Path: news.daimi.aau.dk!jacobse
From: jacobse@daimi.aau.dk (Jacob Seligmann)
Newsgroups: comp.lang.beta
Subject: Re: BETA and X-Windows (was: Re: LISP and X-Windows)
Date: 26 Sep 1994 09:32:50 GMT
Organization: DAIMI, Computer Science Dept. at Aarhus University
Lines: 68
Message-ID: <3664g2$81s@belfort.daimi.aau.dk>
References: <35bn78$ms@belfort.daimi.aau.dk> <362dfc$84v@network.ucsd.edu>
NNTP-Posting-Host: sorbus.daimi.aau.dk

Matt Kennel (mbk@inls1.ucsd.edu) wrote:

> Jacob Seligmann (jacobse@daimi.aau.dk) wrote:
> > Peter da Silva <peter@Starbase.NeoSoft.COM> wrote:
> > > Jacob Seligmann <jacobse@daimi.aau.dk> wrote:
> > > 
> > > > AwEnv(# do (&label(# init:: (# do 'Hello world' -> label #) #)[]).init #)
> > > 
> > > [...]
> > 
> > It's a complex combination, and it's complex to read (especially when 
> > written as a one-liner, and even more so if you're unfamiliar with the 
> > terse syntax), but I still believe it is an excellent demonstration of 
> > BETA's orthogonality.
> 
> Orthogonal to my brain, certainly. ;-) 

:-)

> I'm a newbie---could you "deconstruct" this one-liner?

Sure, here we go:

The one-liner instantiates an object inheriting from the Athena Widget 
X11 environment [AwEnv (# ... #)] with the following action-part [do]: 
Create a new object and return its reference [&... and ...[]], then 
call the init-operation pertaining to that reference [(...).init], the 
new object being a specialized label-object [label(# ... #)] whose 
spezialization consists of a final-binding its virtual init-attribute 
[init:: (# ... #)] to perform an assignment to its label-attribute
['Hello World' -> label].

Succesively easier-to-read versions of the program would therefore be

   AwEnv (#
            hello: label(# init:: (# do 'Hello World' -> label #) #)
         do 
            (&hello[]).init
         #)

   AwEnv (#
            hello: @label(# init:: (# do 'Hello World' -> label #) #)
         do 
            hello.init
         #)

   AwEnv (#
            hello: @label
         do 
            hello.init; 
            'Hello World' -> hello.label
         #)

Actaully, the last version is significantly shorter than my original 
one-liner (especially if "hello" is replaced by simply "h"), but since 
it's not a single expression, I'm not sure if it counts...

I hope this helps!

/Jacob Seligmann
------------------------------------------------------------------------
Mjolner Informatics ApS             Phone:   (+45) 86 20 20 00 ext. 2754
Science Park Aarhus                 Direct:  (+45) 86 20 20 11 - 2754
Gustav Wieds Vej 10                 Fax:     (+45) 86 20 12 22
DK-8000 Aarhus C, Denmark           Email:   jacobse@mjolner.dk       
------------------------------------------------------------------------
                             BETA is betta'                             
------------------------------------------------------------------------