anchor.diff:  
     setupHook = ./setup-hook-3.0.sh;
   
  +  passthru = {
  +    updateScript = writeScript "update-guile-3" ''
  +      #!/usr/bin/env nix-shell
  +      #!nix-shell -i bash -p curl pcre common-updater-scripts
  +
  +      set -eu -o pipefail
  +
  +      # Expect the text in format of '"https://ftp.gnu.org/gnu/guile/guile-3.0.8.tar.gz"'
  +      new_version="$(curl -s https://www.gnu.org/software/guile/download/ |
  +          pcregrep -o1 '"https://ftp.gnu.org/gnu/guile/guile-(3[.0-9]+).tar.gz"')"
  +      update-source-version ${pname} "$new_version"
  +    '';
  +  };
  +
     meta = with lib; {
       homepage = "https://www.gnu.org/software/guile/";
       description = "Embeddable Scheme implementation";
  
positive.code: , pkg-config
  , pkgsBuildBuild
  , readline
  }:
  
  let
  
negative.code: in
  builder rec {
    pname = "guile";
    version = "3.0.8";
  
    src = fetchurl {
      url = "mirror://gnu/${pname}/${pname}-${version}.tar.xz";
      sha256 = "sha256-2qcGClbygE6bdMjX5/6L7tErQ6qyeJo4WFGD/MF7ihM=";
    };
  
    outputs = [ "out" "dev" "info" ];
  