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Formal spec; implementation; nesting Alpert Herb Petrofsky (11 Jan 2005 21:03 UTC)
Re: Formal spec; implementation; nesting Bradd W. Szonye (11 Jan 2005 21:19 UTC)
Re: Formal spec; implementation; nesting Paul Schlie (11 Jan 2005 22:29 UTC)
Re: Formal spec; implementation; nesting Taylor Campbell (12 Jan 2005 00:10 UTC)
Re: Formal spec; implementation; nesting Bradd W. Szonye (12 Jan 2005 00:13 UTC)
Re: Formal spec; implementation; nesting Bradd W. Szonye (12 Jan 2005 00:16 UTC)
Re: Formal spec; implementation; nesting Paul Schlie (17 Jan 2005 03:03 UTC)
Re: Formal spec; implementation; nesting Alpine Petrofsky (12 Jan 2005 00:22 UTC)
Re: Formal spec; implementation; nesting Paul Schlie (12 Jan 2005 01:45 UTC)
Re: Formal spec; implementation; nesting Paul Schlie (12 Jan 2005 02:18 UTC)
Re: Formal spec; implementation; nesting Paul Schlie (12 Jan 2005 14:11 UTC)
Re: Formal spec; implementation; nesting Paul Schlie (12 Jan 2005 14:29 UTC)

Re: Formal spec; implementation; nesting Bradd W. Szonye 11 Jan 2005 21:19 UTC

Alpert Herb Petrofsky wrote:
> I think what you're missing in your comparison of ' and #; is this:
>
> ' consumes one sexp and produces one sexp.  The resulting sexp can
> then be used as the argument of another '.  In contrast, #; consumes
> one sexp and produces zero sexps.  The resulting nothingness cannot be
> used as the argument to another #; because nothing is not a sexp.

Note that I don't feel strongly about this issue. On the one hand, the
behavior you describe is the way most existing implementations work, and
there's value in standardizing that. On the other hand, that behavior
seems counterintuitive and not very useful.

Here's a model that explains my intuition: #; consumes one sexp and
produces one sexp which disappears late in the reading phase. That is,
#;#;FOO is equivalent to (COMMENT (COMMENT FOO)) during parsing, but the
sexp vanishes upon creation of the syntax tree.
--
Bradd W. Szonye
http://www.szonye.com/bradd