Safe Haskell	None
Language	Haskell2010

Optics.Internal.Indexed

Description

Internal implementation details of indexed optics.

This module is intended for internal use only, and may change without warning in subsequent releases.

Synopsis

class is ~ NoIx => AcceptsEmptyIndices (f :: Symbol) (is :: IxList)
class NonEmptyIndices (is :: IxList)
class is ~ '[i] => HasSingleIndex (is :: IxList) (i :: Type)
type family ShowTypes (types :: [Type]) :: ErrorMessage where ...
data IntT f a = IntT !Int (f a)
unIntT :: IntT f a -> f a
newtype Indexing f a = Indexing {
- runIndexing :: Int -> IntT f a
}
indexing :: ((a -> Indexing f b) -> s -> Indexing f t) -> (Int -> a -> f b) -> s -> f t
conjoined :: is `HasSingleIndex` i => Optic k NoIx s t a b -> Optic k is s t a b -> Optic k is s t a b

Documentation

class is ~ NoIx => AcceptsEmptyIndices (f :: Symbol) (is :: IxList) Source #

Show useful error message when a function expects optics without indices.

Instances

AcceptsEmptyIndices f ([] :: [Type]) Source #
Instance details Defined in Optics.Internal.Indexed
((TypeError ((Text "\8216" :<>: Text f) :<>: Text "\8217 accepts only optics with no indices") :: Constraint), (x ': xs) ~ NoIx) => AcceptsEmptyIndices f (x ': xs) Source #
Instance details Defined in Optics.Internal.Indexed

class NonEmptyIndices (is :: IxList) Source #

Check whether a list of indices is not empty and generate sensible error message if it's not.

Instances

(TypeError (Text "Indexed optic is expected") :: Constraint) => NonEmptyIndices ([] :: [Type]) Source #
Instance details Defined in Optics.Internal.Indexed
NonEmptyIndices (x ': xs) Source #
Instance details Defined in Optics.Internal.Indexed

class is ~ '[i] => HasSingleIndex (is :: IxList) (i :: Type) Source #

Generate sensible error messages in case a user tries to pass either an unindexed optic or indexed optic with unflattened indices where indexed optic with a single index is expected.

Instances

((TypeError (Text "Indexed optic is expected") :: Constraint), ([] :: [Type]) ~ (i ': ([] :: [Type]))) => HasSingleIndex ([] :: [Type]) i Source #
Instance details Defined in Optics.Internal.Indexed
((TypeError (Text "Use icomposeN to flatten indices of type " :<>: ShowTypes is) :: Constraint), is ~ (i1 ': (i2 ': (i3 ': (i4 ': (i5 ': (i6 ': is')))))), is ~ (i ': ([] :: [Type]))) => HasSingleIndex (i1 ': (i2 ': (i3 ': (i4 ': (i5 ': (i6 ': is')))))) i Source #
Instance details Defined in Optics.Internal.Indexed
((TypeError (Text "Use icompose5 to flatten indices of type " :<>: ShowTypes is) :: Constraint), is ~ (i1 ': (i2 ': (i3 ': (i4 ': (i5 ': ([] :: [Type])))))), is ~ (i ': ([] :: [Type]))) => HasSingleIndex (i1 ': (i2 ': (i3 ': (i4 ': (i5 ': ([] :: [Type])))))) i Source #
Instance details Defined in Optics.Internal.Indexed
((TypeError (Text "Use icompose4 to combine indices of type " :<>: ShowTypes is) :: Constraint), is ~ (i1 ': (i2 ': (i3 ': (i4 ': ([] :: [Type]))))), is ~ (i ': ([] :: [Type]))) => HasSingleIndex (i1 ': (i2 ': (i3 ': (i4 ': ([] :: [Type]))))) i Source #
Instance details Defined in Optics.Internal.Indexed
((TypeError (Text "Use icompose3 to combine indices of type " :<>: ShowTypes is) :: Constraint), is ~ (i1 ': (i2 ': (i3 ': ([] :: [Type])))), is ~ (i ': ([] :: [Type]))) => HasSingleIndex (i1 ': (i2 ': (i3 ': ([] :: [Type])))) i Source #
Instance details Defined in Optics.Internal.Indexed
((TypeError (Text "Use (<%>) or icompose to combine indices of type " :<>: ShowTypes is) :: Constraint), is ~ (i1 ': (i2 ': ([] :: [Type]))), is ~ (i ': ([] :: [Type]))) => HasSingleIndex (i1 ': (i2 ': ([] :: [Type]))) i Source #
Instance details Defined in Optics.Internal.Indexed
HasSingleIndex (i ': ([] :: [Type])) i Source #
Instance details Defined in Optics.Internal.Indexed

type family ShowTypes (types :: [Type]) :: ErrorMessage where ... Source #

Equations

ShowTypes '[i] = QuoteType i
ShowTypes '[i, j] = (QuoteType i :<>: Text " and ") :<>: QuoteType j
ShowTypes (i ': is) = (QuoteType i :<>: Text ", ") :<>: ShowTypes is

data IntT f a Source #

Constructors

IntT !Int (f a)

unIntT :: IntT f a -> f a Source #

newtype Indexing f a Source #

Constructors

Indexing
Fields runIndexing :: Int -> IntT f a

Instances

Functor f => Functor (Indexing f) Source #
Instance details Defined in Optics.Internal.Indexed Methods fmap :: (a -> b) -> Indexing f a -> Indexing f b # (<$) :: a -> Indexing f b -> Indexing f a #
Applicative f => Applicative (Indexing f) Source #
Instance details Defined in Optics.Internal.Indexed Methods pure :: a -> Indexing f a # (<>) :: Indexing f (a -> b) -> Indexing f a -> Indexing f b # liftA2 :: (a -> b -> c) -> Indexing f a -> Indexing f b -> Indexing f c # (>) :: Indexing f a -> Indexing f b -> Indexing f b # (<*) :: Indexing f a -> Indexing f b -> Indexing f a #

indexing :: ((a -> Indexing f b) -> s -> Indexing f t) -> (Int -> a -> f b) -> s -> f t Source #

Index a traversal by position of visited elements.

conjoined :: is `HasSingleIndex` i => Optic k NoIx s t a b -> Optic k is s t a b -> Optic k is s t a b Source #

Construct a conjoined indexed optic that provides a separate code path when used without indices. Useful for defining indexed optics that are as efficient as their unindexed equivalents when used without indices.

Note: conjoined f g is well-defined if and only if f ≡ noIx g.