Function PathLens

Creates a lens for a nested property.

Returns

A lens to the nested property.

Example

Given a data model:

interface Company {
  readonly id: number;
  readonly name: string;
  readonly description?: string;
  readonly address: Address;
}

interface Address {
  readonly country: string;
  readonly region: string;
  readonly street: Street;
  readonly building: string;
}

interface Street {
  readonly name: string;
  readonly kind: string;
}

Create a lens to a nested property:

const [
  getStreetName,
  setStreetName,
  overStreetName
] = PathLens<Company>()('address', 'street', 'name');

Use "get" function to get a value of the nested property:

console.log(getStreetName(company));           // "Broadway"

Use "set" function to set a value of the nested property:

const newCompany = setStreetName("Main")(company);

console.log(newCompany.address.street.name);   // "Main"

Use "over" function to map and set a value of the nested property:

const newCompany = overStreetName(toUpperCase)(company);

console.log(newCompany.address.street.name);   // "BROADWAY"