Copyright | (C) 2012-16 Edward Kmett |
---|---|
License | BSD-style (see the file LICENSE) |
Maintainer | Edward Kmett <ekmett@gmail.com> |
Stability | provisional |
Portability | Rank2Types |
Safe Haskell | Trustworthy |
Language | Haskell2010 |
(The classes in here need to be defined together for DefaultSignatures
to work.)
Synopsis
- class Conjoined p => Indexable i p where
- indexed :: p a b -> i -> a -> b
- class (Choice p, Corepresentable p, Comonad (Corep p), Traversable (Corep p), Strong p, Representable p, Monad (Rep p), MonadFix (Rep p), Distributive (Rep p), Costrong p, ArrowLoop p, ArrowApply p, ArrowChoice p, Closed p) => Conjoined p where
- newtype Indexed i a b = Indexed {
- runIndexed :: i -> a -> b
- (<.) :: Indexable i p => (Indexed i s t -> r) -> ((a -> b) -> s -> t) -> p a b -> r
- (<.>) :: Indexable (i, j) p => (Indexed i s t -> r) -> (Indexed j a b -> s -> t) -> p a b -> r
- (.>) :: (st -> r) -> (kab -> st) -> kab -> r
- selfIndex :: Indexable a p => p a fb -> a -> fb
- reindexed :: Indexable j p => (i -> j) -> (Indexed i a b -> r) -> p a b -> r
- icompose :: Indexable p c => (i -> j -> p) -> (Indexed i s t -> r) -> (Indexed j a b -> s -> t) -> c a b -> r
- indexing :: Indexable Int p => ((a -> Indexing f b) -> s -> Indexing f t) -> p a (f b) -> s -> f t
- indexing64 :: Indexable Int64 p => ((a -> Indexing64 f b) -> s -> Indexing64 f t) -> p a (f b) -> s -> f t
- class Functor f => FunctorWithIndex i (f :: Type -> Type) | f -> i where
- imap :: (i -> a -> b) -> f a -> f b
- imapped :: FunctorWithIndex i f => IndexedSetter i (f a) (f b) a b
- class Foldable f => FoldableWithIndex i (f :: Type -> Type) | f -> i where
- ifolded :: FoldableWithIndex i f => IndexedFold i (f a) a
- iany :: FoldableWithIndex i f => (i -> a -> Bool) -> f a -> Bool
- iall :: FoldableWithIndex i f => (i -> a -> Bool) -> f a -> Bool
- inone :: FoldableWithIndex i f => (i -> a -> Bool) -> f a -> Bool
- none :: Foldable f => (a -> Bool) -> f a -> Bool
- itraverse_ :: (FoldableWithIndex i t, Applicative f) => (i -> a -> f b) -> t a -> f ()
- ifor_ :: (FoldableWithIndex i t, Applicative f) => t a -> (i -> a -> f b) -> f ()
- imapM_ :: (FoldableWithIndex i t, Monad m) => (i -> a -> m b) -> t a -> m ()
- iforM_ :: (FoldableWithIndex i t, Monad m) => t a -> (i -> a -> m b) -> m ()
- iconcatMap :: FoldableWithIndex i f => (i -> a -> [b]) -> f a -> [b]
- ifind :: FoldableWithIndex i f => (i -> a -> Bool) -> f a -> Maybe (i, a)
- ifoldrM :: (FoldableWithIndex i f, Monad m) => (i -> a -> b -> m b) -> b -> f a -> m b
- ifoldlM :: (FoldableWithIndex i f, Monad m) => (i -> b -> a -> m b) -> b -> f a -> m b
- itoList :: FoldableWithIndex i f => f a -> [(i, a)]
- withIndex :: (Indexable i p, Functor f) => p (i, s) (f (j, t)) -> Indexed i s (f t)
- asIndex :: (Indexable i p, Contravariant f, Functor f) => p i (f i) -> Indexed i s (f s)
- indices :: (Indexable i p, Applicative f) => (i -> Bool) -> Optical' p (Indexed i) f a a
- index :: (Indexable i p, Eq i, Applicative f) => i -> Optical' p (Indexed i) f a a
