Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!rochester!pt.cs.cmu.edu!theory.cs.cmu.edu!tsf
From: tsf@theory.cs.cmu.edu (Timothy Freeman)
Newsgroups: comp.lang.lisp
Subject: Re: Multiple Return values in Common Lisp.
Message-ID: <1004@theory.cs.cmu.edu>
Date: Wed, 3-Dec-86 16:32:17 EST
Article-I.D.: theory.1004
Posted: Wed Dec  3 16:32:17 1986
Date-Received: Wed, 3-Dec-86 22:26:34 EST
References: <1560@sunybcs.UUCP>
Organization: Carnegie-Mellon University, CS/RI
Lines: 37

In article <1560@sunybcs.UUCP> geller@sunybcs.UUCP (James Geller) writes:
>I don't consider myself a great expert on Common Lisp, but
>it seems to me that the idea of "multiple return values" of 
>Common Lisp is ill conceived.
...
>          (defun perimeter (rectangle-name)
>                 (+ (* (extent/1 rectangle-name) 2)
>                    (* (extent/2 #*) 2)))
>

This can be written reasonably well in common lisp already as follows:

(defun perimeter (rectangle-name)
   (multiple-value-bind (x y) (extent rectangle-name)
      (+ (* x 2) (* y 2))))

>         (defun square-of-hard-to-get-number (argument)
>             (* (long-computation argument)
>                (long-computation #*)))
>

This can be written in common lisp as follows:

(defun square-of-hard-to-get-number (argument)
   (let ((res (long-computation argument)))
      (* res res)))

Using the proper binding constructs makes common lisp (or any other
variety of lisp) much more pleasant to use.
--
Tim Freeman

Arpanet: tsf@theory.cs.cmu.edu
-- 
Tim Freeman

Arpanet: tsf@theory.cs.cmu.edu