Grusel++ of the month

/******************************************************************************/
/*                                                                            */
/*                                                            FILE: march.cpp */
/*                                                                            */
/*  Written while trying to understand "Modern C++ Design"                    */
/*  ======================================================                    */
/*                                                                            */
/*  Compiled and tested with GNU g++ V2.96                                    */
/*                                                                            */
/*  V1.00   31-MAR-2003   P. Tellenbach   http://www.heimetli.ch/             */
/*                                                                            */
/******************************************************************************/

#include <iostream>

#define CLASS( c ) struct c { c() { std::cout << #c ; } }

CLASS( H ) ;
CLASS( e ) ;
CLASS( l ) ;
CLASS( o ) ;
CLASS( w ) ;
CLASS( r ) ;
CLASS( d ) ;

struct sp   { sp()   { std::cout << ' '  ; } } ;
struct excl { excl() { std::cout << '!'  ; } } ;
struct nl   { nl()   { std::cout << '\n' ; } } ;

class NullType
{
} ;

template< class H, class T >
struct TypeList
{
   typedef H Head ;
   typedef T Tail ;
} ;

template< class X >
struct Instantiate ;

template<>
struct Instantiate< NullType >
{
} ;

template< class H, class T >
struct Instantiate< TypeList< H, T > >
{
   H              head ;
   Instantiate<T> tail ;
} ;

int main()
{
   Instantiate<
     TypeList< H,
       TypeList< e,
         TypeList< l,
           TypeList< l,
             TypeList< o,
               TypeList< sp,
                 TypeList< w,
                   TypeList< o,
                     TypeList< r,
                       TypeList< l,
                         TypeList< d,
                           TypeList< sp,
                             TypeList< excl,
                               TypeList< nl, NullType >
                                     >
                                   >
                                 >
                               >
                             >
                           >
                         >
                       >
                     >
                   >
                 >
               >
             >
           > instance ;

   return 0 ;
}

Update 31. March 2023

This program compiles and runs without any changes.