Data.Traversable.WithIndex

Indexed Traversables

Indexed Traversables

class (FunctorWithIndex i t, FoldableWithIndex i t, Traversable t) => TraversableWithIndex i t | t -> i where

A Traversable with an additional index.

An instance must satisfy a (modified) form of the Traversable laws:

itraverse (const Identity) ≡ Identity
fmap (itraverse f) . itraverse g ≡ getCompose . itraverse (\i -> Compose . fmap (f i) . g i)

Minimal complete definition

Nothing

Methods

itraverse :: Applicative f => (i -> a -> f b) -> t a -> f (t b)

Traverse an indexed container.

itraverse ≡ itraverseOf itraversed

default itraverse :: (i ~ Int, Applicative f) => (i -> a -> f b) -> t a -> f (t b)

Instances

TraversableWithIndex Int []

Defined in WithIndex

Methods

itraverse :: Applicative f => (Int -> a -> f b) -> [a] -> f [b]

TraversableWithIndex Int ZipList

Defined in WithIndex

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itraverse :: Applicative f => (Int -> a -> f b) -> ZipList a -> f (ZipList b)

TraversableWithIndex Int NonEmpty

Defined in WithIndex

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itraverse :: Applicative f => (Int -> a -> f b) -> NonEmpty a -> f (NonEmpty b)

TraversableWithIndex Int IntMap

Defined in WithIndex

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itraverse :: Applicative f => (Int -> a -> f b) -> IntMap a -> f (IntMap b)

TraversableWithIndex Int Seq

Defined in WithIndex

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itraverse :: Applicative f => (Int -> a -> f b) -> Seq a -> f (Seq b)

TraversableWithIndex () Maybe

Defined in WithIndex

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itraverse :: Applicative f => (() -> a -> f b) -> Maybe a -> f (Maybe b)

TraversableWithIndex () Par1

Defined in WithIndex

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itraverse :: Applicative f => (() -> a -> f b) -> Par1 a -> f (Par1 b)

TraversableWithIndex () Identity

Defined in WithIndex

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itraverse :: Applicative f => (() -> a -> f b) -> Identity a -> f (Identity b)

TraversableWithIndex k (Map k)

Defined in WithIndex

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itraverse :: Applicative f => (k -> a -> f b) -> Map k a -> f (Map k b)

Ix i => TraversableWithIndex i (Array i)

Defined in WithIndex

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itraverse :: Applicative f => (i -> a -> f b) -> Array i a -> f (Array i b)

TraversableWithIndex k ((,) k)

Defined in WithIndex

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itraverse :: Applicative f => (k -> a -> f b) -> (k, a) -> f (k, b)

TraversableWithIndex Void (V1 :: Type -> Type)

Defined in WithIndex

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itraverse :: Applicative f => (Void -> a -> f b) -> V1 a -> f (V1 b)

TraversableWithIndex Void (U1 :: Type -> Type)

Defined in WithIndex

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itraverse :: Applicative f => (Void -> a -> f b) -> U1 a -> f (U1 b)

TraversableWithIndex Void (Proxy :: Type -> Type)

Defined in WithIndex

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itraverse :: Applicative f => (Void -> a -> f b) -> Proxy a -> f (Proxy b)

TraversableWithIndex i f => TraversableWithIndex i (Rec1 f)

Defined in WithIndex

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itraverse :: Applicative f0 => (i -> a -> f0 b) -> Rec1 f a -> f0 (Rec1 f b)

TraversableWithIndex i f => TraversableWithIndex i (Reverse f)

Defined in WithIndex

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itraverse :: Applicative f0 => (i -> a -> f0 b) -> Reverse f a -> f0 (Reverse f b)

TraversableWithIndex i f => TraversableWithIndex i (Backwards f)

Defined in WithIndex

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itraverse :: Applicative f0 => (i -> a -> f0 b) -> Backwards f a -> f0 (Backwards f b)

TraversableWithIndex i m => TraversableWithIndex i (IdentityT m)

Defined in WithIndex

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itraverse :: Applicative f => (i -> a -> f b) -> IdentityT m a -> f (IdentityT m b)

