anchor.diff:  {stdenv, fetchurl, writeText, pkgconfig, ocaml, findlib, camlp5, ncurses, lablgtk ? null, csdp ? null}:
   
   let
  -  version = "8.5pl1";
  +  version = "8.5pl2";
     coq-version = "8.5";
     buildIde = lablgtk != null;
     ideFlags = if buildIde then "-lablgtkdir ${lablgtk}/lib/ocaml/*/site-lib/lablgtk2 -coqide opt" else "";
  
positive.code:     RM=$(type -tp rm)
      substituteInPlace configure --replace "/bin/uname" "$UNAME"
      substituteInPlace tools/beautify-archive --replace "/bin/rm" "$RM"
      substituteInPlace configure.ml --replace "if arch = \"Darwin\" then \"md5" "if arch = \"Darwinx\" then \"md5"
      ${csdpPatch}
    '';
  
  
negative.code: 
    src = fetchurl {
      url = "http://coq.inria.fr/distrib/V${version}/files/coq-${version}.tar.gz";
      sha256 = "0wyywia0darak2zmc5v0ra9rn0b9whwdfiahralm8v5za499s8w3";
    };
  
    buildInputs = [ pkgconfig ocaml findlib camlp5 ncurses lablgtk ];
  