Control.Lens.Internal.Fold

Monoids for folding

newtype Folding f a

A Monoid for a Contravariant Applicative.

Constructors

Folding

Fields

• getFolding :: f a

Instances

(Contravariant f, Applicative f) => Monoid (Folding f a)

Methods

mempty :: Folding f a

mappend :: Folding f a -> Folding f a -> Folding f a

mconcat :: [Folding f a] -> Folding f a

(Contravariant f, Apply f) => Semigroup (Folding f a)

Methods

(<>) :: Folding f a -> Folding f a -> Folding f a

sconcat :: NonEmpty (Folding f a) -> Folding f a

times1p :: Natural -> Folding f a -> Folding f a

newtype Traversed a f

Used internally by traverseOf_ and the like.

The argument a of the result should not be used!

Constructors

Traversed

Fields

• getTraversed :: f a

Instances

Applicative f => Monoid (Traversed a f)

Methods

mempty :: Traversed a f

mappend :: Traversed a f -> Traversed a f -> Traversed a f

mconcat :: [Traversed a f] -> Traversed a f

Apply f => Semigroup (Traversed a f)

Methods

(<>) :: Traversed a f -> Traversed a f -> Traversed a f

sconcat :: NonEmpty (Traversed a f) -> Traversed a f

times1p :: Natural -> Traversed a f -> Traversed a f

newtype Sequenced a m

Used internally by mapM_ and the like.

The argument a of the result should not be used!

Constructors

Sequenced

Fields

• getSequenced :: m a

Instances

Monad m => Monoid (Sequenced a m)

Methods

mempty :: Sequenced a m

mappend :: Sequenced a m -> Sequenced a m -> Sequenced a m

mconcat :: [Sequenced a m] -> Sequenced a m

Apply m => Semigroup (Sequenced a m)

Methods

(<>) :: Sequenced a m -> Sequenced a m -> Sequenced a m

sconcat :: NonEmpty (Sequenced a m) -> Sequenced a m

times1p :: Natural -> Sequenced a m -> Sequenced a m

data Max a

Used for maximumOf.

Constructors

NoMax

Max a

Instances

Ord a => Monoid (Max a)

Methods

mempty :: Max a

mappend :: Max a -> Max a -> Max a

mconcat :: [Max a] -> Max a

Ord a => Semigroup (Max a)

Methods

(<>) :: Max a -> Max a -> Max a

sconcat :: NonEmpty (Max a) -> Max a

times1p :: Natural -> Max a -> Max a

getMax :: Max a -> Maybe a

Obtain the maximum.

data Min a

Used for minimumOf.

Constructors

NoMin

Min a

Instances

Ord a => Monoid (Min a)

Methods

mempty :: Min a

mappend :: Min a -> Min a -> Min a

mconcat :: [Min a] -> Min a

Ord a => Semigroup (Min a)

Methods

(<>) :: Min a -> Min a -> Min a

sconcat :: NonEmpty (Min a) -> Min a

times1p :: Natural -> Min a -> Min a

getMin :: Min a -> Maybe a

Obtain the minimum.

data Leftmost a

Used for preview.

Constructors

LPure

LLeaf a

LStep (Leftmost a)

Instances

Monoid (Leftmost a)

Methods

mempty :: Leftmost a

mappend :: Leftmost a -> Leftmost a -> Leftmost a

mconcat :: [Leftmost a] -> Leftmost a

Semigroup (Leftmost a)

Methods

(<>) :: Leftmost a -> Leftmost a -> Leftmost a

sconcat :: NonEmpty (Leftmost a) -> Leftmost a

times1p :: Natural -> Leftmost a -> Leftmost a

getLeftmost :: Leftmost a -> Maybe a

Extract the Leftmost element. This will fairly eagerly determine that it can return Just the moment it sees any element at all.

data Rightmost a

Used for lastOf.

Constructors

RPure

RLeaf a

RStep (Rightmost a)

Instances

Monoid (Rightmost a)

Methods

mempty :: Rightmost a

mappend :: Rightmost a -> Rightmost a -> Rightmost a

mconcat :: [Rightmost a] -> Rightmost a

Semigroup (Rightmost a)

Methods

(<>) :: Rightmost a -> Rightmost a -> Rightmost a

sconcat :: NonEmpty (Rightmost a) -> Rightmost a

times1p :: Natural -> Rightmost a -> Rightmost a

getRightmost :: Rightmost a -> Maybe a

Extract the Rightmost element. This will fairly eagerly determine that it can return Just the moment it sees any element at all.

data ReifiedMonoid a

Constructors

ReifiedMonoid

Fields

• reifiedMappend :: a -> a -> a
• reifiedMempty :: a

newtype M a s

Constructors

M a

Instances

Reifies * s (ReifiedMonoid a) => Monoid (M a s)

Methods

mempty :: M a s

mappend :: M a s -> M a s -> M a s

mconcat :: [M a s] -> M a s

reifyFold :: (a -> a -> a) -> a -> (forall s. Reifies s (ReifiedMonoid a) => t -> M a s) -> t -> a