Open Prolog Home Page



About Open Prolog

Open Prolog is an Apple Macintosh implementation of Prolog. It is postcardware, copyright © Mike Brady 1994-2005. Download it from here.

Open Prolog supports many of the features of Prolog as defined by the ISO standard, which is largely based on 'Edinburgh' Prolog. Definite Clause Grammar notation is supported. The 'logical' assert and retract semantics of Lindholm & O'Keefe are implemented. Open Prolog supports disjunctive calls, negation, if-then and if-then-else according (we believe) to the ISO Prolog standards. In particular, the handling of cuts complies with that specified in the standard. Open Prolog also supports program-originated catch-and-throw exception handling somewhat similar to ISO Prolog.

Real-number arithmetic and internal database predicates are not supported.

Last Call Optimisation (often called Tail Recursion Optimisation) and first argument indexing are implemented, mainly to detect determinacy so as to improve memory utilisation.

Open Prolog is not copy protected.

System & Memory Requirements

Open Prolog runs on Apple Macintosh machines running Mac OS 7.5.5 and later, and runs in the Classic environment of Mac OS X.

Open Prolog will run in a memory allocation of 4 Megabytes. 16 Megabytes is recommended.

All memory management and garbage collection is automatic. However, the name table is not garbage-collected, so it's possible to overflow it.

Benchmark Speed


Processor & Clock Speed

Naive Reverse Benchmark Speed

iMac (Slot Loading iMac), Mac OS X 10.0.3, Classic mode 350 MHz G3 650 KLips

PowerMac 9500 (120MHz), System 7.5.2

120 MHz 604

190 KLips

Performa 5300, System 7.5.1, Speed Doubler

100 MHz 603e

130 KLips

Performa LC630, System 7.5.1

33 MHz 68LC040

60 KLips

Performa 5300, System 7.5.1

100 MHz 603e

25 KLips

PowerBook 140, System 7.5.1

16 MHz 68030

9 KLips

Macintosh Plus, System 7.1

8 MHz 68000

1.9 KLips

Using Open Prolog

Open Prolog is postcardware - that is, you may use it free of charge on condition that you send the author a postcard from where you live. You can download it from this site, or from many shareware sites around the world. No responsibility is accepted by the author for any consequences of using, or attempting to use, Open Prolog.


Download Open Prolog

Online Documentation

  • This tutorial will help you to begin using Open Prolog


Maintained by Mike Brady. Updated March 31, 2005