optics-core-0.4.1: Optics as an abstract interface: core definitions
Safe Haskell None
Language Haskell2010

Optics.ReadOnly

Description

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

Synopsis

Documentation

class ToReadOnly k s t a b where Source #

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

Methods

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

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

Instances details
(s ~ t, a ~ b) => ToReadOnly A_Fold s t a b Source #
Instance details

Defined in Optics.ReadOnly

(s ~ t, a ~ b) => ToReadOnly An_AffineFold s t a b Source #
Instance details

Defined in Optics.ReadOnly

(s ~ t, a ~ b) => ToReadOnly A_Getter s t a b Source #
Instance details

Defined in Optics.ReadOnly

ToReadOnly A_ReversedPrism s t a b Source #
Instance details

Defined in Optics.ReadOnly

ToReadOnly A_Traversal s t a b Source #
Instance details

Defined in Optics.ReadOnly

ToReadOnly An_AffineTraversal s t a b Source #
Instance details

Defined in Optics.ReadOnly

ToReadOnly A_Prism s t a b Source #
Instance details

Defined in Optics.ReadOnly

ToReadOnly A_Lens s t a b Source #
Instance details

Defined in Optics.ReadOnly

ToReadOnly An_Iso s t a b Source #
Instance details

Defined in Optics.ReadOnly