anchor.diff:        unordered-containers
         uuid
         vector
  +      vinyl
         wai-websockets
         websockets
         wreq
  
positive.code:       safe
        scotty
        shakespeare
        snap
        snap-loader-static
        snap-templates
  
negative.code:         # See: https://github.com/snapframework/heist/pull/111
          heist = dontCheck (doJailbreak super.heist);
          hasktags = dontCheck super.hasktags;
  
          # Allow newer vinyl package.
          composite-base = doJailbreak super.composite-base;
          composite-aeson = doJailbreak super.composite-aeson;
  
          # Vinyl 0.8.x
          vinyl = with self; haskellPackages.mkDerivation {
            pname = "vinyl";
            version = "0.8.1.1";
            src = fetchgit {
              url = "https://github.com/VinylRecords/Vinyl.git";
              rev = "0917b5bed57428be6609ad030cbb3244b39b52ea";
              sha256 = "0jrqa0dzhd3bxv3sp4n1xhs63wn4gd0izy679jasni1wwa7zrbmf";
            };
            libraryHaskellDepends = [ array base ghc-prim ];
            testHaskellDepends = [
              base doctest hspec lens microlens should-not-typecheck singletons
            ];
            benchmarkHaskellDepends = [
              base criterion linear microlens mwc-random primitive tagged vector
            ];
            description = "Extensible Records";
            license = stdenv.lib.licenses.mit;
          };
        };
      };
  
  