MVU like updates

[kekyo]

First time idea, F# can declare immutable type named record. The record usage is simple and safer than standard class type.
If it uses on a ViewModel, could update any property only construction time, but will be made clean and FP like manner.
So we can write update handler only returning new instance of record like MVU.

Pseudo code fragment (can't compile):

// It's a F# record type
type SampleViewModel = {
  
  // The handler would return a value `Async<SampleViewModel>`:
  self.Clicked = CommandFactory.create (fun e:EventArgs -> async {
      return { self.a, self.b self.c+1 }
  }
}

The record type contains getter property and (hidden?) setter property, and they have propchange capability. It code surface has only getter in F# (and C#?) syntax likes purely, but generated binary will have propchange impls. Command handler will transfer each props at returned from handler function. They will call propchanged callback if value is changed.

@tatsuya-midorikawa told me it basic idea.

[tatsuya-midorikawa]

BTW, Elmish.WPF may give you some ideas on how to implement MVU👍