Basically, I developed a whole lot of bebop/poly, but I had some disagreements with the owner of the repo (Timothy Stiles) about direction at the later stages of development. For example, I wanted to standardize all the parsers to use a generic interface, so that they're all used in the same way, while he didn't really want to change anything. There were other features I wanted to add as well - you can see a full list in the changelog (which are the changes since diverging from upstream)