Hi, I am trying to make a template for building sequences of random numbers using Boost.Mpl, but apparently I haven't quite got the hang of it yet ;). Below is my code (adapted from the Boost.Random docs) and the compiler output (GCC v 3.4.2), I seem to have misunderstood the usage of mpl::first and mpl::second in lambdas or something. Can someone clarify what I've done wrong? The whole construct should be invoked with something like typedef utils::make_random_sequence::type random_vector; to generator a vector_c of 10 random numbers. Thanks, Mark #include <cstdlib> #include #include #include #include #include #include #include #include #include #include #include #include #include #include namespace utils { using namespace boost::mpl; template struct random : integral_c< T, template Formula::apply<seed>::value > { typedef random next; template<T new_seed> struct reseed { typedef random type; }; }; template struct linear_congruential { BOOST_STATIC_ASSERT(boost::is_integral<IntType>::value); typedef IntType value_type; template<IntType seed> struct apply : integral_c { }; }; typedef random< long, linear_congruential, 1043618065L > minstd_rand0; typedef random< long, linear_congruential, 399268537L > minstd_rand; template struct make_random_sequence { typedef typename iter_fold< range_c, pair< typename erase< integral_sequence, begin, end >::type, generator >, pair< push_back< first<_1>, second<_1> >::type, second<_1>::next > >::type type; }; } 28: error: missing `>' to terminate the template argument list 28: error: template argument 2 is invalid 28: error: expected `{' before "template" 28: error: expected unqualified-id before "template" 28: error: expected `;' before "template" C:/Boost/include/boost-1_33/boost/mpl/pair.hpp: In instantiation of `boost::mpl::first': C:/Boost/include/boost-1_33/boost/mpl/aux_/has_tag.hpp:20: instantiated from `boost::mpl::aux::has_tag, mpl_::bool_< false> >' C:/Boost/include/boost-1_33/boost/mpl/sequence_tag.hpp:115: instantiated from `boost::mpl::sequence_tag >' C:/Boost/include/boost-1_33/boost/mpl/push_back.hpp:32: instantiated from `boost::mpl::push_back, boost::mpl::second >' 85: instantiated from here C:/Boost/include/boost-1_33/boost/mpl/pair.hpp:43: error: no type named `first' in `struct mpl_::_1' 85: error: `type' is not a member of `boost::mpl::push_back, boost::mpl::second >' 85: error: `type' is not a member of `boost::mpl::push_back, boost::mpl::second >' C:/Boost/include/boost-1_33/boost/mpl/pair.hpp: In instantiation of `boost::mpl::second': 86: instantiated from here C:/Boost/include/boost-1_33/boost/mpl/pair.hpp:56: error: no type named `second' in `struct mpl_::_1' 86: error: `next' is not a member of `boost::mpl::second' 86: error: `next' is not a member of `boost::mpl::second' 88: error: template argument 1 is invalid 88: error: template argument 2 is invalid 88: error: template argument 3 is invalid 88: error: `type' does not name a type