A sample implementation of Monad

Monad-sample.js

//Monad - a sample implementation
class Monad {
    constructor(val) {
        this.__value = val;
    }
    static of(val) {//Monad.of is simpler than "new Monad(val)
        return new Monad(val);
    };
    map(f) {//Applies the function but returns another Monad!
        return Monad.of(f(this.__value));
    };
    join() { // used to get the value out of the Monad
        return this.__value;
    };
    chain(f) {//Helper func that maps and then gets the value out
        return this.map(f).join();
    };
     ap(someOtherMonad) {//Used to deal w/ multiple Monads
        return someOtherMonad.map(this.__value);
    }
}