On 09/07/10 10:41, David Sankel wrote:
On Sun, Sep 5, 2010 at 7:56 PM, Larry Evans <cppljevans@suddenlink.net>wrote: [snip]
However, compiling my first try( the attached) gives: [snip] What am I doing wrong?
int result = app( next, 1 );
With the reference implementation, app should always be used within a lam. In this case you don't need a lam:
int result = next( 1 ).
But if you really wanted to make a nullary function (note the extra '()' at the end):
int result = lam<0>( app( next, 1 ) )();
Looking at the subsequent expression:
int result = app(lam_app,1);
Again we can apply the function directly here:
int result = lam_app(1);
Does that help?
I tried `lam_app(1)` in the following main: [CODE "apply_apply.cpp"] int main() { auto op = lam<1>( app(next,_1_1 ) ); int op_1 = op(1); auto lam_app = lam<1>( app(op,_1_1) ); int lam_app_1 = #if 1 lam_app(1); #else 2; #endif return op_1 + lam_app_1; } [/CODE "apply_apply.cpp"] However, this resulted in: [COMPILE_ERRORS "apply_apply.cpp"] /home/evansl/download/gcc/4.5.1-release/install/bin/g++ -I../include -I/home/evansl/prog_dev/boost-svn/ro/boost_1_44_0 -std=gnu++0x ./apply_apply.cpp -o ../bin/apply_apply.exe In file included from /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/fusion/functional/invocation/invoke.hpp:41:0, from /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/fusion/functional/adapter/fused.hpp:16, from /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/fusion/include/fused.hpp:10, from ../include/DeBruijnBind.hpp:24, from ./apply_apply.cpp:8: /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/utility/result_of.hpp: In instantiation of 'boost::detail::result_of_nested_result<Abs<1, App<int (*)(int), boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<2>, boost::fusion::vector1<int>
, boost::fusion::void_> > >, Abs<1, App<int (*)(int), boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<2>, boost::fusion::vector1<int> , boost::fusion::void_> > >(int&)>': /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/utility/result_of.hpp:87:1: instantiated from 'boost::detail::tr1_result_of_impl<Abs<1, App<int (*)(int), boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<2>, boost::fusion::vector1<int> , boost::fusion::void_> > >, Abs<1, App<int (*)(int), boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<2>, boost::fusion::vector1<int> , boost::fusion::void_> > >(int&), false>' /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/utility/detail/result_of_iterate.hpp:33:65: instantiated from 'boost::tr1_result_of<Abs<1, App<int (*)(int), boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<2>, boost::fusion::vector1<int> , boost::fusion::void_> > >(int&)>' /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/utility/detail/result_of_iterate.hpp:81:46: instantiated from 'boost::result_of<Abs<1, App<int (*)(int), boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<2>, boost::fusion::vector1<int> , boost::fusion::void_> > >(int&)>' /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/fusion/functional/invocation/invoke.hpp:199:60: instantiated from 'boost::fusion::detail::invoke_impl<Abs<1, App<int (*)(int), boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<2>, boost::fusion::vector1<int> , boost::fusion::void_> > >, boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<1>, boost::fusion::vector1<int> , boost::fusion::void_>, 1, false, true>' /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/fusion/functional/invocation/invoke.hpp:159:30: instantiated from 'boost::fusion::result_of::invoke<Abs<1, App<int (*)(int), boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<2>, boost::fusion::vector1<int> , boost::fusion::void_> > >&, boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<1>, boost::fusion::vector1<int> , boost::fusion::void_> >' ./apply_apply.cpp:65:18: instantiated from here /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/utility/result_of.hpp:80:1: error: no class template named 'result' in 'struct Abs<1, App<int (*)(int), boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<2>, boost::fusion::vector1<int> , boost::fusion::void_> > >' In file included from /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/preprocessor/iteration/detail/iter/forward1.hpp:52:0, from /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/fusion/functional/invocation/invoke.hpp:93, from /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/fusion/functional/adapter/fused.hpp:16, from /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/fusion/include/fused.hpp:10, from ../include/DeBruijnBind.hpp:24, from ./apply_apply.cpp:8: /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/fusion/functional/invocation/invoke.hpp: In instantiation of 'boost::fusion::detail::invoke_impl<Abs<1, App<int (*)(int), boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<2>, boost::fusion::vector1<int> , boost::fusion::void_> > >, boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<1>, boost::fusion::vector1<int> , boost::fusion::void_>, 1, false, true>': /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/fusion/functional/invocation/invoke.hpp:159:30: instantiated from 'boost::fusion::result_of::invoke<Abs<1, App<int (*)(int), boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<2>, boost::fusion::vector1<int> , boost::fusion::void_> > >&, boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<1>, boost::fusion::vector1<int> , boost::fusion::void_> >' ./apply_apply.cpp:65:18: instantiated from here /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/fusion/functional/invocation/invoke.hpp:199:60: error: no type named 'type' in 'struct boost::result_of<Abs<1, App<int (*)(int), boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<2>, boost::fusion::vector1<int> , boost::fusion::void_> > >(int&)>' In file included from /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/fusion/functional/invocation/invoke.hpp:41:0, from /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/fusion/functional/adapter/fused.hpp:16, from /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/fusion/include/fused.hpp:10, from ../include/DeBruijnBind.hpp:24, from ./apply_apply.cpp:8: /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/utility/result_of.hpp: In instantiation of 'boost::detail::result_of_nested_result<const Abs<1, App<int (*)(int), boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<2>, boost::fusion::vector1<int> , boost::fusion::void_> > >, const Abs<1, App<int (*)(int), boost::fusion::transform_view<const boost::fusion::vector1<arg<1, 1> >, CReduce1<boost::fusion::pair<mpl_::int_<2>, boost::fusion::vector1<int> , boost::fusion::void_> > >(int&)>': /home/evansl/prog_dev/boost-svn/ro/boost_1_44_0/boost/utility/result_of.hpp:87:1: instantiated from 'boost::detail ... [/COMPILE_ERRORS "apply_apply.cpp"]
and the errors go on for about 40 more lines. Any ideas? TIA. -Larry