From: Anastasia Gornostaeva <ermine@ermine.pp.ru>

> What I need to drink to compile it?
> 
> class foo ch =
> object
>  method myprintf = Printf.fprintf ch
> end
> 
> The compiler says 
> The method myprintf has type ('a, out_channel, unit) format -> 'a where 'a
> is unbound

Since I assume that you want to be able to use differently typed
formats with the same object,

class foo ch = object
  method myprintf : 'a. ('a, out_channel, unit) format -> 'a =
    Printf.fprintf ch
end

Jacques Garrigue