or if you really want to define your own equality, you can use recursive
modules:

module rec H : Hashtbl.HashedType =
struct
    type node =
        | Node of node J.t
        | Leaf of int

    type t = node
    let equal (e1:node) (e2:node) = (==) e1 e2
    let hash (e:node) = Hashtbl.hash e
end

and J : Hashtbl.S = Hashtbl.Make( H )

2009/1/19 Jacques Carette <carette@mcmaster.ca>

> Hugo Ferreira wrote:
>
>> I am attempting to define a type so:
>>
>> type node =
>>  | Node of links
>>  | Leaf of int
>>
>> And I want to implement links as a
>> hashtable whose keys and values are
>> also of type node.
>>
>
> type node =
>  | Node of links
>  | Leaf of int
> and links = (node, node) Hashtbl.t
>
> should do it.
>
> Jacques
>
>
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