anchor.diff:      configureFlagsArray=(
         --datadir="$out/share/maude"
         TECLA_LIBS="-ltecla -lncursesw"
  +      LIBS="-lcln"
         CFLAGS="-O3" CXXFLAGS="-O3"
       )
     '';
  
positive.code:   name = "maude-${version}";
  
    src = fetchurl {
      url = "https://github.com/maude-team/maude/archive/v${version}-ext-hooks.tar.gz";
      sha256 = "02p0snxm69rs8pvm93r91p881dw6p3bxmazr3cfw5pnxpgz0vjl0";
    };
  
    buildInputs = [flex bison ncurses buddy tecla gmpxx libsigsegv makeWrapper unzip];
  
    hardeningDisable = [ "stackprotector" ] ++
      stdenv.lib.optionals stdenv.isi686 [ "pic" "fortify" ];
  
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
  