Re: [PATCH] Per-module reader, take #2

From: Neil Jerram <neil@ossau.uklinux.net>
Subject: Re: [PATCH] Per-module reader, take #2
Date: Wed, 19 Oct 2005 23:23:58 +0100	[thread overview]
Message-ID: <87sluxb0xt.fsf@ossau.uklinux.net> (raw)
In-Reply-To: <87u0ffnudk.fsf@laas.fr> ( Ludovic Courtès's message of "Tue, 18 Oct 2005 09:42:47 +0200")

ludovic.courtes@laas.fr (Ludovic Courtès) writes:

> Neil Jerram <neil@ossau.uklinux.net> writes:
>
>> Thanks for taking my considerations into account and producing this
>> update.  My gut feel is that I do like this new patch better, but I'd
>> like to think about it more.  I also need to go back and finish my
>> draft reply to your previous email - I'll try to do that in the next
>> day or so.
>
> Ok.
>
>> Also, do you have docs for guile-reader up somewhere?
>
> Yes.  The doc for 0.1 is there:
>
>   http://www.laas.fr/~lcourtes/software/guile/guile-reader.html

Thanks, very interesting.  I have some queries about your API, but
I'll leave those for another time.

I've finally reached a clear view on what I think about your reader
patch.  I completely agree with your arguments as regards what is
problematic about the current system of read-hash-extend and read
options, and I think it's great that you are using guile-reader to try
to solve that.  (And the GNU Lightning aspect, which I don't
understand yet, sounds very cool.)

I don't think it should be connected with modules, though.  In my
view:

- modules should be about identifier access and visibility (including
  issues such as possible separate compilation in future), and nothing
  else  (and yes, this does imply that #:use-syntax was a mistake)

- the appropriate unit of scope for your custom readers should be the
  file, not the module; for two reasons in particular:

  - the file makes sense as a unit within which the coder would want
    custom reading rules

  - associating a reader with a file instead of with a module means
    that your whole enhancement will work for code that is not
    organized into a module, as well as for that which is!

What do you think?  If you agree, I think the implication is that two
APIs (which can probably be straightforward procedures) would be
useful:

1. A way to say "change the reader to XXX for the rest of this file".

2. A way to say "load FILE using reader XXX".

Regards,
        Neil

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