I can hardly believe this works.
I copied this trick from Jacque's code

http://wwwfun.kurims.kyoto-u.ac.jp/~garrigue/papers/mixev3.04.ml.txt

Thanks! This is really great stuff.
I feel like a dill: its exactly the same
as the parameterised class trick I already
knew about.
------------------------------------------

type 'a s1 = [`A | `B of 'a]
type  'a s2 = ['a s1 | `C]

type ss1 = 'a s1 as 'a
type ss2 = 'a s2 as 'a

let rec reduce : ss2 -> ss1 = function
     | `A -> `A
     | `B z -> `B (reduce z)
     | `C -> raise Not_found
;;

reduce (`B `C);;

-- 
John Max Skaller, mailto:skaller@ozemail.com.au
snail:10/1 Toxteth Rd, Glebe, NSW 2037, Australia.
voice:61-2-9660-0850


-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners