Hi,
There is a really interesting (and growing) set of solutions for how to traverse and annotate a nested data structure across a variety of programming languages coming together here:
I’m super grateful for @josevalim’s focus on this topic, as it goes straight to the point of where I see the greatest need for improving my personal productivity as an Elixir developer. It’s also the area where I’m most worried that I might run into a wall in the course of building an application with Elixir.
I have by now solved a few annotations / changes of deeply nested data structures in Elixir. I have learned quite a bit about recursion in the process, have received great help here and on Slack with my questions about it, have studied the docs, used the various nested structure functions in Access and Kernel, and experimented with some lens libraries.
Nonetheless, I am still worried about running into a productivity hole when one of these (especially a deeply nested one that requires updates in many places) comes along…
My plan for addressing this was to build up a collection of examples and patterns as a base to work from, but I haven’t gotten around to it yet…
Love the fact that there is a focus on this, and really, really looking forward to any goodies (examples and/or helpers / conveniences) that might potentially come out of it (and already have come out of it in the Elixir folder) 
