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Language	Haskell2010

Monoid

Contents

Monoid

Synopsis

class Semigroup a => Monoid a where
gmempty :: (Generic a, GMonoid (Rep a)) => a

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 laws:

```
x <> mempty = x
```
```
mempty <> x = x
```
x <> (y <> z) = (x <> y) <> z (Semigroup law)
```
mconcat = foldr '(<>)' mempty
```

The method names refer to the monoid of lists under concatenation, but there are many other instances.

Some types can be viewed as a monoid in more than one way, e.g. both addition and multiplication on numbers. In such cases we often define newtypes and make those instances of Monoid, e.g. Sum and Product.

NOTE: Semigroup is a superclass of Monoid since base-4.11.0.0.

Minimal complete definition

mempty

Methods

mempty :: a #

Identity of mappend

mconcat :: [a] -> a #

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.

Instances

Monoid Ordering	Since: base-2.1
Instance details Defined in GHC.Base Methods mempty :: Ordering # mappend :: Ordering -> Ordering -> Ordering # mconcat :: [Ordering] -> Ordering #
Monoid ()	Since: base-2.1
Instance details Defined in GHC.Base Methods mempty :: () # mappend :: () -> () -> () # mconcat :: [()] -> () #
Monoid ByteString
Instance details Defined in Data.ByteString.Internal Methods mempty :: ByteString # mappend :: ByteString -> ByteString -> ByteString # mconcat :: [ByteString] -> ByteString #
Monoid ByteString
Instance details Defined in Data.ByteString.Lazy.Internal Methods mempty :: ByteString # mappend :: ByteString -> ByteString -> ByteString # mconcat :: [ByteString] -> ByteString #
Monoid Builder
Instance details Defined in Data.Text.Internal.Builder Methods mempty :: Builder # mappend :: Builder -> Builder -> Builder # mconcat :: [Builder] -> Builder #
Monoid Builder
Instance details Defined in Data.ByteString.Builder.Internal Methods mempty :: Builder # mappend :: Builder -> Builder -> Builder # mconcat :: [Builder] -> Builder #
Monoid Series
Instance details Defined in Data.Aeson.Encoding.Internal Methods mempty :: Series # mappend :: Series -> Series -> Series # mconcat :: [Series] -> Series #
Monoid EventLifetime	Since: base-4.8.0.0
Instance details Defined in GHC.Event.Internal Methods mempty :: EventLifetime # mappend :: EventLifetime -> EventLifetime -> EventLifetime # mconcat :: [EventLifetime] -> EventLifetime #
Monoid Event	Since: base-4.3.1.0
Instance details Defined in GHC.Event.Internal Methods mempty :: Event # mappend :: Event -> Event -> Event # mconcat :: [Event] -> Event #
Monoid Lifetime	`mappend` takes the longer of two lifetimes. Since: base-4.8.0.0
Instance details Defined in GHC.Event.Internal Methods mempty :: Lifetime # mappend :: Lifetime -> Lifetime -> Lifetime # mconcat :: [Lifetime] -> Lifetime #
Monoid All	Since: base-2.1
Instance details Defined in Data.Semigroup.Internal Methods mempty :: All # mappend :: All -> All -> All # mconcat :: [All] -> All #
Monoid Any	Since: base-2.1
Instance details Defined in Data.Semigroup.Internal Methods mempty :: Any # mappend :: Any -> Any -> Any # mconcat :: [Any] -> Any #
Monoid ShortByteString
Instance details Defined in Data.ByteString.Short.Internal Methods mempty :: ShortByteString # mappend :: ShortByteString -> ShortByteString -> ShortByteString # mconcat :: [ShortByteString] -> ShortByteString #
Monoid ByteArray
Instance details Defined in Data.Primitive.ByteArray Methods mempty :: ByteArray # mappend :: ByteArray -> ByteArray -> ByteArray # mconcat :: [ByteArray] -> ByteArray #
Monoid IntSet
Instance details Defined in Data.IntSet.Internal Methods mempty :: IntSet # mappend :: IntSet -> IntSet -> IntSet # mconcat :: [IntSet] -> IntSet #
Monoid ExactPi	The multiplicative monoid over `Rational`s augmented with multiples of `pi`.
Instance details Defined in Data.ExactPi Methods mempty :: ExactPi # mappend :: ExactPi -> ExactPi -> ExactPi # mconcat :: [ExactPi] -> ExactPi #
Monoid IntMultiSet
Instance details Defined in Data.IntMultiSet Methods mempty :: IntMultiSet # mappend :: IntMultiSet -> IntMultiSet -> IntMultiSet # mconcat :: [IntMultiSet] -> IntMultiSet #
Monoid PrefsMod
Instance details Defined in Options.Applicative.Builder Methods mempty :: PrefsMod # mappend :: PrefsMod -> PrefsMod -> PrefsMod # mconcat :: [PrefsMod] -> PrefsMod #
Monoid ParseError
Instance details Defined in Options.Applicative.Types Methods mempty :: ParseError # mappend :: ParseError -> ParseError -> ParseError # mconcat :: [ParseError] -> ParseError #
Monoid Completer
Instance details Defined in Options.Applicative.Types Methods mempty :: Completer # mappend :: Completer -> Completer -> Completer # mconcat :: [Completer] -> Completer #
Monoid ParserHelp
Instance details Defined in Options.Applicative.Help.Types Methods mempty :: ParserHelp # mappend :: ParserHelp -> ParserHelp -> ParserHelp # mconcat :: [ParserHelp] -> ParserHelp #
Monoid Doc
Instance details Defined in Text.PrettyPrint.HughesPJ Methods mempty :: Doc # mappend :: Doc -> Doc -> Doc # mconcat :: [Doc] -> Doc #
Monoid AnsiStyle	`mempty` does nothing, which is equivalent to inheriting the style of the surrounding doc, or the terminal’s default if no style has been set yet.
Instance details Defined in Data.Text.Prettyprint.Doc.Render.Terminal.Internal Methods mempty :: AnsiStyle # mappend :: AnsiStyle -> AnsiStyle -> AnsiStyle # mconcat :: [AnsiStyle] -> AnsiStyle #
Monoid ShortText
Instance details Defined in Data.Text.Short.Internal Methods mempty :: ShortText # mappend :: ShortText -> ShortText -> ShortText # mconcat :: [ShortText] -> ShortText #
a :=> (Monoid (Dict a))
Instance details Defined in Data.Constraint Methods ins :: a :- Monoid (Dict a) #
() :=> (Monoid [a])
Instance details Defined in Data.Constraint Methods ins :: () :- Monoid [a] #
() :=> (Monoid Ordering)
Instance details Defined in Data.Constraint Methods ins :: () :- Monoid Ordering #
() :=> (Monoid ())
Instance details Defined in Data.Constraint Methods ins :: () :- Monoid () #
Monoid [a]	Since: base-2.1
Instance details Defined in GHC.Base Methods mempty :: [a] # mappend :: [a] -> [a] -> [a] # mconcat :: [[a]] -> [a] #
Semigroup a => Monoid (Maybe a)	Lift a semigroup into `Maybe` forming a `Monoid` according to http://en.wikipedia.org/wiki/Monoid: "Any semigroup `S` may be turned into a monoid simply by adjoining an element `e` not in `S` and defining `ee = e` and `es = s = se` for all `s ∈ S`." Since 4.11.0: constraint on inner `a` value generalised from `Monoid` to `Semigroup`. Since: base-2.1*
Instance details Defined in GHC.Base Methods mempty :: Maybe a # mappend :: Maybe a -> Maybe a -> Maybe a # mconcat :: [Maybe a] -> Maybe a #
Monoid a => Monoid (IO a)	Since: base-4.9.0.0
Instance details Defined in GHC.Base Methods mempty :: IO a # mappend :: IO a -> IO a -> IO a # mconcat :: [IO a] -> IO a #
Monoid (IResult a)
Instance details Defined in Data.Aeson.Types.Internal Methods mempty :: IResult a # mappend :: IResult a -> IResult a -> IResult a # mconcat :: [IResult a] -> IResult a #
