Read (First a) Source # | Since: base-4.9.0.0 |
| Show a => Show (First a) Source # | Since: base-4.9.0.0 |
| Eq a => Eq (First a) Source # | Since: base-4.9.0.0 |
| Ord a => Ord (First a) Source # | Since: base-4.9.0.0 |
| type Rep1 First Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| type Rep (First a) Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
Beware that Data.Semigroup.Last is different from Data.Monoid.Last. The former simply returns the last value, so x <> Data.Semigroup.Last Nothing = Data.Semigroup.Last Nothing. The latter returns the last non-Nothing, thus x <> Data.Monoid.Last Nothing = x.
Instances
| MonadFix Last Source # | Since: base-4.9.0.0 |
| Foldable Last Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods fold :: Monoid m => Last m -> m Source # foldMap :: Monoid m => (a -> m) -> Last a -> m Source # foldMap' :: Monoid m => (a -> m) -> Last a -> m Source # foldr :: (a -> b -> b) -> b -> Last a -> b Source # foldr' :: (a -> b -> b) -> b -> Last a -> b Source # foldl :: (b -> a -> b) -> b -> Last a -> b Source # foldl' :: (b -> a -> b) -> b -> Last a -> b Source # foldr1 :: (a -> a -> a) -> Last a -> a Source # foldl1 :: (a -> a -> a) -> Last a -> a Source # toList :: Last a -> [a] Source # null :: Last a -> Bool Source # length :: Last a -> Int Source # elem :: Eq a => a -> Last a -> Bool Source # maximum :: Ord a => Last a -> a Source # minimum :: Ord a => Last a -> a Source # | |
| Foldable1 Last Source # | |
Defined in Data.Foldable1 Methods fold1 :: Semigroup m => Last m -> m Source # foldMap1 :: Semigroup m => (a -> m) -> Last a -> m Source # foldMap1' :: Semigroup m => (a -> m) -> Last a -> m Source # toNonEmpty :: Last a -> NonEmpty a Source # maximum :: Ord a => Last a -> a Source # minimum :: Ord a => Last a -> a Source # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Last a -> b Source # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Last a -> b Source # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Last a -> b Source # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Last a -> b Source # | |
| Traversable Last Source # | Since: base-4.9.0.0 |
| Applicative Last Source # | Since: base-4.9.0.0 |
| Functor Last Source # | Since: base-4.9.0.0 |
| Monad Last Source # | Since: base-4.9.0.0 |
| Generic1 Last Source # | |
| Data a => Data (Last a) Source # | 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) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Last a) Source # toConstr :: Last a -> Constr Source # dataTypeOf :: Last a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Last a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Last a)) Source # gmapT :: (forall b. Data b => b -> b) -> Last a -> Last a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Last a -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Last a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Last a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Last a -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Last a -> m (Last a) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Last a -> m (Last a) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Last a -> m (Last a) Source # | |
| Semigroup (Last a) Source # | Since: base-4.9.0.0 |
| Bounded a => Bounded (Last a) Source # | Since: base-4.9.0.0 |
| Enum a => Enum (Last a) Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods succ :: Last a -> Last a Source # pred :: Last a -> Last a Source # toEnum :: Int -> Last a Source # fromEnum :: Last a -> Int Source # enumFrom :: Last a -> [Last a] Source # enumFromThen :: Last a -> Last a -> [Last a] Source # enumFromTo :: Last a -> Last a -> [Last a] Source # enumFromThenTo :: Last a -> Last a -> Last a -> [Last a] Source # | |
| Generic (Last a) Source # | |
| Read a => Read (Last a) Source # | Since: base-4.9.0.0 |
| Show a => Show (Last a) Source # | Since: base-4.9.0.0 |
| Eq a => Eq (Last a) Source # | Since: base-4.9.0.0 |
| Ord a => Ord (Last a) Source # | Since: base-4.9.0.0 |
| type Rep1 Last Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| type Rep (Last a) Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
newtype WrappedMonoid m Source #
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
| MonadFix Dual Source # | Since: base-4.8.0.0 |
| MonadZip Dual Source # | Since: base-4.8.0.0 |
| Foldable Dual Source # | Since: base-4.8.0.0 |
Defined in Data.Foldable Methods fold :: Monoid m => Dual m -> m Source # foldMap :: Monoid m => (a -> m) -> Dual a -> m Source # foldMap' :: Monoid m => (a -> m) -> Dual a -> m Source # foldr :: (a -> b -> b) -> b -> Dual a -> b Source # foldr' :: (a -> b -> b) -> b -> Dual a -> b Source # foldl :: (b -> a -> b) -> b -> Dual a -> b Source # foldl' :: (b -> a -> b) -> b -> Dual a -> b Source # foldr1 :: (a -> a -> a) -> Dual a -> a Source # foldl1 :: (a -> a -> a) -> Dual a -> a Source # toList :: Dual a -> [a] Source # null :: Dual a -> Bool Source # length :: Dual a -> Int Source # elem :: Eq a => a -> Dual a -> Bool Source # maximum :: Ord a => Dual a -> a Source # minimum :: Ord a => Dual a -> a Source # | |
