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From: josh@klaatu.rutgers.edu (J Storrs Hall)
Newsgroups: comp.lang.apl
Subject: Interesting feature of J
Message-ID: <Sep.25.16.10.08.1990.1736@klaatu.rutgers.edu>
Date: 25 Sep 90 20:10:13 GMT
Organization: Rutgers Univ., New Brunswick, N.J.
Lines: 18

As far as I can tell (still without manual), J lacks what would
in Lisp be called "destructive operations".  I.e. you can't do 
the equivalent of APL's  A[B]<--C  .

You can do a=.c b}a  but the difference is that you haven't 
changed (part of) the contents of an object but have created
a new object and reassigned a name.  

Assuming my guess is right, that should make for a notably 
easier job for an optimizer trying to do structure-sharing;
it makes one suspect a compiler of some kind is planned.

(On the other hand, the rest of J seems designed to be as
hard as possible to compile!)

Anyone know anything definite?

--JoSH