API to define recursive traversals

[cowboyd]

Hi There,

I'm loving this library, and I'm trying to explore all the ways in which I could use it.

I want to do something similar to what's described here https://www.michaelpj.com/blog/2020/08/02/lenses-for-tree-traversals.html where you can treat a recursive substructure as a simple traversal.

For example, let's say I wanted to get all the input elements in a DOM as a flat list. How would I write this custom traversal?

import { collect } from 'optics-ts';
import { inputs } from 'my-dom-library';

collect(inputs)(document.documentElement) //=> HTMLInputElement[]

(I know that the DOM isn't an immutable structure, but it's the first example that came to me.)

[akheron]

Interesting idea!

Currently, the optics-ts internals don't model traversals with applicatives like that, so not sure how to actually implement this. Also, typing the applicative construct in TypeScript might prove hard.

Another possibility could be to do this like how L.lazy works in partial.lenses, but typing that construction might be even more impossible :smile: