anchor.diff: -{ stdenv, fetchFromGitHub, coq, ssreflect }:
  +{ stdenv, fetchFromGitHub, coq, ssreflect, coq-ext-lib, simple-io }:
   
   let params =
     {
  
positive.code:     inherit (param) rev sha256;
    };
  
    buildInputs = with coq.ocamlPackages; [ ocaml camlp5 findlib ];
    propagatedBuildInputs = [ coq ssreflect ];
  
    enableParallelBuilding = false;
  
    installPhase = ''
      make -f Makefile.coq COQLIB=$out/lib/coq/${coq.coq-version}/ install
  
negative.code:       rev = "195e550a1cf0810497734356437a1720ebb6d744";
        sha256 = "0zm23y89z0h4iamy74qk9qi2pz2cj3ga6ygav0w79n0qyqwhxcq1";
      };
      "8.8" = rec {
        preConfigure = "substituteInPlace Makefile --replace quickChickTool.byte quickChickTool.native";
        version = "1.0.2";
        rev = "v${version}";
        sha256 = "1mcbsp07ra3gdcmir36pf27ig3xv8nagyfp7w5pwqi4gj9w81ffn";
        buildInputs = with coq.ocamlPackages; [ ocamlbuild num ];
        propagatedBuildInputs = [ coq-ext-lib simple-io ];
      };
    };
    param = params."${coq.coq-version}";
  in
  