[plt-scheme] Keyword arguments and multiple values?

From: Carl Eastlund (carl.eastlund at gmail.com)
Date: Thu Sep 17 10:32:03 EDT 2009

On Thu, Sep 17, 2009 at 9:48 AM, Scott McLoughlin <scott at adrenaline.com> wrote:
> I noticed when using scheme/cmdline that the #once-any keyword argument
> can take multiple argument values.  I didn't notice this feature described
> in the general
> keyword argument documentation.
> Am I missing something?  Any pointers into the documentation welcome.
> Thanks in advance!
> Scott


Note that the command-line form is a macro, not a function.  Functions
always take arguments the same way: any number of positional
arguments, interleaved with keywords that take exactly one argument.
Macros get to parse their own arguments, so they can interpret
keywords any way they want to.  In the case of command-line, all of
its arguments use keywords, so they can take any number of expressions
as arguments; it simply keeps parsing arguments until it gets to the
next keyword.

I hope that helps clear it up.


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