anchor.diff:    outputs = [ "out" "dev" "doc" ];
   
     nativeBuildInputs = [
  +    bison
       cmake
  +    flex
       fop
       libxml2
       libxslt
  
positive.code: 
    buildInputs = [
      arpack
      bison
      blas
      flex
      glpk
      gmp
      lapack
  
negative.code: 
  stdenv.mkDerivation rec {
    pname = "igraph";
    version = "0.9.2";
  
    src = fetchFromGitHub {
      owner = "igraph";
      repo = pname;
      rev = version;
      sha256 = "sha256-Ylw02Mz9H4wIWfq59za/X7xfhgW9o0DNU55nLFqeUeo=";
    };
  
    # Normally, igraph wants us to call bootstrap.sh, which will call
    # tools/getversion.sh. Instead, we're going to put the version directly
  