ADT representations in SwiftData

Using Swift
,
1

Hi all,

I have come up against a use case while using SwiftData that would heavily benefit from modelling using some ADT-like structure. The most straightforward method does not work:

// does not compile!
@Model
enum ADT {
    case foo(Int)
    case bar(String)
}

The first thing I thought to try from there was using an empty protocol that the discriminants could conform to:

protocol ADT: Hashable {
    
}

@Model
final class Foo: ADT {
    var date: Date
    
    init(date: Date = Date()) {
        self.date = date
    }
}

But this doesn't work because any ADT does not conform to Hashable and therefore can't be used as the principal argument in ForEach, which I need for my use case:

struct SomeView: View {
    @Query var foos: [Foo]
    var adts: [any ADT] {
        foos
    }
    
    var body: some View {
        // does not compile!
        ForEach(adts, id: \.self) { _ in
            Text("hello, world")
        }
    }
}

Subclassing also doesn't work because SwiftData doesn't support it.

My last resort will be a kind of manual discriminated union, which I dread having to implement for the number of mistakes I'm sure to make. So I thought to check here first—any ideas would be most welcome.

Thank you!