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From: Panicz Maciej Godek <godek.maciek@gmail.com>
To: "Ludovic Courtès" <ludo@gnu.org>
Cc: guile-user@gnu.org
Subject: Re: Expanding macros
Date: Fri, 28 Sep 2012 17:52:19 +0200	[thread overview]
Message-ID: <CAMFYt2Yp2=XhoLD+6Wjz29jJNu2o1x=3yitmgULZVnQkEC_CMA@mail.gmail.com> (raw)
In-Reply-To: <873924phzt.fsf@gnu.org>

Bonjour,

> There’s the ,expand command at the REPL.
>
> It’s implemented like this:
>
>   (define (repl-expand repl form)
>     (let ((from (repl-language repl))
>           (opts (repl-compile-options repl)))
>       (decompile (compile form #:from from #:to 'tree-il #:opts opts
>                           #:env (current-module))
>                  #:from 'tree-il #:to from)))
>
> Psyntax, the macro expander, returns tree-il, hence the need to go
> through ‘decompile’.

Thanks a lot. By the way, the (undocumented, as of 2.0.5) decompile
function returns two values -- the first being the expanded expression
and the second -- #f.
As I've figured out from system/base/compile, the second return value
is the environment, but I've been wondering under what circumstances
would that value be different from #f.

Best regards
MG



  reply	other threads:[~2012-09-28 15:52 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-09-24 21:47 Expanding macros Panicz Maciej Godek
2012-09-26 21:54 ` Ludovic Courtès
2012-09-28 15:52   ` Panicz Maciej Godek [this message]
2012-10-02 14:04     ` Ludovic Courtès

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