- class (FunctorWithIndex i t, FoldableWithIndex i t, Traversable t) => TraversableWithIndex i (t :: Type -> Type) | t -> i where
- itraverse :: Applicative f => (i -> a -> f b) -> t a -> f (t b)
- itraversed :: TraversableWithIndex i t => IndexedTraversal i (t a) (t b) a b
- ifor :: (TraversableWithIndex i t, Applicative f) => t a -> (i -> a -> f b) -> f (t b)
- imapM :: (TraversableWithIndex i t, Monad m) => (i -> a -> m b) -> t a -> m (t b)
- iforM :: (TraversableWithIndex i t, Monad m) => t a -> (i -> a -> m b) -> m (t b)
- imapAccumR :: TraversableWithIndex i t => (i -> s -> a -> (s, b)) -> s -> t a -> (s, t b)
- imapAccumL :: TraversableWithIndex i t => (i -> s -> a -> (s, b)) -> s -> t a -> (s, t b)
- ifoldMapBy :: FoldableWithIndex i t => (r -> r -> r) -> r -> (i -> a -> r) -> t a -> r
- ifoldMapByOf :: IndexedFold i t a -> (r -> r -> r) -> r -> (i -> a -> r) -> t -> r
- itraverseBy :: TraversableWithIndex i t => (forall x. x -> f x) -> (forall x y. f (x -> y) -> f x -> f y) -> (i -> a -> f b) -> t a -> f (t b)
- itraverseByOf :: IndexedTraversal i s t a b -> (forall x. x -> f x) -> (forall x y. f (x -> y) -> f x -> f y) -> (i -> a -> f b) -> s -> f t
Indexing
class Conjoined p => Indexable i p where Source #
This class permits overloading of function application for things that also admit a notion of a key or index.
class (Choice p, Corepresentable p, Comonad (Corep p), Traversable (Corep p), Strong p, Representable p, Monad (Rep p), MonadFix (Rep p), Distributive (Rep p), Costrong p, ArrowLoop p, ArrowApply p, ArrowChoice p, Closed p) => Conjoined p where Source #
This is a Profunctor
that is both Corepresentable
by f
and Representable
by g
such
that f
is left adjoint to g
. From this you can derive a lot of structure due
to the preservation of limits and colimits.
Nothing
distrib :: Functor f => p a b -> p (f a) (f b) Source #
Conjoined
is strong enough to let us distribute every Conjoined
Profunctor
over every Haskell Functor
. This is effectively a
generalization of fmap
.
conjoined :: (p ~ (->) => q (a -> b) r) -> q (p a b) r -> q (p a b) r Source #
This permits us to make a decision at an outermost point about whether or not we use an index.
Ideally any use of this function should be done in such a way so that you compute the same answer, but this cannot be enforced at the type level.
Instances
Conjoined ReifiedGetter Source # | |
Defined in Control.Lens.Reified distrib :: Functor f => ReifiedGetter a b -> ReifiedGetter (f a) (f b) Source # conjoined :: (ReifiedGetter ~ (->) => q (a -> b) r) -> q (ReifiedGetter a b) r -> q (ReifiedGetter a b) r Source # | |
Conjoined (Indexed i) Source # | |
Conjoined (->) Source # | |
newtype Indexed i a b Source #
A function with access to a index. This constructor may be useful when you need to store
an Indexable
in a container to avoid ImpredicativeTypes
.
index :: Indexed i a b -> i -> a -> b
Indexed | |
|
Instances
(<.) :: Indexable i p => (Indexed i s t -> r) -> ((a -> b) -> s -> t) -> p a b -> r infixr 9 Source #
Compose an Indexed
function with a non-indexed function.
Mnemonically, the <
points to the indexing we want to preserve.
