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composeLens()

composeLens<A, B, C>(ab, bc): Lens<A, C>

Compose two lenses together.

Given a lens A ⭢ B and a lens B ⭢ C, produces a lens A ⭢ C.

Type Parameters​

A​

A

The type of the first object being inspected.

B​

B

The type of the second object being inspected.

C​

C

The type of the property value on the second lens.

Parameters​

ab​

Lens<A, B>

The lens from A ⭢ B.

bc​

Lens<B, C>

The lens from B ⭢ C.

Returns​

Lens<A, C>

Remarks​

pure function

Example​

const addressLens = lens(
  (person: Person) => property(person)('address'),
  (person) => (addr) => associateDeep(person)('address')(addr)
);
const cityLens = lens(
  (address?: Address) => optionalProperty(address)('city'),
  (address) => (city) => associateDeep(address)('city')(city)
);

const personCityLens = composeLens(addressLens, cityLens);