Function Objects and Lambdas

How do you hand an algorithm a piece of behaviour? We build a function object, see why the compiler can inline it where a function pointer gets in the way, and then open up a lambda to find the ordinary class the compiler writes for it: captures become members, the body becomes a const call operator. We finish with init captures, generic and constexpr lambdas, and the classic dangling captured-this bug, caught by AddressSanitizer and fixed with [*this].