After discovering Borland's Turbo Pascal in the late eighties and programming in that for some time, I switched to Borland's Turbo Prolog - which was rather like TurboPascal - and programmed quite a lot in that, and also in its successor PDC Prolog.
In fact Turbo Prolog was Borland's implementation of what later became PDC Prolog. Both incorporated the same idea: To translate Prolog-code into C, and compile that. This worked quite well, and I wrote rather a lot of code in Turbo Prolog, including a hypertext-editor, for which PDC produced a special compiler around 1990 that I bought.
At the time this hypertext-editor - called Edith - was at the forefront of technology: It had indexes, long filenames, the ability to start programs and return etc. and I used it as my personal text-editor for several years, simply because it was the best for my purposes, and I could do many things with it I couldn't do with any other editor running with DOS.
All this was before the days of the internet and before Windows95 and later. I tried several other Prologs such as LPA Prolog but at the time - 1990-1995 - PDC Prolog met my programming needs best.
Then the internet and html were invented, and there rapidly appeared WYSIWYG-editors for html to which I switched, since this was much more pleasant to the eye than DOS-programs, and also more useful and productive.
PDC Prolog was for DOS, but got revamped for Windows as VIP Prolog or Visual Prolog. I bought an early release of that, but didn't much like it, and switched for programming for Windows to Delphi, which was Borland's followup of Pascal.
PDC Prolog at this time of writing - May 2007 - still exists and still develops Visual Prolog, but I haven't looked at it after Visual Prolog 6.0, in part because I didn't like it much, and in part because it is neither open source nor free, and I am much in favour of programming with free open source.
Also, it seems to me that these days the sort of search-engine programming at which Prolog excels (backtracking) can be written just a well in another high-level language.