ISO Prolog works

Since 1995-06-01 the programming language Prolog has an ISO/IEC standard: 13211. Work is active since then and has regained momentum recently. If you are using Prolog or one of the hosted systems like CLP(FD) or CHR consider to join us in WG17!

But prior to joining, get and read the relevant document. You obtain it from your national member body for about USD 300. If you want to read it for your information (but do not need it for legal purposes) there is an extra rebate — only USD 30 as INCITS/ISO/IEC 13211-1-1995 (R2007) from the ANSI webstore. Please note that in many countries, there is a "nationalized" version of 13211-1 present. These versions differ by a slightly modified coversheet which makes it clear that the document is a national standard too.

Currently I am editing the following documents for ISO/IEC JTC1 SC22 WG17 (Document register, _{2011-06-29,
2011-01-27ii,
2011-01-27,
2010-09-20}).

Comments welcome! If you have questions about the standard, don't hesitate to ask! If you ask your questions publicly, also others will profit! Use either

comp.lang.prolog or
Stackoverflow with the tag [iso-prolog]

DTC3: Some (sketchy) material for preparing the next corrigendum.

Please comment!

Prolog prologue

The aim of this task is to identify and codify predicates for a prologue for Prolog. Current steps: length/2.

DCGs

A simple reference implementation
Documents in Lexington
Comments on DCGs draft 2010-07-18: Comments, July 2010.
Comments on DCGs draft 2010-04-01: Comments, June 2010.

Conformity assessment I: Syntax.

Current differences between implementations. Please contribute!

Draft Technical Corrigendum 2 (DTC2)

Incorporates N226, N225, N224 and partially N220 which all were partially based on N208. Submitted as ISO/IEC JTC1/SC 22 N4587 for DCOR ballot. Approved. Summary of voting N4603. Revised DCOR text submitted to ITTF for publication N4626. Published 2012-02-15 as ISO/IEC 13211-1:1995/Cor 2:2012.

Documents which where incorporated into DTC2:

A comparison of implementations of number_chars/2: This was the basis for fixing the error conditions.
Noname operators: Discussion paper, June 2010. Integrated into DTC2.
N226 An error class for unexpected instantiations: Action item in Pasadena. Delivered 2009-10-29 as N213, 2010-07-26 as N226, 2010-09-07 integrated into DTC2.
N225 Built-in predicates, current practice: Discussion paper, October 2009 - July 2010
N224 Evaluable functors, current practice: Discussion paper, October 2009 - July 2010
N220 Three steps to syntax harmony: Discussion paper, June 2010. Partially integrated into DTC2.
Syntax extension for |: Discussion paper, December 2009. This was the first step before N220.
Comments on DTC1: Comments mostly on the unresolved issues of DTC1 with considerations for their inclusion into DTC2.

post-N215 setup_call_cleanup/3

Action item in Udine, 2008. Prepared for Pasadena, 2009 as N211. Further refinements due to Pasadena resolutions and user feedback. Delivered 2009-10-29 as N215. As of SE 7, 2011-07-28, Java has try-with-resources which suppresses exceptions in the same way as setup_call_cleanup/3.

Drafts at WG17 site

Documents by others related to Prolog standardization:

ISO/IEC 10967 Language independent arithmetic (vl. LIA).

The working group for this standard is WG11, documents. LIA consists of 3 parts:

LIA-1 Integer and floating point arithmetic.

The first edition of 1994-12-15 is now considered outdated. Already LIA-2 and LIA-3 are no longer based on it. The most recent public draft is N514. As of 2011-01-07, there is an FCD under ballot (N 4593). Please note that the Prolog standard incorporates arithmetics according to a draft prior to 10967-1:1994. In the meantime, LIA-1 changed at least twice which makes following LIA-1 very difficult.

Normative references to LIA-1:

1st CD N92	1992-03	Language compatible arithmetic	1st CD	1991-03
2nd CD N110	1993-03	Language independent arithmetic - Part 1	2nd CD	1992-08
DIS N128	1994-03	Language independent arithmetic - Part 1	DIS	1993-09
IS 13211-1	1995-06-01	Language independent arithmetic - Part 1	IS 10967-1	1994-12-15

LIA-2 Elementary numerical functions.

2001-08-15

LIA-3 Complex integer and floating point arithmetic and complex elementary numerical functions.

2006-05-01

ISO/IEC 11404:2007, General purpose datatypes.

2007

Multi-Octet Character Set Handling

As a general remark note that in ISO/IEC 13211-1 there is a clean separation between characters and bytes. E.g., there is character I/O (8.12) and byte I/O (8.13). The processor character set PCS is implementation defined (6.5). This means, that conforming implementations may use ASCII, JIS, EBCDIC, ISO 8859-1, ISO 8859-5, Unicode, TRON, UTF-2000, GCS, GBK, GB 2312, GB 18030, or whatever other character set, provided

this character set fulfills the requirements of 6.5 and 6.6, and
the documentation accompanying the processor defines how the extended characters are mapped to Prolog syntax (6).

Some difficulties with understanding the problems related to Unicode are due to the so called Han unification. An account from the perspective of the TRON project.

How many Unicode characters are there?

Possible character classification schemes to consider:

For Unicode, by Richard O'Keefe, 2011-02-17.
SICStus Prolog.
Jekejeke Prolog. Previous Drafts: 2011-03-22.
Syntax of Haskell: 98, 2010.
Unicode: Unicode Identifier and Pattern Syntax, Numeric types

Modules

There is a module standard: ISO/IEC 13211-2:2000.

Current contributions: ECLiPSe ModuleSystem. Previous versions: 2012-03-29

ISO Prolog standard and standards compliance of Prolog implementations

Improving the ISO Prolog standard by analyzing compliance test results by Péter Szabó and Péter Szeredi. Some suggestions are part of TC1 and DTC2. Still some things to do for DTC3.

Is the ISO Prolog standard taken seriously? by Roberto Bagnara. [local copy]