| Safe Haskell | Safe-Inferred |
|---|---|
| Language | Haskell2010 |
Data.Monoid.Compat
Synopsis
- newtype Any = Any {}
- newtype Last a = Last {}
- newtype First a = First {}
- class Semigroup a => Monoid a where
- newtype Alt (f :: k -> Type) (a :: k) = Alt {
- getAlt :: f a
- newtype Product a = Product {
- getProduct :: a
- newtype Sum a = Sum {
- getSum :: a
- newtype All = All {}
- newtype Endo a = Endo {
- appEndo :: a -> a
- newtype Dual a = Dual {
- getDual :: a
- newtype Ap (f :: k -> Type) (a :: k) = Ap {
- getAp :: f a
- (<>) :: Semigroup a => a -> a -> a
Documentation
Boolean monoid under disjunction (||).
Any x <> Any y = Any (x || y)
Examples
>>>Any True <> mempty <> Any FalseAny {getAny = True}
>>>mconcat (map (\x -> Any (even x)) [2,4,6,7,8])Any {getAny = True}
>>>Any False <> memptyAny {getAny = False}
Instances
| Monoid Any | Since: base-2.1 | ||||
| Semigroup Any | Since: base-4.9.0.0 | ||||
| Bounded Any | Since: base-2.1 | ||||
| Generic Any | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
| Read Any | Since: base-2.1 | ||||
| Show Any | Since: base-2.1 | ||||
| Eq Any | Since: base-2.1 | ||||
| Ord Any | Since: base-2.1 | ||||
| type Rep Any | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
Maybe monoid returning the rightmost non-Nothing value.
is isomorphic to Last a, and thus to
Dual (First a)Dual (Alt Maybe a)
Data.Semigroup.Last. The former returns the last non-Nothing,
so x <> Data.Monoid.Last Nothing = x. The latter simply returns the last value,
thus x <> Data.Semigroup.Last Nothing = Data.Semigroup.Last Nothing.
Examples
>>>Last (Just "hello") <> Last Nothing <> Last (Just "world")Last {getLast = Just "world"}
>>>Last Nothing <> memptyLast {getLast = Nothing}
Instances
| MonadZip Last | Since: base-4.8.0.0 | ||||
| Applicative Last | Since: base-4.8.0.0 | ||||
| Functor Last | Since: base-4.8.0.0 | ||||
| Monad Last | Since: base-4.8.0.0 | ||||
| Foldable Last | Since: base-4.8.0.0 | ||||
Defined in GHC.Internal.Data.Foldable Methods fold :: Monoid m => Last m -> m # foldMap :: Monoid m => (a -> m) -> Last a -> 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-4.8.0.0 | ||||
| Generic1 Last | |||||
Defined in GHC.Internal.Data.Monoid Associated Types
| |||||
| Monoid (Last a) | Since: base-2.1 | ||||
| Semigroup (Last a) | Since: base-4.9.0.0 | ||||
| Generic (Last a) | |||||
Defined in GHC.Internal.Data.Monoid Associated Types
| |||||
| Read a => Read (Last a) | Since: base-2.1 | ||||
| Show a => Show (Last a) | Since: base-2.1 | ||||
| Eq a => Eq (Last a) | Since: base-2.1 | ||||
| Ord a => Ord (Last a) | Since: base-2.1 | ||||
| type Rep1 Last | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Monoid | |||||
| type Rep (Last a) | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Monoid | |||||
Maybe monoid returning the leftmost non-Nothing value.
is isomorphic to First a, but precedes it
historically.Alt Maybe a
Beware that Data.Monoid.First is different from
Data.Semigroup.First. The former returns the first non-Nothing,
so Data.Monoid.First Nothing <> x = x. The latter simply returns the first value,
thus Data.Semigroup.First Nothing <> x = Data.Semigroup.First Nothing.
