From: Alex Shinn <alexshinn@gmail.com>
To: "Ludovic Courtès" <ludo@gnu.org>
Cc: guile-devel@gnu.org
Subject: Re: ‘match’ and “k or more” patterns
Date: Wed, 8 Sep 2010 11:18:18 +0900 [thread overview]
Message-ID: <AANLkTikKbVssXkdfc=DnKgEJr2xJxsNrbjL1vifqkYV2@mail.gmail.com> (raw)
In-Reply-To: <874oe36pgn.fsf@gnu.org>
On Mon, Sep 6, 2010 at 9:12 PM, Ludovic Courtès <ludo@gnu.org> wrote:
>
> Well, since there are only 9 of them, they could probably be implemented
> as special cases, with an augmented ‘match-gen-ellipses’, which would be
> told the minimum number of elements expected?
Oh, the Wright syntax limited you to 9 forms, so "..10" is illegal?
Then this could be done in pure syntax-rules.
>> Do you have any code which actually uses the ..k
>> patterns? :)
>
> I do! :-)
>
> http://git.sv.gnu.org/cgit/guile-rpc.git/tree/modules/rpc/compiler.scm#n312
>
> Well it uses only ‘..1’. The same code would work with ‘..1’ replaced
> by ‘...’, but then errors in the input wouldn’t be detected as nicely.
"..1" is actually useful - it's the analog of "+" in regular
expressions, and allows simplifying many syntax-rules
patterns you see written (elt0 elt1 ...) as (elt ..1). If
the elements are more complex patterns this is a big
win.
--
Alex
next prev parent reply other threads:[~2010-09-08 2:18 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-05 15:04 ‘match’ and “k or more” patterns Ludovic Courtès
2010-09-06 1:46 ` Alex Shinn
2010-09-06 12:12 ` Ludovic Courtès
2010-09-08 2:18 ` Alex Shinn [this message]
2010-09-08 12:06 ` Ludovic Courtès
2010-09-08 18:53 ` Andy Wingo
2010-09-19 21:30 ` Ludovic Courtès
[not found] ` <2083922817.3379621.1285477344869.JavaMail.root@zmbs1.inria.fr>
2010-09-27 21:56 ` Ludovic Courtès
2010-09-28 1:20 ` Alex Shinn
[not found] ` <704726234.3471946.1285636813715.JavaMail.root@zmbs1.inria.fr>
2010-09-28 10:27 ` Ludovic Courtès
2010-10-02 7:13 ` Alex Shinn
2010-10-03 10:24 ` Andy Wingo
[not found] ` <2087670639.297243.1286101256715.JavaMail.root@zmbs1.inria.fr>
2010-10-03 12:35 ` Ludovic Courtès
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