ISO/IEC JTC1 SC22 WG17 Minutes via Zoom
Date of meeting: 2022-06-06
Time of meeting: 17:00 - 18:09 UTC

1. Greeting and introduction of participants, administrativa

WG17 members:
Klaus Däßler (Germany)
Stefan Kral (Austria)
Markus Triska (Austria)
Manuel Hermenegildo (Spain)
Mark Thom (Canada)
Ulrich Neumerkel (convener)

Invited non-member experts:
Adrian Arroyo Calle (Spain)
Jose A. Riaza (Spain)
Yukata Ichibangase (Japan)
Jose Morales (Spain)
Neng-Fa Zhou (US) for 10 minutes

Ad 1.1 Minutes of 2021 meeting N284 were approved.
Convener reports that NWIP for a TS of DCG passed.

Ad 1.2 Recent progress in Prolog systems.
In particular Scryer, Tau, Trealla improved as testified by e.g.
length/2.

Ad 1.3 Prolog 50.
ALP activities under prologyear.logicprogramming.org,
there will be a celebration on November 10th in Paris.
A short movie L'aventure Prolog about Alain Colmerauer was created.

Ad 1.4 Prolog archive.
The archive by Paul McJones collects documents and artefacts related
to Prolog history.  Currently, some systems are not represented.
Convener encourages submission.

Ad 2 Further corrigenda.

N289 (stc) was briefly reviewed, no items requiring an
urgent reaction were identified.

Ad 3 Prolog prologue.

Progress with length/2.  The difficulties related to non-terminating
queries like #22 length(L,L) were resolved by
either looping or producing a resource error (7.12.2 h).

nth/3, nth1/3 and nth0/3 were only briefly mentioned.

New entry call_nth/2 N288 was discussed. The new format for examples
(n.n.n.4) now features questions using answer descriptions being
valid Prolog terms.  This avoids verbiage in examples.
An example of IS 13211-1 8.16.2.4 not discussed in the meeting

atom_concat(T1, T2, 'hello').
   Succeeds, unifying T1 with '',
      and T2 with 'hello'.
   On re-execution, succeeds,
      unifying T1 with 'h', and T2 with 'ello'.
   [...]

is now:

?- atom_concat(T1, T2, 'hello').
   T1 = '', T2 = hello
;  T1 = h, T2 = ello
;  ... .

See also number_chars_quad.pl, length_quad.pl, 13211-1-Prolog_quad.pl.

Ad 4 DCG progress.

N292 uses better example syntax.

Ad 5

In addtion to the annual meeting on the first Monday in June, a real
meeting will take place in Vienna, October 27th-29th.

Meeting adjourned at 18:09 UTC.