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
Language	Haskell98

Control.Lens.Internal.Fold

Contents

Monoids for folding

Description

Synopsis

Monoids for folding

newtype Folding f a Source

A Monoid for a Contravariant Applicative.

Constructors

Folding
Fields getFolding :: f a

Instances

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

newtype Traversed a f Source

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) Source
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) Source
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

newtype Sequenced a m Source

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) Source
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) Source
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

data Max a Source

Used for maximumOf.

Constructors

NoMax
Max a

Instances

Ord a => Monoid (Max a) Source
Methods mempty :: Max a mappend :: Max a -> Max a -> Max a mconcat :: [Max a] -> Max a
Ord a => Semigroup (Max a) Source
Methods (<>) :: Max a -> Max a -> Max a sconcat :: NonEmpty (Max a) -> Max a stimes :: Integral b => b -> Max a -> Max a

getMax :: Max a -> Maybe a Source

Obtain the maximum.

data Min a Source

Used for minimumOf.

Constructors

NoMin
Min a

Instances

Ord a => Monoid (Min a) Source
Methods mempty :: Min a mappend :: Min a -> Min a -> Min a mconcat :: [Min a] -> Min a
Ord a => Semigroup (Min a) Source
Methods (<>) :: Min a -> Min a -> Min a sconcat :: NonEmpty (Min a) -> Min a stimes :: Integral b => b -> Min a -> Min a

getMin :: Min a -> Maybe a Source

Obtain the minimum.

data Leftmost a Source

Used for preview.

Constructors

LPure
LLeaf a
LStep (Leftmost a)

Instances

Monoid (Leftmost a) Source
Methods mempty :: Leftmost a mappend :: Leftmost a -> Leftmost a -> Leftmost a mconcat :: [Leftmost a] -> Leftmost a
Semigroup (Leftmost a) Source
Methods (<>) :: Leftmost a -> Leftmost a -> Leftmost a sconcat :: NonEmpty (Leftmost a) -> Leftmost a stimes :: Integral b => b -> Leftmost a -> Leftmost a

getLeftmost :: Leftmost a -> Maybe a Source

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 Source

Used for lastOf.

Constructors

RPure
RLeaf a
RStep (Rightmost a)

Instances

Monoid (Rightmost a) Source
Methods mempty :: Rightmost a mappend :: Rightmost a -> Rightmost a -> Rightmost a mconcat :: [Rightmost a] -> Rightmost a
Semigroup (Rightmost a) Source
Methods (<>) :: Rightmost a -> Rightmost a -> Rightmost a sconcat :: NonEmpty (Rightmost a) -> Rightmost a stimes :: Integral b => b -> Rightmost a -> Rightmost a

getRightmost :: Rightmost a -> Maybe a Source

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