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Received: from SCRC-EUPHRATES by SCRC-QUABBIN via CHAOS with CHAOS-MAIL id 79561; Fri 7-Sep-84 16:17:53-EDT
Date: Fri, 7 Sep 84 16:18 EDT
From: "David A. Moon" <Moon@SCRC-STONY-BROOK.ARPA>
Subject: Sequence function predicate arg order
To: "Bernard S. Greenberg" <BSG@SCRC-STONY-BROOK.ARPA>
cc: Common-Lisp@SU-AI.ARPA, bug-clcp@SCRC-STONY-BROOK.ARPA,
    dla@SCRC-STONY-BROOK.ARPA
In-Reply-To: <840907153454.7.BSG@CONCORD.SCRC.Symbolics>
Message-ID: <840907161802.5.MOON@EUPHRATES.SCRC.Symbolics>

    Date: Friday, 7 September 1984, 15:34-EDT
    From: Bernard S. Greenberg <BSG at SCRC-TENEX>

    The following issue was encountered today by David Andre.  He wanted
    to find the position of first element in a string which was not an element of a list
    he had in hand....
    Possible outcomes:
      1.  Magic keyword to sequence functions to reverse test arg order?  ECCH!
      2.  More string-specific primitives.
      3.  Maybe he should have said :test #'(lambda (x y)(member y x)).

Among your alternatives, I'd prefer #3, i.e. write
	(position list sequence :test-not #'(lambda (x y) (member y x)))
I would actually write
	(position-if-not #'(lambda (item) (member item list)) sequence)