Great work! I've been working on a Rust parser combinator library myself ( https://github.com/DanSimon/peruse ), though I've been focusing more on parsing syntax trees than binary formats, and it's really cool to see the different approaches you've taken. I had been planning on working on stream parsers next, but I may just defer to nom since it basically looks like what I had wanted to do.
I really like your approach with trait objects. This is something I would have liked in nom when I started it, but macros proved more useful for my experimentations (less types to rewrite when I change something).
For the streaming part, it is still a work in progress. I need a way to better represent input enabled state machines, otherwise we'll end up with streaming switch based state machines, and they are a security nigtmare.