Examples
>>>First (Just "hello") <> First Nothing <> First (Just "world")First {getFirst = Just "hello"}
>>>First Nothing <> memptyFirst {getFirst = Nothing}
Instances
| MonadZip First | Since: base-4.8.0.0 | ||||
| Applicative First | Since: base-4.8.0.0 | ||||
| Functor First | Since: base-4.8.0.0 | ||||
| Monad First | Since: base-4.8.0.0 | ||||
| Foldable First | Since: base-4.8.0.0 | ||||
Defined in GHC.Internal.Data.Foldable Methods fold :: Monoid m => First m -> m # foldMap :: Monoid m => (a -> m) -> First a -> 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-4.8.0.0 | ||||
| Generic1 First | |||||
Defined in GHC.Internal.Data.Monoid Associated Types
| |||||
| Monoid (First a) | Since: base-2.1 | ||||
| Semigroup (First a) | Since: base-4.9.0.0 | ||||
| Generic (First a) | |||||
Defined in GHC.Internal.Data.Monoid Associated Types
| |||||
| Read a => Read (First a) | Since: base-2.1 | ||||
| Show a => Show (First a) | Since: base-2.1 | ||||
| Eq a => Eq (First a) | Since: base-2.1 | ||||
| Ord a => Ord (First a) | Since: base-2.1 | ||||
Defined in GHC.Internal.Data.Monoid | |||||
| type Rep1 First | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Monoid | |||||
| type Rep (First a) | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Monoid | |||||
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
You can alternatively define mconcat instead of mempty, in which case the
laws are:
- Unit
mconcat(purex) = x- Multiplication
mconcat(joinxss) =mconcat(fmapmconcatxss)- Subclass
mconcat(toListxs) =sconcatxs
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.
Methods
Identity of mappend
Examples
>>>"Hello world" <> mempty"Hello world"
>>>mempty <> [1, 2, 3][1,2,3]
An associative operation
NOTE: This method is redundant and has the default
implementation since base-4.11.0.0.
Should it be implemented manually, since 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
| Monoid ByteArray | Since: base-4.17.0.0 |
| Monoid All | Since: base-2.1 |
| Monoid Any | Since: base-2.1 |
| Monoid Ordering | Since: base-2.1 |
| Monoid () | Since: base-2.1 |
| Monoid (Comparison a) |
mempty :: Comparison a mempty = Comparison _ _ -> EQ |
Defined in Data.Functor.Contravariant Methods mempty :: Comparison a # mappend :: Comparison a -> Comparison a -> Comparison a # mconcat :: [Comparison a] -> Comparison a # | |
| Monoid (Equivalence a) |
mempty :: Equivalence a mempty = Equivalence _ _ -> True |
Defined in Data.Functor.Contravariant Methods mempty :: Equivalence a # mappend :: Equivalence a -> Equivalence a -> Equivalence a # mconcat :: [Equivalence a] -> Equivalence a # | |
| Monoid (Predicate a) |
mempty :: Predicate a mempty = _ -> True |
| (Ord a, Bounded a) => Monoid (Max a) | Since: base-4.9.0.0 |
| (Ord a, Bounded a) => Monoid (Min a) | Since: base-4.9.0.0 |
| Monoid m => Monoid (WrappedMonoid m) | Since: base-4.9.0.0 |
Defined in Data.Semigroup Methods mempty :: WrappedMonoid m # mappend :: WrappedMonoid m -> WrappedMonoid m -> WrappedMonoid m # mconcat :: [WrappedMonoid m] -> WrappedMonoid m # | |
| Monoid a => Monoid (STM a) | Since: base-4.17.0.0 |
| FiniteBits a => Monoid (And a) | This constraint is arguably too strong. However,
as some types (such as Since: base-4.16 |
| FiniteBits a => Monoid (Iff a) | This constraint is arguably
too strong. However, as some types (such as Since: base-4.16 |
| Bits a => Monoid (Ior a) | Since: base-4.16 |
| Bits a => Monoid (Xor a) | Since: base-4.16 |
| Monoid a => Monoid (Identity a) | Since: base-4.9.0.0 |
| Monoid (First a) | Since: base-2.1 |
| Monoid (Last a) | Since: base-2.1 |
| Monoid a => Monoid (Dual a) | Since: base-2.1 |
| Monoid (Endo a) | Since: base-2.1 |
| Num a => Monoid (Product a) | Since: base-2.1 |
| Num a => Monoid (Sum a) | Since: base-2.1 |
| Monoid a => Monoid (IO a) | Since: base-4.9.0.0 |
| Semigroup a => Monoid (Maybe a) | Lift a semigroup into Since 4.11.0: constraint on inner Since: base-2.1 |
