import std.stdio;

template Declare(T) { T Declare; }

struct Empty {}
 
template TupleType(A = Empty, B = Empty, C = Empty, D = Empty, E = Empty, F = Empty, G = Empty /*,...*/) {
  static if (is(A == Empty))
    alias Empty TupleType;
  else
    alias List!(Dynify!(A),.TupleType!(B,C,D,E,F,G/*,...*/)) TupleType;
}

template Tuple(A = Empty, B = Empty, C = Empty, D = Empty, E = Empty, F = Empty, G = Empty /*,...*/) {
  TupleType!(A,B,C,D,E,F,G /*,...*/) Tuple(A a = Init!(A), B b = Init!(B), C c = Init!(C), D d = Init!(D), E e = Init!(E), F f = Init!(F), G g = Init!(G) /*,...*/) {
    static if (is(A == Empty))
      return Empty.init;
    else
      return List!(Dynify!(A),TupleType!(B,C,D,E,F,G/*,...*/))(a,.Tuple(b,c,d,e,f,g /*,...*/));
  }
}

struct List(A,B) {
  A head;
  B tail;
  static List opCall(A a, B b) {
    List!(A,B) ret;
    ret.head = a;
    ret.tail = b;
    return ret;
  }
}

template Dynify(T) {
  static if( is(typeof(Declare!(T)[0]) E))
    static if (is(T:E[]))
      alias E[] Dynify;
    else
      alias T Dynify;
  else
    alias T Dynify;
}

template Init(T) {
  const T Init = void;
}

template decl_vararg_func(alias realFunc) {
  template decl_vararg_func(A = Empty, B = Empty, C = Empty, D = Empty, E = Empty, F = Empty, G = Empty /*, ...*/) {
    typeof(realFunc(Declare!(TupleType!(A,B,C,D,E,F,G/*,...*/)))) decl_vararg_func(A a = Init!(A), B b = Init!(B), C c = Init!(C), D d = Init!(D), E e = Init!(E), F f = Init!(F), G g = Init!(G) /*,...*/) {
      return realFunc(Tuple(a,b,c,d,e,f,g /*,...*/));
    }
  }
}

template funcImpl(T) {
  void funcImpl(T args) {
    static if (is(T == Empty)) {
      writefln("Done!");
    } else {
      writefln("Got argument: (%s) %s",typeid(typeof(args.head)),args.head);
      .funcImpl(args.tail);
    }
  }
}

alias decl_vararg_func!(funcImpl) func;

template funcImpl2(T) {
  int funcImpl2(T args, int n = 0) {
    static if (is(T == Empty)) {
      writefln("funcImpl2 called with %s argument(s)",n);
    } else {
      .funcImpl2(args.tail, n+1);
    }
    return 5;
  }
}

alias decl_vararg_func!(funcImpl2) func2;

void main() {
  func(1,5.6,3L,"test");
  writefln("func2() = ",func2());
  func(null);
  func("test","test2",3);
}