Newsgroups: comp.lang.apl
Path: watmath!watserv1!utgpu!news-server.csri.toronto.edu!torsqnt!jtsv16!itcyyz!yrloc!hui
From: hui@yrloc.ipsa.reuter.COM (Roger Hui)
Subject: Re: 'Locatives' in J
Message-ID: <1992Apr8.033326.96@yrloc.ipsa.reuter.COM>
Keywords: J locale locative
Organization: Iverson Software Inc.
References: <1992Mar30.102215.4967@watmath.waterloo.edu> <92090.153719HAC041@DJUKFA11.BITNET> <1992Apr2.072353.14016@yrloc.ipsa.reuter.COM> <1992Apr2.204836.13312@apollo.hp.com>
Date: Wed, 8 Apr 92 03:33:26 GMT


Mark Keil writes:

> Can locales only be saved workspaces?
> Will more than one workspace be able to be loaded simultanously?
> Just what is the J definition of a locale?
> What is the effect of using "_" in a name just for calrity?
> Does that establish a locale?
 
These questions are answered in Lesson 18 of "An Introduction to J",
which is shorter than the amount of network traffic on it:
 
  A name that includes an underbar (_) is a locative.  Names used in a
  locale F can be referred to in another locale G by using the prefix F
  in a locative name of the form F_pqr, thus avoiding conflict with 
  otherwise identical names in the locale G.
 
  The referent of a locative can be established in either of two ways:
 
  a) By assignment, as in F_pqr=. i. 5 .
 
  b) By saving a session in the manner discussed in Lesson 11; the names
  established in the session can thereafter be referred to by using the
  locale as a prefix in a locative name.  For example:
     names=. 4!:1
     copy=. 2!:4
     save=. 2!:2
     save <'TOOLS'
  1
     4!:55 names 3
  1 1 1
     TOOLS_copy <'TOOLS'
  1
     names 3
  +----+-----+----+
  |copy|names|save|
  +----+-----+----+
 
> Also, what are the plans for upcomming versions of J,
> and when are they likely to be available?
 
I prefer to discuss what is already available (because plans butter
no parsnips, a bird in hand is better than two in the bush, make no promises
you can't keep, ...).  The following are new since February 1992:
 
. Test scripts
. J for the PC386 system, which includes a DOS extender that provides a
  large workspace and large arrays in extended and virtual memory.

------------------------------------
Roger Hui, Iverson Software Inc., 33 Major Street, Toronto, Ontario  M5S 2K9
Phone: (416) 925 6096;  Fax: (416) 488 7559
