Re: historical question about CASE

[Guy Steele <gls@Think.COM>]

    Date: Thu, 11 Jun 87 10:07:37 PDT
    From: Andy Freeman <FREEMAN@sumex-aim.stanford.edu>

    You wrote:
	I use the idiom ",@(when foo `(...baz...))" a LOT.

    I thought that it was considered poor style to use "when" for its
    value.  I may be confusing my dialects, but is there actually a
    guarantee that "when"'s definition is much like following?

    (defmacro when (pred &body x)
      `(if , pred (progn '() ,@ x)
	   '()))

Yes, there is such a guarantee: the second sentence of the
description of WHEN in CLTL, page 115.  (Did you look there?)

I agree that in this case I am not consistent; strictly speaking
perhaps AND is more appropriate, but I find WHEN mnemonically
more appealing in this context, and there is no question that
the value is being used, because of the presence of ",@" right
before the form.

--Guy