>>>
let nestedMap = (fmap Map.fromList . Map.fromList) [(1, [(10, "one,ten"), (20, "one,twenty")]), (2, [(30, "two,thirty"), (40,"two,forty")])]
>>>
nestedMap^..(itraversed<.itraversed).withIndex
[(1,"one,ten"),(1,"one,twenty"),(2,"two,thirty"),(2,"two,forty")]
(<.>) :: Indexable (i, j) p => (Indexed i s t -> r) -> (Indexed j a b -> s -> t) -> p a b -> r infixr 9 Source #
Composition of Indexed
functions.
Mnemonically, the <
and >
points to the fact that we want to preserve the indices.
>>>
let nestedMap = (fmap Map.fromList . Map.fromList) [(1, [(10, "one,ten"), (20, "one,twenty")]), (2, [(30, "two,thirty"), (40,"two,forty")])]
>>>
nestedMap^..(itraversed<.>itraversed).withIndex
[((1,10),"one,ten"),((1,20),"one,twenty"),((2,30),"two,thirty"),((2,40),"two,forty")]
(.>) :: (st -> r) -> (kab -> st) -> kab -> r infixr 9 Source #
Compose a non-indexed function with an Indexed
function.
Mnemonically, the >
points to the indexing we want to preserve.
This is the same as (
..
)
f
(and .
gf
) gives you the index of .>
gg
unless g
is index-preserving, like a
Prism
, Iso
or Equality
, in which case it'll pass through the index of f
.
>>>
let nestedMap = (fmap Map.fromList . Map.fromList) [(1, [(10, "one,ten"), (20, "one,twenty")]), (2, [(30, "two,thirty"), (40,"two,forty")])]
>>>
nestedMap^..(itraversed.>itraversed).withIndex
[(10,"one,ten"),(20,"one,twenty"),(30,"two,thirty"),(40,"two,forty")]
selfIndex :: Indexable a p => p a fb -> a -> fb Source #
Use a value itself as its own index. This is essentially an indexed version of id
.
Note: When used to modify the value, this can break the index requirements assumed by indices
and similar,
so this is only properly an IndexedGetter
, but it can be used as more.
selfIndex
::IndexedGetter
a a b
reindexed :: Indexable j p => (i -> j) -> (Indexed i a b -> r) -> p a b -> r Source #
Remap the index.
icompose :: Indexable p c => (i -> j -> p) -> (Indexed i s t -> r) -> (Indexed j a b -> s -> t) -> c a b -> r Source #
Composition of Indexed
functions with a user supplied function for combining indices.
indexing :: Indexable Int p => ((a -> Indexing f b) -> s -> Indexing f t) -> p a (f b) -> s -> f t Source #
Transform a Traversal
into an IndexedTraversal
or
a Fold
into an IndexedFold
, etc.
indexing
::Traversal
s t a b ->IndexedTraversal
Int
s t a bindexing
::Prism
s t a b ->IndexedTraversal
Int
s t a bindexing
::Lens
s t a b ->IndexedLens
Int
s t a bindexing
::Iso
s t a b ->IndexedLens
Int
s t a bindexing
::Fold
s a ->IndexedFold
Int
s aindexing
::Getter
s a ->IndexedGetter
Int
s a
indexing
::Indexable
Int
p =>LensLike
(Indexing
f) s t a b ->Over
p f s t a b
indexing64 :: Indexable Int64 p => ((a -> Indexing64 f b) -> s -> Indexing64 f t) -> p a (f b) -> s -> f t Source #
Transform a Traversal
into an IndexedTraversal
or
a Fold
into an IndexedFold
, etc.
This combinator is like indexing
except that it handles large traversals and folds gracefully.
indexing64
::Traversal
s t a b ->IndexedTraversal
Int64
s t a bindexing64
::Prism
s t a b ->IndexedTraversal
Int64
s t a bindexing64
::Lens
s t a b ->IndexedLens
Int64
s t a bindexing64
::Iso
s t a b ->IndexedLens
Int64
s t a bindexing64
::Fold
s a ->IndexedFold
Int64
s aindexing64
::Getter
s a ->IndexedGetter
Int64
s a
indexing64
::Indexable
Int64
p =>LensLike
(Indexing64
f) s t a b ->Over
p f s t a b
Indexed Functors
class Functor f => FunctorWithIndex i (f :: Type -> Type) | f -> i where #
A Functor
with an additional index.
