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From: feeley@chaos.cs.brandeis.edu (Marc Feeley)
Newsgroups: comp.lang.scheme
Subject: Kleene puzzle
Message-ID: <FEELEY.91Apr2224740@chaos.cs.brandeis.edu>
Date: 3 Apr 91 03:47:40 GMT
Sender: usenet@news.cs.brandeis.edu
Organization: Computer Science, Brandeis University, Waltham, MA, USA
Lines: 10

Here is a little puzzle for all Schemers: what is the shortest standard
Scheme program that writes itself on the current output port?  Note that
we are interested with what is PRINTED by the program and not the value of
the program itself (if this was the case the single character program 0
(or any other digit) would do the trick).  Here is one "self-printing"
program.  Is there a shorter one?

(let ((x '(write `(let ((x ',x)) ,x)))) (write `(let ((x ',x)) ,x)))

Marc -- feeley@cs.brandeis.edu