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From: smc@mit-vax.UUCP (Stewart M. Clamen)
Newsgroups: net.lang.lisp
Subject: Re: Abusing "define" in Scheme... (car crashes?)
Message-ID: <73@mit-vax.UUCP>
Date: Sun, 25-May-86 19:41:40 EDT
Article-I.D.: mit-vax.73
Posted: Sun May 25 19:41:40 1986
Date-Received: Tue, 27-May-86 06:53:31 EDT
References: <13508@ucla-cs.ARPA>
Reply-To: smc@mit-vax.UUCP (Stewart M. Clamen)
Distribution: net
Organization: MIT, Cambridge, MA
Lines: 23
Keywords: Scheme, S&ICP, CAR

In article <13508@ucla-cs.ARPA> hydar@ucla-cs.ARPA (Dan Hydar) writes:
>
>     
>        Does anyone know if Scheme is defined such that ANY binding can be
>   changed or is there some set of functions/identifiers that can be (or
>   MUST be) prevented from being re-defined?
>
>        For instance --- are you able to do blatantly stupid things like:
>
>                        (define car  5)


As a matter of fact, redefinition of the PAIR abstraction (mainly CAR,
CDR, and CONS) is the subject of a number of examples in Abelson and
Sussman's _Structure_and_Interpretation_of_Computer_Programs_.
Exercises 2.3 and 2.4 ask the student to define a new implementation
for the "primitives" which preserve their functionality.

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