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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