Extracting data from a function chain without arrays

Question

This is an advanced topic of

How to store data of a functional chain of Monoidal List?

I am pretty sure we can somehow extract data from a function chain wit

Answer 1

Work in progress

Thanks to the stunning contribution by @user3297291 , I somehow could refactor the code to fit my specification, but not working because I am lost the concept during the implementation :(

The point is whole thing must be curried, and no object.method is involved.

Can anyone "debug" please :)

The initial value is set to the first element, in this example as 1

I think this is almost done.

const isFunction = f => (typeof f === 'function');

const Empty = Symbol();

const L = (x = Empty) => (y = Empty) => z => isFunction(z)
    ? (() => {
        const fold = f => seed => f(x)(y) === Empty
            ? seed
            : (L)(y)(f);
        return fold(z)(x);
    })()
    : L(z)(L(x)(y));


const sum = a => b => a + b;


console.log(
    L(1)(2)(3)(4)(5)(6)(sum)
);

Output

 z => isFunction(z)
    ? (() => {
        const fold = f => seed => f(x)(y) === Empty
            ? seed
            : (L)(y)(f);
        return fold(z)(x);
    })()
    : L(z)(L(x)(y))