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Redefining CAR/CDR/other standard symbols (was Re: [Q] Dylan to Java/JVM compiler?)

Hello!

In article <3AFA3AF6.363109AF@no.spam.mindspring.com.no.spam>,
Lyman Taylor  <lyman.taylor@no.spam.mindspring.com.no.spam> wrote:
>Lieven Marchand wrote:
>....
>> <off-topic>
>> BTW, why does LispWorks complain about the equivalent CL code? The
>> Hyperspec specifically allows users to augment the MAKE-INSTANCE
>> generic function.

>  The Hyperspec allows users to define CAR and CDR. 
>  That doesn't mean a prudent implementation might not warn
>  you or ask for confirmation before carrying that out. ;-) 

Huh?

In section 11.1.2.1.2 of the Hyperspec, you find:

11.1.2.1.2 Constraints on the COMMON-LISP Package for Conforming Programs
   
   Except where explicitly allowed, the consequences are undefined if any
   of the following actions are performed on an [12]external symbol of
   the COMMON-LISP package:
   
   1. [13]Binding or altering its value (lexically or dynamically). (Some
          exceptions are noted below.)
       
   2. Defining, undefining, or [14]binding it as a [15]function. (Some
          exceptions are noted below.)
     
   3. Defining, undefining, or [16]binding it as a [17]macro or
          [18]compiler macro. (Some exceptions are noted below.)

[...]

So I'd guess a (defun car ...) has undefined consequences.

>[...]

Kind regards,

Hannah.

[XP+F'up c.l.lisp]
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