This is partly why I'm so curious about languages like Racket, that let you start with easy, freewheeling dynamic typing, and then move, in parts, to Typed Rack

This is partly why I'm so curious about languages like Racket, that let you start with easy, freewheeling dynamic typing, and then move, in parts, to Typed Racket. We just need to convince some big software engineering project to start down that road, so we can collect the data about the approach :-p