Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!husc6!think!barmar From: barmar@think.COM (Barry Margolin) Newsgroups: comp.lang.lisp Subject: Re: pointers in Lisp Message-ID: <36318@think.UUCP> Date: 10 Feb 89 16:49:04 GMT References: <1710@cps3xx.UUCP> <33722@tut.cis.ohio-state.edu> <49734@yale-celray.yale.UUCP> <36238@think.UUCP> <624@internal.Apple.COM> Sender: news@think.UUCP Reply-To: barmar@kulla.think.com.UUCP (Barry Margolin) Organization: Thinking Machines Corporation, Cambridge, MA Lines: 21 In article <624@internal.Apple.COM> shebs@Apple.COM (Stanley Todd Shebs) writes: >In article <36238@think.UUCP> barmar@kulla.think.com.UUCP (Barry Margolin) writes: >>Note that Lispms aren't the only Lisps with CDR-coding. I believe >>that a number of Lisps for conventional processors do CDR-coding these >>days. It's a time/space tradeoff in these cases. >Whoa! Which ones do you know for sure do cdr-coding?? I've not seen any >myself, even after an extensive survey of systems, which wasn't surprising >because you lose big if you don't have hardware support for forwarding ptrs... No, I don't know for sure. I thought I'd heard people from Lucid and/or Franz mention such things at X3J13 meetings, but perhaps I am either mistaken or I misunderstood. Maybe they only use CDR-coding in very restricted cases (if you never REPLACD in a CDR-coded list, you don't need forwarding pointers, so maybe there is a declaration that specifies this). Barry Margolin Thinking Machines Corp. barmar@think.com {uunet,harvard}!think!barmar