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From: Goswin von Brederlow <goswin-v-b@web.de>
To: Jacques Garrigue <garrigue@math.nagoya-u.ac.jp>
Cc: goswin-v-b@web.de, caml-list@inria.fr
Subject: Re: [Caml-list] Subtyping
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	<87bpr86kti.fsf@frosties.localdomain>
	<20090408.103501.38023937.garrigue@math.nagoya-u.ac.jp>
Date: Wed, 08 Apr 2009 07:16:41 +0200
In-Reply-To: <20090408.103501.38023937.garrigue@math.nagoya-u.ac.jp> (Jacques
	Garrigue's message of "Wed, 08 Apr 2009 10:35:01 +0900 (JST)")
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X-Spam: no; 0.00; subtyping:01 iter:01 verbose:01 1.2:98 mfg:98 closures:01 closures:01 caml-list:01 int:01 writes:01 closure:01 encoding:02 objects:02 garrigue:03 garrigue:03 

Jacques Garrigue <garrigue@math.nagoya-u.ac.jp> writes:

> type 'a base = {x : 'a; fn : 'a -> unit}
> type 'b base_op = {bop: 'a. 'a base -> 'b}
> type base_wrapper = {base: 'b. 'b base_op -> 'b}
>
> let l =
>   let a = {x = 1; fn = print_int}
>   and b = {x = 1.2; fn = print_float} in
>   [{base = fun x -> x.bop a}; {base = fun x -> x.bop b}]
>
> List.iter (fun w -> w.base {bop = fun r -> r.fn r.x}) l
>
> As you can see, the result is rather verbose, but this works.
> Fortunately, closure and objects are usually enough...
>
> Jacques Garrigue

That is exactly what I ment. I knew closures could have "'a. ..."
types but I didn't think of encoding the record and the method to
call both as closures.

MfG
        Goswin