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Re: CL package serious deficiencies

From: Juanma Barranquero
Subject: Re: CL package serious deficiencies
Date: Sat, 11 Feb 2012 23:33:44 +0100

On Sat, Feb 11, 2012 at 17:56, Johan Bockgård <address@hidden> wrote:

> There is no promise about in which order the sequence will be traversed
> (only from which end elements are :count'ed).

You're right. At least, I see no such guarantee in the appropriate 17.3 section.

It is surprising, though, that the promise does exist for COUNT,

"The from-end has no direct effect on the result. However, if from-end
is true, the elements of sequence will be supplied as arguments to the
test, test-not, and key in reverse order, which may change the
side-effects, if any, of those functions."

I mean, :from-end would not be useful for COUNT otherwise, so the
language designers gave it something to do. But the result is that
COUNT and friends are the only sequence functions which guarantee the
order (and so, side effects) of the test and key.



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