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Date: Tue, 19 Nov 2002 10:09:00 -0800
From: David Brown <caml-list@davidb.org>
To: Daniel de Rauglaudre <daniel.de_rauglaudre@inria.fr>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] Even at compile time 2*2=4!
Message-ID: <20021119180900.GA24889@opus.davidb.org>
References: <001901c28f7a$5a7feb30$3101000a@redmond.corp.microsoft.com> <20021119121201.A18538@verdot.inria.fr>
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On Tue, Nov 19, 2002 at 12:12:01PM +0100, Daniel de Rauglaudre wrote:

> In some cases, you could resolve your problem with Camlp4, if your
> computation can be done at parse time. We can imagine a syntax
> extension, e.g. "compute" followed by an expression, ask the
> preprocessor to evalutate it and build the syntax tree of the
> result. For example:
>     compute (2*2)
> would generate at parse time:
>     4
> 
> But this could not work:
>     let x = 2 in
>     compute(x*x)
> because the preprocessor does not know what is "x".

To be useful, you would probably also have to be able to define
functions for the preprocessor that could be used to compute the value.

This also makes the interesting possibility of compiles that don't
terminate...

      compute (forever ())

Dave Brown
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