Hi, Why can't lambda figure out the return type of operator[] for array? Does it know about vectors? I know I can fix the compile error by using bl::ret<double>(bl::_1[0])... But for obvious reasons, I'd much rather not! #include <vector> #include <algorithm> #include <boost/array.hpp> #include <boost/lambda/lambda.hpp> int main() { namespace bl=boost::lambda; using std::vector; using boost::array; array<double,3> cpy = {1}; vector<vector<double> > a(10,vector<double>(3,1)); vector<array<double,3> > b(10,cpy); std::find_if(a.begin(),a.end(),bl::_1[0]==5); std::find_if(b.begin(),b.end(),bl::_1[0]==5); } Thanks! Sohail