Elixir tuple, struct and map



Elixir Tuple

To declare a tuple, you simply declare

d = {1, "b", :c"}

And to retrieve it use elem function.

 elem(d, 0) // return 1
 elem(d, 1) // return "b"

You can use Tuple function to help out with tuple manipulation.

Elixir Map

Sometimes it can be confusing because we are declaring  map using the same operator {}.

Map are key value pair.

To declare, simple type

a = %{  a  => 1, b => 2 } // you can't do this

 a = %{"a" => 1, "b" => 2} // ok

if you're using ATOM, you can declare as follows (notice the change of parameter from => (arrow key) to ":" below) :-

 l = %{a: 1, b: 2 }

Accessing map (Non-Atom Map), you can simply, 

 a["a"] // output 1 
 a["b"] // output 2 

Or you can use 

Map.get(a, "a") // output 1 
Map.get(a, "b") // output 2

Accessing Atom map 
If your map is declare this way :  
 l = %{a: 1, b: 2 } 

l[:a] //output 1 
Map.get(l, :a) // output 1 

Elixir struct 

struct is used to define a custom data structure. It is really extension of Elixir's Map.
defstruct is used to do this.


defmodule Test do
  defstruct name: "Angelina", age: 27
end

And to instantiate the structure, you write (with the module name in front) like so;

 %Test{}  # Outputs %Test{age: 27, name: "Angelina"}
%Test{name: "Vincent"} # Outputs : %Test{age: 27, name: "Vincent"}

When you're dealing with Ecto, you will use this alot. 

Just thought i outline the ABC of working with tuple, maps and struct which could look pretty similar. 






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