This is hard tobaco example in the test-cases

... but modified

struct Dict {
    var words = [String]()
    var wordz = Set<String>()
    var jesus  = String()
}
let dict = Dict()
print(dict.words.count)
print(dict.wordz.count)
print(dict.jesus)

... as an array or set could be understood as structs themselfs ... they have initializers themselfs? ... even a string itself has an initializer? ... so without an explicit initializer to Dict .... all the initializers of Array / Set / String is called when calling let dict = Dict() ?

Paul said one hour per day .... with examples like this ... digesting one test-case needs an hour (rofl)

All types have an initializer, even if it's only a default one that the language provides automatically.

There are times you have to explicitly write an initializer, such as for a class that has no default values for its properties.

There are other times you do not have to write one because the compiler creates them for you, such as the memberwise initializer that all structs implicitly get.