Hi Nick,

You can wrap the different key types in an existential:

type local_key = LK : 'a * (module Cipher with type local_t = 'a) -> LK

type self_t = local_key list

Cheers,
Nicolas



On Thu, Jan 14, 2016 at 12:14 PM, Nick Betteridge <
lists.nick.betteridge@gmail.com> wrote:

> Hi,
>
> I'm trying to create a functor for different type of cipher which have
> the same signature. The functor compiles Ok, but I can't work out how to
> phrase my self_t to build up a list of local key types. Could anyone
> suggest a way forward? Thanks, Nick.
>
>
> module type Cipher = sig
>
>   type local_t
>   type remote_t
>
>   val local_create : unit -> local_t
>   val local_sign : local_t -> Cstruct.t -> Cstruct.t
>   val remote_create : Cstruct.t -> remote_t
>   val remote_validate : remote_t -> Cstruct.t -> bool
>
> end
>
> module Make_cipher :
>
>   functor (Cipher_impl : Cipher) ->
>     sig
>       type local_t = Cipher_impl.local_t
>       type remote_t = Cipher_impl.remote_t
>       val local_create : unit -> local_t
>       val local_sign : local_t -> Cstruct.t -> Cstruct.t
>       val remote_create : Cstruct.t -> remote_t
>       val remote_validate : remote_t -> Cstruct.t -> bool
>     end
>
> type self_t =
>   {
>     mutable modules : (module Cipher) list;
>     mutable locals : Cipher_impl.local_t list;
>   }
>
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