Subject: Re: &REST in VALUES type specifier
From: Erik Naggum <>
Date: Fri, 21 Dec 2001 09:36:36 GMT
Newsgroups: comp.lang.lisp
Message-ID: <>

* Alberto Riva
| Is the VALUES declaration in BAR legal?

  Yes.  (Although the term should be "conforming".)

| I saw it used in a numerical integration package, and it seems to comply
| with ANSI 4.4.22, although the explanation there is not very clear to me.

  Please note that entries in the dictionary clauses of the standard are
  not numbered.  You should be aware of this if you use Franz Inc's
  modified version of the text of the standard.  Please say "type specifier
  values" if that is the entry you are referring to.

| So my question is: is the above one the correct way of using &rest in a
| (values) specifier [...] or is the declaration wrong?

  It is the correct way of using &rest in a values type specifier.

| (meaning that both ACL and LW are non-compliant in different ways)

  File bug reports and complain vociferously about this.  Please let us
  know how the vendors respond.  The nervousness that results from not
  being able to use the specification to which the product purports to
  conform as the basis of your own coding and expectations is a major
  detractor from fully exploiting the language.  Just because nobody
  "needed" this sufficiently to make some vendor implement it so far, does
  not mean that it is not important.  The fact that they have "overlooked"
  such a feature means that other advanced and seldom-used features are
  probably also "overlooked", which again means that in order to feel safe
  about using a language that has a stable and unchanging standard and
  specification since 1995, one has to figure out where the "mainstream" is
  and make sure to stay within it.  That is _so_ not in the (Common) Lisp
  tradition.  We have advanced and seldom-used features in the language
  because they turn out to be very useful when they _are_ needed.

  Causing a conforming program to fail either compilation or execution is
  _really_ bad when it comes to declarations, because it teaches people not
  to use them and not to trust them, and this is communicated to other
  users, either by reading about problems like this on USENET now or using
  various search engines, or by dangerous "memes" that hang around much
  longer than the bugs do.  Like some incompetent C programmers feel _fear_
  around memory management issues because they have been bitten by memory
  leaks and problems that crashed their toy computers years ago, Common
  Lisp newbies will learn that using the full power of the language causes
  wrong results and other unexpected behavior.  This is detrimental to all
  the effort that went into creating a standard and a community around it.

  The past is not more important than the future, despite what your culture
  has taught you.  Your future observations, conclusions, and beliefs are
  more important to you than those in your past ever will be.  The world is
  changing so fast the balance between the past and the future has shifted.