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Interface: Lens<S, A>

Defined in: lens/types.ts:19

A Lens is a composable getter/setter pair for immutable updates.

A lens focuses on a specific part of a data structure, allowing you to read and update that part without mutating the original structure.

Example​

// Lens focusing on a user's name
const nameLens: Lens<User, string> = {
  get: (user) => user.name,
  set: (name) => (user) => ({ ...user, name })
}

Type Parameters​

S​

S

The source type (the whole data structure)

A​

A

The focus type (the part being accessed)

Properties​

get()​

readonly get: (source) => A

Defined in: lens/types.ts:23

Gets the focused value from the source.

Parameters​

source​

S

Returns​

A

set()​

readonly set: (value) => (source) => S

Defined in: lens/types.ts:28

Sets the focused value in the source, returning a new source.

Parameters​

value​

A

Returns​

(source): S

Parameters​
source​

S

Returns​

S