| Foldable1 Dual Source # | |
Defined in Data.Foldable1 Methods fold1 :: Semigroup m => Dual m -> m Source # foldMap1 :: Semigroup m => (a -> m) -> Dual a -> m Source # foldMap1' :: Semigroup m => (a -> m) -> Dual a -> m Source # toNonEmpty :: Dual a -> NonEmpty a Source # maximum :: Ord a => Dual a -> a Source # minimum :: Ord a => Dual a -> a Source # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Dual a -> b Source # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Dual a -> b Source # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Dual a -> b Source # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Dual a -> b Source # | |
| Traversable Dual Source # | Since: base-4.8.0.0 |
| Applicative Dual Source # | Since: base-4.8.0.0 |
| Functor Dual Source # | Since: base-4.8.0.0 |
| Monad Dual Source # | Since: base-4.8.0.0 |
| Generic1 Dual Source # | |
| Data a => Data (Dual a) Source # | 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) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Dual a) Source # toConstr :: Dual a -> Constr Source # dataTypeOf :: Dual a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Dual a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Dual a)) Source # gmapT :: (forall b. Data b => b -> b) -> Dual a -> Dual a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Dual a -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Dual a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Dual a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Dual a -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Dual a -> m (Dual a) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Dual a -> m (Dual a) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Dual a -> m (Dual a) Source # | |
| Monoid a => Monoid (Dual a) Source # | Since: base-2.1 |
| Semigroup a => Semigroup (Dual a) Source # | Since: base-4.9.0.0 |
| Bounded a => Bounded (Dual a) Source # | Since: base-2.1 |
| Generic (Dual a) Source # | |
| Read a => Read (Dual a) Source # | Since: base-2.1 |
| Show a => Show (Dual a) Source # | Since: base-2.1 |
| Eq a => Eq (Dual a) Source # | Since: base-2.1 |
| Ord a => Ord (Dual a) Source # | Since: base-2.1 |
| type Rep1 Dual Source # | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
| type Rep (Dual a) Source # | 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
| Data All Source # | 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 Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c All Source # toConstr :: All -> Constr Source # dataTypeOf :: All -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c All) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c All) Source # gmapT :: (forall b. Data b => b -> b) -> All -> All Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> All -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> All -> r Source # gmapQ :: (forall d. Data d => d -> u) -> All -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> All -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> All -> m All Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> All -> m All Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> All -> m All Source # | |
| Monoid All Source # | Since: base-2.1 |
| Semigroup All Source # | Since: base-4.9.0.0 |
| Bounded All Source # | Since: base-2.1 |
| Generic All Source # | |
| Read All Source # | Since: base-2.1 |
| Show All Source # | Since: base-2.1 |
| Eq All Source # | Since: base-2.1 |
| Ord All Source # | Since: base-2.1 |
| type Rep All Source # | 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
| Data Any Source # | 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 Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Any Source # toConstr :: Any -> Constr Source # dataTypeOf :: Any -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Any) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Any) Source # gmapT :: (forall b. Data b => b -> b) -> Any -> Any Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Any -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Any -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Any -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Any -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Any -> m Any Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Any -> m Any Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Any -> m Any Source # | |
| Monoid Any Source # | Since: base-2.1 |
| Semigroup Any Source # | Since: base-4.9.0.0 |
| Bounded Any Source # | Since: base-2.1 |
| Generic Any Source # | |
| Read Any Source # | Since: base-2.1 |
| Show Any Source # | Since: base-2.1 |
| Eq Any Source # | Since: base-2.1 |
| Ord Any Source # | Since: base-2.1 |
| type Rep Any Source # | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
Monoid under addition.
