I have Boost 1.33.1 installed. I'm trying to use Boost.Lamda. I included all the headers mentioned in the documentation as an attempt to fix the compile error. #include <boost/lambda/lambda.hpp> #include <boost/lambda/bind.hpp> #include <boost/lambda/loops.hpp> #include <boost/lambda/algorithm.hpp> #include <boost/lambda/if.hpp> #include <boost/lambda/switch.hpp> #include <boost/lambda/construct.hpp> #include <boost/lambda/casts.hpp> #include <boost/lambda/exceptions.hpp> #include <iostream> #include <list> int main() { using namespace std; using boost::lambda; list<int> v(10); for_each(v.begin(), v.end(), _1 = 1); } % g++ lambda.cpp lambda.cpp: In function `int main()': lambda.cpp:20: error: `_1' undeclared (first use this function) lambda.cpp:20: error: (Each undeclared identifier is reported only once for each function it appears in.) Using gcc 3.3.1. Any ideas? Thansk, Joe