anchor.diff:  
       for arg in \$($out/bin/ghc-get-packages.sh ${ghc.version} \"\$(dirname \$0)\"); do
         case "\$arg" in
  -        -package-conf) ;;
  +        ${packageDBFlag}) ;;
           *)
             CANONICALIZED="\$(${stdenv.lib.optionalString stdenv.isDarwin "${coreutils}/bin/"}readlink -f "\$arg")"
             GHC_PACKAGES_HASH["\$CANONICALIZED"]= ;;
  
positive.code:   inherit ghc;
    inherit (ghc) meta;
    ghcVersion = ghc.version;
  }
  
negative.code:       makeWrapper $ghc/bin/$prg $out/bin/$prg --add-flags "\$($out/bin/ghc-get-packages.sh ${ghc.version} \"\$(dirname \$0)\")"
      done
      for prg in runghc runhaskell; do
        makeWrapper $ghc/bin/$prg $out/bin/$prg --add-flags "\$($out/bin/ghc-get-packages.sh ${ghc.version} \"\$(dirname \$0)\" \" ${packageDBFlag} --ghc-arg=\")"
      done
      for prg in ghc-pkg ghc-pkg-${ghc.version}; do
        makeWrapper $ghc/bin/$prg $out/bin/$prg --add-flags "\$($out/bin/ghc-get-packages.sh ${ghc.version} \"\$(dirname \$0)\" -${packageDBFlag}=)"
      done
      for prg in hp2ps hpc hasktags hsc2hs; do
        test -x $ghc/bin/$prg && ln -s $ghc/bin/$prg $out/bin/$prg
  