>>>getSum (Sum 1 <> Sum 2 <> mempty)3
Instances
| MonadFix Sum Source # | Since: base-4.8.0.0 |
| MonadZip Sum Source # | Since: base-4.8.0.0 |
| Foldable Sum Source # | Since: base-4.8.0.0 |
Defined in Data.Foldable Methods fold :: Monoid m => Sum m -> m Source # foldMap :: Monoid m => (a -> m) -> Sum a -> m Source # foldMap' :: Monoid m => (a -> m) -> Sum a -> m Source # foldr :: (a -> b -> b) -> b -> Sum a -> b Source # foldr' :: (a -> b -> b) -> b -> Sum a -> b Source # foldl :: (b -> a -> b) -> b -> Sum a -> b Source # foldl' :: (b -> a -> b) -> b -> Sum a -> b Source # foldr1 :: (a -> a -> a) -> Sum a -> a Source # foldl1 :: (a -> a -> a) -> Sum a -> a Source # toList :: Sum a -> [a] Source # null :: Sum a -> Bool Source # length :: Sum a -> Int Source # elem :: Eq a => a -> Sum a -> Bool Source # maximum :: Ord a => Sum a -> a Source # minimum :: Ord a => Sum a -> a Source # | |
| Foldable1 Sum Source # | |
Defined in Data.Foldable1 Methods fold1 :: Semigroup m => Sum m -> m Source # foldMap1 :: Semigroup m => (a -> m) -> Sum a -> m Source # foldMap1' :: Semigroup m => (a -> m) -> Sum a -> m Source # toNonEmpty :: Sum a -> NonEmpty a Source # maximum :: Ord a => Sum a -> a Source # minimum :: Ord a => Sum a -> a Source # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Sum a -> b Source # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Sum a -> b Source # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Sum a -> b Source # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Sum a -> b Source # | |
| Traversable Sum Source # | Since: base-4.8.0.0 |
| Applicative Sum Source # | Since: base-4.8.0.0 |
| Functor Sum Source # | Since: base-4.8.0.0 |
| Monad Sum Source # | Since: base-4.8.0.0 |
| Generic1 Sum Source # | |
| Data a => Data (Sum a) Source # | 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) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Sum a) Source # toConstr :: Sum a -> Constr Source # dataTypeOf :: Sum a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Sum a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Sum a)) Source # gmapT :: (forall b. Data b => b -> b) -> Sum a -> Sum a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Sum a -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Sum a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Sum a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Sum a -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Sum a -> m (Sum a) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Sum a -> m (Sum a) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Sum a -> m (Sum a) Source # | |
| Num a => Monoid (Sum a) Source # | Since: base-2.1 |
| Num a => Semigroup (Sum a) Source # | Since: base-4.9.0.0 |
| Bounded a => Bounded (Sum a) Source # | Since: base-2.1 |
| Generic (Sum a) Source # | |
| Num a => Num (Sum a) Source # | Since: base-4.7.0.0 |
| Read a => Read (Sum a) Source # | Since: base-2.1 |
| Show a => Show (Sum a) Source # | Since: base-2.1 |
| Eq a => Eq (Sum a) Source # | Since: base-2.1 |
| Ord a => Ord (Sum a) Source # | Since: base-2.1 |
Defined in Data.Semigroup.Internal | |
| type Rep1 Sum Source # | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
| type Rep (Sum a) Source # | 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
| MonadFix Product Source # | Since: base-4.8.0.0 |
| MonadZip Product Source # | Since: base-4.8.0.0 |
| Foldable Product Source # | Since: base-4.8.0.0 |
