I totally agree. My point is that because I did not start by wanting to write a complete parser, but rather something that can convert to pattern matching, it never crossed my mind to write a complete parser. And even though now I am aware it could be a complete parser, I don’t have the time to pour into studying what a complete parser is, so I either continue evolving it piece by piece with fantastic input like yours or I don’t evolve it at all.
I completely understand this is not ideal and I completely understand that by saying this some people may not use nimble_parsec as they would prefer a parsing library built on proper foundations. That’s fine by me because that was never my concern. 
In any case, I have lookahead ready for choice and lookahead_not should be an invert of that, I will push soon, but I need to understand how it works with things like traverse and repeat before I consider it done.