Instances must satisfy a modified form of the Functor
laws:
imap
f.
imap
g ≡imap
(\i -> f i.
g i)imap
(\_ a -> a) ≡id
Nothing
Instances
Indexed Functor Combinators
imapped :: FunctorWithIndex i f => IndexedSetter i (f a) (f b) a b Source #
The IndexedSetter
for a FunctorWithIndex
.
If you don't need access to the index, then mapped
is more flexible in what it accepts.
Indexed Foldables
class Foldable f => FoldableWithIndex i (f :: Type -> Type) | f -> i where #
A container that supports folding with an additional index.
Nothing
ifoldMap :: Monoid m => (i -> a -> m) -> f a -> m #
Fold a container by mapping value to an arbitrary Monoid
with access to the index i
.
When you don't need access to the index then foldMap
is more flexible in what it accepts.
foldMap
≡ifoldMap
.
const
ifoldMap' :: Monoid m => (i -> a -> m) -> f a -> m #
A variant of ifoldMap
that is strict in the accumulator.
When you don't need access to the index then foldMap'
is more flexible in what it accepts.
foldMap'
≡ifoldMap'
.
const
ifoldr :: (i -> a -> b -> b) -> b -> f a -> b #
Right-associative fold of an indexed container with access to the index i
.
When you don't need access to the index then foldr
is more flexible in what it accepts.
foldr
≡ifoldr
.
const
ifoldl :: (i -> b -> a -> b) -> b -> f a -> b #
Left-associative fold of an indexed container with access to the index i
.
When you don't need access to the index then foldl
is more flexible in what it accepts.
foldl
≡ifoldl
.
const
Instances
FoldableWithIndex () Identity | |
Defined in WithIndex | |
FoldableWithIndex () Par1 | |
FoldableWithIndex () Maybe | |
FoldableWithIndex Int ZipList | |
Defined in WithIndex | |
FoldableWithIndex Int IntMap | |
Defined in WithIndex | |
FoldableWithIndex Int Seq | |
FoldableWithIndex Int Deque Source # | |
Defined in Control.Lens.Internal.Deque | |
FoldableWithIndex Int NonEmpty | |
Defined in WithIndex | |
FoldableWithIndex Int [] | |
FoldableWithIndex Void (Proxy :: Type -> Type) | |
Defined in WithIndex | |
FoldableWithIndex Void (U1 :: Type -> Type) | |
FoldableWithIndex Void (V1 :: Type -> Type) | |
Ix i => FoldableWithIndex i (Array i) | |
FoldableWithIndex i (Level i) Source # | |
Defined in Control.Lens.Internal.Level | |
FoldableWithIndex k (Map k) | |
FoldableWithIndex k ((,) k) | |
FoldableWithIndex Void (Const e :: Type -> Type) | |
Defined in WithIndex | |
FoldableWithIndex Void (Constant e :: Type -> Type) | |
Defined in WithIndex ifoldMap :: Monoid m => (Void -> a -> m) -> Constant e a -> m # ifoldMap' :: Monoid m => (Void -> a -> m) -> Constant e a -> m # ifoldr :: (Void -> a -> b -> b) -> b -> Constant e a -> b # ifoldl :: (Void -> b -> a -> b) -> b -> Constant e a -> b # ifoldr' :: (Void -> a -> b -> b) -> b -> Constant e a -> b # ifoldl' :: (Void -> b -> a -> b) -> b -> Constant e a -> b # | |
FoldableWithIndex i f => FoldableWithIndex i (Rec1 f) | |
