example of currying in c++

curry.cpp

#include <stdarg.h>
#include <stdlib.h>
#include <iostream>

using namespace std;
typedef void* vp;
typedef vp(*Me)(vp);

template<class T>
vp addOne(vp vtemp) {
	T *temp = (T*)vtemp;
	T val = 1;
	cout << "temp " << *temp << " val " << val << endl;
	*temp += val;
	return (vp)temp;
};

template<class T>
vp multByTwo(vp vtemp) {
	T *temp = (T*)vtemp;
	T val = 2;
	cout << "temp " << *temp << " val " << val << endl;
	*temp *= val;
	return (vp)temp;
};

template<class T>
vp subSeven(vp vtemp) {
	T *temp = (T*)vtemp;
	T val = 7;
	cout << "temp " << *temp << " val " << val << endl;
	*temp -= val;
	return (vp)temp;
};

template<class T>
vp divByTen(vp vtemp) {
	T *temp = (T*)vtemp;
	T val = 10;
	cout << "temp " << *temp << " val " << val << endl;
	*temp /= val;
	return (vp)temp;
};


template <class T>
vp curry(long nleft,va_list a) {
	if (nleft > 1) {
		Me f = va_arg( a, Me );
		return f(curry<T>(nleft-1,a));
	}
	else {
		vp varg;
		varg = va_arg(a,vp);
		T *arg = (T*)varg;
		cout << "extracting val from curry " << *arg << endl;
		return (vp)arg;
	}
};

template <class T>
T sCurry(long n,...) {
	va_list a;
	va_start(a,n);
	return *(T*)(curry<T>(n,a));
};


int main(int argc, char *argv[])
{
	if (argc != 2) {
		cout << argv[0] << " baseval\n";
		exit(-1);
	}
	
	//Me is of type void* (*f)(void*), setting template function pointers
	Me f1 = &addOne<double>;
	Me f2 = &multByTwo<double>;
	Me f7 = &subSeven<double>;
	Me f10 = &divByTen<double>;

	double val = atof(argv[1]), val2 = atof(argv[1]);
	cout << "Address to base numeric " << &val << " base val " << val << endl;
	cout << "addOne-> " << *(double *)f1((vp)&val) << " curried addOne " << sCurry<double>(2,f1,(vp)&val2) << endl;
	
	cout << "start curry val " << val << endl;
	cout << "curried output f10(f7(f2(f1(val)))) or ((val+1)*2-7)/10 = " << sCurry<double>(5,f10,f7,f2,f1,(vp)&val) << endl;
	return 1;
}