anchor.diff:  { stdenv, fetchurl, makeWrapper, jre }:
   
  -stdenv.mkDerivation {
  -  name = "jruby-1.6.5.1";
  +stdenv.mkDerivation rec {
  +  name = "jruby-${version}";
  +
  +  version = "1.7.12";
   
     src = fetchurl {
  -    url = http://jruby.org.s3.amazonaws.com/downloads/1.6.5.1/jruby-bin-1.6.5.1.tar.gz;
  -    sha256 = "1j0iv1q950lyir9vqfgg2533f1q28jaz7vnxqswsaix1mjhm29qd";
  +    url = "http://jruby.org.s3.amazonaws.com/downloads/${version}/jruby-bin-${version}.tar.gz";
  +    sha1 = "056cee1138e49da40a77f179b771372692479002";
     };
   
     buildInputs = [ makeWrapper ];
  
positive.code:      done
    '';
  
    meta = { 
      description = "Ruby interpreter written in Java";
      homepage = http://jruby.org/;
      license = "CPL-1.0 GPL-2 LGPL-2.1"; # one of those
  
negative.code:      mkdir -pv $out
       mv * $out
       rm $out/bin/*.{bat,dll,exe,sh}
       mv $out/COPYING $out/LICENSE* $out/docs
  
       for i in $out/bin/*; do
         wrapProgram $i \
  