anchor.diff: -{ stdenv, fetchurl, ocaml, findlib, mysql, camlp4 }:
  +{ stdenv, fetchurl, ocaml, findlib, mysql }:
   
   # TODO: la versione stabile da' un errore di compilazione dovuto a
   # qualche cambiamento negli header .h
  
positive.code:      "--libdir=$out/lib/ocaml/${ocaml.version}/site-lib/mysql"
    ];
  
    buildInputs = [ocaml findlib camlp4 ];
  
    createFindlibDestdir = true;
  
    propagatedBuildInputs = [ mysql.client ];
  
    buildPhase = ''
      make
      make opt
    '';
  
    meta = {
      homepage = http://ocaml-mysql.forge.ocamlcore.org;
  
negative.code: 
  stdenv.mkDerivation rec {
    name = "${pname}-${version}";
    version = "1.2.1";
  
    src = fetchurl {
      url = "http://ygrek.org.ua/p/release/ocaml-mysql/${name}.tar.gz";
      sha256 = "06mb2bq7v37wn0lza61917zqgb4bsg1xxb73myjyn88p6khl6yl2";
    };
  
    configureFlags = [ 
  