Optics.Internal.Optic.TypeLevel

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

Documentation

type IxList = [Type]

A list of index types, used for indexed optics.

Since: 0.2

type NoIx = '[] :: IxList

An alias for an empty index-list

type WithIx i = '[i] :: IxList

Singleton index list

type family ShowSymbolWithOrigin symbol origin :: ErrorMessage where ...

Equations

ShowSymbolWithOrigin symbol origin = ((('Text " " :<>: QuoteSymbol symbol) :<>: 'Text " (from ") :<>: 'Text origin) :<>: 'Text ")"

type family ShowSymbolsWithOrigin (fs :: [(Symbol, Symbol)]) :: ErrorMessage where ...

Equations

ShowSymbolsWithOrigin '['(symbol, origin)] = ShowSymbolWithOrigin symbol origin

ShowSymbolsWithOrigin ('(symbol, origin) ': rest) = ShowSymbolWithOrigin symbol origin :$$: ShowSymbolsWithOrigin rest

type family ShowOperators (ops :: [Symbol]) :: ErrorMessage where ...

Equations

ShowOperators '[op] = QuoteSymbol op :<>: 'Text " (from Optics.Operators)"

ShowOperators (op ': rest) = (QuoteSymbol op :<>: 'Text " ") :<>: ShowOperators rest

type family AppendEliminations a b where ...

Equations

AppendEliminations '(fs1, ops1) '(fs2, ops2) = '(Append fs1 fs2, Append ops1 ops2)

type family ShowEliminations forms :: ErrorMessage where ...

Equations

ShowEliminations '(fs, ops) = ShowSymbolsWithOrigin fs :$$: ('Text " " :<>: ShowOperators ops)

type family Reverse (xs :: [k]) (acc :: [k]) :: [k] where ...

Reverse a type-level list.

Equations

Reverse '[] acc = acc

Reverse (x ': xs) acc = Reverse xs (x ': acc)

type family Curry (xs :: IxList) (y :: Type) :: Type where ...

Curry a type-level list.

In pseudo (dependent-)Haskell:

Curry xs y = foldr (->) y xs

Equations

Curry '[] y = y

Curry (x ': xs) y = x -> Curry xs y

type family Append (xs :: [k]) (ys :: [k]) :: [k] where ...

Append two type-level lists together.

Equations

Append '[] ys = ys

Append xs '[] = xs

Append (x ': xs) ys = x ': Append xs ys

class CurryCompose xs where

Class that is inhabited by all type-level lists xs, providing the ability to compose a function under Curry xs.

Methods

composeN :: (i -> j) -> Curry xs i -> Curry xs j

Compose a function under Curry xs. This generalises (.) (aka fmap for (->)) to work for curried functions with one argument for each type in the list.

Instances

CurryCompose ('[] :: [Type])

Defined in Optics.Internal.Optic.TypeLevel

Methods

composeN :: (i -> j) -> Curry '[] i -> Curry '[] j

CurryCompose xs => CurryCompose (x ': xs)

Defined in Optics.Internal.Optic.TypeLevel

Methods

composeN :: (i -> j) -> Curry (x ': xs) i -> Curry (x ': xs) j

data IxEq i is js where

Tagged version of 'Data.Type.Equality.(:~:)' for carrying evidence that two index lists in a curried form are equal.

Constructors

IxEq :: IxEq i is is

class AppendIndices xs ys ks | xs ys -> ks where

In pseudo (dependent-)Haskell, provide a witness

foldr f (foldr f init xs) ys = foldr f init (ys ++ xs)
   where f = (->)

Since: 0.4

Methods

appendIndices :: IxEq i (Curry xs (Curry ys i)) (Curry ks i)

Instances

AppendIndices xs ('[] :: [Type]) xs

If the second list is empty, we can shortcircuit and pick the first list immediately.

Defined in Optics.Internal.Optic.TypeLevel

Methods

appendIndices :: IxEq i (Curry xs (Curry '[] i)) (Curry xs i)

AppendIndices ('[] :: [Type]) ys ys

Defined in Optics.Internal.Optic.TypeLevel

Methods

appendIndices :: IxEq i (Curry '[] (Curry ys i)) (Curry ys i)

AppendIndices xs ys ks => AppendIndices (x ': xs) ys (x ': ks)

Defined in Optics.Internal.Optic.TypeLevel

Methods

appendIndices :: IxEq i (Curry (x ': xs) (Curry ys i)) (Curry (x ': ks) i)

type family FirstRight (m1 :: Either e a) (m2 :: Either e a) :: Either e a where ...

If lhs is Right, return it. Otherwise check rhs.

Equations

FirstRight ('Right a) _ = 'Right a

FirstRight _ b = b

type family FromRight (def :: b) (e :: Either a b) :: b where ...

Equations

FromRight _ ('Right b) = b

FromRight def ('Left _) = def

type family IsLeft (e :: Either a b) :: Bool where ...

Equations

IsLeft ('Left _) = 'True

IsLeft ('Right _) = 'False

type family When (p :: Bool) (err :: Constraint) :: Constraint where ...

Show a custom type error if p is true.

Equations

When 'True err = err

When 'False _ = ()

type family Unless (p :: Bool) (err :: Constraint) :: Constraint where ...

Show a custom type error if p is false (or stuck).

Equations

Unless 'True _ = ()

Unless 'False err = err

type family Defined (f :: k) :: Bool where ...

Use with Unless to detect stuck (undefined) type families.

Equations

Defined (f _) = Defined f

Defined _ = 'True

type family QuoteType (x :: t) :: ErrorMessage where ...

Show a type surrounded by quote marks.

Equations

QuoteType x = ('Text "\8216" :<>: 'ShowType x) :<>: 'Text "\8217"

type family QuoteSymbol (x :: Symbol) :: ErrorMessage where ...

Show a symbol surrounded by quote marks.

Equations

QuoteSymbol x = ('Text "\8216" :<>: 'Text x) :<>: 'Text "\8217"

type family ToOrdinal (n :: Nat) :: ErrorMessage where ...

Equations

ToOrdinal 1 = 'Text "1st"

ToOrdinal 2 = 'Text "2nd"

ToOrdinal 3 = 'Text "3rd"

ToOrdinal n = 'ShowType n :<>: 'Text "th"

class HasShapeOf (a :: k) (b :: k)

Derive the shape of a from the shape of b.

Instances

a ~ b => HasShapeOf (a :: k) (b :: k)

Defined in Optics.Internal.Optic.TypeLevel

(fa ~ f a, HasShapeOf f g) => HasShapeOf (fa :: k1) (g b :: k1)

Defined in Optics.Internal.Optic.TypeLevel