Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!samsung!uunet!mcsun!ukc!edcastle!aiai!jeff
From: jeff@aiai.ed.ac.uk (Jeff Dalton)
Newsgroups: comp.lang.lisp
Subject: Re: Question about INTERN
Message-ID: <4037@skye.ed.ac.uk>
Date: 30 Jan 91 10:56:38 GMT
References: <1991Jan29.055536.1523@magnus.ircc.ohio-state.edu> <5783@idunno.Princeton.EDU>
Reply-To: jeff@aiai.UUCP (Jeff Dalton)
Organization: AIAI, University of Edinburgh, Scotland
Lines: 19

In article <5783@idunno.Princeton.EDU> eliot@phoenix.Princeton.EDU (Eliot Handelman) writes:

>The problem is that TYPE-OF doesn't guarantee returning the most specific
>type of an object, so if this used to work and now doesn't it's almost
>certainly because your two TYPE-OF's aren't behaving consistently.

I agree that this is likely to be the right explanation.  However...

>Common Lisp says that (TYPE-OF any-house) might return T.

Actually, according to CLtL II, page 66, TYPE-OF never returns T.
Moreover (page 67), "for any object created by a DEFSTRUCT constructor
function, where the defstruct has the name _name_ and no :TYPE option,
TYPE-OF will return _name_.

This relationship between TYPE-OF and defstruct was also true in
CLtL I.

-- jd