Chris@10: (*
Chris@10:  * Copyright (c) 1997-1999 Massachusetts Institute of Technology
Chris@10:  * Copyright (c) 2003, 2007-11 Matteo Frigo
Chris@10:  * Copyright (c) 2003, 2007-11 Massachusetts Institute of Technology
Chris@10:  *
Chris@10:  * This program is free software; you can redistribute it and/or modify
Chris@10:  * it under the terms of the GNU General Public License as published by
Chris@10:  * the Free Software Foundation; either version 2 of the License, or
Chris@10:  * (at your option) any later version.
Chris@10:  *
Chris@10:  * This program is distributed in the hope that it will be useful,
Chris@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
Chris@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
Chris@10:  * GNU General Public License for more details.
Chris@10:  *
Chris@10:  * You should have received a copy of the GNU General Public License
Chris@10:  * along with this program; if not, write to the Free Software
Chris@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
Chris@10:  *
Chris@10:  *)
Chris@10: 
Chris@10: (* repository of unique tokens *)
Chris@10: 
Chris@10: type unique = Unique of unit
Chris@10: 
Chris@10: (* this depends on the compiler not being too smart *)
Chris@10: let make () =
Chris@10:   let make_aux x = Unique x in
Chris@10:   make_aux ()
Chris@10: 
Chris@10: (* note that the obvious definition
Chris@10: 
Chris@10:       let make () = Unique ()
Chris@10: 
Chris@10:    fails *)
Chris@10: 
Chris@10: let same (a : unique) (b : unique) =
Chris@10:   (a == b)