TraversableWithIndex Void (Const e :: Type -> Type)

Defined in WithIndex

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itraverse :: Applicative f => (Void -> a -> f b) -> Const e a -> f (Const e b)

TraversableWithIndex Void (Constant e :: Type -> Type)

Defined in WithIndex

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itraverse :: Applicative f => (Void -> a -> f b) -> Constant e a -> f (Constant e b)

TraversableWithIndex Void (K1 i c :: Type -> Type)

Defined in WithIndex

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itraverse :: Applicative f => (Void -> a -> f b) -> K1 i c a -> f (K1 i c b)

TraversableWithIndex [Int] Tree

Defined in WithIndex

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itraverse :: Applicative f => ([Int] -> a -> f b) -> Tree a -> f (Tree b)

(TraversableWithIndex i f, TraversableWithIndex j g) => TraversableWithIndex (Either i j) (f :+: g)

Defined in WithIndex

Methods

itraverse :: Applicative f0 => (Either i j -> a -> f0 b) -> (f :+: g) a -> f0 ((f :+: g) b)

(TraversableWithIndex i f, TraversableWithIndex j g) => TraversableWithIndex (Either i j) (f :*: g)

Defined in WithIndex

Methods

itraverse :: Applicative f0 => (Either i j -> a -> f0 b) -> (f :*: g) a -> f0 ((f :*: g) b)

(TraversableWithIndex i f, TraversableWithIndex j g) => TraversableWithIndex (Either i j) (Product f g)

Defined in WithIndex

Methods

itraverse :: Applicative f0 => (Either i j -> a -> f0 b) -> Product f g a -> f0 (Product f g b)

(TraversableWithIndex i f, TraversableWithIndex j g) => TraversableWithIndex (Either i j) (Sum f g)

Defined in WithIndex

Methods

itraverse :: Applicative f0 => (Either i j -> a -> f0 b) -> Sum f g a -> f0 (Sum f g b)

(TraversableWithIndex i f, TraversableWithIndex j g) => TraversableWithIndex (i, j) (f :.: g)

Defined in WithIndex

Methods

itraverse :: Applicative f0 => ((i, j) -> a -> f0 b) -> (f :.: g) a -> f0 ((f :.: g) b)

(TraversableWithIndex i f, TraversableWithIndex j g) => TraversableWithIndex (i, j) (Compose f g)

Defined in WithIndex

Methods

itraverse :: Applicative f0 => ((i, j) -> a -> f0 b) -> Compose f g a -> f0 (Compose f g b)

Indexed Traversable Combinators

ifor :: (TraversableWithIndex i t, Applicative f) => t a -> (i -> a -> f b) -> f (t b)

Traverse with an index (and the arguments flipped).

for a ≡ ifor a . const
ifor ≡ flip itraverse

imapM :: (TraversableWithIndex i t, Monad m) => (i -> a -> m b) -> t a -> m (t b)

Map each element of a structure to a monadic action, evaluate these actions from left to right, and collect the results, with access the index.

When you don't need access to the index mapM is more liberal in what it can accept.

mapM ≡ imapM . const

iforM :: (TraversableWithIndex i t, Monad m) => t a -> (i -> a -> m b) -> m (t b)

Map each element of a structure to a monadic action, evaluate these actions from left to right, and collect the results, with access its position (and the arguments flipped).

forM a ≡ iforM a . const
iforM ≡ flip imapM

imapAccumR :: TraversableWithIndex i t => (i -> s -> a -> (s, b)) -> s -> t a -> (s, t b)

Generalizes mapAccumR to add access to the index.

imapAccumROf accumulates state from right to left.

mapAccumR ≡ imapAccumR . const

imapAccumL :: TraversableWithIndex i t => (i -> s -> a -> (s, b)) -> s -> t a -> (s, t b)

Generalizes mapAccumL to add access to the index.

imapAccumLOf accumulates state from left to right.

mapAccumLOf ≡ imapAccumL . const

Default implementations

imapDefault :: TraversableWithIndex i f => (i -> a -> b) -> f a -> f b

ifoldMapDefault :: (TraversableWithIndex i f, Monoid m) => (i -> a -> m) -> f a -> m