Monoid (Result a)
Instance details Defined in Data.Aeson.Types.Internal Methods mempty :: Result a # mappend :: Result a -> Result a -> Result a # mconcat :: [Result a] -> Result a #
Monoid (Parser a)
Instance details Defined in Data.Aeson.Types.Internal Methods mempty :: Parser a # mappend :: Parser a -> Parser a -> Parser a # mconcat :: [Parser a] -> Parser a #
(Semigroup a, Monoid a) => Monoid (Concurrently a)	Since: async-2.1.0
Instance details Defined in Control.Concurrent.Async Methods mempty :: Concurrently a # mappend :: Concurrently a -> Concurrently a -> Concurrently a # mconcat :: [Concurrently a] -> Concurrently a #
(Ord a, Bounded a) => Monoid (Min a)	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods mempty :: Min a # mappend :: Min a -> Min a -> Min a # mconcat :: [Min a] -> Min a #
(Ord a, Bounded a) => Monoid (Max a)	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods mempty :: Max a # mappend :: Max a -> Max a -> Max a # mconcat :: [Max a] -> Max a #
Monoid m => Monoid (WrappedMonoid m)	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods mempty :: WrappedMonoid m # mappend :: WrappedMonoid m -> WrappedMonoid m -> WrappedMonoid m # mconcat :: [WrappedMonoid m] -> WrappedMonoid m #
Semigroup a => Monoid (Option a)	Since: base-4.9.0.0
Instance details Defined in Data.Semigroup Methods mempty :: Option a # mappend :: Option a -> Option a -> Option a # mconcat :: [Option a] -> Option a #
Monoid a => Monoid (Identity a)
Instance details Defined in Data.Functor.Identity Methods mempty :: Identity a # mappend :: Identity a -> Identity a -> Identity a # mconcat :: [Identity a] -> Identity a #
Monoid (First a)	Since: base-2.1
Instance details Defined in Data.Monoid Methods mempty :: First a # mappend :: First a -> First a -> First a # mconcat :: [First a] -> First a #
Monoid (Last a)	Since: base-2.1
Instance details Defined in Data.Monoid Methods mempty :: Last a # mappend :: Last a -> Last a -> Last a # mconcat :: [Last a] -> Last a #
Monoid a => Monoid (Dual a)	Since: base-2.1
Instance details Defined in Data.Semigroup.Internal Methods mempty :: Dual a # mappend :: Dual a -> Dual a -> Dual a # mconcat :: [Dual a] -> Dual a #
Monoid (Endo a)	Since: base-2.1
Instance details Defined in Data.Semigroup.Internal Methods mempty :: Endo a # mappend :: Endo a -> Endo a -> Endo a # mconcat :: [Endo a] -> Endo a #
Num a => Monoid (Sum a)	Since: base-2.1
Instance details Defined in Data.Semigroup.Internal Methods mempty :: Sum a # mappend :: Sum a -> Sum a -> Sum a # mconcat :: [Sum a] -> Sum a #
Num a => Monoid (Product a)	Since: base-2.1
Instance details Defined in Data.Semigroup.Internal Methods mempty :: Product a # mappend :: Product a -> Product a -> Product a # mconcat :: [Product a] -> Product a #
Monoid a => Monoid (Down a)	Since: base-4.11.0.0
Instance details Defined in Data.Ord Methods mempty :: Down a # mappend :: Down a -> Down a -> Down a # mconcat :: [Down a] -> Down a #
Monoid s => Monoid (CI s)
Instance details Defined in Data.CaseInsensitive.Internal Methods mempty :: CI s # mappend :: CI s -> CI s -> CI s # mconcat :: [CI s] -> CI s #
a => Monoid (Dict a)
Instance details Defined in Data.Constraint Methods mempty :: Dict a # mappend :: Dict a -> Dict a -> Dict a # mconcat :: [Dict a] -> Dict a #
Monoid (IntMap a)
Instance details Defined in Data.IntMap.Internal Methods mempty :: IntMap a # mappend :: IntMap a -> IntMap a -> IntMap a # mconcat :: [IntMap a] -> IntMap a #
