anchor.diff: -{stdenv, fetchurl, readline, ghc, perl, m4, gmp, ncurses}:
  +{stdenv, fetchurl, readline, ghc, perl, m4, gmp, ncurses, haddock}:
   
   stdenv.mkDerivation (rec {
     name = "ghc-6.8.3";
  
positive.code:     "--with-gcc=${gcc}/bin/gcc"
    ];
  
    preConfigure = "
      # still requires a hack for ncurses
      sed -i \"s|^\\\(ld-options.*$\\\)|\\\1 -L${ncurses}/lib|\" libraries/readline/readline.buildinfo.in
    ";
  
    inherit (stdenv) gcc;
    inherit readline gmp ncurses;
  
negative.code:     }
    ];
  
    buildInputs = [ghc readline perl m4 gmp haddock];
  
    # The setup hook is executed by other packages building with ghc.
    # It then looks for package configurations that are available and
  