Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!decwrl!labrea!rutgers!mailrus!tut.cis.ohio-state.edu!bloom-beacon!mit-eddie!fenchurch!jbs
From: jbs@fenchurch.mit.edu (Jeff Siegal)
Newsgroups: comp.lang.scheme
Subject: Re: Why does (eq? car car) ==> () in MacScheme?
Message-ID: <10634@eddie.MIT.EDU>
Date: 10 Dec 88 21:23:04 GMT
References: <1440@uw-nsr.UUCP>
Sender: uucp@eddie.MIT.EDU
Reply-To: jbs@fenchurch.UUCP (Jeff Siegal)
Organization: MIT, EE/CS Computer Facilities, Cambridge, MA
Lines: 17

In article <1440@uw-nsr.UUCP> john@nsr.bioeng.washington.edu (John Sambrook 548-4386) writes:
>[...]in MacScheme
>it is the case that (eq? car car) ==> ().  [...]
>Could someone please explain what's going on here?  

I can guess at the following explanation:

In MacScheme, Scheme primitives are not really procedures, but when
you reference them, the compiler generates a procedure "wrapper" (i.e.
"car" becomes "(lambda (l) (car l))" 

It does this each time the primitive is used as a value (so each "car"
refers to a different wrapper procedure).  

This behavior is wrong according to R3RS (3/4 of the way into Sect 6.2)

Jeff Siegal