Unlocking the Potential of Declarative Languages in Modern Computing

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In our increasingly digital world, programming has seamlessly integrated into our online existence. Educational institutions, especially schools, have acknowledged the significance of incorporating programming into their curricula [1,2]. However, when people contemplate programming, they often envision scenes from movies with scrolling screens displaying highlighted code or monochrome terminals. This perception can be daunting to many. Nevertheless, it’s vital to recognize that text-based programming is just one aspect of this domain. Some programming languages necessitate a fundamental understanding of underlying systems, but there are also visual [3] and natural programming languages that transcend the need for memorizing countless keywords and complex syntax or semantics.

In the era of generative AI [4], programming undergoes a rapid transformation. Instead of issuing machines with intricate step-by-step instructions, we could simply make use of generative AI tools to write software [5,6]. And if you believe this concept is novel, you’d be mistaken. Computer scientists have long been dedicated to making computers accessible to all and democratizing programming. Over the past few decades, there has been a significant evolution in programming languages. One particular approach, often termed declarative programming [7], has a long-standing history.

The Historical Significance of Declarative Programming

Historically, declarative programming can trace its origins back to the mid-20th century when the field of computer science was still in its infancy. Declarative programming emerged in response to the increasing complexity of software development. In the early days of computing, imperative and procedural programming reigned supreme, demanding that programmers specify not only what a program should accomplish but also how it should achieve it. This approach resulted in intricate and error-prone code, making software development a daunting endeavor. Declarative programming, as we understand it today, started taking form in the 1970s with the development of languages like Prolog [8] and Lisp [9]. These languages introduced the concept of emphasizing what needs to be achieved, shifting the responsibility of ‘how’ to the compiler or interpreter. Over the years, declarative programming has evolved and expanded into various domains, establishing itself as a cornerstone of modern software development.

Declarative programming offers several distinct advantages. One of its primary strengths lies in abstracting away the intricate details of implementation, resulting in more concise and readable code. This abstraction fosters reusability, as declarative code typically follows a modular structure independent of underlying hardware or software alterations. Declarative programming finds its niche in tasks where ‘what’ holds more significance than ‘how,’ such as data retrieval, web design, and infrastructure management. However, it’s essential to recognize its limitations. Declarative programming may not be the optimal choice for tasks necessitating fine-grained control over execution, such as performance-critical applications or scenarios where efficiency is paramount. In such situations, procedural and imperative programming, offering precise control over execution flow, may be the preferred option. The selection between these paradigms often hinges on the specific project requirements, underscoring the programmer’s responsibility to comprehend and select the most appropriate paradigm for the given task.

Declarative Programming in Action

Declarative programming finds diverse and impactful applications in the real world. Consider data analysis and reporting; languages like SQL empower analysts to effortlessly retrieve, filter, and manipulate extensive datasets without immersing themselves in the intricacies of data storage and retrieval. In web development, CSS (Cascading Style Sheets) is another illustration. It enables web designers to declaratively define the styling of web pages, specifying the appearance of elements without scripting the detailed steps for each styling effect. In web application development, declarative approaches, like extensions to XForms [10], serve both client and server-side programming, communication, and storage, striving for consistency and minimizing the need for multiple programming languages to meet varying requirements.

Having explored the world of databases, I’ve grown fascinated by declarative programming. The paradigm is vividly apparent in SQL, where programmers state what should be accomplished, rather than the steps to achieve it. SQL empowers programmers to store, manipulate, delete, and execute complex queries without delving into the intricacies of database storage. Unlike procedural and imperative programming, declarative programming brings a high level of abstraction, offering a concise set of commands, primarily centered on the CRUD operations: create, read, update, and delete [11].

Database administrators and users commence by establishing a schema and related tables. They then populate these tables with data for future manipulation. The necessary knowledge for querying and manipulating the database focuses on the relational schema, including tables and their attributes. End users remain blissfully unaware of low-level technical details such as file allocations, memory management, and system calls. Declarative programming boasts a gentle learning curve, as seen in SQL, where users can swiftly begin with a minimal command subset, including SELECT, UPDATE, CREATE, DELETE, WHERE,…. While SQL primarily serves relational database management, it also stands as a fundamental language in computer science education, encompassing data management and analysis within a single linguistic field.

Implementing Declarative Languages

Effectively implementing declarative languages necessitates a profound comprehension of the domain and the associated resources. One might question the rationale behind creating new programming languages. For CRUD operations and analytical tasks, SQL takes center stage. SQL enables the seamless execution of operations, ranging from straightforward, natural language-like queries such as SELECT … FROM … WHERE … to more complex ones employing NOT, UNION, and other operators. Can we devise a universal, SQL-like language encompassing file handling, command-line operations, networking, process management, memory and storage management, and distributed environments? This idea is exemplified by osquery [12], which provides SQL-like commands for managing system resources. Another instance is Hive [13], a data warehouse infrastructure built atop Hadoop, introducing a SQL-like query language, HiveQL, for querying and managing large datasets in a distributed setting.

Declarative languages should prioritize readability and expressiveness, enabling users to succinctly convey their intentions. As the ultimate objective is to conceal the intricacies of the underlying machinery and systems, developers of declarative languages should make use of existing libraries and frameworks whenever feasible. Leveraging established components can significantly expedite development. While declarative programming is renowned for its abstraction, optimizing performance when necessary remains critical. Declarative languages may excel in handling access patterns such as input and output, but what about error handling? [14] Reflecting on the requisite level of abstraction becomes imperative. How do we strike a balance between abstraction and performance in the domain of declarative programming?

Conclusion

As technology advances, declarative programming is evolving to meet the changing landscape. In the current environment, there is a noticeable drive to extend the reach of declarative languages to encompass a wider array of tasks. Beyond data manipulation and web design, the goal is to develop declarative solutions for activities like cloud computing and the management of distributed or decentralized systems. The objective is to furnish developers with a unified language that streamlines multiple facets of software development.

Peering into the future, an exciting trend is the integration of declarative programming with emerging technologies such as AI and machine learning. As AI-powered tools become increasingly proficient at comprehending natural language, we can anticipate declarative programming languages that are even more user-friendly, enabling developers to express their intentions in everyday language. Additionally, with the growing significance of cloud computing and serverless architectures, declarative approaches for infrastructure as code [15] and deployment pipelines are poised to gain prominence. These trends signify that declarative programming is well-positioned to continue shaping the software development landscape, rendering intricate tasks more accessible and expediting the development process. How will the convergence of declarative programming and AI transform the way we interact with computers and develop software in the future?

References

1. Computer Science: The Future of Education
2. Why all our kids should be taught how to code
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4. Generative artificial intelligence
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7. Declarative Programming
8. Colmerauer, Alain, et Philippe Roussel. “ The birth of Prolog “. The second ACM SIGPLAN conference on History of programming languages, Association for Computing Machinery, 1993, p. 37‑52. ACM Digital Library, https://doi.org/10.1145/154766.155362.
9. Steele, Guy L., et Richard P. Gabriel. “ The evolution of Lisp “. The second ACM SIGPLAN conference on History of programming languages, Association for Computing Machinery, 1993, p. 231‑70. ACM Digital Library, https://doi.org/10.1145/154766.155373.
10. Vuorimaa, Petri, et al. “Leveraging Declarative Languages in Web Application Development.” World Wide Web, vol. 19, no. 4, July 2016, pp. 519–43. Springer Link, doi:10.1007/s11280–015–0339-z
11. Create, read, update and delete
12. osquery
13. Apache Hive
14. Exception handling
15. Infrastructure as code

Originally published at https://johnsamuel.info.