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From: quale@saavik.cs.wisc.edu (Douglas E. Quale)
Newsgroups: comp.lang.misc
Subject: Re: The powerlessness of Lisp
Message-ID: <1991Mar28.164024.21829@daffy.cs.wisc.edu>
Date: 28 Mar 91 16:40:24 GMT
References: <16060:Mar2515:41:5691@kramden.acf.nyu.edu> <1991Mar26.165516.13035@daffy.cs.wisc.edu> <26146:Mar2804:56:5791@kramden.acf.nyu.edu>
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Organization: University of Wisconsin -- Madison
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The original challenge was so short I'll repeat it:

In Common Lisp,

(defun compose (f g)
  (lambda (&rest) (funcall f (apply g &rest))))

I think it looks better in Scheme,

(define (compose f g)
  (lambda x (f (apply g x))))

These definitions use dynamic typing to obtain polymorphism.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

And now Dan's response:


In article <26146:Mar2804:56:5791@kramden.acf.nyu.edu> brnstnd@kramden.acf.nyu.edu (Dan Bernstein) writes:
>Enclosed is another copy of the first article, since you didn't respond
>to any of my offers via email. This qualifies you as a royal asshole, by
>the way. Also enclosed for completeness are references to your first two
>articles implying that my compose() didn't work, and, just in case, one
>of the intermediate articles that you lied about.

Probably mail isn't working on this machine correctly.  I bear some
responsibility for that, but I am content to let the judgement of which of us
is a royal asshole to the readers of this newsgroup.

>
>The interested reader (I doubt there are any) will note that my
>compose() nests properly, while Doug has said repeatedly that it
>doesn't. As I recall, he also claims to have been reading comp.lang.misc
>for more than three months.
>
>> You bristle when asked for any evidence that what you're saying isn't just
>> hot air.
>
>Yes, I do, as the challenges come from a perverting pain in the butt.
>I don't believe I have left any of your ``questions'' unanswered; I do
>hope that you learn some civility before you have the nerve to show your
>userid again in this newsgroup. If you claim once more that my compose()
>doesn't nest properly, or that I have been reticent in providing
>evidence that it does, I will feel no compunction in thrashing you in
>public for the next twenty mistakes you make. Don't take this as a
>threat, though; I don't want you to tell the truth until you understand
>that it really is the truth.
>
>---Dan

And Dan gives a pathetic attempt to code compose in C.

Naturally his compose is not polymorphic, a key advantage of dynamic typing
that was the whole point of this exercise.  That point was specifically
mentioned in the challenge since I figured Dan would try to worm out of it --
support for genericity is weak in C.

As a parting thought, how long is Dan's nonpolymorphic compose compared to the
fully polymorphic lisp versions?  Seems like his code is infinitely less
capable and well over three times longer.  What a surprise.

Go ahead Dan.  Thrash me in public.  You'll only make more of an ass of
yourself than you already have, if that's possible.  I'm still waiting for a
polymorphic compose in C.  That was quite clear in my post, but I'm saying it
again since you seem to have trouble with English.

-- Doug Quale
quale@saavik.cs.wisc.edu