One of his definitions of a pure function is one that only has by value parameters and doesn't change state. Am I correct in thinking that in C++, the advent of C++11 lambdas allows you to be explicit about this and prevent the compiler from allowing you to accidentally use variables from outside the scope of the function's parameters, by writing lambadas (named, if necessary, like a normal function) with no-capture lists ("[]") which would force you to work in a more pure style. In C++, what other method might help you enforce purity?