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In this portion of our guide to programming languages and Prolog, we will focus on Logtalk, an object-oriented, logic-programming language that builds upon Prolog with features suitable for programming in the large.

In software development, programming in the large can involve programming by larger groups of people or by smaller groups over a longer period of time.

Designed by Paulo Moura, Logtalk first appeared in 1998, and it continues to be maintained and developed by the Logtalk community. As of this writing, the last stable release was on May 30, 2023.

The greatest influence over Logtalk, of course, was Prolog, from which it inherits its logic programming foundation. However, Logtalk was also influenced by Smalltalk, Objective-C, Java, and C++.

Logtalk is designed to extend and leverage Prolog with a strong emphasis on portability. It provides modern code encapsulation and code reuse mechanisms while enhancing predicate semantics. Implemented as a trans-compiler, Logtalk can use most modern and standards-compliant Prolog implementations as a backend compiler.

Logtalk is distinguished by its multi-paradigm nature. It supports modules for organizing code into separate units, prototypes for defining reusable templates, classes to enable object-oriented programming, protocols (interfaces) to define common behavior, categories (components and hot patching) to enhance code reuse, event-driven programming for handling asynchronous events, and high-level multi-threading programming to facilitate concurrent execution.

Code encapsulation, code reuse, and improved predicate semantics were among the design goals of Logtalk.

It emphasizes encapsulation, allowing developers to hide implementation details and expose only the necessary interfaces. The language provides mechanisms for reusing code across different contexts, and it refines Prolog's predicate semantics, improving intuitiveness and predictability.

Modularity, object-oriented features, and portability are among Logtalk's greatest strengths. Its module system promotes the clean separation of concerns, and its use of classes, protocols, and categories enhances code organization and reuse, while its trans-compiler allows Logtalk to run on various Prolog platforms.

Its weaknesses include a niche community, given its smaller user base, and the learning curve that might confront developers familiar with Prolog, particularly given its object-oriented paradigm.

Logtalk is well-suited for large-scale software development and metaprogramming, while its logic programming capabilities make it useful for representing complex knowledge domains.

While its community is small, as compared to mainstream programming languages, Logtalk is regularly maintained, with regular updates and improvements. Its community contributes libraries, tools, and documentation to enrich the Logtalk ecosystem.

Smalltalk is available through the Artistic License and the Apache License.

Logtalk bridges the gap between logic programming and software engineering, offering a versatile platform for building robust and reusable solutions.



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