| Monoid a => Monoid (Solo a) | Since: base-4.15 |
| Monoid [a] | Since: base-2.1 |
| Monoid a => Monoid (Op a b) |
mempty :: Op a b mempty = Op _ -> mempty |
| Monoid (Proxy s) | Since: base-4.7.0.0 |
| Monoid a => Monoid (ST s a) | Since: base-4.11.0.0 |
| (Monoid a, Monoid b) => Monoid (a, b) | Since: base-2.1 |
| Monoid b => Monoid (a -> b) | Since: base-2.1 |
| Monoid a => Monoid (Const a b) | Since: base-4.9.0.0 |
| (Applicative f, Monoid a) => Monoid (Ap f a) | Since: base-4.12.0.0 |
| Alternative f => Monoid (Alt f a) | Since: base-4.8.0.0 |
| (Monoid a, Monoid b, Monoid c) => Monoid (a, b, c) | Since: base-2.1 |
| (Monoid (f a), Monoid (g a)) => Monoid (Product f g a) | Since: base-4.16.0.0 |
| (Monoid a, Monoid b, Monoid c, Monoid d) => Monoid (a, b, c, d) | Since: base-2.1 |
| Monoid (f (g a)) => Monoid (Compose f g a) | Since: base-4.16.0.0 |
| (Monoid a, Monoid b, Monoid c, Monoid d, Monoid e) => Monoid (a, b, c, d, e) | Since: base-2.1 |
newtype Alt (f :: k -> Type) (a :: k) #
Monoid under <|>.
Alt l <> Alt r == Alt (l <|> r)
Examples
>>>Alt (Just 12) <> Alt (Just 24)Alt {getAlt = Just 12}
>>>Alt Nothing <> Alt (Just 24)Alt {getAlt = Just 24}
Since: base-4.8.0.0
Instances
| Generic1 (Alt f :: k -> Type) | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
| MonadZip f => MonadZip (Alt f) | Since: base-4.8.0.0 | ||||
| Foldable1 f => Foldable1 (Alt f) | Since: base-4.18.0.0 | ||||
Defined in Data.Foldable1 Methods fold1 :: Semigroup m => Alt f m -> m # foldMap1 :: Semigroup m => (a -> m) -> Alt f a -> m # foldMap1' :: Semigroup m => (a -> m) -> Alt f a -> m # toNonEmpty :: Alt f a -> NonEmpty a # maximum :: Ord a => Alt f a -> a # minimum :: Ord a => Alt f a -> a # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Alt f a -> b # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Alt f a -> b # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Alt f a -> b # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Alt f a -> b # | |||||
| Contravariant f => Contravariant (Alt f) | |||||
| Alternative f => Alternative (Alt f) | Since: base-4.8.0.0 | ||||
| Applicative f => Applicative (Alt f) | Since: base-4.8.0.0 | ||||
| Functor f => Functor (Alt f) | Since: base-4.8.0.0 | ||||
| Monad f => Monad (Alt f) | Since: base-4.8.0.0 | ||||
| MonadPlus f => MonadPlus (Alt f) | Since: base-4.8.0.0 | ||||
| Foldable f => Foldable (Alt f) | Since: base-4.12.0.0 | ||||
Defined in GHC.Internal.Data.Foldable Methods fold :: Monoid m => Alt f m -> m # foldMap :: Monoid m => (a -> m) -> Alt f a -> m # foldMap' :: Monoid m => (a -> m) -> Alt f a -> m # foldr :: (a -> b -> b) -> b -> Alt f a -> b # foldr' :: (a -> b -> b) -> b -> Alt f a -> b # foldl :: (b -> a -> b) -> b -> Alt f a -> b # foldl' :: (b -> a -> b) -> b -> Alt f a -> b # foldr1 :: (a -> a -> a) -> Alt f a -> a # foldl1 :: (a -> a -> a) -> Alt f a -> a # elem :: Eq a => a -> Alt f a -> Bool # maximum :: Ord a => Alt f a -> a # minimum :: Ord a => Alt f a -> a # | |||||
| Traversable f => Traversable (Alt f) | Since: base-4.12.0.0 | ||||
| Alternative f => Monoid (Alt f a) | Since: base-4.8.0.0 | ||||
| Alternative f => Semigroup (Alt f a) | Since: base-4.9.0.0 | ||||
| Enum (f a) => Enum (Alt f a) | Since: base-4.8.0.0 | ||||
| Generic (Alt f a) | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
| Num (f a) => Num (Alt f a) | Since: base-4.8.0.0 | ||||
| Read (f a) => Read (Alt f a) | Since: base-4.8.0.0 | ||||
| Show (f a) => Show (Alt f a) | Since: base-4.8.0.0 | ||||
| Eq (f a) => Eq (Alt f a) | Since: base-4.8.0.0 | ||||
| Ord (f a) => Ord (Alt f a) | Since: base-4.8.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
| type Rep1 (Alt f :: k -> Type) | Since: base-4.8.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
| type Rep (Alt f a) | Since: base-4.8.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
Monoid under multiplication.
