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Date: Mon, 19 Aug 2013 22:18:58 -0500
Message-Id: <201308200318.r7K3Iw5t000609@poisson.math.northwestern.edu>
From: Bill Richter <richter@math.northwestern.edu>
To: Goswin von Brederlow <goswin-v-b@web.de>
CC: caml-list@inria.fr
In-reply-to: <20130819155116.GA3104@frosties> (message from Goswin von
	Brederlow on Mon, 19 Aug 2013 17:51:16 +0200)
References: <201308120312.r7C3Cn35015470@poisson.math.northwestern.edu> <20130819155116.GA3104@frosties>
Subject: Re: [Caml-list] Obj.magic, Toploop, HOL Light & pretty-printing
 exceptions

Goswin, thanks for the reply!  I'm not sure if I'm using Obj.magic (I'll study this question), and I couldn't tell if your prohibition of Obj.magic extends to Toploop.getvalue, which I definitely am using:

>    let exec = ignore o Toploop.execute_phrase false Format.std_formatter
>      o !Toploop.parse_toplevel_phrase o Lexing.from_string;;

Thanks for explaining why `eval' crashes the GC because of advanced pointers by 2. Perhaps I can draw you into what I think is the real discussion.  How does one complete the standard Scheme-type exercise of building an ocaml meta-interpreter inside ocaml?  You can do this easily in Scheme because of the quote feature.  What I and my teachers Freek, Mark and Vince are doing is, I think, trying to emulate the Scheme quote feature with Toploop & Obj.magic.  

-- 
Best,
Bill