A rapid application development system featuring an IDE, debugger, linker and a strongly typed Prolog native code compiler, known informally as VIP. Versions 5.x could notably cross compile to DOS, OS/2 and MS Windows 16 bit targets in addition to 32 bit OS/2 and MS Windows GUI and text mode targets with almost full source compatibility, in addition to the ability to compile Linux and SCO Unix text mode applications. Sadly with version 6 and newer support for all development host and targets other than 32 bit Microsoft Windows NT derivatives was dropped although more modern versions have added 64 bit Windows as a targets as well.
As for Visual Prolog as a programming language it is a strongly typed version of Prolog, best described as almost a hybrid of Prolog and Modula 2. In some ways it strangely reminiscent of the more modern programming language Mercury that took a similar path of Wirth family/Prolog family language hybridisation to getting a usable compiled code out of a Prolog system that otherwise would be interpreted. The main difference being that the VIP system is a bona fide business application development system with RAD generators, debuggers and everything else you need to ship a working code while like so many of the Unix derived tools used today, just getting Mercury to compile is a pain involving hops and intermediate C compilers, you can forget about debugging and rapid GUI development.
See also: PDC Prolog
Version 4 brought a name change to Visual Prolog and some changes to the language, this may have been necessary in part since Prolog and traditional GUI's are not a natural fit, Prolog wants to go recursive in the background at every given opportunity while a GUI wants the back end of the program to wait for any input it may have. The GUI part of the development system was improved in particular. With Version 4.1 released in 1997 there was a huge improvement in the support for 32 bit OS/2 with improvements in the GUI front libraries and back end as well, although the Windows part of the system remained 16 bit.
Visual Prolog version 5 was delivered in January 1998 and bought with it harmonisation of all the separate VPI 16 and 32 bit versions into one cross platform toolkit supporting text mode development on OS/2, Windows, DOS, SCO Unix and Linux/386 and GUI development on OS/2 and Windows. But otherwise changes from 4.1 were primarily internet related and back end improvements, the compiler itself was improved, the system gained a debugger and a new flexible linker was introduced that supported Unices as well as the traditional x86 operating systems meaning that you no longer had to use a native linker or C compiler to deliver compiled applications for the supported Unices.
With version 5.1 the company started to offer a special cut-down version of the system called simply "Teach Yourself Prolog" that was intended as an introduction to the system and Prolog in general and was available from their homepage as a download or for a nominal fee as a CD disk, prior to this the company had offered a free "1st Step version" of the Windows 16 bit compiler and time limited demos. With version 5.2 they started to offer a "Personal Edition" of VIP that was available as a CD that contained the full system but would only compile programs that started by displaying a "No commercial usage clause" before the main program ran, and again was sold for a nominal fee to cover postage and packaging fees. A little later the company started to offer the a cut down version as a download, with more recent versions the full "Personal Editions" are no longer available but a cut-down version with fewer functions and libraries has been offered as a free download.
- Last OS/2 version: Visual Prolog 5.2
- Version 5.1 is the last version that contains support for old Borland Graphics toolkits.
- Latest Windows version: 8.0 (build 801)
- Commercial software. OS/2 version discontinued
- Author: Prolog Development Center (PDC)
- Polynomial-Time Effectiveness of Pascal, Turbo Prolog, Visual Prolog and Refal-5 Programs
- Logic Programming In Native OS/2 Environment - Gregory Bourassa - SCOUG - 1998 Slides
- Visual Prolog 5.2 discussion forum
- Real world applications
- Carsten Andersson: A Prolog Implementation of an automated Neural-Network for Diagnosis of Rotating Machinery
- Development of a analysis system for companies financial statements analysis - Balance Consulting - 1998
- The Practical Application of Prolog - From AI Expert 1993