Product x <> Product y == Product (x * y)
Examples
>>>Product 3 <> Product 4 <> memptyProduct {getProduct = 12}
>>>mconcat [ Product n | n <- [2 .. 10]]Product {getProduct = 3628800}
Constructors
| Product | |
Fields
| |
Instances
| MonadZip Product | Since: base-4.8.0.0 | ||||
| Foldable1 Product | Since: base-4.18.0.0 | ||||
Defined in Data.Foldable1 Methods fold1 :: Semigroup m => Product m -> m # foldMap1 :: Semigroup m => (a -> m) -> Product a -> m # foldMap1' :: Semigroup m => (a -> m) -> Product a -> m # toNonEmpty :: Product a -> NonEmpty a # maximum :: Ord a => Product a -> a # minimum :: Ord a => Product a -> a # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Product a -> b # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Product a -> b # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Product a -> b # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Product a -> b # | |||||
| Applicative Product | Since: base-4.8.0.0 | ||||
| Functor Product | Since: base-4.8.0.0 | ||||
| Monad Product | Since: base-4.8.0.0 | ||||
| Foldable Product | Since: base-4.8.0.0 | ||||
Defined in GHC.Internal.Data.Foldable Methods fold :: Monoid m => Product m -> m # foldMap :: Monoid m => (a -> m) -> Product a -> 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 | ||||
| Generic1 Product | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
| Num a => Monoid (Product a) | Since: base-2.1 | ||||
| Num a => Semigroup (Product a) | Since: base-4.9.0.0 | ||||
| Bounded a => Bounded (Product a) | Since: base-2.1 | ||||
| Generic (Product a) | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
| Num a => Num (Product a) | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
| Read a => Read (Product a) | Since: base-2.1 | ||||
| Show a => Show (Product a) | Since: base-2.1 | ||||
| Eq a => Eq (Product a) | Since: base-2.1 | ||||
| Ord a => Ord (Product a) | Since: base-2.1 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
| type Rep1 Product | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
| type Rep (Product a) | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
Monoid under addition.
Sum a <> Sum b = Sum (a + b)
Examples
>>>Sum 1 <> Sum 2 <> memptySum {getSum = 3}
>>>mconcat [ Sum n | n <- [3 .. 9]]Sum {getSum = 42}
Instances
| MonadZip Sum | Since: base-4.8.0.0 | ||||
| Foldable1 Sum | Since: base-4.18.0.0 | ||||
Defined in Data.Foldable1 Methods fold1 :: Semigroup m => Sum m -> m # foldMap1 :: Semigroup m => (a -> m) -> Sum a -> m # foldMap1' :: Semigroup m => (a -> m) -> Sum a -> m # toNonEmpty :: Sum a -> NonEmpty a # maximum :: Ord a => Sum a -> a # minimum :: Ord a => Sum a -> a # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Sum a -> b # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Sum a -> b # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Sum a -> b # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Sum a -> b # | |||||
| Applicative Sum | Since: base-4.8.0.0 | ||||
| Functor Sum | Since: base-4.8.0.0 | ||||
| Monad Sum | Since: base-4.8.0.0 | ||||
| Foldable Sum | Since: base-4.8.0.0 | ||||
Defined in GHC.Internal.Data.Foldable Methods fold :: Monoid m => Sum m -> m # foldMap :: Monoid m => (a -> m) -> Sum a -> 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 | ||||
| Generic1 Sum | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
| Num a => Monoid (Sum a) | Since: base-2.1 | ||||
| Num a => Semigroup (Sum a) | Since: base-4.9.0.0 | ||||
| Bounded a => Bounded (Sum a) | Since: base-2.1 | ||||
| Generic (Sum a) | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
| Num a => Num (Sum a) | Since: base-4.7.0.0 | ||||
| Read a => Read (Sum a) | Since: base-2.1 | ||||
| Show a => Show (Sum a) | Since: base-2.1 | ||||
| Eq a => Eq (Sum a) | Since: base-2.1 | ||||
| Ord a => Ord (Sum a) | Since: base-2.1 | ||||
| type Rep1 Sum | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
| type Rep (Sum a) | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
Boolean monoid under conjunction (&&).
