[Boost-users] [MPL] unique not working?

I pass a mpl::vector with duplicates to mpl::unique and the result still has duplicates. What am I doing wrong? http://coliru.stacked-crooked.com/a/fe85b5739eb4c15f #include #include #include #include #include #include template< typename... Args > void test( const Args&... args ) { using namespace boost::mpl; using namespace boost::mpl::placeholders; typedef vector args_types; typedef typename unique >::type unique_types; print< unique_types > x; } int main() { int a = 0; char b = 0; test( a, b, a ); } + g++-4.8 -std=c++11 -O2 -Wall -pedantic -pthread main.cpp main.cpp: In instantiation of ‘void test(const Args& ...) [with Args = {int, char, int}]’: main.cpp:22:19: required from here main.cpp:15:27: warning: unused variable ‘x’ [-Wunused-variable] print< unique_types > x; ^ + ./a.out