anchor.diff:    homepage = "http://haskell.org/ghc";
   
     src = fetchurl {
  -    url = "${homepage}/dist/current/dist/${name}-src.tar.bz2";
  -    sha256 = "0b5pg6688yfzd5zfaffjp21y933vp94h94ds85gwi156f4g3bkij";
  +    url = "${homepage}/dist/${label}/${name}-src.tar.bz2";
  +    sha256 = "18jbw5na4v8v2vzswbi8xfd73mx8zv1diym0bg5bns5337q76lzi";
     };
   
     buildInputs = [ghc perl gmp ncurses];
  
positive.code:     platforms = stdenv.lib.platforms.linux;
    };
  
    # TODO: requires a comment as to what it does and why it is needed.
    passthru = {
      corePackages = [
         [ "Cabal" "1.8.0.2" ]
         [ "array" "0.3.0.0" ]
         [ "base" "3.0.3.2" ]
         [ "base" "4.2.0.0" ]
         [ "bin-package-db" "0.0.0.0" ]
         [ "bytestring" "0.9.1.5" ]
         [ "containers" "0.3.0.0" ]
         [ "directory" "1.0.1.0" ]
         [ "dph-base" "0.4.0" ]
         [ "dph-par" "0.4.0" ]
         [ "dph-prim-interface" "0.4.0" ]
         [ "dph-prim-par" "0.4.0" ]
         [ "dph-prim-seq" "0.4.0" ]
         [ "dph-seq" "0.4.0" ]
         [ "extensible-exceptions" "0.1.1.1" ]
         [ "ffi" "1.0" ]
         [ "filepath" "1.1.0.3" ]
         [ "ghc" "6.12.1" ]
         [ "ghc-binary" "0.5.0.2" ]
         [ "ghc-prim" "0.2.0.0" ]
         [ "haskell98" "1.0.1.1" ]
         [ "hpc" "0.5.0.4" ]
         [ "integer-gmp" "0.2.0.0" ]
         [ "old-locale" "1.0.0.2" ]
         [ "old-time" "1.0.0.3" ]
         [ "pretty" "1.0.1.1" ]
         [ "process" "1.0.1.2" ]
         [ "random" "1.0.0.2" ]
         [ "rts" "1.0" ]
         [ "syb" "0.1.0.2" ]
         [ "template-haskell" "2.4.0.0" ]
         [ "time" "1.1.4" ]
         [ "unix" "2.4.0.0" ]
         [ "utf8-string" "0.3.4" ]
      ];
    };
  }
  
negative.code: {stdenv, fetchurl, ghc, perl, gmp, ncurses}:
  
  stdenv.mkDerivation rec {
    version = "7.0.1.20110217";
    label = "7.0.2-rc2";
    
    name = "ghc-${version}";
    
  