Path: utzoo!attcan!uunet!know!sdd.hp.com!elroy.jpl.nasa.gov!forsight!gat
From: gat@robotics.Jpl.Nasa.Gov (Erann Gat)
Newsgroups: comp.lang.lisp
Subject: Re: STRUCTUREP
Message-ID: <754@forsight.Jpl.Nasa.Gov>
Date: 10 Oct 90 17:17:09 GMT
References: <753@forsight.Jpl.Nasa.Gov> <1990Oct10.091722.4495@hellgate.utah.edu>
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 32

In article <1990Oct10.091722.4495@hellgate.utah.edu>, moore%cdr.utah.edu@cs.utah.edu (Tim Moore) writes:
> In article <753@forsight.Jpl.Nasa.Gov> gat@robotics.Jpl.Nasa.Gov (Erann Gat) writes:
> >Is there any way in Common Lisp to test if an object is a structure?  There
> >doesn't seem to be a structurep function.
> >
> >E.
> 
> Not portably.

Thanks, that's what I wanted to know.

In a later article, Tim writes:
> Incidently, I feel that Common Lisp, with the exception of call/cc,
> has the same semantic power (and much more) of scheme. Any
> disagreement? (Warning, religious war ahead!)

You are right, of course.  However, there are a number of things that you
can do in T which you can't do in Common Lisp.  Among these are:

1.  Create callable objects (which allow you to do things like SETF a locative
passed to a function as an argument)
2.  Tell if an object is a structure :-)

Personally, I think that it's the "and much more" part that is Common
Lisp's biggest problem.  It's getting to the point where it is very difficult
to get a grip on the entire language.  Not only does this make CL hard to
write, it encourages writing code that is nearly impossible to read without
a copy of CLTL in hand (and sometimes even then).  (It also makes it harder
to tell when some crtitical feature has been omitted from the language :->)

Just my opinion.
E.