anchor.diff:        for prg in $out/bin"/"*;do
           if [[ -f $prg && -x $prg ]]; then
             wrapProgram $prg \
  -            --prefix PATH : "${nixpkgs.lib.makeBinPath ([ihaskellEnv] ++ sysPackages)}" \
  +            --prefix PATH : "${nixpkgs.lib.makeBinPath ([ihaskellEnv] ++ (systemPackages nixpkgs))}" \
               --prefix JUPYTER_PATH : "${ihaskellDataDir}"
           fi
         done
  
positive.code:   };
    ihaskellDataDir = ihaskellDataDirFunc ihaskellKernelSpec ihaskellLabextension;
  
    ihaskellBuildEnvFunc = { ihaskellEnv, jupyterlab, sysPackages, ihaskellDataDir }: nixpkgs.buildEnv {
      name = "ihaskell-with-packages";
      buildInputs = [ nixpkgs.makeWrapper ];
      paths = [ ihaskellEnv jupyterlab ];
  
negative.code:       inherit haskellPackages;
        inherit ihaskellExe;
        inherit ihaskellEnv;
        inherit ihaskellLabextension;
        inherit jupyterlab;
        inherit ihaskellGhcLibFunc;
        inherit ihaskellKernelFileFunc;
        inherit ihaskellKernelSpecFunc;
        inherit ihaskellDataDirFunc;
        inherit ihaskellBuildEnvFunc;
      };
    };
  
    ihaskellBuildEnv = ihaskellBuildEnvFunc {
      inherit ihaskellEnv jupyterlab ihaskellDataDir systemPackages;
    };
  
  in ihaskellBuildEnv
  