> Thank you very much. Now I find that a mutable linked list can
> indeed be elegantly implemented in ocaml, e.g.:
> 
> type 'a mlist = Empty | Node of 'a mlist ref * 'a ref;;

If efficiency is really crucial, you could also write

type 'a mlist = Empty | Node of 'a mcell
and 'a mcell = {mutable hd : 'a; mutable tl : 'a mlist}

You may have a look at the Caml FAQ, where the existence and
manipulation of pointers in Caml is discussed:

http://pauillac.inria.fr/caml/FAQ/pointers-eng.html

(Fresh english translation written for the occasion).

Best regards,
-- 
Pierre Weis

INRIA, Projet Cristal, http://pauillac.inria.fr/~weis