Matthew Might gave this talk at Stanford describing his and his student's work on parsing with derivatives. It was much easier to follow for me than their paper. [Edit: I was originally speaking of their original ArXiv paper. The version I linked to here is th Functional Pearl, which is significantly better. Yay, a victory for peer review! The video is better still, though.] Also, in the first few minutes he motivates the work very well, focusing on open or incremental parsers for network protocols, syntax highlighting, and the zillions of organically grown configuration file formats. I expect the picture is not quite as rosy as he implies, particularly in terms of the cpu and memory available for parsing, and that the current state-of-the-art is not quite as bad.