actor A {
    var dict: [Int: (string: String, int: Int)] = [:]
}

@main struct Main {
    static func main() async {
        let a = A()
        print(await a.dict)
        print(await a.dict[42] as Any)
        print(await a.dict[42] ?? "42")
        print(await a.dict[42]?.string ?? "42") // error: Actor-isolated property 'dict' can not be mutated from the main actor
    }
}

actor A {
    private(set) var dict: [Int: (string: String, int: Int)] = [:]
}

struct S {
    let string: String
}

actor A {
    var dict: [Int: S] = [:]
}