C++ experiments

Monoid.cpp

template <typename T>
struct LinkedList {
    T head;
    LinkedList *tail;
};

template<typename Monoid>
typename Monoid::T fold(LinkedList<typename Monoid::T> *l) {
    typename Monoid::T acc = Monoid::mempty();
    while (l) {
        acc = Monoid::mappend(acc, l->head);
        l = l->tail;
    }
    return acc;
};

struct IntMonoid {
    using T = int;
    static T mempty() { return 0; }
    static T mappend(T x, T y) { return x + y; }
};