anchor.diff:  
     src = fetchurl {
       url = "http://coq.inria.fr/distrib/V${version}/files/coq-${version}.tar.gz";
  -    sha256 = "0wyywia0darak2zmc5v0ra9rn0b9whwdfiahralm8v5za499s8w3";
  +    sha256 = "0fyk2a4fpifibq8y8jhx1891k55qnsnlygglch64sva0bph94nrh";
     };
   
     buildInputs = [ pkgconfig ocaml findlib camlp5 ncurses lablgtk ];
  
positive.code: {stdenv, fetchurl, writeText, pkgconfig, ocaml, findlib, camlp5, ncurses, lablgtk ? null, csdp ? null}:
  
  let
    version = "8.5pl2";
    coq-version = "8.5";
    buildIde = lablgtk != null;
    ideFlags = if buildIde then "-lablgtkdir ${lablgtk}/lib/ocaml/*/site-lib/lablgtk2 -coqide opt" else "";
  
negative.code:     RM=$(type -tp rm)
      substituteInPlace configure --replace "/bin/uname" "$UNAME"
      substituteInPlace tools/beautify-archive --replace "/bin/rm" "$RM"
      substituteInPlace configure.ml --replace '"md5 -q"' '"md5sum"'
      ${csdpPatch}
    '';
  
  