Monoid (Seq a)
Instance details Defined in Data.Sequence.Internal Methods mempty :: Seq a # mappend :: Seq a -> Seq a -> Seq a # mconcat :: [Seq a] -> Seq a #
Ord a => Monoid (Set a)
Instance details Defined in Data.Set.Internal Methods mempty :: Set a # mappend :: Set a -> Set a -> Set a # mconcat :: [Set a] -> Set a #
Monoid (Predicate a)
Instance details Defined in Data.Functor.Contravariant Methods mempty :: Predicate a # mappend :: Predicate a -> Predicate a -> Predicate a # mconcat :: [Predicate a] -> Predicate a #
Monoid (Comparison a)
Instance details Defined in Data.Functor.Contravariant Methods mempty :: Comparison a # mappend :: Comparison a -> Comparison a -> Comparison a # mconcat :: [Comparison a] -> Comparison a #
Monoid (Equivalence a)
Instance details Defined in Data.Functor.Contravariant Methods mempty :: Equivalence a # mappend :: Equivalence a -> Equivalence a -> Equivalence a # mconcat :: [Equivalence a] -> Equivalence a #
Divisible divisible => Monoid (Supplied divisible)
Instance details Defined in Contravariant.Extras Methods mempty :: Supplied divisible # mappend :: Supplied divisible -> Supplied divisible -> Supplied divisible # mconcat :: [Supplied divisible] -> Supplied divisible #
Monoid (DList a)
Instance details Defined in Data.DList Methods mempty :: DList a # mappend :: DList a -> DList a -> DList a # mconcat :: [DList a] -> DList a #
Monoid (Heap a)
Instance details Defined in Data.Heap Methods mempty :: Heap a # mappend :: Heap a -> Heap a -> Heap a # mconcat :: [Heap a] -> Heap a #
Prim a => Monoid (Vector a)
Instance details Defined in Data.Vector.Primitive Methods mempty :: Vector a # mappend :: Vector a -> Vector a -> Vector a # mconcat :: [Vector a] -> Vector a #
Storable a => Monoid (Vector a)
Instance details Defined in Data.Vector.Storable Methods mempty :: Vector a # mappend :: Vector a -> Vector a -> Vector a # mconcat :: [Vector a] -> Vector a #
(Hashable a, Eq a) => Monoid (HashSet a)
Instance details Defined in Data.HashSet Methods mempty :: HashSet a # mappend :: HashSet a -> HashSet a -> HashSet a # mconcat :: [HashSet a] -> HashSet a #
Monoid (Vector a)
Instance details Defined in Data.Vector Methods mempty :: Vector a # mappend :: Vector a -> Vector a -> Vector a # mconcat :: [Vector a] -> Vector a #
Ord a => Monoid (Min a)
Instance details Defined in Control.Lens.Internal.Fold Methods mempty :: Min a # mappend :: Min a -> Min a -> Min a # mconcat :: [Min a] -> Min a #
Ord a => Monoid (Max a)
Instance details Defined in Control.Lens.Internal.Fold Methods mempty :: Max a # mappend :: Max a -> Max a -> Max a # mconcat :: [Max a] -> Max a #
Monoid (Leftmost a)
Instance details Defined in Control.Lens.Internal.Fold Methods mempty :: Leftmost a # mappend :: Leftmost a -> Leftmost a -> Leftmost a # mconcat :: [Leftmost a] -> Leftmost a #
Monoid (Rightmost a)
Instance details Defined in Control.Lens.Internal.Fold Methods mempty :: Rightmost a # mappend :: Rightmost a -> Rightmost a -> Rightmost a # mconcat :: [Rightmost a] -> Rightmost a #
(Precise a, RealFloat a) => Monoid (Log a)
Instance details Defined in Numeric.Log Methods mempty :: Log a # mappend :: Log a -> Log a -> Log a # mconcat :: [Log a] -> Log a #
Monoid a => Monoid (Managed a)
Instance details Defined in Control.Monad.Managed Methods mempty :: Managed a # mappend :: Managed a -> Managed a -> Managed a # mconcat :: [Managed a] -> Managed a #
