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Re: [Chicken-users] The predicate "atom?" considered bizarre

From: felix winkelmann
Subject: Re: [Chicken-users] The predicate "atom?" considered bizarre
Date: Fri, 1 Sep 2006 08:59:34 +0200

On 8/31/06, John Cowan <address@hidden> wrote:
While messing around with some stuff in Paul Graham's paper "The Roots
of Lisp" I was quite surprised to find that Chicken's "atom?" predicate
returns #f on the empty list.  This is the documented behavior.

This is contrary to historic practice from Lisp 1.5 through Common Lisp.
(Of course that is partly because () = NIL in that tradition, and NIL
is a symbol.)  R1RS was the last Scheme standard to specify ATOM, and
it had the same semantics then.

Why was this changed?  Can it be fixed?

I have changes this. Note that "atom?" is now equivalent to



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