'use strict';

const view = (lens, obj) => lens.get(obj);

const set = (lens, val, obj) => lens.set(val, obj);

const over = (lens, map, obj) => lens.set(map(lens.get(obj)), obj);

const remove = (lens, obj) => lens.delete(obj);

const lens = (source, destination = source) => ({

get: (obj) => obj[source],

set: (val, obj) => ({ ...obj, [destination]: val }),

delete: (obj) => {

const { [destination]: forgot, ...other } = obj;

return other;

},

});

// Usage

const person = {

name: 'Marcus Aurelius',

city: 'Rome',

born: 121,

};

const upper = (s) => s.toUpperCase();

console.log('\nExample 1\n');

const nameLens = lens('name');

console.log('view name:', view(nameLens, person));

console.log('set name:', set(nameLens, 'Marcus', person));

console.log('over name:', over(nameLens, upper, person));

console.log('\nExample 2');

const renameLens = lens('name', 'personName');

console.log('view name:', view(renameLens, person));

console.log('set name:', set(renameLens, 'Marcus', person));

console.log('over name:', over(renameLens, upper, person));

console.log('\nExample 3\n');

const exampleLens = lens('name');

console.log('remove name:', remove(exampleLens, person));