Lists are a basic data structure in functional languages, but they are also quite confusing for people accustomed to dealing with mutable arrays in imperative languages. The two things: arrays and lists are used in similar situations, they are however more different than it may seem. I’d like to address that explaining how lists work and implementing couple of functions form Enum module ourselves. What is a list? Elixir (and Erlang, and most functional languages) as a primary collection data type use what is called in the literature a linked list.