anchor.diff:  { stdenv, lib, runCommand, patchelf, makeWrapper, pkg-config, curl
  -, fetchpatch
   , openssl, gmp, zlib, fetchFromGitHub, rustPlatform, libiconv }:
   
   let
  
positive.code:        --subst-var dynamicLinker \
         --subst-var libPath
      '')
      # fix build, will be included in 1.1.1
      (fetchpatch {
        url = "https://github.com/leanprover/elan/commit/8d1dec09d67b2ac1768b111d24f1a1cabdd563fa.patch";
        sha256 = "sha256-yMdnXqycu4VF9EKavZ85EuspvAqvzDSIm5894SB+3+A=";
      })
    ];
  
    postInstall = ''
  
negative.code: 
  rustPlatform.buildRustPackage rec {
    pname = "elan";
    version = "1.2.0";
  
    src = fetchFromGitHub {
      owner = "leanprover";
      repo = "elan";
      rev = "v${version}";
      sha256 = "0q3gay0j45c6cmykbis14gmc7xm89d0gqyz7lnysl0pgr5k20j6b";
    };
  
    cargoSha256 = "1cklpi40fbiwz8m9p0cknmslpj0vwpr0x8j02vam6sng9dsb50i9";
  
    nativeBuildInputs = [ pkg-config makeWrapper ];
  
  