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Visual Prolog Features

Visual Prolog 8 is the newest generation of the Visual Prolog logical programming language that might be used for creating industrial strength application for sthe Microsoft Windows platform.

It is a strongly typed object oriented programming language based on the Prolog programming language.

Language Features

The main characteristics/notions of the Visual Prolog programming language are:

The object system is constructed for loose coupling between a provider and a user.  Objects can only be accessed through interfaces, and interfaces are only loosely coupled to implementations.  Any class can implement any interface with or without inheriting implementation from other classes.

The combination of strong type check, no-need-for-pointer-arithmetic, and automatic memory management practically removed access violations.

Visual Prolog has a long reputation for not producing access violations. As one of our good users once said: That kind of errors is just not an option in Visual Prolog.  We intend to keep it that way and Visual Prolog 7 family is no exception from this principle.  Our goal is that you will have to interface to foreign code or insist on making pointer arithmetic to provoke access violations.

Algebraic data types, fact databases and pattern matching combined with non-deterministic search makes Visual Prolog very well suited for dealing with complex structured knowledge.

All Visual Prolog data except predicate values and objects have a human readable textual representation that can be written and read back into programs.

Integrated Development Environment (IDE)

Visual Prolog Integrated Development Environment (IDE)  is designed to make it easy, convenient and fast to develop, test, and modify applications written in Visual Prolog.

It might be especially useful in developing of large projects.

Please see Environment Overview for detailed information and screenshots.


The Visual Prolog compiler is a successor of the Turbo Prolog compiler created in 1980s that was the first Prolog compiler. Since that time the Prolog Development Center has been developing and improving its compiler. Currently Visual Prolog compiler is a powerful and efficient compiler that can:


Visual Prolog contains a powerful linker that can:


The Visual Prolog Development Environment contains a built-in graphical debugger that can:

Examples included in Visual Prolog

Both Visual Prolog Personal and Commercial editions include a number of example projects that demonstrate various Visual Prolog features.

The examples include samples corresponding to the online tutorials, which are found in the _tutorials subdirectory in the examples directory.

See also:

New features in Visual Prolog 10 build 1000.