Monoid (Hints t)
Instance details Defined in Text.Megaparsec.Internal Methods mempty :: Hints t # mappend :: Hints t -> Hints t -> Hints t # mconcat :: [Hints t] -> Hints t #
Ord a => Monoid (MultiSet a)
Instance details Defined in Data.MultiSet Methods mempty :: MultiSet a # mappend :: MultiSet a -> MultiSet a -> MultiSet a # mconcat :: [MultiSet a] -> MultiSet a #
Monoid (InfoMod a)
Instance details Defined in Options.Applicative.Builder Methods mempty :: InfoMod a # mappend :: InfoMod a -> InfoMod a -> InfoMod a # mconcat :: [InfoMod a] -> InfoMod a #
Monoid (DefaultProp a)
Instance details Defined in Options.Applicative.Builder.Internal Methods mempty :: DefaultProp a # mappend :: DefaultProp a -> DefaultProp a -> DefaultProp a # mconcat :: [DefaultProp a] -> DefaultProp a #
Monoid (Doc a)
Instance details Defined in Text.PrettyPrint.Annotated.HughesPJ Methods mempty :: Doc a # mappend :: Doc a -> Doc a -> Doc a # mconcat :: [Doc a] -> Doc a #
Monoid (Doc ann)	`mempty` = `emptyDoc` `mconcat` = `hcat` `>>>` `mappend "hello" "world" :: Doc ann`helloworld
Instance details Defined in Data.Text.Prettyprint.Doc.Internal Methods mempty :: Doc ann # mappend :: Doc ann -> Doc ann -> Doc ann # mconcat :: [Doc ann] -> Doc ann #
PrimUnlifted a => Monoid (UnliftedArray a)	Since: primitive-0.6.4.0
Instance details Defined in Data.Primitive.UnliftedArray Methods mempty :: UnliftedArray a # mappend :: UnliftedArray a -> UnliftedArray a -> UnliftedArray a # mconcat :: [UnliftedArray a] -> UnliftedArray a #
Monoid (PrimArray a)	Since: primitive-0.6.4.0
Instance details Defined in Data.Primitive.PrimArray Methods mempty :: PrimArray a # mappend :: PrimArray a -> PrimArray a -> PrimArray a # mconcat :: [PrimArray a] -> PrimArray a #
Monoid (SmallArray a)
Instance details Defined in Data.Primitive.SmallArray Methods mempty :: SmallArray a # mappend :: SmallArray a -> SmallArray a -> SmallArray a # mconcat :: [SmallArray a] -> SmallArray a #
Monoid (Array a)
Instance details Defined in Data.Primitive.Array Methods mempty :: Array a # mappend :: Array a -> Array a -> Array a # mconcat :: [Array a] -> Array a #
Semigroup a => Monoid (Event a)	The combinator `mempty` represents an event that never occurs. It is a synonym, mempty :: Event a mempty = never
Instance details Defined in Reactive.Banana.Types Methods mempty :: Event a # mappend :: Event a -> Event a -> Event a # mconcat :: [Event a] -> Event a #
(Upper a, Meet a) => Monoid (Meeting a)	`Meeting` `mempty` is the left- and right-identity. let (l, r) = (mappend mempty (Meeting x), mappend (Meeting x) mempty) in l == Meeting x && r == Meeting (x :: Bool)
Instance details Defined in Data.Semilattice.Meet Methods mempty :: Meeting a # mappend :: Meeting a -> Meeting a -> Meeting a # mconcat :: [Meeting a] -> Meeting a #
(Lower a, Join a) => Monoid (Joining a)	`Joining` `mempty` is the left- and right-identity. \ x -> let (l, r) = (mappend mempty (Joining x), mappend (Joining x) mempty) in l == Joining x && r == Joining (x :: IntSet)
Instance details Defined in Data.Semilattice.Join Methods mempty :: Joining a # mappend :: Joining a -> Joining a -> Joining a # mconcat :: [Joining a] -> Joining a #
Monoid (Builder element)	Provides support for O(1) concatenation.
Instance details Defined in VectorBuilder.Core.Builder Methods mempty :: Builder element # mappend :: Builder element -> Builder element -> Builder element # mconcat :: [Builder element] -> Builder element #
Monoid (MergeSet a)
