Re: SWI-Prolog is open source

On 12/04/2013 03:00 PM, Ovnicraft wrote:
>> - Jan is free to evolve his Prolog implementation in any direction that he
>> >finds best for his goals
>> >- Jan is free to make (what other people perceive as) mistakes
>> >- Jan is under no obligation to implement any standards
>> >- Jan is under no obligation to ditch or backtrack on his design decisions
>> >for his work
>> >
> I am not agree with your conclusions, so in OSS world community decide what
> changes are better or not, in fact be OSS is the best choice to get high
> quality software.
>
> Community, users, always has the chance to judge any implementation because
> everybody has access to code, OSS is about community knowledge, all of us
> are learning together (fast/slow).

SWI-Prolog as a project doesn't have a process to make decisions about
its future other than me taking them. Note that the new stuff didn't
fall out of the blue sky. I started thinking and talking about this at
ICLP last August. I've made the initial prototype available to a group
of about 12 users. This lead to some changes. After V7 became the
official development version, several things have been modified thanks
to input on this list.

The general line of thinking has people strongly in favour and strongly
opposed. SWI-Prolog cannot satisfy both. Restricting to strict ISO
extensions would criple the syntax and functionality. The list changes
that are required both to get new syntax and to deal better with untyped
dynamic data structures must apply to the whole system and must be
installed very early in the initialization process of the system.

Based on my own experience and interacting with users, in particular
wrt. using Prolog as a language for programming applications, I believe
that V7 is the way to go.

Surely, I have made wrong decissions and there will be further changes
to the new features before 7.2.0 (stable). It is always hard to predict
the future, but I do not expect 7.2.0 soon.

As Michael Ben Yosef correctly concludes, you will be able to run the
core Prolog system and some of its packages forever using --traditional,
but new libraries and tools will increasingly rely on the V7 features.
Similar as you can only run some of the libraries and tools after
enabling the ISO compatibility flag.

In conclusion, if you rely on SWI-Prolog, stick with 6.6.0 for your
operational application. At the same time, give 7.7 a go, see what
breaks and report on this, so we can try to work out a solution. If you
want ISO Prolog, examine Ulrich's evaluations and pick your system.

	Cheers --- Jan