Copyright	(C) 2012-2016 Edward Kmett
License	BSD-style (see the file LICENSE)
Maintainer	Edward Kmett <ekmett@gmail.com>
Stability	experimental
Portability	non-portable
Safe Haskell	Safe-Inferred
Language	Haskell2010

Control.Lens.Internal.Fold

Contents

Monoids for folding
Semigroups for folding

Description

Synopsis

newtype Folding f a = Folding {
- getFolding :: f a
}
newtype Traversed a f = Traversed {
- getTraversed :: f a
}
newtype TraversedF a f = TraversedF {
- getTraversedF :: f a
}
newtype Sequenced a m = Sequenced {
- getSequenced :: m a
}
data Max a
- = NoMax
- | Max a
getMax :: Max a -> Maybe a
data Min a
- = NoMin
- | Min a
getMin :: Min a -> Maybe a
data Leftmost a
- = LPure
- | LLeaf a
- | LStep (Leftmost a)
getLeftmost :: Leftmost a -> Maybe a
data Rightmost a
- = RPure
- | RLeaf a
- | RStep (Rightmost a)
getRightmost :: Rightmost a -> Maybe a
data ReifiedMonoid a = ReifiedMonoid {
- reifiedMappend :: a -> a -> a
- reifiedMempty :: a
}
newtype NonEmptyDList a = NonEmptyDList {
- getNonEmptyDList :: [a] -> NonEmpty a
}

Monoids for folding

newtype Folding f a #

A Monoid for a Contravariant Applicative.

Constructors

Folding
Fields getFolding :: f a

Instances

Instances details

(Contravariant f, Applicative f) => Semigroup (Folding f a) #
Instance details Defined in Control.Lens.Internal.Fold Methods (<>) :: Folding f a -> Folding f a -> Folding f a # sconcat :: NonEmpty (Folding f a) -> Folding f a # stimes :: Integral b => b -> Folding f a -> Folding 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 #

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

Instances details

Applicative f => Semigroup (Traversed a f) #
Instance details Defined in Control.Lens.Internal.Fold Methods (<>) :: Traversed a f -> Traversed a f -> Traversed a f # sconcat :: NonEmpty (Traversed a f) -> Traversed a f # stimes :: Integral b => b -> Traversed a f -> Traversed a f #
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 #

newtype TraversedF a f #

Used internally by traverse1Of_ and the like.

Since: 4.16

Constructors

TraversedF
Fields getTraversedF :: f a

Instances

Instances details

Apply f => Semigroup (TraversedF a f) #
Instance details Defined in Control.Lens.Internal.Fold Methods (<>) :: TraversedF a f -> TraversedF a f -> TraversedF a f # sconcat :: NonEmpty (TraversedF a f) -> TraversedF a f # stimes :: Integral b => b -> TraversedF a f -> TraversedF 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 #

newtype Sequenced a m #

Used internally by mapM_ and the like.

The argument a of the result should not be used!

See 4.16 Changelog entry for the explanation of "why not Apply f =>"?

Constructors

Sequenced
Fields getSequenced :: m a

Instances

Instances details

Monad m => Semigroup (Sequenced a m) #
Instance details Defined in Control.Lens.Internal.Fold Methods (<>) :: Sequenced a m -> Sequenced a m -> Sequenced a m # sconcat :: NonEmpty (Sequenced a m) -> Sequenced a m # stimes :: Integral b => b -> Sequenced a m -> Sequenced a m #
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 #

data Max a #

Used for maximumOf.

Constructors

NoMax
Max a

Instances

Instances details

Ord a => Semigroup (Max a) #
Instance details Defined in Control.Lens.Internal.Fold Methods (<>) :: Max a -> Max a -> Max a # sconcat :: NonEmpty (Max a) -> Max a # stimes :: Integral b => b -> Max a -> Max 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 #

getMax :: Max a -> Maybe a #

Obtain the maximum.

data Min a #

Used for minimumOf.

Constructors

NoMin
Min a

Instances

Instances details

Ord a => Semigroup (Min a) #
Instance details Defined in Control.Lens.Internal.Fold Methods (<>) :: Min a -> Min a -> Min a # sconcat :: NonEmpty (Min a) -> Min a # stimes :: Integral b => b -> Min a -> Min 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 #

getMin :: Min a -> Maybe a #

Obtain the minimum.

data Leftmost a #

Used for firstOf.

Constructors

LPure
LLeaf a
LStep (Leftmost a)

Instances

Instances details

Semigroup (Leftmost a) #
Instance details Defined in Control.Lens.Internal.Fold Methods (<>) :: Leftmost a -> Leftmost a -> Leftmost a # sconcat :: NonEmpty (Leftmost a) -> Leftmost a # stimes :: Integral b => b -> Leftmost a -> Leftmost 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 #

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

Instances details

Semigroup (Rightmost a) #
Instance details Defined in Control.Lens.Internal.Fold Methods (<>) :: Rightmost a -> Rightmost a -> Rightmost a # sconcat :: NonEmpty (Rightmost a) -> Rightmost a # stimes :: Integral b => b -> Rightmost a -> Rightmost 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 #

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

Semigroups for folding

newtype NonEmptyDList a #

Constructors

NonEmptyDList
Fields getNonEmptyDList :: [a] -> NonEmpty a

Instances

Instances details

Semigroup (NonEmptyDList a) #
Instance details Defined in Control.Lens.Internal.Fold Methods (<>) :: NonEmptyDList a -> NonEmptyDList a -> NonEmptyDList a # sconcat :: NonEmpty (NonEmptyDList a) -> NonEmptyDList a # stimes :: Integral b => b -> NonEmptyDList a -> NonEmptyDList a #