I updated Cristian Merighi (Ryoushin)’s F# Silverlight demo to build and run with Visual Studio 2010 and Silverlight 4. See his original 2009-07 blog post titled “Silverlight and F# happily ever after” for more details. His original code, my changes, and a working solution are available here. Here is the Silverlight app. It is fun to play around with. Move your mouse around and click several times to make a shape.