Optics.ReadOnly

This module defines getting, which turns a read-write optic into its read-only counterpart.

Documentation

class ToReadOnly k s t a b where

Class for read-write optics that have their read-only counterparts.

Associated Types

type ReadOnlyOptic k :: OpticKind

Methods

getting :: Optic k is s t a b -> Optic' (ReadOnlyOptic k) is s a

Turn read-write optic into its read-only counterpart (or leave read-only optics as-is).

This is useful when you have an optic :: Optic k is s t a b of read-write kind k such that s, t, a, b are rigid, there is no evidence that s ~ t and a ~ b and you want to pass optic to one of the functions that accept read-only optic kinds.

Example:

>>> let fstIntToChar = _1 :: Lens (Int, r) (Char, r) Int Char

>>> :t view fstIntToChar
...
...Couldn't match type ‘Char’ with ‘Int’
...

>>> :t view (getting fstIntToChar)
view (getting fstIntToChar) :: (Int, r) -> Int

Instances

(s ~ t, a ~ b) => ToReadOnly A_Fold s t a b

Defined in Optics.ReadOnly

Associated Types

type ReadOnlyOptic A_Fold

Methods

getting :: forall (is :: IxList). Optic A_Fold is s t a b -> Optic' (ReadOnlyOptic A_Fold) is s a

(s ~ t, a ~ b) => ToReadOnly A_Getter s t a b

Defined in Optics.ReadOnly

Associated Types

type ReadOnlyOptic A_Getter

Methods

getting :: forall (is :: IxList). Optic A_Getter is s t a b -> Optic' (ReadOnlyOptic A_Getter) is s a

ToReadOnly A_Lens s t a b

Defined in Optics.ReadOnly

Associated Types

type ReadOnlyOptic A_Lens

Methods

getting :: forall (is :: IxList). Optic A_Lens is s t a b -> Optic' (ReadOnlyOptic A_Lens) is s a

ToReadOnly A_Prism s t a b

Defined in Optics.ReadOnly

Associated Types

type ReadOnlyOptic A_Prism

Methods

getting :: forall (is :: IxList). Optic A_Prism is s t a b -> Optic' (ReadOnlyOptic A_Prism) is s a

ToReadOnly A_ReversedPrism s t a b

Defined in Optics.ReadOnly

Associated Types

type ReadOnlyOptic A_ReversedPrism

Methods

getting :: forall (is :: IxList). Optic A_ReversedPrism is s t a b -> Optic' (ReadOnlyOptic A_ReversedPrism) is s a

ToReadOnly A_Traversal s t a b

Defined in Optics.ReadOnly

Associated Types

type ReadOnlyOptic A_Traversal

Methods

getting :: forall (is :: IxList). Optic A_Traversal is s t a b -> Optic' (ReadOnlyOptic A_Traversal) is s a

(s ~ t, a ~ b) => ToReadOnly An_AffineFold s t a b

Defined in Optics.ReadOnly

Associated Types

type ReadOnlyOptic An_AffineFold

Methods

getting :: forall (is :: IxList). Optic An_AffineFold is s t a b -> Optic' (ReadOnlyOptic An_AffineFold) is s a

ToReadOnly An_AffineTraversal s t a b

Defined in Optics.ReadOnly

Associated Types

type ReadOnlyOptic An_AffineTraversal

Methods

getting :: forall (is :: IxList). Optic An_AffineTraversal is s t a b -> Optic' (ReadOnlyOptic An_AffineTraversal) is s a

ToReadOnly An_Iso s t a b

Defined in Optics.ReadOnly

Associated Types

type ReadOnlyOptic An_Iso

Methods

getting :: forall (is :: IxList). Optic An_Iso is s t a b -> Optic' (ReadOnlyOptic An_Iso) is s a