accessing node path from walk / visit

[felixroos]

Hello, thanks for this cool lib. Is there any possibility to access the path info of a node inside walk or visit?

Simple example:

const SimpleZipper = makeZipper(
  n => !!n.children?.length,
  n => n?.children,
  (parent, children) => {
    console.log('make node', parent, children)
    return { children, parent }
  }
);

const s = SimpleZipper({
  children: [
    'a',
    { children: ['b', 'c'] }
  ]
});

console.log(s.value())
// { children: [ 'a', { children: [ 'b', 'c' ] } ] }

console.log(s.next().next().next().value()) 
// 'b'

// on a Zipper node, i get the parentItems as I would want them:
console.log(s.next().next().next().path.parentItems)
/* [
  { children: [ 'a', { children: [ 'b', 'c' ] } ] }, // grandparent
  { children: [ 'b', 'c' ] } // parent
] */

So far so good, but if I use preWalk, the passed node is not a Zipper, but just what would be returned from value():

const mapLeafs = mapFn => makeZipper => preWalk(
  (node) => { // ideally, node should be a Zipper
    const t = makeZipper(node); // I tried creating a "subzipper" (without path info)
    if (t.isLeaf()) {
      console.log('map', node)
      return t.edit(item => mapFn(item /*,path*/).item; // would need path here
    }
    return node;
  }
);

const uppercase = mapLeafs(leaf => leaf.toUpperCase())(SimpleZipper);
const uppercased = uppercase(s).value();

console.log(uppercased);
// { children: [ 'A', { children: [ 'B', 'C' ] } ] }

For this case (🙊) the mapping works, but without the path, I have no structural info of the current node, which would be needed for many common operations (like accumulating parent values to a child).

My second attempt was creating a reduce function like mentioned in the readme:

const makeReduceVisitor = fn => onPre((item, state) => {
  return ({ state: fn(state, item) })
});
const reduce = (fn, initialAcc, z) => {
  const { state } = visit([makeReduceVisitor(fn)], initialAcc, z);
  return state;
}

reduce((acc, node) => {
  if(!node.children) {
    // also no Zipper object here
    return acc + node 
  }
  return acc;
}, '', s)
// yields 'abc'

Still no luck here, as the given node is also just the value.

Am I missing something? The only other solution I can think of is using pipe magic like described in the readme for arrays, but I think it would be much simpler to have a Zipper instead of just the value available to walk/visit.

Thank you for this refreshing lib, which would be the perfect candidate to reimplement my hierarchical music format :)