Conf.check_prog ~required:false "Ocaml native compiler" "ocamlopt -version";;
Conf.check_prog "ocamlbuild" "ocamlbuild -version";;
Conf.check_prog "ocamlfind" "ocamlfind printconf";;
-Conf.check_prog "pkg-config" "pkg-config --version";;
Conf.check_prog "camlp4" "ocamlfind query camlp4";;
Conf.check_prog "ulex" "ocamlfind query ulex";;