[CMCDragonkai]

Would you consider using Nail to not just parse content-formats like JSON, but (dependent/semantic) type validation on the values of the data itself. Some of this involves business logic as well. For example, let's say I encode some data in JSON. Well I can parse JSON well, but then I need something inside that JSON to be an integer. Ok, that's fairly easy. But then I need that integer to be between 10 and 20. Ok, we have a filter now. But then, I need that integer to be less than or equal to a value defined elsewhere, but only if that value exists, because it's optional. And then, finally if a certain business condition is not met (by contacting the database), the entire input must be considered invalid and discarded. All of this is a form of data validation, but it increasingly involves more and more complexity.