Minutes of the 3rd IEEE Scheme Working Group meeting

[Chris Haynes <chaynes@iuvax.cs.indiana.edu>]

		IEEE/MSC/P1178 Working Group on Scheme

                Unapproved Minutes of the Third Meeting

			     7 July 1989
			  MIT, Cambridge, MA


SUMMARY

R4RS numbers accepted.

Group believes all major technical issues have been resolved in
preparation for submission of draft.

Next meeting at POPL '90.


ACTIONS

The meeting was called to order by Chris Haynes at about 9:45AM.  The
following attendance list was collected:

	Hal Abelson			MIT
	Bill Campbell			University of Mass at Boston
	William Clinger			University of Oregon
	Ken Dickey			Tektronix
	Dan Friedman			Indiana University
	Dick Gabriel			Stanford University
	Chris Hanson			MIT
	Chris Haynes			Indiana University
	Sidney Marshal			Xerox
	Tim McNerney			ILA
	James S. Miller			Brandeis University
	Eric Ost			Indiana University
	John D. Ramsdell		The MITRE Corporation
	Guillerimo J. Rozas		MIT
	Gerald Jay Sussman		MIT
	Mitchell Wand			Northeastern University

1. The agenda was amended; the changes are reflected by the minutes.

2. John D. Ramsdell was elected secretary.

3. Minutes of the second meeting were accepted with no changes.

4. Differences from the last draft.

Chris Hanson described the changes to the draft introduce since the
last meeting.

Changes agreed on at last meeting:
   * "User Interface" appendix removed.
   * Restore `substring'.
   * Delete `with-input-from-port' and `with-output-to-port'.

Changes from R3.95RS:
   * Many small editorial changes.
   * Characters added to "extended alphabet" set: + - .
   * Added number section (pending outcome of third meeting).
   * Added description of "implementation error" in support of numbers section.
   * New description of:
	number->string
	string->number
	integer->char
	char->integer
	peek-char

5. Discuss the number section of the standard.

A long discussion followed, which continued until about 2:00PM (with a
lunch break).  This resulted in a much wider understanding and
appreciation of the exact/inexact distinction.  (In the process it was
clarified that non-numeric operations on numbers, such as storing and
retrieving them, are not allowed to affect their exactness.)

5.1 Moved and accepted: The editors will change wording in section
1.3.1 to clarify the notion of an implementation error.
Specific directions include, dropping the word "arbitrary" in
paragraph 3 and changing the following two sentences to read something
like: "When an implementation error is reported, the report must make
clear that an implementation restriction was violated. Implementation
restrictions are of course discouraged, but reporting their violation
is encouraged."

5.2 Moved and unanimously accepted: We accept the number section of
R4RS with some editorial changes.

5.3 Moved and accepted: We recommend that the R4RS authors rename the
procedure max to sup, and procedure min to inf.

5.4 Moved and rejected: If R4RS does not change the names of max and
min, P1178 should eliminate max and min.

5.5 Moved and accepted: Add expt to the list of procedures which
must return an exact result when given exact arguments (section 6.5.3).

5.6 Moved and accepted: Add an example showing the use of explicit
coercion of an inexact argument as an index of vector-ref.

5.7 Moved and unanimously accepted: The editors will add to the body
of the text the requirement that implementations must support a
minimal subset of numeric procedures and request that the R4RS authors
change the status to essential of any unessential procedure required
to support the minimal subset.

It was noted that the proscriptive wording (e.g., "shall", "must") in
appendix B.3) should be softened (e.g., "should").

The editors reaffirmed their intention to substantially extend
appendix B.3, including, for instance, a discussion of the
transitivity requirements for the numeric order and equality predicates.

6. R4RS status report

Will Clinger described the changes he expected between R3.95RS and
R4RS.  He promised a R3.99RS (R4RS without macro appendices) within a
month.  

* Add ... as a <peculiar identifier>.
* Change the branch cuts of some trig functions to be like Common Lisp's.
* Make char->integer and integer->char one-to-one.
* Return char-upper-case? to R4RS, which was dropped due to an editing error.
* Leave it unspecified as to whether the empty list counts as false.
* Change number->string description.

7. Moved and accepted:  We request that the R4RS authors add a
sentence encouraging that implementations support an international
character set, most likely ISO Latin 1 (ISO8859-1).

8. A move that ":" be change to not be an extended alphanumeric
character was not seconded.

9. Moved and accepted:  We request that the R4RS authors consider
making just list-ref (and not list-tail) essential.

10. A move to discuss changing the semantics of internal definitions was
not seconded.

11. Moved and accepted:  It is suggested that the next meeting of the
IEEE Scheme Working Group be on January 19, 1989, following the
Principles of Programming Languages conference in San Francisco, CA.

There was general consensus that at the next meeting the Working Group
could probably approve the draft standard for submission to the MSC
for public comment and balloting.  Therefore the draft to be
considered at the next meeting should be mailed to all those on the
Working Group mailing list no later than mid-November.

12. Moved and unanimously accepted:  The draft standard distributed at
the meeting (reflecting the changes detailed under item 4 above)
should be submitted to ISO WG-16 for consideration, with a brief 
cover statement to be drafted by Chris Haynes.

Dick Gabriel reported that ANSII asked X3J13 whether Scheme and Common
Lisp were distinct enough to justify two standards.  Bob Mathis
provided technical arguments convincing ANSII that they were distinct.

Meeting adjourned at about 3:30PM.


-- Minutes by John D. Ramsdell, edited by Chris Haynes