Path: utzoo!attcan!uunet!husc6!think!barmar
From: barmar@think.COM (Barry Margolin)
Newsgroups: comp.lang.lisp
Subject: Re: What's the value of lexical scoping?
Message-ID: <22214@think.UUCP>
Date: 19 Jun 88 02:29:01 GMT
References: <24508@ucbvax.BERKELEY.EDU> <515@dcl-csvax.comp.lancs.ac.uk> <199@esosun.UUCP> <525@dcl-csvax.comp.lancs.ac.uk> <209@esosun.UUCP>
Sender: usenet@think.UUCP
Reply-To: barmar@kulla.think.com.UUCP (Barry Margolin)
Organization: Thinking Machines Corporation, Cambridge, MA
Lines: 35

In article <209@esosun.UUCP> jackson@esosun.UUCP (Jerry Jackson) writes:
>1) packages -- The package system of CL is based on the wrong idea..
>A programmer doesn't care if someone else uses the same symbol as *data*;
>He only cares if it is a variable name or a function name, etc.  Since
>what is important is the set of *bindings* for a symbol, an environment
>system would be more appropriate.  

One program's function name is another program's data.  Macros, for
instance, are programs whose data will later be interpreted as a
program.

And what about symbols used in property lists?  Both a quantum physics
program and an auto inventory program might use the COLOR property of
symbols.

>4) A nit-pik -- has anyone ever found a use for the top level form: '-' ? 

Not for anything serious.  It's just a holdover from MacLisp.  It's
trivial to implement, and I guess the CL designers saw no reason to
drop it.

In MacLisp, which didn't have the LABELS construct, it could be used
to do recursion without actually defining a new function.  For
example, factorial(10) could be done with:

((lambda (n)
   (if (< x 2) 1
       (* n (funcall (car -) (1- n)))))
 10)

Barry Margolin
Thinking Machines Corp.

barmar@think.com
{uunet,harvard}!think!barmar