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	 Mon, 19 Jan 2009 17:23:29 +0000
Message-ID: <4974B7AA.9010004@inescporto.pt>
Date: Mon, 19 Jan 2009 17:26:02 +0000
From: Hugo Ferreira <hmf@inescporto.pt>
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To: caml-list@yquem.inria.fr
Subject: Defining type that requires hashtables with recursive definition
  
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X-Spam: no; 0.00; hashtables:01 recursive:01 node:01 node:01 hashtable:01 struct:01 hash:01 hashtbl:01 hash:01 hashtbl:01 recursive:01 hashtable:01 int:01 define:02 defining:02 

Hello,

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. Note that the idea
is to use object address comparison
for the keys so:

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

module J = Hashtbl.Make( H )

However this requires a recursive definition on
the hashtable. How may a declare node and hashtable
to allow this?

TIA,
Hugo F.