All x <> All y = All (x && y)
Examples
>>>All True <> mempty <> All False)All {getAll = False}
>>>mconcat (map (\x -> All (even x)) [2,4,6,7,8])All {getAll = False}
>>>All True <> memptyAll {getAll = True}
Instances
| Monoid All | Since: base-2.1 | ||||
| Semigroup All | Since: base-4.9.0.0 | ||||
| Bounded All | Since: base-2.1 | ||||
| Generic All | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
| Read All | Since: base-2.1 | ||||
| Show All | Since: base-2.1 | ||||
| Eq All | Since: base-2.1 | ||||
| Ord All | Since: base-2.1 | ||||
| type Rep All | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
The monoid of endomorphisms under composition.
Endo f <> Endo g == Endo (f . g)
Examples
>>>let computation = Endo ("Hello, " ++) <> Endo (++ "!")>>>appEndo computation "Haskell""Hello, Haskell!"
>>>let computation = Endo (*3) <> Endo (+1)>>>appEndo computation 16
Instances
| Monoid (Endo a) | Since: base-2.1 | ||||
| Semigroup (Endo a) | Since: base-4.9.0.0 | ||||
| Generic (Endo a) | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
| |||||
| type Rep (Endo a) | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
The dual of a Monoid, obtained by swapping the arguments of (<>).
Dual a <> Dual b == Dual (b <> a)
Examples
>>>Dual "Hello" <> Dual "World"Dual {getDual = "WorldHello"}
>>>Dual (Dual "Hello") <> Dual (Dual "World")Dual {getDual = Dual {getDual = "HelloWorld"}}
Instances
| MonadZip Dual | Since: base-4.8.0.0 | ||||
| Foldable1 Dual | Since: base-4.18.0.0 | ||||
Defined in Data.Foldable1 Methods fold1 :: Semigroup m => Dual m -> m # foldMap1 :: Semigroup m => (a -> m) -> Dual a -> m # foldMap1' :: Semigroup m => (a -> m) -> Dual a -> m # toNonEmpty :: Dual a -> NonEmpty a # maximum :: Ord a => Dual a -> a # minimum :: Ord a => Dual a -> a # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Dual a -> b # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Dual a -> b # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Dual a -> b # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Dual a -> b # | |||||
| Applicative Dual | Since: base-4.8.0.0 | ||||
| Functor Dual | Since: base-4.8.0.0 | ||||
| Monad Dual | Since: base-4.8.0.0 | ||||
| Foldable Dual | Since: base-4.8.0.0 | ||||
Defined in GHC.Internal.Data.Foldable Methods fold :: Monoid m => Dual m -> m # foldMap :: Monoid m => (a -> m) -> Dual a -> 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 | ||||
| Generic1 Dual | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
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| Monoid a => Monoid (Dual a) | Since: base-2.1 | ||||
| Semigroup a => Semigroup (Dual a) | Since: base-4.9.0.0 | ||||
| Bounded a => Bounded (Dual a) | Since: base-2.1 | ||||
| Generic (Dual a) | |||||
Defined in GHC.Internal.Data.Semigroup.Internal Associated Types
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| Read a => Read (Dual a) | Since: base-2.1 | ||||
| Show a => Show (Dual a) | Since: base-2.1 | ||||
| Eq a => Eq (Dual a) | Since: base-2.1 | ||||
| Ord a => Ord (Dual a) | Since: base-2.1 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
| type Rep1 Dual | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
| type Rep (Dual a) | Since: base-4.7.0.0 | ||||
Defined in GHC.Internal.Data.Semigroup.Internal | |||||
newtype Ap (f :: k -> Type) (a :: k) #
This data type witnesses the lifting of a Monoid into an
Applicative pointwise.
