anchor.diff:    name = "maude-${version}";
   
     src = fetchurl {
  -    url = "https://github.com/maude-team/maude/archive/v${version}-ext-hooks.tar.gz";
  -    sha256 = "02p0snxm69rs8pvm93r91p881dw6p3bxmazr3cfw5pnxpgz0vjl0";
  +    url = "http://maude.cs.illinois.edu/w/images/d/d8/Maude-${version}.tar.gz";
  +    sha256 = "0jskn5dm8vvbd3mlryjxdb6wfpkvyx174wk7ci9a31aylxzpr25i";
     };
   
  -  buildInputs = [flex bison ncurses buddy tecla gmpxx libsigsegv makeWrapper unzip];
  +  buildInputs = [
  +    flex bison ncurses buddy tecla gmpxx libsigsegv makeWrapper unzip cvc4 cln
  +  ];
   
     hardeningDisable = [ "stackprotector" ] ++
       stdenv.lib.optionals stdenv.isi686 [ "pic" "fortify" ];
  
positive.code: 
    postInstall = ''
      for n in "$out/bin/"*; do wrapProgram "$n" --suffix MAUDE_LIB ':' "$out/share/maude"; done
      install -D -m 444 ${fullMaude} $out/share/maude/full-maude.maude
    '';
  
    meta = {
      homepage = "http://maude.cs.uiuc.edu/";
      description = "High-level specification language";
      license = stdenv.lib.licenses.gpl2;
  
  
negative.code: { stdenv, fetchurl, unzip, makeWrapper , flex, bison, ncurses, buddy, tecla
  , libsigsegv, gmpxx, cvc4, cln
  }:
  
  let
  
    version = "2.7.1";
  
    fullMaude = fetchurl {
      url = "http://maude.cs.illinois.edu/w/images/c/ca/Full-Maude-${version}.zip";
      sha256 = "0y4gn7n8vh24r24vckhpkd46hb5hqsbrm4w9zr6dz4paafq12fjc";
    };
  
  in
  