Odtnhj

With the following code:

[
 %Quizz
 question: "L'unità d' Italia",
 answers: [
 %answer: 1900, result: false,
 %answer: 1861, result: true,
 %answer: 1848, result: false,
 ]
 ,
 %Quizz
 question: "La Rivoluzione Francese",
 answers: [
 %answer: 1789, result: true,
 %answer: 1818, result: false,
 %answer: 1766, result: false,
 ]
 ,
 %Quizz
 question: "La scoperta dell'America",
 answers: [
 %answer: 1280, result: false,
 %answer: 1500, result: false,
 %answer: 1492, result: true,
 ]
 
]

I would like to shuffle the 3 quizz structs using Enum.shuffle and shuffle the list of answers for each struct. I am able to shuffle the list but I'm struggling to updated the answers list for each struct. How can I do that?

You can shuffle the list and then map over it, replacing each answers field with a shuffled version of it

Enum.shuffle(list_of_quizzes)
|> Enum.map(fn(%answers: answers = quizz) -> 
 %quizz 
end)

I would go with Kernel.SpecialForms.for/1 comprehension:

for quizz <- Enum.shuffle(quizzes),
 do: %Quizzquizz 

or, other way round:

for quizz <- Enum.shuffle(quizzes),
 answers = Enum.shuffle(quizz.answers),
 do: %Quizzquizz 

You can also use Map.update!/3 or Kernel.update_in/3:

quiz_list
|> Enum.shuffle
|> Enum.map(fn q -> Map.update!(q, :answers, &Enum.shuffle/1) end)