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Re: [Caml-list] type var in functor instance?
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Date: 2004-09-20 (20:15)
From: Daniel_Bünzli <daniel.buenzli@e...>
Subject: Re: [Caml-list] type var in functor instance?

Accidentally I'm running into the same problem. I'd like to have a 
polymorphic Hashtbl that uses physical equality. Using Hashtbl.Make is 
not possible since the type t of the input signature HashedType has no 

More precisely I would like to have a key with the following type

type 'a 'b key = 'a option * 'b option

and the following equal function,

let equal k k' = match k, k' with
| (Some x, y), (Some x', y') -> if x == x' then y = y' else false
| _, _ -> k = k'

which tests for physical equality when the first component of the key 
is "Some" in both keys.

Any hints besides those already suggested ?


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