Instance details Defined in Data.Set.Internal Methods mempty :: MergeSet a # mappend :: MergeSet a -> MergeSet a -> MergeSet a # mconcat :: [MergeSet a] -> MergeSet a #
Class (Semigroup a) (Monoid a)
Instance details Defined in Data.Constraint Methods cls :: Monoid a :- Semigroup a #
(Monoid a) :=> (Monoid (Maybe a))
Instance details Defined in Data.Constraint Methods ins :: Monoid a :- Monoid (Maybe a) #
(Monoid a) :=> (Monoid (Const a b))
Instance details Defined in Data.Constraint Methods ins :: Monoid a :- Monoid (Const a b) #
(Monoid a) :=> (Monoid (Identity a))
Instance details Defined in Data.Constraint Methods ins :: Monoid a :- Monoid (Identity a) #
(Monoid a) :=> (Monoid (IO a))
Instance details Defined in Data.Constraint Methods ins :: Monoid a :- Monoid (IO a) #
(Monoid a) :=> (Applicative ((,) a))
Instance details Defined in Data.Constraint Methods ins :: Monoid a :- Applicative ((,) a) #
(Monoid a) :=> (Applicative (Const a :: * -> *))
Instance details Defined in Data.Constraint Methods ins :: Monoid a :- Applicative (Const a) #
Monoid b => Monoid (a -> b)	Since: base-2.1
Instance details Defined in GHC.Base Methods mempty :: a -> b # mappend :: (a -> b) -> (a -> b) -> a -> b # mconcat :: [a -> b] -> a -> b #
(Monoid a, Monoid b) => Monoid (a, b)	Since: base-2.1
Instance details Defined in GHC.Base Methods mempty :: (a, b) # mappend :: (a, b) -> (a, b) -> (a, b) # mconcat :: [(a, b)] -> (a, b) #
Monoid a => Monoid (ST s a)	Since: base-4.11.0.0
Instance details Defined in GHC.ST Methods mempty :: ST s a # mappend :: ST s a -> ST s a -> ST s a # mconcat :: [ST s a] -> ST s a #
Monoid (Results s a)
Instance details Defined in Text.Earley.Parser.Internal Methods mempty :: Results s a # mappend :: Results s a -> Results s a -> Results s a # mconcat :: [Results s a] -> Results s a #
Monoid a => Monoid (Op a b)
Instance details Defined in Data.Functor.Contravariant Methods mempty :: Op a b # mappend :: Op a b -> Op a b -> Op a b # mconcat :: [Op a b] -> Op a b #
(Eq k, Hashable k) => Monoid (HashMap k v)
Instance details Defined in Data.HashMap.Base Methods mempty :: HashMap k v # mappend :: HashMap k v -> HashMap k v -> HashMap k v # mconcat :: [HashMap k v] -> HashMap k v #
Ord k => Monoid (Map k v)
Instance details Defined in Data.Map.Internal Methods mempty :: Map k v # mappend :: Map k v -> Map k v -> Map k v # mconcat :: [Map k v] -> Map k v #
Monoid (Proxy s)	Since: base-4.7.0.0
Instance details Defined in Data.Proxy Methods mempty :: Proxy s # mappend :: Proxy s -> Proxy s -> Proxy s # mconcat :: [Proxy s] -> Proxy s #
Monoid b => Monoid (Fold a b)
Instance details Defined in Control.Foldl Methods mempty :: Fold a b # mappend :: Fold a b -> Fold a b -> Fold a b # mconcat :: [Fold a b] -> Fold a b #
Monad m => Monoid (EndoM m a)
Instance details Defined in Control.Foldl Methods mempty :: EndoM m a # mappend :: EndoM m a -> EndoM m a -> EndoM m a # mconcat :: [EndoM m a] -> EndoM m a #
Monoid (List ([] :: [(m, Type)]))
Instance details Defined in Data.Generics.Product.Internal.List Methods mempty :: List [] # mappend :: List [] -> List [] -> List [] # mconcat :: [List []] -> List [] #
(Monoid a, Monoid (List as)) => Monoid (List ((,) k a ': as))
Instance details Defined in Data.Generics.Product.Internal.List Methods mempty :: List ((k, a) ': as) # mappend :: List ((k, a) ': as) -> List ((k, a) ': as) -> List ((k, a) ': as) # mconcat :: [List ((k, a) ': as)] -> List ((k, a) ': as) #
(Eq k, Hashable k) => Monoid (InsOrdHashMap k v)
