Whats the purpose of using the "Head and tail" Syntax?

[adamu]

The first week or two of Advent of Code is great practice for fundamentals. Day 5 is good for lists.

Advent of Code 2022 - Day 5

Today’s challenge for me was about using reduce: defmodule Prob5 do def move([[h1 | rest] = _list1, list2]) do [rest, [h1 | list2]] end def move_n([l1, l2], n) do Enum.reduce(1..n, [l1, l2], fn _, acc -> move(acc) end) end def single_instruction(input, [n, from_ind, to_ind], move_function) do from_ind = from_ind - 1 to_ind = to_ind - 1 [from, to] = move_function.([Enum.at(input, from_ind), Enum.at(input, to_ind)], n) input |> List.replace_at(from_ind, fro…