FoldableWithIndex i f => FoldableWithIndex i (Backwards f) | |
Defined in WithIndex | |
FoldableWithIndex i m => FoldableWithIndex i (IdentityT m) | |
Defined in WithIndex ifoldMap :: Monoid m0 => (i -> a -> m0) -> IdentityT m a -> m0 # ifoldMap' :: Monoid m0 => (i -> a -> m0) -> IdentityT m a -> m0 # ifoldr :: (i -> a -> b -> b) -> b -> IdentityT m a -> b # ifoldl :: (i -> b -> a -> b) -> b -> IdentityT m a -> b # | |
FoldableWithIndex i f => FoldableWithIndex i (Reverse f) | |
Defined in WithIndex | |
FoldableWithIndex Void (K1 i c :: Type -> Type) | |
Defined in WithIndex | |
FoldableWithIndex i (Magma i t b) Source # | |
Defined in Control.Lens.Internal.Magma ifoldMap :: Monoid m => (i -> a -> m) -> Magma i t b a -> m # ifoldMap' :: Monoid m => (i -> a -> m) -> Magma i t b a -> m # ifoldr :: (i -> a -> b0 -> b0) -> b0 -> Magma i t b a -> b0 # ifoldl :: (i -> b0 -> a -> b0) -> b0 -> Magma i t b a -> b0 # ifoldr' :: (i -> a -> b0 -> b0) -> b0 -> Magma i t b a -> b0 # ifoldl' :: (i -> b0 -> a -> b0) -> b0 -> Magma i t b a -> b0 # | |
FoldableWithIndex [Int] Tree | |
Defined in WithIndex | |
FoldableWithIndex i f => FoldableWithIndex [i] (Cofree f) | |
Defined in Control.Comonad.Cofree | |
FoldableWithIndex i f => FoldableWithIndex [i] (Free f) | |
Defined in Control.Monad.Free | |
(FoldableWithIndex i f, FoldableWithIndex j g) => FoldableWithIndex (Either i j) (Product f g) | |
Defined in WithIndex ifoldMap :: Monoid m => (Either i j -> a -> m) -> Product f g a -> m # ifoldMap' :: Monoid m => (Either i j -> a -> m) -> Product f g a -> m # ifoldr :: (Either i j -> a -> b -> b) -> b -> Product f g a -> b # ifoldl :: (Either i j -> b -> a -> b) -> b -> Product f g a -> b # ifoldr' :: (Either i j -> a -> b -> b) -> b -> Product f g a -> b # ifoldl' :: (Either i j -> b -> a -> b) -> b -> Product f g a -> b # | |
(FoldableWithIndex i f, FoldableWithIndex j g) => FoldableWithIndex (Either i j) (Sum f g) | |
Defined in WithIndex ifoldMap :: Monoid m => (Either i j -> a -> m) -> Sum f g a -> m # ifoldMap' :: Monoid m => (Either i j -> a -> m) -> Sum f g a -> m # ifoldr :: (Either i j -> a -> b -> b) -> b -> Sum f g a -> b # ifoldl :: (Either i j -> b -> a -> b) -> b -> Sum f g a -> b # ifoldr' :: (Either i j -> a -> b -> b) -> b -> Sum f g a -> b # ifoldl' :: (Either i j -> b -> a -> b) -> b -> Sum f g a -> b # | |
(FoldableWithIndex i f, FoldableWithIndex j g) => FoldableWithIndex (Either i j) (f :*: g) | |
Defined in WithIndex ifoldMap :: Monoid m => (Either i j -> a -> m) -> (f :*: g) a -> m # ifoldMap' :: Monoid m => (Either i j -> a -> m) -> (f :*: g) a -> m # ifoldr :: (Either i j -> a -> b -> b) -> b -> (f :*: g) a -> b # ifoldl :: (Either i j -> b -> a -> b) -> b -> (f :*: g) a -> b # ifoldr' :: (Either i j -> a -> b -> b) -> b -> (f :*: g) a -> b # ifoldl' :: (Either i j -> b -> a -> b) -> b -> (f :*: g) a -> b # | |
(FoldableWithIndex i f, FoldableWithIndex j g) => FoldableWithIndex (Either i j) (f :+: g) | |
