Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!gatech!bloom-beacon!husc6!mit-eddie!genrad!decvax!ucbvax!dill.Berkeley.EDU!larus From: larus@dill.Berkeley.EDU.berkeley.edu (James Larus) Newsgroups: comp.lang.lisp Subject: Re: Importance of REPLACA, REPLACD, and - (nf) Message-ID: <19747@ucbvax.BERKELEY.EDU> Date: Fri, 17-Jul-87 13:16:50 EDT Article-I.D.: ucbvax.19747 Posted: Fri Jul 17 13:16:50 1987 Date-Received: Sat, 18-Jul-87 14:55:42 EDT References: <22@citcom.UUCP> <6900008@iaoobelix.UUCP> Sender: usenet@ucbvax.BERKELEY.EDU Reply-To: larus@paris.Berkeley.EDU(James Larus) Organization: University of California, Berkeley Lines: 16 Luddy Harrison (of the Center for Supercomputing Research & Development at the Univ. of Illinois) has done some very nice work on using vector-like structures to store lists. The purpose of this work is to make fast, concurrent reduction operations possible on multiprocessors. It has other advantages in that certain common operations, such as APPEND, become very fast and efficient. It's main disadvantage is that RPLACA and RPLACD are outlawed because they screw up the structure-sharing. Luddy argues that a lot of cases in which these operations were previously necessary for efficiency reasons are not as important, i.e., NCONC is unnecessary when APPEND is almost constant-time. There is a paper in the 1986 Parallel Processing Conf. and a couple of tech. reports on this work. /Jim