Javascript (kinda) Monad test

monad.js

class Monad {
    static ret(input) {
        return {
            bind: (lambda, ...args) => this.bind(lambda, input, ...args),
            flatten: function*() {
                yield* input;
            }
        };
    }

    static unit(...input) {
        return this.ret([...input])
    }

    static bind(lambda, input, ...args) {
        return this.ret(
            input.map((x) => {
                if (x == null) return null;
                else return lambda(x, ...args);
            })
        );
    }

    static compose(inputlambda, defaultlambda = (a) => a) {
        const compose = (value) => inputlambda(defaultlambda(value));
        compose.compose = (clambda) => this.compose(clambda, compose);
        return compose;
    }
}

const add2 = (a) => a * 7
const add1 = (a) => a * 6
const add3 = (a) => a * 8

const addall = Monad.compose(add2).compose(add1).compose(add3).compose(add2)

// constructing new functions
console.log(
    addall(4)
)

// on the fly binding
var bind =
    Monad.unit(5, 1, null)
    	.bind(add2)
    	.bind(add1)
    	.bind(add3)
    	.flatten()
console.log(
    bind.next(),
    bind.next(),
    bind.next()
)