Defined in WithIndex ifoldMap :: Monoid m => (Either i j -> a -> m) -> (f :+: g) a -> m # ifoldMap' :: Monoid m => (Either i j -> a -> m) -> (f :+: g) a -> m # ifoldr :: (Either i j -> a -> b -> b) -> b -> (f :+: g) a -> b # ifoldl :: (Either i j -> b -> a -> b) -> b -> (f :+: g) a -> b # ifoldr' :: (Either i j -> a -> b -> b) -> b -> (f :+: g) a -> b # ifoldl' :: (Either i j -> b -> a -> b) -> b -> (f :+: g) a -> b # | |
(FoldableWithIndex i f, FoldableWithIndex j g) => FoldableWithIndex (i, j) (Compose f g) | |
Defined in WithIndex ifoldMap :: Monoid m => ((i, j) -> a -> m) -> Compose f g a -> m # ifoldMap' :: Monoid m => ((i, j) -> a -> m) -> Compose f g a -> m # ifoldr :: ((i, j) -> a -> b -> b) -> b -> Compose f g a -> b # ifoldl :: ((i, j) -> b -> a -> b) -> b -> Compose f g a -> b # ifoldr' :: ((i, j) -> a -> b -> b) -> b -> Compose f g a -> b # ifoldl' :: ((i, j) -> b -> a -> b) -> b -> Compose f g a -> b # | |
(FoldableWithIndex i f, FoldableWithIndex j g) => FoldableWithIndex (i, j) (f :.: g) | |
Defined in WithIndex ifoldMap :: Monoid m => ((i, j) -> a -> m) -> (f :.: g) a -> m # ifoldMap' :: Monoid m => ((i, j) -> a -> m) -> (f :.: g) a -> m # ifoldr :: ((i, j) -> a -> b -> b) -> b -> (f :.: g) a -> b # ifoldl :: ((i, j) -> b -> a -> b) -> b -> (f :.: g) a -> b # ifoldr' :: ((i, j) -> a -> b -> b) -> b -> (f :.: g) a -> b # ifoldl' :: ((i, j) -> b -> a -> b) -> b -> (f :.: g) a -> b # |
Indexed Foldable Combinators
ifolded :: FoldableWithIndex i f => IndexedFold i (f a) a Source #
The IndexedFold
of a FoldableWithIndex
container.
is a fold over the keys of a ifolded
.
asIndex
FoldableWithIndex
.
>>>
Data.Map.fromList [(2, "hello"), (1, "world")]^..ifolded.asIndex
[1,2]
iany :: FoldableWithIndex i f => (i -> a -> Bool) -> f a -> Bool #
iall :: FoldableWithIndex i f => (i -> a -> Bool) -> f a -> Bool #
inone :: FoldableWithIndex i f => (i -> a -> Bool) -> f a -> Bool #
itraverse_ :: (FoldableWithIndex i t, Applicative f) => (i -> a -> f b) -> t a -> f () #
ifor_ :: (FoldableWithIndex i t, Applicative f) => t a -> (i -> a -> f b) -> f () #
Traverse elements with access to the index i
, discarding the results (with the arguments flipped).
ifor_
≡flip
itraverse_
When you don't need access to the index then for_
is more flexible in what it accepts.
for_
a ≡ifor_
a.
const
imapM_ :: (FoldableWithIndex i t, Monad m) => (i -> a -> m b) -> t a -> m () #
Run monadic actions for each target of an IndexedFold
or IndexedTraversal
with access to the index,
discarding the results.
When you don't need access to the index then mapMOf_
is more flexible in what it accepts.
mapM_
≡imapM
.
const
iforM_ :: (FoldableWithIndex i t, Monad m) => t a -> (i -> a -> m b) -> m () #
iconcatMap :: FoldableWithIndex i f => (i -> a -> [b]) -> f a -> [b] #
Concatenate the results of a function of the elements of an indexed container with access to the index.
