Four Important Friends

There are three Elixir modules that you'll use most often when working with lists of data: Enum, List and Keyword:

• Enum does enumeration functions. Mapping data, filtering, finding, grouping... things like that. This module is absolutely fundamental; get to know it!
• List handles list-specific operations whereas Enum will work with anything that you iterate over (or that is enumerable). Inserting, deleting, first and last - the List module is another that you'll want to know well.
• As you might suspect, Keyword does a lot of what List does, but for keyword lists.

In addition to these, Elixir supports list comprehensions. This is syntactic sugar for iterating over enumerable structures, but comes with built-in filters and the unique ability to have more than one generator. We'll get to these last - they can be quite complicated.