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From: kwh@bentley.UUCP (KW Heuer)
Newsgroups: net.lang.apl
Subject: Re: Nested arrays
Message-ID: <861@bentley.UUCP>
Date: Tue, 27-May-86 14:24:48 EDT
Article-I.D.: bentley.861
Posted: Tue May 27 14:24:48 1986
Date-Received: Thu, 29-May-86 02:40:59 EDT
References: <957@h-sc2.UUCP>
Organization: AT&T Bell Laboratories, Liberty Corner
Lines: 18

In article <957@h-sc2.UUCP> h-sc2!moews_2 writes:
>In article <834@bentley.UUCP> kwh@bentley.UUCP (KW Heuer) writes:
>>I find this one easiest to understand.  Enclose always returns a scalar of
>>(new) type "tree"; arrays are still homogeneous but the scalars in a tree
>>array may disclose to any object; the "standard scalar" of type tree (the
>>filler value for overtake or expand, corresponding to numeric zero and
>>character blank) is the enclosure of an empty tree.  This is the "grounded"
>>tree model....
>
>   Uh, but what exactly is the "empty tree"?  If we define
>   <scalar> ::= <number> | <character> | enclose(<array>)
>   <array> ::= n-dimensional array of (<scalar>)'s, n >= 0
>then there IS no empty tree --- every enclosure has an array inside it.

By "empty tree" I meant "zero-length vector of type tree."  The "standard
tree scalar" is  ENCLOSE 0 RHO ENCLOSE anything.  Sorry about the confusion.

Karl W. Z. Heuer (ihnp4!bentley!kwh), The Walking Lint