When you don't need access to the index then concatMap
is more flexible in what it accepts.
concatMap
≡iconcatMap
.
const
iconcatMap
≡ifoldMap
ifind :: FoldableWithIndex i f => (i -> a -> Bool) -> f a -> Maybe (i, a) #
ifoldrM :: (FoldableWithIndex i f, Monad m) => (i -> a -> b -> m b) -> b -> f a -> m b #
ifoldlM :: (FoldableWithIndex i f, Monad m) => (i -> b -> a -> m b) -> b -> f a -> m b #
itoList :: FoldableWithIndex i f => f a -> [(i, a)] #
Converting to Folds
withIndex :: (Indexable i p, Functor f) => p (i, s) (f (j, t)) -> Indexed i s (f t) Source #
Fold a container with indices returning both the indices and the values.
The result is only valid to compose in a Traversal
, if you don't edit the
index as edits to the index have no effect.
>>>
[10, 20, 30] ^.. ifolded . withIndex
[(0,10),(1,20),(2,30)]
>>>
[10, 20, 30] ^.. ifolded . withIndex . alongside negated (re _Show)
[(0,"10"),(-1,"20"),(-2,"30")]
asIndex :: (Indexable i p, Contravariant f, Functor f) => p i (f i) -> Indexed i s (f s) Source #
When composed with an IndexedFold
or IndexedTraversal
this yields an
(Indexed
) Fold
of the indices.
Restricting by Index
indices :: (Indexable i p, Applicative f) => (i -> Bool) -> Optical' p (Indexed i) f a a Source #
This allows you to filter an IndexedFold
, IndexedGetter
, IndexedTraversal
or IndexedLens
based on a predicate
on the indices.
>>>
["hello","the","world","!!!"]^..traversed.indices even
["hello","world"]
>>>
over (traversed.indices (>0)) Prelude.reverse $ ["He","was","stressed","o_O"]
["He","saw","desserts","O_o"]
index :: (Indexable i p, Eq i, Applicative f) => i -> Optical' p (Indexed i) f a a Source #
This allows you to filter an IndexedFold
, IndexedGetter
, IndexedTraversal
or IndexedLens
based on an index.
>>>
["hello","the","world","!!!"]^?traversed.index 2
Just "world"
Indexed Traversables
class (FunctorWithIndex i t, FoldableWithIndex i t, Traversable t) => TraversableWithIndex i (t :: Type -> Type) | 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)
Nothing
itraverse :: Applicative f => (i -> a -> f b) -> t a -> f (t b) #
Traverse an indexed container.
itraverse
≡itraverseOf
itraversed
Instances
Indexed Traversable Combinators
itraversed :: TraversableWithIndex i t => IndexedTraversal i (t a) (t b) a b Source #
The IndexedTraversal
of a TraversableWithIndex
container.
ifor :: (TraversableWithIndex i t, Applicative f) => t a -> (i -> a -> f b) -> f (t b) #
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) #
imapAccumR :: TraversableWithIndex i t => (i -> s -> a -> (s, b)) -> s -> t a -> (s, t b) #
Generalizes mapAccumR
to add access to the index.
imapAccumR
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.
imapAccumL
accumulates state from left to right.
mapAccumL
≡imapAccumL
.
const
Indexed Folds with Reified Monoid
ifoldMapBy :: FoldableWithIndex i t => (r -> r -> r) -> r -> (i -> a -> r) -> t a -> r Source #
ifoldMapByOf :: IndexedFold i t a -> (r -> r -> r) -> r -> (i -> a -> r) -> t -> r Source #
Indexed Traversals with Reified Applicative
itraverseBy :: TraversableWithIndex i t => (forall x. x -> f x) -> (forall x y. f (x -> y) -> f x -> f y) -> (i -> a -> f b) -> t a -> f (t b) Source #
itraverseByOf :: IndexedTraversal i s t a b -> (forall x. x -> f x) -> (forall x y. f (x -> y) -> f x -> f y) -> (i -> a -> f b) -> s -> f t Source #