Dear all, A few weeks ago, I asked for help about an EDSL which can handle expressions like x >> f >> g >> h so that they're equivalent to h(g(f(x))) once evaluated. Eric kindly provided me with the solution in the P.S. I was just playing around with his code and thought about extending it with a simple case when f's and g's are actually functions, as opposed to function objects. So, I added the following two lines: int plus1(int i) {return i + 1;} const terminal<pointer_to_unary_function<int, int> >::type plus_one = {ptr_fun(&plus1)}; And, I get a segmentation fault (GCC 4.5.1, MinGW32, WinXP, SP3) when I run the following line: 1 >> plus_one >> plus_one Any ideas? TIA, --Hossein P.S. #include <boost/proto/proto.hpp> #include <iostream> namespace proto = boost::proto; using proto::_; struct add_one_ { typedef int result_type; int operator()(int i) const { return i + 1; } }; proto::terminal<add_one_>::type const add_one = {}; struct GetFun : proto::call<proto::_value(proto::_right)> {}; struct EvalStream : proto::or_< proto::when< proto::terminal<_> , proto::_value > , proto::when< proto::shift_right<EvalStream, proto::terminal<_> > , proto::lazy< GetFun(EvalStream(proto::_left)) > > > {}; int main() { // This prints "3" std::cout << EvalStream()( 1 >> add_one >> add_one ) << std::endl; }