Hi, I am trying to get the type of the first element in a fusion vector using mpl::at_c. This seems simple enough. // Here is the code #include #include int main() { typedef boost::fusion::vector VectorType; typedef boost::mpl::at_c::type value0; return 0; } This won't compile on vc-8.0, and I get the following error message: ...patience... ...found 467 targets... ...updating 2 targets... msvc.compile.c++ bin\msvc-8.0\debug\example2.obj example2.cpp using native typeof boost\boost/mpl/begin_end.hpp(35) : error C2903: 'apply' : symbol is neither a class template nor a function template boost\boost/mpl/aux_/at_impl.hpp(33) : see reference to class template instantiation 'boost::mpl::begin<Sequence>' being compiled with [ Sequence=VectorType ] boost\boost/mpl/at.hpp(45) : see reference to class template instantiation 'boost::mpl::at_impl<Tag>::apply' being compiled with [ Tag=boost::fusion::fusion_sequence_tag, Sequence=VectorType, N=boost::mpl::long_<0> ] examples\example2.cpp(11) : see reference to class template instantiation 'boost::mpl::at_c' being compiled with [ Sequence=VectorType, N=0 ] boost\boost/mpl/begin_end.hpp(35) : error C2027: use of undefined type 'boost::mpl::begin_implboost::fusion::fusion_sequence_tag' boost\boost/mpl/begin_end.hpp(35) : error C2059: syntax error : '<' boost\boost/mpl/begin_end.hpp(35) : error C2039: 'type' : is not a member of '`global namespace'' boost\boost/mpl/begin_end.hpp(35) : error C2238: unexpected token(s) preceding ';' boost\boost/mpl/aux_/at_impl.hpp(33) : error C2039: 'type' : is not a member of 'boost::mpl::begin<Sequence>' with [ Sequence=VectorType ] boost\boost/mpl/aux_/at_impl.hpp(34) : error C2146: syntax error : missing ',' before identifier 'type' boost\boost/mpl/aux_/at_impl.hpp(34) : error C2065: 'type' : undeclared identifier boost\boost/mpl/aux_/at_impl.hpp(35) : error C2955: 'boost::mpl::advance' : use of class template requires template argument list boost\boost/mpl/advance.hpp(60) : see declaration of 'boost::mpl::advance' boost\boost/mpl/aux_/at_impl.hpp(35) : error C2039: 'type' : is not a member of 'boost::mpl::advance' boost\boost/mpl/advance.hpp(60) : see declaration of 'boost::mpl::advance' boost\boost/mpl/aux_/at_impl.hpp(35) : error C2146: syntax error : missing ';' before identifier 'iter_' boost\boost/mpl/aux_/at_impl.hpp(35) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int boost\boost/mpl/aux_/at_impl.hpp(35) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int boost\boost/mpl/aux_/at_impl.hpp(37) : error C2065: 'iter_' : undeclared identifier boost\boost/mpl/aux_/at_impl.hpp(37) : error C2955: 'boost::mpl::deref' : use of class template requires template argument list boost\boost/mpl/deref.hpp(35) : see declaration of 'boost::mpl::deref' boost\boost/mpl/aux_/at_impl.hpp(37) : error C2371: 'boost::mpl::at_impl<Tag>::apply::type' : redefinition; different basic types with [ Tag=boost::fusion::fusion_sequence_tag, Sequence=VectorType, N=boost::mpl::long_<0> ] boost\boost/mpl/aux_/at_impl.hpp(35) : see declaration of 'boost::mpl::at_impl<Tag>::apply::type' with [ Tag=boost::fusion::fusion_sequence_tag, Sequence=VectorType, N=boost::mpl::long_<0> ] call "C:\Program Files\Microsoft Visual Studio 8\VC\vcvarsall.bat" x86 >nul cl /Zm800 -nologo -TP /Z7 /Od /Ob0 /W3 /GR /MDd /Zc:forScope /Zc:wchar_t /wd4675 /EHs @"bin\msvc-8.0\debug\example2.obj.rsp" -c -Fo"bin\msvc-8.0\debug\example2.obj" ...failed msvc.compile.c++ bin\msvc-8.0\debug\example2.obj... ...skipped example2.exe for lack of example2.obj... ...failed updating 1 target... ...skipped 1 target...