Path: utzoo!attcan!uunet!samsung!zaphod.mps.ohio-state.edu!wuarchive!usc!bbn.com!sboisen
From: sboisen@bbn.com (Sean Boisen)
Newsgroups: comp.lang.lisp
Subject: scope/extent interaction with flet and load
Message-ID: <60375@bbn.BBN.COM>
Date: 26 Oct 90 15:54:24 GMT
Sender: news@bbn.com
Distribution: comp
Lines: 36


Scenario: assume a file foo.lisp which contains the following single form.

	(print (+ 1 2))

What i expected to see when executing the following

> (flet ((+ (a b) (cons a b))) (load "foo"))

was something like
(1 . 2)

Instead (at least under Lucid and Allegro on a Sun) i see 

3

In other words, my flet "redefinition" of + wasn't in effect when the
file got loaded, even though it seems to me the loading is inside the
scope of the flet, according to the rules in CLtL. Can somebody
explain to me why this behavior is correct (assuming it is)? 


(This is of course a silly example, for illustrative purposes: what i
*really* want to work like this is a macrolet, because i have a big
file containing macro forms, and i want to load this file with a
slightly altered macro definition, without trashing the existing macro
definition. That seems to me like just what macrolet was designed for,
but i'm frustrated that it doesn't work: i get the existing macro
definition, not the new one i've created with macrolet. Then i
discovered that flet has the same property, which makes it look like
that's the way things are supposed to work. Extra credit if you can
tell me how to accomplish my original intent!)
--


Sean