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From: pf@islington-terrace.csc.ti.com (Paul Fuqua)
Newsgroups: comp.lang.lisp
Subject: Re: NCONC & Functions
Message-ID: <100049@ti-csl.csc.ti.com>
Date: 29 Nov 89 18:36:23 GMT
References: <31792@news.Think.COM>
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    Date: Tuesday, November 28, 1989  9:56pm (CST)
    From: barmar at think.com
    Subject: Re: NCONC & Functions
    Newsgroups: comp.lang.lisp
    
    In article <464@ntcsd1.UUCP> mps@ntcsd1.UUCP (Michael Smith) writes:
    >	>(DEFUN foo1 () '(a b c))
    >	>(NCONC (foo1) '(d e f))
    
			       A compiler would be justified in storing
    constant data structures on read-only pages, so the above NCONC *could*
    result in a core dump!

In fact, the Explorer compiler will put such constants into read-only
areas when compiling a file (just compiling a function won't do it).
For some reason, it causes lots of user confusion, so around Release 3
we modified the message for write-into-read-only errors to add the
phrase "the code was probably trying to modify a program constant" when
appropriate.

Paul Fuqua                     pf@csc.ti.com
                               {smu,texsun,cs.utexas.edu,rice}!ti-csl!pf
Texas Instruments Computer Science Center
PO Box 655474 MS 238, Dallas, Texas 75265