#include <stdio.h>
#include <string.h>

#define __GPROLOG_FOREIGN_STRICT__
#include "gprolog.h"

int pay(char a, char b)
{
	int payment = -1;
	PlTerm arg[3];

	int func = Pl_Find_Atom("pay");

	Pl_Query_Begin(PL_TRUE);

	arg[0] = Pl_Mk_Char(a);
	arg[1] = Pl_Mk_Char(b);
	arg[2] = Pl_Mk_Variable();

	if (Pl_Query_Call(func, 3, arg)) {
		payment = Pl_Rd_Integer(arg[2]);
	}
	Pl_Query_End(PL_RECOVER);

	return payment;
}

int
main(int argc, char *argv[])
{
	Pl_Start_Prolog(argc, argv);

	printf("pay: %d\n", pay('d', 'c'));

	Pl_Stop_Prolog();
	return 0;
}