Hi Everyone, According to the documentation (http://www.boost.org/doc/libs/1_40_0/libs/iterator/doc/zip_iterator.html): All iterator types in the argument IteratorTuple shall model Readable Iterator. When I use a BidirectionalIterator (list<...>::iterator) zip_iterator fails to compile, while when I use a RandomAccessIterator (vector<...>) it compiles just fine. I have a nesting like this: make_filter_iterator( filter(), make_zip_iterator( make_tuple( container.begin(), make_transform_iterator( container.begin(), function() ) ) ) The first line in the error logs is: /home/dean/boost/boost/iterator/detail/minimum_category.hpp: In instantiation of ‘boost::detail::minimum_category_impl<false, false>::apply<boost::detail::iterator_category_with_traversal<std::input_iterator_tag, boost::bidirectional_traversal_tag>, boost::random_access_traversal_tag> I'm using Boost SVN trunk updated to revision 56153 -- did I find a bug? HTH -- Dean Michael Berris blog.cplusplus-soup.com | twitter.com/mikhailberis linkedin.com/in/mikhailberis | facebook.com/dean.berris | deanberris.com