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lens()

lens<T, V>(getter, setter): Lens<T, V>

Focus on and manipulate a specific property or substructure within an object.

Type Parameters​

T​

T

The type of the object being inspected.

V​

V

The type of the property value.

Parameters​

getter​

LenseGet<T, V>

The lens get function to use.

setter​

LenseSet<T, V>

The lens set function to use.

Returns​

Lens<T, V>

Remarks​

pure function

Example​

const nameLens = lens(
  (person: Person) => person.name,
  (person, name) => ({ ...person, name })
);

const name = nameLens.get(person);

const { get: getUsername, set: setUsername } = lens(
  (user: User) => property(user)('username'),
  (user, name) => associateDeep(user)('username')(name)
);

const username = getUsername(user);