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Re: possibly bug with ,@
- To: Martin Grabmueller <mgrabmue at cs dot tu-berlin dot de>
- Subject: Re: possibly bug with ,@
- From: Per Bothner <per at bothner dot com>
- Date: 18 May 2000 15:01:34 -0700
- Cc: guile at sourceware dot cygnus dot com
- References: <200005181807.UAA13241@fiesta.cs.tu-berlin.de>
Martin Grabmueller <mgrabmue@cs.tu-berlin.de> writes:
> Hello folks,
>
> I found the book ``The Scheme Programming Language (2nd Edition)'' on the
> web and tried out some examples. In the book, the expression
>
> (let ((a 1) (b 2))
> `(,a ,@b))
>
> evaluates to
>
> (1 . 2)
The book is wrong. The code probably works as a Chez Scheme extension,
but it is not standard Scheme.
> R5RS did not help me about this. Can you tell me who is right?
R5RS is quite clear:
If a comma appears followed immediately by an at-sign (@), then
the following expression must evaluate to a list; ...
Now, whether this is a useful enough extension to be more
widely supported is a different matter.
--
--Per Bothner
per@bothner.com http://www.bothner.com/~per/