[<CLIMutable>] for discriminated unions (adding setter to properties when compiled

I am playing with MVVM pattern in Silverlight, using F# for the viewmodel code in a separate library project.

As far as I can see, the properties of the cases have only get methods, and no setters. I think it might be useful to add [<CLIMutable>] also for discriminated unions, this way I can let the fields be changed through the GUI easily.

Below is an example of what I am doing.  Btw. I am using Fody.PropertyChanged to implement the INotifyPropertyChanged interface for me :)

These are the types in the VM code:

 [<ImplementPropertyChangedAttribute>]
 [<CLIMutableAttribute>]
 type Record =
    {
        Field1 : string
        Field2 : int
    }
 
[<ImplementPropertyChangedAttribute>]
type Union =
    | CaseA of string
    | CaseB of int
    | CaseC of Record
 
[<ImplementPropertyChangedAttribute>]
type ViewModel() =
     member val Model = CaseB 5
        with get, setAnd this is how I bind them in XAML:

For cases A and B -> two way binding doesn't work here, I suppose because there is no setter

<TextBox Text="{Binding Model.Item, Mode=TwoWay}"></TextBox>
For case C where there is a record -> here the binding works as expected

<TextBox Text="{Binding Model.Item.Field1, Mode=TwoWay}"></TextBox>
Is there maybe a better way to do this?
I found a solution for this - I created a Fody addin which creates setters for fields of union cases through IL weaving after the assembly has been compiled. You can find more information about IL weaving at https-://github.-com/Fody/Fody/.

My solution can be found at https-://github.-com/ndamjan/FSharpHelper.Fody. What this addin also does is that it removes the need to put CLIMutableAttribute on record types, the addin creates a default contructor and adds setters to otherwise readonly properties.

Feel free to contact me if you need more information.