Re: [Scheme-reports] ANN: first draft of R7RS small language available
Alex Shinn 18 Apr 2011 01:58 UTC
Hi Peter, thanks for the comments!
On Sat, Apr 16, 2011 at 10:59 PM, Peter Bex <Peter.Bex@xs4all.nl> wrote:
>
> Section 4.3.2:
>
> Why is it neccessary to define underscore as a specially-treated
> wildcard? [...]
>
> I might be missing something but AIUI when an underscore doesn't appear
> in the <template> part of a <syntax rule>, the behaviour of that macro
> is exactly the same whether the underscore is treated as a wildcard or
> not.
The only difference is if you use multiple wildcards in the pattern,
which would have been an error in R5RS. I'm not particularly fond
of the syntax, but I suppose it helps if you have lots of subpatterns
that you don't care about and don't want to think up descriptive
names.
> Section 6.3.7:
>
> The blob interface could be simplified by getting rid of
> partial-blob and partial-blob-copy! and making blob-copy and blob-copy!'s
> signatures accept optional arguments:
I agree, I'll add a ticket for this.
> Section 7.1:
>
> This says case is insignificant in the BNF; but it isn't really when the
> Scheme is not in case-folding mode. Possibly only for #x and a few
> others? For example, are the <expression keyword>s case-insensitive?
> If case is insignificant, why are there uppercase letters under
> <hex digit>?
The BNF is case-insensitive. The uppercase letters in <hex digit> are
for emphasis. I thought I had removed the <expression keywords>s
and <syntactic keywords> - Scheme has no reserved words, and I'm
not sure what the original motivation for them was.
--
Alex
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