anchor.diff:  { stdenv, fetchurl, gmp, bison, perl, autoconf, ncurses, readline, coreutils, pkgconfig
   , autoreconfHook
  +, file
   , flint
   , ntl
   , cddlib
  
positive.code:     sha256 = "0wvgz7l1b7zkpmim0r3mvv4fp8xnhlbz4c7hc90rn30snlansnf1";
    };
  
    configureFlags = stdenv.lib.optionals enableFactory [
      "--enable-factory"
    ] ++ stdenv.lib.optionals enableGfanlib [
      "--enable-gfanlib"
  
negative.code:   ] ++ stdenv.lib.optionals enableGfanlib [
      cddlib
    ];
    nativeBuildInputs = [
      bison
      perl
      pkgconfig
      autoreconfHook
    ];
  
    preAutoreconf = ''
      find . -type f -readable -writable -exec sed \
        -e 's@/bin/rm@${coreutils}&@g' \
        -e 's@/bin/uname@${coreutils}&@g' \
        -e 's@/usr/bin/file@${file}/bin/file@g' \
        -i '{}' ';'
    '';
  
    hardeningDisable = stdenv.lib.optional stdenv.isi686 "stackprotector";
  