This doesn't really work because you still end up needing specific types for the output of every "parser" you have and then you still need a way of combining th

This doesn't really work because you still end up needing specific types for the output of every "parser" you have and then you still need a way of combining those types together. Or you get the ability to forge evidence (e.g. you use the evidence provided by a parser for one integer as evidence for another). This works better for dependency injection scenarios (the Has* pattern).