> OK, so I understand the following error message:
> 
>   # type 'a t = 'a and u = int t and v = bool t;;
>   This type bool should be an instance of type int
> 
> But then, why is the following declaration accepted?
> 
>   # type 'a t = 'a and u = A of int t and v = B of bool t;;
>   type 'a t = 'a
>   type u = | A of int t
>   type v = | B of bool t
> 
> I am still confused...

And ought to be... this is a bug:

        Objective Caml version 2.02

# type 'a t = 'a constraint 'a = int and u = A of int t and v = B of bool t;;
Uncaught exception: Ctype.Unify(_)

Is it already corrected ?

	Jacques
---------------------------------------------------------------------------
Jacques Garrigue      Kyoto University     garrigue at kurims.kyoto-u.ac.jp
		<A HREF=http://wwwfun.kurims.kyoto-u.ac.jp/~garrigue/>JG</A>