Child feature scoped to state from an optional enum

[pm-dev]

Having some trouble understanding CasePath/KeyPath syntax.

Take the following where a child is based on some result:

struct State {
    var result: Result<Child.State?, Error>
}
var body {
  Reduce {}
  .ifLet(\.result[case: \.success], action: \.action) {
       Child()
   }
}

This works, but I actually want it to be modeled like:

struct State {
    var result: Result<Child.State, Error>?
}

I can't figure out how to scope the child correctly and can't find any examples like this where a nested enum value is optional. Any help would be appreciated!

[pm-dev]

This is similar to #1296 but here, the enum value is nullable. Also that discussion looks stale and not sure if 1.7 introduced any updated syntax.

[pm-dev]

The solution I found is pretty clunky:

struct State {
    var result: Result?
    
    @CasePathable
    @dynamicMemberLookup
    enum Result { // Have to re-define Result to use @dynamicMemberLookup
       case success(Child.State)
       case failure(Error)
    }
}
var body {
    Reduce {}
    .ifLet(\.result, action: \.action) {
      Scope(state: \.success, action: \.self) {
        Child()
    }
}

Then in the view layer:

if let store1 = store.scope(state: \.result, action: \.action) {
    self.cancellable = store1.scope(state: \.success, action: \.self).ifLet { store in
        ChildView(store: store)
    }
}