anchor.diff:       ld: cannot find -lruby-1.8.7-p72
   
      */
  -  buildInputs = [ cmake /* ruby */ ];
  +  buildInputs = [ cmake perl /* ruby */ ];
   
     preConfigure =
       # Make it so that libsimgrid.so will be found when running programs from
  
positive.code: 
    makeFlags = "VERBOSE=1";
  
    patchPhase =
      '' for i in "src/smpi/"*
         do
           sed -i "$i" -e's|/bin/bash|/bin/sh|g'
         done
      '';
  
    installPhase = "make install-simgrid";
  
    # Fixing the few tests that fail is left as an exercise to the reader.
    doCheck = false;
  
negative.code: { fetchurl, stdenv, cmake, perl, ruby }:
  
  stdenv.mkDerivation rec {
    name = "simgrid-3.5";
  
    src = fetchurl {
      url = "https://gforge.inria.fr/frs/download.php/28017/${name}.tar.gz";
      sha256 = "1vd4pvrcyii1nfwyca3kpbwshbc965lfpn083zd8rigg6ydchq8y";
    };
  
    /* FIXME: Ruby currently disabled because of this:
  