Instance details Defined in Data.HashMap.Strict.InsOrd Methods mempty :: InsOrdHashMap k v # mappend :: InsOrdHashMap k v -> InsOrdHashMap k v -> InsOrdHashMap k v # mconcat :: [InsOrdHashMap k v] -> InsOrdHashMap k v #
Monoid (ReifiedFold s a)
Instance details Defined in Control.Lens.Reified Methods mempty :: ReifiedFold s a # mappend :: ReifiedFold s a -> ReifiedFold s a -> ReifiedFold s a # mconcat :: [ReifiedFold s a] -> ReifiedFold s a #
Monoid (f a) => Monoid (Indexing f a)	`>>>` `"cat" ^@.. (folded <> folded)`[(0,'c'),(1,'a'),(2,'t'),(0,'c'),(1,'a'),(2,'t')] `>>>` `"cat" ^@.. indexing (folded <> folded)`[(0,'c'),(1,'a'),(2,'t'),(3,'c'),(4,'a'),(5,'t')]
Instance details Defined in Control.Lens.Internal.Indexed Methods mempty :: Indexing f a # mappend :: Indexing f a -> Indexing f a -> Indexing f a # mconcat :: [Indexing f a] -> Indexing f a #
(Contravariant f, Applicative f) => Monoid (Folding f a)
Instance details Defined in Control.Lens.Internal.Fold Methods mempty :: Folding f a # mappend :: Folding f a -> Folding f a -> Folding f a # mconcat :: [Folding f a] -> Folding f a #
Applicative f => Monoid (Traversed a f)
Instance details Defined in Control.Lens.Internal.Fold Methods mempty :: Traversed a f # mappend :: Traversed a f -> Traversed a f -> Traversed a f # mconcat :: [Traversed a f] -> Traversed a f #
(Apply f, Applicative f) => Monoid (TraversedF a f)
Instance details Defined in Control.Lens.Internal.Fold Methods mempty :: TraversedF a f # mappend :: TraversedF a f -> TraversedF a f -> TraversedF a f # mconcat :: [TraversedF a f] -> TraversedF a f #
Monad m => Monoid (Sequenced a m)
Instance details Defined in Control.Lens.Internal.Fold Methods mempty :: Sequenced a m # mappend :: Sequenced a m -> Sequenced a m -> Sequenced a m # mconcat :: [Sequenced a m] -> Sequenced a m #
(Monad m, Semigroup a, Monoid a) => Monoid (ListT m a)
Instance details Defined in List.Transformer Methods mempty :: ListT m a # mappend :: ListT m a -> ListT m a -> ListT m a # mconcat :: [ListT m a] -> ListT m a #
(Ord t, Ord e) => Monoid (ParseError t e)
Instance details Defined in Text.Megaparsec.Error Methods mempty :: ParseError t e # mappend :: ParseError t e -> ParseError t e -> ParseError t e # mconcat :: [ParseError t e] -> ParseError t e #
Monoid (Mod f a)
Instance details Defined in Options.Applicative.Builder.Internal Methods mempty :: Mod f a # mappend :: Mod f a -> Mod f a -> Mod f a # mconcat :: [Mod f a] -> Mod f a #
(Semigroup a, Monoid a, MonadUnliftIO m) => Monoid (Concurrently m a)	Since: unliftio-0.1.0.0
Instance details Defined in UnliftIO.Async Methods mempty :: Concurrently m a # mappend :: Concurrently m a -> Concurrently m a -> Concurrently m a # mconcat :: [Concurrently m a] -> Concurrently m a #
Alternative f => Monoid (AltSum f a)
Instance details Defined in Control.Compactable Methods mempty :: AltSum f a # mappend :: AltSum f a -> AltSum f a -> AltSum f a # mconcat :: [AltSum f a] -> AltSum f a #
(Monoid a, Monoid b) :=> (Monoid (a, b))
Instance details Defined in Data.Constraint Methods ins :: (Monoid a, Monoid b) :- Monoid (a, b) #
(Monoid a, Monoid b, Monoid c) => Monoid (a, b, c)	Since: base-2.1
Instance details Defined in GHC.Base Methods mempty :: (a, b, c) # mappend :: (a, b, c) -> (a, b, c) -> (a, b, c) # mconcat :: [(a, b, c)] -> (a, b, c) #
Monoid (Results s t a)
Instance details Defined in Text.Earley.Generator.Internal Methods mempty :: Results s t a # mappend :: Results s t a -> Results s t a -> Results s t a # mconcat :: [Results s t a] -> Results s t a #
