Example of c++11/14 numeric vector transform into squares

SquaresForVector.cpp

#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>

template <typename T>
void traceVectorValues(const std::vector<T> &);

template <typename T>
void transformVectorWithUnaryFunction(std::vector<T> &, std::function<T(T)>);

int main(){
    using namespace std;
    typedef double InputType; // If we need to change inputs type, we just have to do it here.

    vector<InputType> values{1,2,3,4,5,6,7,8,9.6};
    auto squareFunc = [](auto input){return input * input;};

    traceVectorValues(values);
    transformVectorWithUnaryFunction<InputType>(values, squareFunc);
    traceVectorValues(values);

    return 0;
}

template <typename T>
void traceVectorValues(const std::vector<T> &vec) {
    using namespace std;

    cout << "[";
    for (auto current : vec){
        cout << current << ", ";
    }
    cout << "\b\b]" << endl;
}

template <typename T>
void transformVectorWithUnaryFunction(std::vector<T> &vec, std::function<T(T)> func) {
    using namespace std;

    transform(vec.begin(), vec.end(), vec.begin(), func);
}

I think that one big improvement would be to restrict transformVectorWithUnaryFunction() template parameter to numeric value. However, I don't know how I can do that.