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From: jonl%kuwait@lucid.COM (Jon L White)
Newsgroups: comp.lang.scheme
Subject: Destructuring / pattern-matching (was: Multiple return values)
Message-ID: <9104151943.AA10970@kuwait>
Date: 15 Apr 91 19:43:04 GMT
References: <9104151633.AA16272@garlic.Stanford.EDU>
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 51

re:  It just takes one conservative member of the team to 
       demand that no macros be used for trivial extensions; and this rules 
       out the one-liner JONL-BIND in favor of the three-lines involving LET, 
       DESTRUCTURING-BIND, and MULTIPLE-VALUE-BIND.

    I sure hope they don't feel the same way about procedures.  :-)  If not, I
    think that they should consider for a while why procedural abstraction is
    acceptable, but abstration using macros is not.   . . . 

I wouldn't be so sure about this.  The problem is one of complexity --
current buzzword: MegaProgramming -- and not of whether the interface
is procedureal, functional, meta (macros and "hooks"), or what-not.


re: The logical extension of this argument is CommonLisp.  Dump so much in 
    the language that noone can ever imagine extending it in any way.  If 
    you do find a way, just go to the CL standard committee and they will 
    add it to the next release.  :-)

Since you mention the word "release", I must assume you are referring to
the history of the MIT Lisp Machine project, and its notable commercial
follow-on (Symblics), wherein new and often incompatible "releases" 
occured nearly every six months.  Indeed, in the time period between 
1978 and 1985, one could substantiate the charge you make; but the X3J13 
committee (for CL standards) has yet to make a "release".

So how did Common Lisp come by the reputation you mention (I am, sadly,
acknowledging a "ring of truth" if not complete factuality to your 
comment)?  First, recall that Common Lisp is the evolutionary extension
of a series of Lisps beginning with the historic "1.5" at MIT nearly
30 years ago  -- progressing through CTSS Lisp  (ever hear of the 
"Compatible Time Sharing System?"), PDP6 Lisp, PDP10 MacLisp,
LispMachineLisp, SPICELisp, and so on.  A bit of middle-aged fat is 
beginning to show.

But perhaps more importantly is the influence during the early 1980's
of the idea that "Lisp" is the world's best programming _environment_.
A parallel with the Unix world is (1) a computer language usually
known by it's one-letter name, (2) an enormous non-standard set of
library routines and utilities [although some standards bodies are 
addressing this question.]  It's probably too late for Common Lisp ever 
to go back to a pure "kernel" language idea, but some of the "stock 
hardware" vendors of Common Lisp implementations have indeed been 
trying to unbundle pieces of the MonsterLispMachine inheritance from 
the required part of a Lisp system.  [Contact me privately for details
on what is happening; or, contact your favorite vendor's salesman;
but please try to resist any intrusion of a "Marketing Blitzkrieg"
into this email list, as has already happend on some other lists.]


-- JonL --