Optics.Internal.Indexed

Internal implementation details of indexed optics.

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

Documentation

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

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

Instances

AcceptsEmptyIndices f ('[] :: [Type])

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)

Defined in Optics.Internal.Indexed

class NonEmptyIndices (is :: IxList)

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])

Defined in Optics.Internal.Indexed

NonEmptyIndices (x ': xs)

Defined in Optics.Internal.Indexed

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

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]) => HasSingleIndex ('[] :: [Type]) i

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]) => HasSingleIndex (i1 ': (i2 ': (i3 ': (i4 ': (i5 ': (i6 ': is')))))) i

Defined in Optics.Internal.Indexed

(TypeError ('Text "Use icompose5 to flatten indices of type " :<>: ShowTypes is) :: Constraint, is ~ '[i1, i2, i3, i4, i5], is ~ '[i]) => HasSingleIndex '[i1, i2, i3, i4, i5] i

Defined in Optics.Internal.Indexed

(TypeError ('Text "Use icompose4 to combine indices of type " :<>: ShowTypes is) :: Constraint, is ~ '[i1, i2, i3, i4], is ~ '[i]) => HasSingleIndex '[i1, i2, i3, i4] i

Defined in Optics.Internal.Indexed

(TypeError ('Text "Use icompose3 to combine indices of type " :<>: ShowTypes is) :: Constraint, is ~ '[i1, i2, i3], is ~ '[i]) => HasSingleIndex '[i1, i2, i3] i

Defined in Optics.Internal.Indexed

(TypeError ('Text "Use (<%>) or icompose to combine indices of type " :<>: ShowTypes is) :: Constraint, is ~ '[i1, i2], is ~ '[i]) => HasSingleIndex '[i1, i2] i

Defined in Optics.Internal.Indexed

HasSingleIndex '[i] i

Defined in Optics.Internal.Indexed

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

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

Constructors

IntT !Int (f a)

unIntT :: IntT f a -> f a

newtype Indexing f a

Constructors

Indexing

Fields

• runIndexing :: Int -> IntT f a

Instances

Functor f => Functor (Indexing f)

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)

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

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

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.