Hi, A few months ago, I had a problem with mpl::is_sequence. It seems that the problem is not yet fixed. Anyway, to simplify, here's the code that exhibits the problem: #include <boost/mpl/is_sequence.hpp> int main() { bool r = boost::mpl::is_sequence<boost::mpl::int_<0> >::value; return 0; } The code does not compile on all compilers that I use regularly (VC++, g++ and Comeau). Here's a another code that does not compile: #include <boost/mpl/is_sequence.hpp> struct x { typedef int tag; }; int main() { bool r = boost::mpl::is_sequence<x>::value; return 0; } Is there any chance for this to be fixed in the immediate future? I rely on mpl::is_sequence for constrained genericity and concept checking in fusion. Regards, -- Joel de Guzman http://www.boost-consulting.com http://spirit.sf.net