[derdi]

I acknowledge that you also included your nice talking point in a paper you published on arXiv. Citing yourself doesn't convince me any more of the credibility of this argument.

> is there even the slightest doubt about the importance of standards when building and operating giant particle accelerators

The particle accelerator application is a checker for existing JSON config files. The accelerator is already running with those files. The proposed project is in an early stage. The checker will add more assurance, which is nice. The checker's author does not talk about the importance of warranties or standards. The checker could just as well be implemented in some non-ISO dialect as long as that dialect has a reliable specification and implementation.

So yes, there is the slightest doubt.

Edit: BTW, your oncology paper heavily uses CLP(Z), which does not have an ISO standard, so your argument is... The base language must be standardized, but arbitrary nonstandard extensions are OK? Please clarify as I've probably misunderstood.

[triska]

> CLP(Z), which does not have an ISO standard

CLP(FD/Z) is a candidate for inclusion in the Prolog standard: Several Prolog systems provide it with notable commonalities in features, it fits perfectly into the existing language, and it follows the logic of the standard including its error system. It can even be implemented within Prolog, provided a few basic features are present in a Prolog system. For instance, the CLP(Z) system I provide and which is used in the paper runs with little modifications already in several different Prolog systems, including SICStus, Scryer and Trealla. CLP(FD/Z) is an admissible extension of the existing standard:

    5.5 Extensions

    A processor may support, as an implementation specific
    feature, any construct that is implicitly or explicitly
    undefined in the part of ISO/IEC 13211.

This is completely different from modifications of the standard that do not fit at all into the standard. For instance, interpreting double-quoted strings differently from what the standard prescribes is not an extension in the sense the standard defines it, but a modification of the standard.

In addition, Scryer Prolog has an execution mode where all its extensions are turned off. This is called a strictly conforming mode, and is also prescribed by the standard:

    5 Compliance

    5.1 Prolog processor

    A conforming Prolog processor shall:

      ...

      e) Offer a strictly conforming mode which shall reject
      the use of an implementation specific feature in Prolog
      text or while executing a goal.

In Scryer Prolog, the strictly conforming mode is the default execution mode.

Regarding the other points you mention: Even though it may sound easy to say "as long as that dialect has a reliable specification and implementation", I know no such system that exists, and what I see from systems that do not adhere to the Prolog standard makes me doubt that such a thing is possible. The systems that do not follow the standard often have elementary syntactic problems, such as reading a Prolog term that they themselves emit into a different Prolog term, a recipe for disaster and unacceptable in every domain I know.

[derdi]

> For instance, interpreting double-quoted strings differently from what the standard prescribes is not an extension in the sense the standard defines it, but a modification of the standard.

Agreed, but also minor as you can and should set the double_quotes flag, otherwise your program doesn't have portable semantics even among ISO Prolog systems.

> Even though it may sound easy to say "as long as that dialect has a reliable specification and implementation", I know no such system that exists, and what I see from systems that do not adhere to the Prolog standard makes me doubt that such a thing is possible.

Of course it is possible to program against the quirks of a given implementation. That's what you yourself are doing with your CLP libraries. As you note, your main target has different quirks from other targets.

More broadly, Scryer itself demonstrates that it's possible to program against a programming language that doesn't have an ISO standard but does have a good enough specification and an implementation that adheres to that specification.

> The systems that do not follow the standard often have elementary syntactic problems, such as reading a Prolog term that they themselves emit into a different Prolog term, a recipe for disaster and unacceptable in every domain I know.

You're painting with a very broad brush here. What implementations, and what kinds of terms? If your examples involve infix dot, that would be the kind of term nobody uses and nobody should use in modern Prolog, as you well know. Some of these syntactic problems only appear if you go looking for them. Minor syntactic annoyances will be caught in testing.

I agree that such things are bad, but they are knowable, controllable, and quite probably much less relevant in practice than you suggest.

Very very tangentially: The company I work for is very serious about its software supply chains. If we want to use external software for development, we must apply for permission. For that permission, actual programmers and lawyers trawl through the code and licenses and documentation. Scryer's license file lists one copyright holder, and there are many source files without copyright headers, and then there are many source files with copyright headers that name another copyright holder. Our lawyers would not allow us to touch such a system. If you're serious about promoting Scryer as a serious Prolog for serious use, you might want to consider cleaning this up.