Re: REDUCE args

[David C. Plummer <DCP@QUABBIN.SCRC.Symbolics.COM>]

    Date: 24 Jul 1986 13:39-EDT
    From: NGALL@G.BBN.COM

	
	Date: Thu, 24 Jul 1986  13:11 EDT
	From: ALR%OZ.AI.MIT.EDU@XX.LCS.MIT.EDU
	To:   common-lisp@SU-AI.ARPA
	Subject: REDUCE args
	In-Reply-To: Msg of 24 Jul 1986  00:23-EDT from NGALL at G.BBN.COM
	Message-ID: <ALR.12225273192.BABYL@MIT-OZ>
    
	Does anybody else wish that REDUCE took a KEY argument, similarly to MEMBER.
	i.e.
    
	(reduce #'+ list-of-objects :KEY #'object-quantity)
    
	would apply the function OBJECT-QUANTITY to each element of the
	list-of-objects before reducing it with +.
    
	Andrew
    
		  --------------------
		
    YES!  I ran into the same need a while back.

Ditto.  I think GLS made some comment about this usage of :KEY being
different than most.  Maybe that was in a different discussion.  There
are possibly other related operations that should take KEY.  One could
also add :TEST to avoid calling the operator on objects you don't want
to.  Maybe this was Steele's point: Does the key apply before or after
the test?  I think the intuitive usage is backwards from the other
usages.