Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!ames!eos!ptolemy!raymond
From: raymond@ptolemy.arc.nasa.gov (Eric A. Raymond)
Newsgroups: comp.lang.lisp
Subject: Re: pointers in Lisp
Message-ID: <984@ptolemy.arc.nasa.gov>
Date: 3 Feb 89 21:50:26 GMT
References: <1710@cps3xx.UUCP> <27884@ucbvax.BERKELEY.EDU>
Reply-To: raymond@ptolemy.UUCP (Eric A. Raymond)
Organization: NASA Ames Research Center, Moffett Field, CA
Lines: 28

In article <27884@ucbvax.BERKELEY.EDU> edward@ucbarpa.Berkeley.EDU.UUCP (Edward Wang) writes:
>In article <1710@cps3xx.UUCP> artzi@cpsvax.cps.msu.edu (Ytshak Artzi - CPS) writes:
><      I need to implement (in Common Lisp) a structure with pointers. I will
><          Please don't propose an array of pointers with a flag randomly
><       chosen between 1 and 10.
>
>How about not having a size field at all but use array-dimension
>when you need to know?

What about those things called lists?

By the way, the beauty of Lisp is that you don't have to pre-type
your variables.  For example in

  (defstruct thing
     component1
     component2
     ...)

you can setq anything (i.e. atom, list, array, structure) to any of the
components.  

Don't worry about pointers in Lisp.  It's not really that important a
concept as it is in C or Pascal.  The language shields you from the hassle
(and in only a few instances does this really get in the way).
-- 
Eric A. Raymond  (raymond@pluto.arc.nasa.gov)
Nothing left to do but :-) :-) :-)