@aL_ : I agree. As a developer of both silverlight and WPF applications, it would make it a lot easier to share code and resources between the two.
Also, I am interested to see the details around the 3D api. I'm hoping it's a low enough level API that the XNA team could conceivably support it as a surface for XNA games with good (enough) performance. This is one way they could allow XNA/Silverlight integration in future versions of Windows Phone, assuming SL5 is ported to that platform.
It is interesting in that it demonstrates a little of what Jonathon Edwards was talking about. By the middle of the paper I was excited about FRP and DataFlow programming in general, but by the end of it I was trying to wrap my head around the complex compositional
relationships I would now have to manage. If you were to use instead a declarative model, a large portion of the complexity could simply be represented by implied relationships in a declarative expression.
In defense of scala (though I personally have a love-hate relationship with the language), scala has an expression-based syntax, not a statement based one (like C#, not counting LINQ). This single distinction makes custom declarative programming models a
natural part of the language, and in fact this is one of the features that are critical to implementing internal DSLs in scala. For example, you can (and some have tried already: http://github.com/vladimirk/scalalinq/) implement things like linq in scala without
using any custom syntax or compiler plugins - just plain scala.