Functor

functor.js

const log = (i) => {
    console.log(i);
    return i;
};

const base = v => ({
    valueOf: () => v,
    toString: () => v.toString()
});

const createFunctor = v => fn => (['map', 'first', 'then', 'finally'].reduce((obj, key) =>  ({ ...{[key]: fn}, ...obj }), base(v)));

const id = v => createFunctor(v)(fn => id(fn(v)));
const transform10 = id(10);
const add1 = a => a + 1;
const multiplyByTen = b => b * 10;
const divideBy3 = c => (c / 3);

console.log(
    transform10
        .first(add1)
        .then(multiplyByTen)
        .finally(divideBy3)
        .toString()
);