Examples
>>>Ap (Just [1, 2, 3]) <> Ap NothingAp {getAp = Nothing}
>>>Ap [Sum 10, Sum 20] <> Ap [Sum 1, Sum 2]Ap {getAp = [Sum {getSum = 11},Sum {getSum = 12},Sum {getSum = 21},Sum {getSum = 22}]}
Since: base-4.12.0.0
Instances
| Generic1 (Ap f :: k -> Type) | |||||
Defined in GHC.Internal.Data.Monoid Associated Types
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| Foldable1 f => Foldable1 (Ap f) | Since: base-4.18.0.0 | ||||
Defined in Data.Foldable1 Methods fold1 :: Semigroup m => Ap f m -> m # foldMap1 :: Semigroup m => (a -> m) -> Ap f a -> m # foldMap1' :: Semigroup m => (a -> m) -> Ap f a -> m # toNonEmpty :: Ap f a -> NonEmpty a # maximum :: Ord a => Ap f a -> a # minimum :: Ord a => Ap f a -> a # foldrMap1 :: (a -> b) -> (a -> b -> b) -> Ap f a -> b # foldlMap1' :: (a -> b) -> (b -> a -> b) -> Ap f a -> b # foldlMap1 :: (a -> b) -> (b -> a -> b) -> Ap f a -> b # foldrMap1' :: (a -> b) -> (a -> b -> b) -> Ap f a -> b # | |||||
| Alternative f => Alternative (Ap f) | Since: base-4.12.0.0 | ||||
| Applicative f => Applicative (Ap f) | Since: base-4.12.0.0 | ||||
| Functor f => Functor (Ap f) | Since: base-4.12.0.0 | ||||
| Monad f => Monad (Ap f) | Since: base-4.12.0.0 | ||||
| MonadPlus f => MonadPlus (Ap f) | Since: base-4.12.0.0 | ||||
| MonadFail f => MonadFail (Ap f) | Since: base-4.12.0.0 | ||||
Defined in GHC.Internal.Data.Monoid | |||||
| Foldable f => Foldable (Ap f) | Since: base-4.12.0.0 | ||||
Defined in GHC.Internal.Data.Foldable Methods fold :: Monoid m => Ap f m -> m # foldMap :: Monoid m => (a -> m) -> Ap f a -> m # foldMap' :: Monoid m => (a -> m) -> Ap f a -> m # foldr :: (a -> b -> b) -> b -> Ap f a -> b # foldr' :: (a -> b -> b) -> b -> Ap f a -> b # foldl :: (b -> a -> b) -> b -> Ap f a -> b # foldl' :: (b -> a -> b) -> b -> Ap f a -> b # foldr1 :: (a -> a -> a) -> Ap f a -> a # foldl1 :: (a -> a -> a) -> Ap f a -> a # elem :: Eq a => a -> Ap f a -> Bool # maximum :: Ord a => Ap f a -> a # | |||||
| Traversable f => Traversable (Ap f) | Since: base-4.12.0.0 | ||||
| (Applicative f, Monoid a) => Monoid (Ap f a) | Since: base-4.12.0.0 | ||||
| (Applicative f, Semigroup a) => Semigroup (Ap f a) | Since: base-4.12.0.0 | ||||
| (Applicative f, Bounded a) => Bounded (Ap f a) | Since: base-4.12.0.0 | ||||
| Enum (f a) => Enum (Ap f a) | Since: base-4.12.0.0 | ||||
Defined in GHC.Internal.Data.Monoid | |||||
| Generic (Ap f a) | |||||
Defined in GHC.Internal.Data.Monoid Associated Types
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| (Applicative f, Num a) => Num (Ap f a) | Note that even if the underlying Commutativity:
Additive inverse:
Distributivity:
Since: base-4.12.0.0 | ||||
| Read (f a) => Read (Ap f a) | Since: base-4.12.0.0 | ||||
| Show (f a) => Show (Ap f a) | Since: base-4.12.0.0 | ||||
| Eq (f a) => Eq (Ap f a) | Since: base-4.12.0.0 | ||||
| Ord (f a) => Ord (Ap f a) | Since: base-4.12.0.0 | ||||
| type Rep1 (Ap f :: k -> Type) | Since: base-4.12.0.0 | ||||
Defined in GHC.Internal.Data.Monoid | |||||
| type Rep (Ap f a) | Since: base-4.12.0.0 | ||||
Defined in GHC.Internal.Data.Monoid | |||||