Re: Remarks on SWI 7

On Nov 26, 2013, at 19:10, Ulrich Neumerkel <[email protected]> wrote:

> What I do know for sure is that this system is no longer Prolog. […]
> 
> All that said, let us not forget the breakthroughs and victories of
> SWI in the last years: occurs_check, the ingenious algorithm for
> unify_with_occurs_check/2 with infinite trees […]

I would like to add my voice to this.  

I am interested in being able to use „hard-core” Prolog for various projects, which are sometimes quite large (tens of thousands of lines) and may stretch the limits of the language (circular terms are a case in point).

Some five years ago I decided that SWI-Prolog is the best implementation for my needs (for the reasons mentioned by Ulrich, and others), and since then I have been truly happy with it, though the impressive speed with which it was being improved and extended was not only a source of frequent pleasant surprises, but occasionally also a cause for some concern.

Now SWI-Prolog seems to be becoming a new language.  It might be a better one, for all I know.  There might even be a need for it, though the evidence seems scanty so far.  But I am very much afraid that it might soon evolve to a point where it is no longer Prolog: that „traditional” flag is likely to become more and more of a burden, and command less and less attention (even Jan’s very considerable talents and energy are necessarily limited).

It would be a great pity if things turned out that way.  To my mind, this is truly an _excellent_ implementation of Prolog, and Prolog — with all its warts — is one of the few truly great programming languages!


[A cautionary tale: during the course of this year I found out that there is no longer a viable extant implementation of standard Pascal (another great language!).  It was subjected to the death of a thousand cuts.  For example, the seemingly innocuous addition of an unsigned integer type effectively destroyed the usefulness of range types.  Language design is much harder than any of us realises.
]


Well, this is just an expression of concern from an old-timer.  Jan has the right to make his own choices, of course.  I can only express my gratitude for the ride he has given us all so far.

— Feliks