What do you think of a parameterized class ?

class ['a] c = object
  method m (x:'a) =
    match x with
      | `A -> ()
      | `B -> ()
      | `C -> ()
end

class [[< `A | `B | `C] as 'b] c :
  object constraint 'b = 'b method m : 'b -> unit end    

Beware that the 'a parameter is freezed for each instance of the class,
that is you cannot call method m twice on the same object with
incompatible arguments.


--
Didier Le Botlan
http://cristal.inria.fr/~lebotlan
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