You can use the JSON handler app for handlering jsons.
But even in the BetterLogicLibrary you can use arrays.
Just place [1,2,3,4] in a variable for instance.
Now, use the BLL expression cards and place the variable containing the array in it, plus [0] behind it, and you will recieve the fiest element in the array.
BLL alows predefined functions, so you can create push functions for instance.