Defined in Data.Foldable Methods fold :: Monoid m => Product m -> m Source # foldMap :: Monoid m => (a -> m) -> Product a -> m Source # foldMap' :: Monoid m => (a -> m) -> Product a -> m Source # foldr :: (a -> b -> b) -> b -> Product a -> b Source # foldr' :: (a -> b -> b) -> b -> Product a -> b Source # foldl :: (b -> a -> b) -> b -> Product a -> b Source # foldl' :: (b -> a -> b) -> b -> Product a -> b Source # foldr1 :: (a -> a -> a) -> Product a -> a Source # foldl1 :: (a -> a -> a) -> Product a -> a Source # toList :: Product a -> [a] Source # null :: Product a -> Bool Source # length :: Product a -> Int Source # elem :: Eq a => a -> Product a -> Bool Source # maximum :: Ord a => Product a -> a Source # minimum :: Ord a => Product a -> a Source # | |
| Foldable1 Product Source # | |
Defined in Data.Foldable1 Methods fold1 :: Semigroup m => Product m -> m Source # foldMap1 :: Semigroup m => (a -> m) -> Product a -> m Source # foldMap1' :: Semigroup m => (a -> m) -> Product a -> m Source # toNonEmpty :: Product a -> NonEmpty a Source # maximum :: Ord a => Product a -> a Source # minimum :: Ord a => Product a -> a Source # head :: Product a -> a Source # last :: Product a -> a Source # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Product a -> b Source # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Product a -> b Source # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Product a -> b Source # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Product a -> b Source # | |
| Traversable Product Source # | Since: base-4.8.0.0 |
Defined in Data.Traversable | |
| Applicative Product Source # | Since: base-4.8.0.0 |
Defined in Data.Semigroup.Internal | |
| Functor Product Source # | Since: base-4.8.0.0 |
| Monad Product Source # | Since: base-4.8.0.0 |
| Generic1 Product Source # | |
| Data a => Data (Product a) Source # | 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) Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Product a) Source # toConstr :: Product a -> Constr Source # dataTypeOf :: Product a -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Product a)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Product a)) Source # gmapT :: (forall b. Data b => b -> b) -> Product a -> Product a Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Product a -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Product a -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Product a -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Product a -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Product a -> m (Product a) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Product a -> m (Product a) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Product a -> m (Product a) Source # | |
| Num a => Monoid (Product a) Source # | Since: base-2.1 |
| Num a => Semigroup (Product a) Source # | Since: base-4.9.0.0 |
| Bounded a => Bounded (Product a) Source # | Since: base-2.1 |
| Generic (Product a) Source # | |
| Num a => Num (Product a) Source # | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal Methods (+) :: Product a -> Product a -> Product a Source # (-) :: Product a -> Product a -> Product a Source # (*) :: Product a -> Product a -> Product a Source # negate :: Product a -> Product a Source # abs :: Product a -> Product a Source # signum :: Product a -> Product a Source # fromInteger :: Integer -> Product a Source # | |
| Read a => Read (Product a) Source # | Since: base-2.1 |
| Show a => Show (Product a) Source # | Since: base-2.1 |
| Eq a => Eq (Product a) Source # | Since: base-2.1 |
| Ord a => Ord (Product a) Source # | Since: base-2.1 |
Defined in Data.Semigroup.Internal | |
| type Rep1 Product Source # | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
| type Rep (Product a) Source # | Since: base-4.7.0.0 |
Defined in Data.Semigroup.Internal | |
Difference lists of a semigroup
diff :: Semigroup m => m -> Endo m Source #
This lets you use a difference list of a Semigroup as a Monoid.
