Hello, I find that parser correctness is often hard to verify. Therefore, I'm interested in techniques that others have used successfully, especially with Haskell. Techniques I'm aware of: * Round trip checks: Generate a datastructure, render as a string, parse back, and compare. Quickcheck can be used to automate this. * Fuzz testing: What tools exist to help me? * Formal verification: Has anyone been using this with Haskell parsers? Other than general theorem provers, say Isabelle, what tools exist? My specific need: The immediate challenge I have is that I'm modifying the parser that Darcs uses and we would like to improve the parser's test suite as well. The parser abstraction used in this case follows parsec's API. Left to my own devices I would use round trip checks, written with quickcheck, for this exercise. Because we're using a parsec style parser, I don't have a nice neat grammar handy. Thanks in advance for any advice you have! Thanks, Jason