That's not the same thing though; to be able to actually REPL a complete app or stick in an interpreter where you need it. I tried workbooks and it's more a toy (like Swift playgrounds by the way). It helps for sure, but when we are working on bigger existing apps, we want to plug in REPLs in particular places and iterate. Or generally iterate; both do not fit with the VS REPL or Workbooks.

In that regard nothing matches commercial Common Lisp environments or Smalltalk.

I agree with you, but having the Mono interpreter (which does not have the same issues) fully work for mobile (Xamarin Android/iOS) and desktop (it is with --interpreter) and web (it is with Blazor) would make life easier for this kind of mainstream development.