Hi Steffen,

Your question contains the answer :) You can indeed expose an object type
and a class type without exposing the class.

module Example : sig
  class type t = object
      method print : unit
    end
end = struct
    class t = object
      method print = print_endline "yep"
    end
  end

The class implementation will not be exposed, so `new Example.t` will say
`Unbound class Example.t`. But, the class type and object type will be
exposed,
e.g, you may say `type printable = Example.t` (yes, class type declaration
declares both the type and the class type).

Regards,
Ivan


On Mon, Feb 13, 2017 at 1:23 PM, Steffen Smolka <smolka@cs.cornell.edu>
wrote:

> Hi,
>
> Is it possible to expose an object or class type in OCaml without exposing
> the constructor, i.e. the ability to construct objects of the type? OCaml
> supports private ADTs and type synonyms, but the private keyword doesn't
> seem to work with classes or objects.
>
> Thanks,
> -- Steffen
>