Why can't I create a vector of lambdas (of the same type) in C++11?

Every lambda has a different type—even if they have the same signature. You must use a run-time encapsulating container such as std::function if you want to do something like that.

e.g.:

std::vector<std::function<int()>> functors;
functors.push_back([&] { return 100; });
functors.push_back([&] { return  10; });

All lambda expressions have a different type, even if they are identical character-by-character. You're pushing a lambda of a different type (because it's another expression) into the vector, and that obviously won't work.

One solution is to make a vector of std::function<int()> instead.

auto ignore = [&]() { return 10; };
std::vector<std::function<int()>> v;
v.push_back(ignore);
v.push_back([&]() { return 100; });

On another note, it's not a good idea to use [&] when you're not capturing anything.

While what others have said is relevant, it is still possible to declare and use a vector of lambda, although it's not very useful:

auto lambda = [] { return 10; };
std::vector<decltype(lambda)> vec;
vec.push_back(lambda);

So, you can store any number of lambdas in there, so long as it's a copy/move of lambda!