This is always somthing I have wanted to do for video stream processing, writeing a limited proceedural language which can be refactored as a dataflow graph for efficent implementation (of video processing).
I'm sure you could do some stuff, but lots of interesting video and audio processing involves a graph thats not linear, sometimes even with cycles in it. There are lots of systems out there that let you hook up arbitrary graphs of video or audio processing modules. Many of em are gui based, but some are command language based.
-Steve
Tim Newsham | www.thenewsh.com/~newsham | thenewsh.blogspot.com