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Elixir Cookbook by Paulo A Pereira

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Creating and manipulating keyword lists

Tuples are often used to represent associative data structures. In Elixir, a list of two element tuples whose first element is an atom is called a keyword list.

Keyword lists have some particular features:

  • They maintain the order of the elements as defined when creating and adding elements
  • They allow repeated keys

Getting ready

Start a new IEx session by entering iex in your command line.

How to do it…

We will follow these steps to create and manipulate keyword lists:

  1. Create a list with three tuples:
    iex(1)> t1 = {:jane, 23}
    iex(2)> t2 = {:jill, 44}
    iex(3)> t3 = {:joe, 32}
    iex(4)> kw_list = [t1, t2, t3]
    [jane: 23, jill: 44, joe: 32]
    
  2. Add a new entry at the end of the list:
    iex(5)> kw_list = kw_list ++ [anthony: ...

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