Monoid a => Monoid (Const a b)
Instance details Defined in Data.Functor.Const Methods mempty :: Const a b # mappend :: Const a b -> Const a b -> Const a b # mconcat :: [Const a b] -> Const a b #
Alternative f => Monoid (Alt f a)	Since: base-4.8.0.0
Instance details Defined in Data.Semigroup.Internal Methods mempty :: Alt f a # mappend :: Alt f a -> Alt f a -> Alt f a # mconcat :: [Alt f a] -> Alt f a #
(Monoid b, Monad m) => Monoid (FoldM m a b)
Instance details Defined in Control.Foldl Methods mempty :: FoldM m a b # mappend :: FoldM m a b -> FoldM m a b -> FoldM m a b # mconcat :: [FoldM m a b] -> FoldM m a b #
Monoid (ReifiedIndexedFold i s a)
Instance details Defined in Control.Lens.Reified Methods mempty :: ReifiedIndexedFold i s a # mappend :: ReifiedIndexedFold i s a -> ReifiedIndexedFold i s a -> ReifiedIndexedFold i s a # mconcat :: [ReifiedIndexedFold i s a] -> ReifiedIndexedFold i s a #
(Profunctor p, Arrow p, Semigroup b, Monoid b) => Monoid (Closure p a b)
Instance details Defined in Data.Profunctor.Closed Methods mempty :: Closure p a b # mappend :: Closure p a b -> Closure p a b -> Closure p a b # mconcat :: [Closure p a b] -> Closure p a b #
ArrowPlus p => Monoid (Tambara p a b)
Instance details Defined in Data.Profunctor.Strong Methods mempty :: Tambara p a b # mappend :: Tambara p a b -> Tambara p a b -> Tambara p a b # mconcat :: [Tambara p a b] -> Tambara p a b #
Reifies s (ReifiedMonoid a) => Monoid (ReflectedMonoid a s)
Instance details Defined in Data.Reflection Methods mempty :: ReflectedMonoid a s # mappend :: ReflectedMonoid a s -> ReflectedMonoid a s -> ReflectedMonoid a s # mconcat :: [ReflectedMonoid a s] -> ReflectedMonoid a s #
(Semigroup a, Monoid a) => Monoid (Tagged s a)
Instance details Defined in Data.Tagged Methods mempty :: Tagged s a # mappend :: Tagged s a -> Tagged s a -> Tagged s a # mconcat :: [Tagged s a] -> Tagged s a #
(Monoid a, Monoid b, Monoid c, Monoid d) => Monoid (a, b, c, d)	Since: base-2.1
Instance details Defined in GHC.Base Methods mempty :: (a, b, c, d) # mappend :: (a, b, c, d) -> (a, b, c, d) -> (a, b, c, d) # mconcat :: [(a, b, c, d)] -> (a, b, c, d) #
Monoid (Prod r e t a)
Instance details Defined in Text.Earley.Grammar Methods mempty :: Prod r e t a # mappend :: Prod r e t a -> Prod r e t a -> Prod r e t a # mconcat :: [Prod r e t a] -> Prod r e t a #
(Stream s, Monoid a) => Monoid (ParsecT e s m a)	Since: megaparsec-5.3.0
Instance details Defined in Text.Megaparsec.Internal Methods mempty :: ParsecT e s m a # mappend :: ParsecT e s m a -> ParsecT e s m a -> ParsecT e s m a # mconcat :: [ParsecT e s m a] -> ParsecT e s m a #
(Monoid a, Monoid b, Monoid c, Monoid d, Monoid e) => Monoid (a, b, c, d, e)	Since: base-2.1
Instance details Defined in GHC.Base Methods mempty :: (a, b, c, d, e) # mappend :: (a, b, c, d, e) -> (a, b, c, d, e) -> (a, b, c, d, e) # mconcat :: [(a, b, c, d, e)] -> (a, b, c, d, e) #
Contravariant g => Monoid (BazaarT p g a b t)
Instance details Defined in Control.Lens.Internal.Bazaar Methods mempty :: BazaarT p g a b t # mappend :: BazaarT p g a b t -> BazaarT p g a b t -> BazaarT p g a b t # mconcat :: [BazaarT p g a b t] -> BazaarT p g a b t #

gmempty :: (Generic a, GMonoid (Rep a)) => a #

Generically generate a Monoid mempty for any product-like type implementing Generic.

It is only defined for product types.

gmappend gmempty a = a = gmappend a gmempty