Example:
>>>let hello = diff "Hello, ">>>appEndo hello "World!""Hello, World!">>>appEndo (hello <> mempty) "World!""Hello, World!">>>appEndo (mempty <> hello) "World!""Hello, World!">>>let world = diff "World">>>let excl = diff "!">>>appEndo (hello <> (world <> excl)) mempty"Hello, World!">>>appEndo ((hello <> world) <> excl) mempty"Hello, World!"
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.
>>>minimum [ Arg (x * x) x | x <- [-10 .. 10] ]Arg 0 0
Constructors
| Arg | |
Instances
| Bifoldable Arg Source # | Since: base-4.10.0.0 |
| Bifoldable1 Arg Source # | |
| Bifunctor Arg Source # | Since: base-4.9.0.0 |
| Bitraversable Arg Source # | 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) Source # | |
| Generic1 (Arg a :: Type -> Type) Source # | |
| Foldable (Arg a) Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods fold :: Monoid m => Arg a m -> m Source # foldMap :: Monoid m => (a0 -> m) -> Arg a a0 -> m Source # foldMap' :: Monoid m => (a0 -> m) -> Arg a a0 -> m Source # foldr :: (a0 -> b -> b) -> b -> Arg a a0 -> b Source # foldr' :: (a0 -> b -> b) -> b -> Arg a a0 -> b Source # foldl :: (b -> a0 -> b) -> b -> Arg a a0 -> b Source # foldl' :: (b -> a0 -> b) -> b -> Arg a a0 -> b Source # foldr1 :: (a0 -> a0 -> a0) -> Arg a a0 -> a0 Source # foldl1 :: (a0 -> a0 -> a0) -> Arg a a0 -> a0 Source # toList :: Arg a a0 -> [a0] Source # null :: Arg a a0 -> Bool Source # length :: Arg a a0 -> Int Source # elem :: Eq a0 => a0 -> Arg a a0 -> Bool Source # maximum :: Ord a0 => Arg a a0 -> a0 Source # minimum :: Ord a0 => Arg a a0 -> a0 Source # | |
| Traversable (Arg a) Source # | Since: base-4.9.0.0 |
Defined in Data.Semigroup | |
| Functor (Arg a) Source # | Since: base-4.9.0.0 |
| (Data a, Data b) => Data (Arg a b) Source # | 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) Source # gunfold :: (forall b0 r. Data b0 => c (b0 -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Arg a b) Source # toConstr :: Arg a b -> Constr Source # dataTypeOf :: Arg a b -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Arg a b)) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Arg a b)) Source # gmapT :: (forall b0. Data b0 => b0 -> b0) -> Arg a b -> Arg a b Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Arg a b -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Arg a b -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Arg a b -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Arg a b -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Arg a b -> m (Arg a b) Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Arg a b -> m (Arg a b) Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Arg a b -> m (Arg a b) Source # | |
| Generic (Arg a b) Source # | |
| (Read a, Read b) => Read (Arg a b) Source # | Since: base-4.9.0.0 |
| (Show a, Show b) => Show (Arg a b) Source # | Since: base-4.9.0.0 |
| Eq a => Eq (Arg a b) Source # | Since: base-4.9.0.0 |
| Ord a => Ord (Arg a b) Source # | Since: base-4.9.0.0 |
| type Rep1 (Arg a :: Type -> Type) Source # | 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) Source # | 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))) | |