Newsgroups: comp.lang.apl
Path: watmath!watserv2.uwaterloo.ca!torn!utnut!utzoo!censor!geac!jtsv16!itcyyz!yrloc!rbe
From: rbe@yrloc.ipsa.reuter.COM (Robert Bernecky)
Subject: Re: APL2 vs VSAPL
Message-ID: <1993Apr11.191800.9510@yrloc.ipsa.reuter.COM>
Reply-To: rbe@yrloc.ipsa.reuter.COM (Robert Bernecky)
Organization: Snake Island Research Inc, Toronto
References: <9304071952.AA04015@unb.ca>
Date: Sun, 11 Apr 93 19:18:00 GMT

In article <9304071952.AA04015@unb.ca> Jeff Richards <jeff@AESYVR1.PWC.AES.DOE.CA> writes:
>>
>> From: jeff@math.uchicago.edu (Jeff Adler)
>> -----------------------------------------
>Does APL2 still rely solely on the Branch operator for flow of control or have
>they added anything along the structured line of programming to the language?


Unfortunately, APL still doesn't believe in control structures, in spite
of claims to the contrary by a number of posters here. Array semantics 
and adverbs do indeed reduce the need for explicit loops. HOWEVER, that need
is STILL there.

J, however, does have control structures. See the Bernecky & Hui paper
"Gerunds and Representations" in ACM SIGAPL Quote Quad, August 1991.

We propose (and Roger implemented in J) control structures in APL which
are merely adverbs (Operators to the unwashed), and thereby do not require
any syntactic changes to the language. Gerunds, functions treated as 
data, offer significant power (ability to compute on functions, for example),
and work well with these control structures. 

The structures we propose fit very nicely on top of existing APL. It merely
waits for some APL implementer to go do it.
BOb


Robert Bernecky      rbe@yrloc.ipsa.reuter.com  bernecky@itrchq.itrc.on.ca 
Snake Island Research Inc  (416) 368-6944   FAX: (416) 360-4694 
18 Fifth Street, Ward's Island
Toronto, Ontario M5J 2B9 
Canada
