ISO/IEC JTC1 SC22 WG17 Minutes via Zoom
Date of meeting: 2025-06-02
Time of meeting: 16:00 - 18:10 UTC

Ad 1. Greeting and introduction of participants, administrativa

WG17 members:
Klaus Däßler (Germany)
Manuel Hermenegildo (Spain)
Jose Morales (Spain)
Mark Thom (Canada)
Markus Triska (Austria)
Johan Ponin (France)

Ulrich Neumerkel (convener)

Invited non-member experts:
Kaue Hunnicutt Bazilli (Brazil)
Fred Mesnard (France)

Ad 1.1, minutes of 2024 meeting N301 were approved.

Ad 1.2 Unicode characters in quoted characters of Prolog text (DTS
13211-4)

An initial set of test cases has been made available and was
discussed.

Ad 1.4 Retaining clause numbering in existing standards.

Resolution R1

WG17 asks JTC1 to make an exception to subclause renumbering and
hanging paragraphs in existing standards.  Most notably, the syntax
definition of term (6.3 Terms IS 13211-1:1995) is spread over 16
production rules for the same non-terminal spanning hanging paragraphs
and over 11 subclauses. A renumbering would unavoidably lead to
confusion thereby contravening the purpose of standards as a reliable
reference.

Unanimous.

Ad 2.1 Recent progress in Prolog systems

On reviewing new conformity tests #327 up to #337,
no issues requiring an immediate reaction were identified.

Ad 2.2 Syntax extension double bar

Daniel Cabeza was identified as the original inventor in CIAO-Prolog.

Resolution R2

WG17 accepts to use the double bar notation as an extension to term
syntax only after double quoted lists (6.4.6) (option 1) and rejects
to use bar token instead of bar (option 2).

Unanimous.

Ad 2.3 Comparison of handling (:-)/1 and (:-)/2

The table was discussed (Action item 2024). No disagreement.

Ad 2.4 DCG extension phrase//2 and phrase//3

The need for these extensions to ensure portable code was discussed.

Ad 2.5 Syntax extension digit separators

Resolution R3

WG17 accepts digit separators as an extension with digit separators as
a single underscore (option 1), optionally followed by layout chars
(option 3) and optionally followed by layout text (option 3).  WG17
rejects single spaces as digit separators (option 5), multiple spaces
for decimals, octals and binary (option 6), and layout chars for
decimals, octals, and binary (option 7).  WG17 remains undecided about
multiple underscores (option 2).

Unanimous.

Ad 2.7 crypto_data_hash/3


The current definition was reviewed.  Due to increased urgency in
privacy, there was interest in a portable Prolog reference implementation.

Ad 2.10 Further corrigenda

https://www.complang.tuwien.ac.at/ulrich/iso-prolog/stc#60 and #61
were reviewed. No issues requiring an immediate reaction were identified.

Ad 3 Forthcoming events:

2025-09-12..13: Prolog Improvement Proposals (PIPs) Workshop Rende, Italy.

2025-11-13..14: Scryer meetup Düsseldorf, Germany.

Meeting adjourned at 18:10 UTC.