Interfacing D to C R standalone math library

[TJB]

Hello!

I am still wet behind the ears with D.  I am trying to interface 
to an existing C library from the R standalone math library 
(www.r-project.org).  I can call the library quite easily from a 
C++ program as follows:


#include <iostream>
#include <time.h>
#define MATHLIB_STANDALONE
#include "Rmath.h"

using namespace std;

int main() {
   int i, n;
   double sum, x;
   time_t tt;

   tt = time(NULL);

   set_seed(tt, 77911);

   cout << "How many random normals to find the mean? ";
   cin >> n;

   sum = 0.0;
   for(i = 0; i < n; i++) {
     sum += rnorm(0, 1);
   }

   cout << "mean is " << sum/n << endl;

   return 0;
}

I can compile this with:

$ g++ -o rnorm rnorm.cpp -I /usr/include -L /usr/lib -lRmath -lm

When I grep rnorm from the Rmath.h header file I get:

$ grep rnorm Rmath.h
#define rnorm		Rf_rnorm
double	rnorm(double, double);

I have written D code to call this as follows:

import std.stdio;

extern (C) double rnorm(double, double);

void main() {
   writeln(myfunc(0.0, 1.0));
}

double myfunc(double a, double b) {
   return rnorm(a, b);
}

But I don't know what I need to do to compile it.  What flags do 
I add? What else do I have to do?

Thanks for your help!