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The ". $" notation (was: Re: how useful are collecting lists?)
Alan Manuel Gloria
(18 Mar 2013 01:26 UTC)
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Re: The ". $" notation
Shiro Kawai
(18 Mar 2013 02:42 UTC)
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Re: The ". $" notation
Alan Manuel Gloria
(18 Mar 2013 02:44 UTC)
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Re: The ". $" notation
Shiro Kawai
(18 Mar 2013 04:45 UTC)
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Re: The ". $" notation David A. Wheeler (18 Mar 2013 16:25 UTC)
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Re: The ". $" notation
Alan Manuel Gloria
(19 Mar 2013 00:17 UTC)
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Re: The ". $" notation
David A. Wheeler
(19 Mar 2013 03:28 UTC)
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Re: The ". $" notation
Alan Manuel Gloria
(19 Mar 2013 05:52 UTC)
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Re: The ". $" notation
David A. Wheeler
(19 Mar 2013 10:44 UTC)
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Handling scomments after "."
David A. Wheeler
(19 Mar 2013 03:41 UTC)
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Re: Handling scomments after "."
David A. Wheeler
(19 Mar 2013 04:12 UTC)
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Re: The ". $" notation (was: Re: how useful are collecting lists?)
David A. Wheeler
(18 Mar 2013 03:09 UTC)
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Alan Manuel Gloria:
> >> 1. Allow "foo . EOL INDENT x ..." ==> "(foo . (x ...))"
> >> 2. Allow "foo . $ x ..." ==> "(foo x ...)"
Unfortunately, those 2 forms greatly differ in ease-of-implementation.
The *second* form is easy to add to the BNF. Here's the patch:
diff --git a/sweet.g b/sweet.g
index 82055ea..937e54d 100644
--- a/sweet.g
+++ b/sweet.g
@@ -1061,6 +1061,7 @@ rest returns [Object v]
(pn=n_expr hspace* (n_expr error)? {$v = $pn.v;}
| COLLECTING hspace* pc=collecting_tail hspace*
(n_expr error)? {$v = $pc.v;}
+ | SUBLIST hspace* ps=rest {$v = $ps.v;}
| empty {$v = list(".");})
| empty {$v = list(".");})
| scomment hspace* (sr=rest {$v = $sr.v;} | empty {$v = null;} )
So we could easily support form #2, and I don't see any big downside.
I'll post the ANTLR patch on git; we can revert it later, or implement it in the
Scheme implementation, depending on what people say.
I don't see an obvious way to add the first form to the BNF, though, and
I don't think we should reorganize everything for such a bizarre case.
Also, I can see form #1 being created accidentally, so *preventing* it seems wise.
Granted, that's a minor inconsistency, but ". $" is such a bizarre useless
sequence that I'm going to lose any sleep over it (if we add it).
--- David A. Wheeler