[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: NIL and DEFCONSTANT [Gall: Bug Report]
- To: "Scott E. Fahlman" <Fahlman@CMU-CS-C.ARPA>
- Subject: Re: NIL and DEFCONSTANT [Gall: Bug Report]
- From: Nick Gall <Gall@MIT-MULTICS.ARPA>
- Date: Wed, 3 Apr 85 23:52 EST
- Cc: "David A. Moon" <Moon@SCRC-STONY-BROOK.ARPA>, common-lisp@SU-AI.ARPA
- In-reply-to: Message of 2 Apr 85 23:14 EST from "Scott E. Fahlman"
Date: 2 April 1985 23:14 est
From: Scott E. Fahlman <Fahlman at CMU-CS-C>
Subject: NIL and DEFCONSTANT [Gall: Bug Report]
I agree with Moon that it "is an error" to redefine built-in constants.
It probably is not required that an implementation stop you from doing
this, but it would be a good idea.
I think that the description on page 56 is OK as it is. First it says
that there are built-in named constants that you don't get to change.
Here it talks about such things as T and NIL. Then it says that
"constant symbols defined by Defconstant" are also treated this way, but
that they may be redefined if necessary by using Defconstant again. I
don't see anything that would imply that T and NIL are implicitly
defined by Defconstant and that they are therefore redefinable.
I agree with Moon also. And I agree that pg. 56 is ok too. It is pg.
69 that is a little shaky, and pg. 324 DEFINITELY states that NIL and T
are defined with DEFCONSTANT.