I could not disagree more.
Oh, wait, I could.
Access is something I use in each and every project, I even created the library to inject a performant Access implementation into home-baked structs (estructura.) Also anyone who dealt with deeply nested structures at least once, would use it again and again for its simplicity, elegance and uniformness.
Yeah, I’ve seen this library, and it is a nice idea, but it doesn’t work for already present structures. For example, Access could be useful for Plug.Conn, but it is unimplemented for it. And reason behind this is purely historical, because Access was meant to be a protocol, but it was changed to behaviour because of performance.
On the other hand, do we even need to define getters and setters per-structure? I’d suggest using the different approach. Instead of defining getters and setters per-structure, we can simply define lenses for every structure or key we need.
I’ve tried this idea in multiple projects and it worked really well. Take a look at pathex, it does everything Access can, but with performance, more functional style and richer set of functions.
The first question about Access I get is “why can’t I get a value from structure” and the second one is “how do I separate nil from not found value”. From this moment, everyone just stops using this module and Access.key doesn’t help here.
Yes! Let me add one ad:
Now here for you. New and shiny. Added with 1.14… Access.slice!!!
Enum.reduce(instructions, stacks, fn [amount, from, to], stacks ->
{crates, stacks} = pop_in(stacks, [from, Access.slice(0..(amount - 1))])
Map.update(stacks, to, crates, &place_crates_on_stack(model, crates, &1))
end)
https://github.com/mruoss/advent_of_code/blob/main/2022/day05.livemd
Yes, I saw it and it looks great. I am still fine with an stdlib Access though.
You don’t. That’s the thing. If you need to separate nil from no value, you are abusing nil in your code. nil semantically stays for “no value.” If you need something else, use :undefined, or :none, or like. nil is not something one wants to distinguish from “none.” Otherwise we must complain that in non-strict boolean operators it acts as false (nil && 42.)
I got a json from external service, and I need to know if the field is present in the structure or not
I go get_in ["users", name, "middlename"], and I don’t know if the user just forgot to provide the middle name, or user just has no middlename.
if the user just forgot to provide the middle name, or user just has no middlename
There is no difference from the point of view of your application. No difference. None.
Also, asking for user name, as well as for their address must be a single string field. Otherwise, sooner or later you’ll end up with the user who cannot enter their data.
But this is an edge case, it rarely happens and I understand this maybe-style design behind Access. However, I prefer for edge-cases to be covered, to not go inventing a tool each time an edge case occurs. The same problem with Repo.get simply drives me crazy
I thought about Access but I thought, “piles of crates with an index” sounds like a map!
Just throwing mine into the mix.
this. defp move_9000(0, from, to), do: {from, to}
defp move_9000(number, [crate | from], to), do: move_9000(number - 1, from, [crate | to])
defp move_9001(number, from, to) do
{moving, moved_from} = Enum.split(from, number)
{moved_from, moving ++ to}
end
Completing in <100μs so can’t be too bad 
https://git.adamu.jp/adam/AdventOfCode/src/branch/main/2022/day5.exs
I found it really hard to read the input data. Ended up with code similar to some others that split the characters and chunk them.
But what really confused me and “annoyed” me is the following thing that i can’t figure out: I usually have the example input from the website in a module attribute like
defmodule AOC2022.Day5Test do
use ExUnit.Case
alias AOC2022.Day5, as: Day
doctest Day
@example_input """
[D]
[N] [C]
[Z] [M] [P]
1 2 3
"""
# ...
end
and it’s not shown here but when saving the file it removes the trailing whitespaces from the multiline string, thus making my input “wrong”. Can i somehow stop that from happening?
Edit: Screenshots to the rescue 
Want this
