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From: dsmith@hplabsc.UUCP (David Smith)
Newsgroups: net.ai,net.lang.lisp
Subject: Re: Common LISP style standards.
Message-ID: <265@hplabsc.UUCP>
Date: Mon, 2-Jun-86 13:10:26 EDT
Article-I.D.: hplabsc.265
Posted: Mon Jun  2 13:10:26 1986
Date-Received: Wed, 4-Jun-86 06:37:03 EDT
References: <2784@jhunix.UUCP> <3787@utah-cs.UUCP> <545@bcsaic.UUCP>
Distribution: net
Organization: Hewlett Packard Labs, Palo Alto CA
Lines: 31
Xref: linus net.ai:3266 net.lang.lisp:766

> In article <3787@utah-cs.UUCP> shebs@utah-cs.UUCP (Stanley Shebs) writes:
> >Sequence functions and mapping functions are generally preferable to
> >handwritten loops, ...
> 
> I'm in a little different boat, since we're using Franz rather than Common
> Lisp, so perhaps the issues are a bit different ...
> A common situation we find ourselves in is the following.  We have a long list,
> and we wish to apply some test to each member of the list.  However, at some
> point in the list, if the test returns a certain value, there is no need to
> look further: we can jump out of processing the list right there, and thus
> save time.  ...
> 
> Mike Maxwell

CMU incorporated functions of CMUlisp into Franz, and these are apparently
shipped with Franz:  at least, on my computer, they are in
/usr/src/ucb/lisp/lisplib/cmufncs.l.  One of these functions is the
function some.

	(some 'mylist 'func1 'func2)

returns the first tail of mylist for which func1 of its car returns a
non-nil value.  Otherwise nil is returned.  Successive tails of mylist
are obtained by repeated application of func2 (usually cdr, or nil,
which implies cdr).  A nice cover macro for this is "exists".
Example:
	(exists i '(2 5 3 8 4 1) (> i 6))
returns (8 4 1).

			David Smith
			HP Labs