Jonathan Lalou's Blog

Lecturer

Dr. Venkat Subramaniam is an award-winning author, founder of Agile Developer, Inc., and a professor at the University of Houston. He mentors developers globally and has authored books like Practices of an Agile Developer. Relevant links: Agile Developer Website (publications); LinkedIn Profile (professional page).

Abstract

This article delves into Venkat Subramaniam’s exploration of creating internal domain-specific languages (DSLs) in Kotlin. Set in the context of reducing code ceremony, it analyzes Kotlin’s features like infix notation and implicit receivers. Methodologies for fluent APIs and implications for domain-driven design are highlighted, emphasizing Kotlin’s suitability for expressive DSLs.

Introduction and Context

Venkat Subramaniam presented at KotlinConf 2018 on crafting internal DSLs, which offer concise, context-aware syntax for specific domains. Kotlin’s low-ceremony nature and behavioral injection make it ideal for DSLs, unlike Java’s rigidity. This narrative unfolds where developers seek to encapsulate domain logic fluently, enhancing readability and maintainability in agile projects.

Methodological Approaches to DSL Creation

Subramaniam began with DSL characteristics: fluency, conciseness, and implicit context. He used Kotlin’s infix functions for natural syntax (e.g., 1 plus 2). Lambda-with-receiver enabled context objects, allowing methods like left or right within a scope. Extension functions injected behavior, while lexical scoping resolved properties dynamically. Examples included a report DSL, where configurations were set declaratively, and a context-switching DSL for flexible execution.

Analysis of Innovations and Features

Kotlin’s infix notation innovates by mimicking natural language, reducing syntactic noise. Implicit receivers create intuitive contexts, unlike Java’s explicit calls. Extension functions enable seamless domain extensions. Compared to external DSLs, internal DSLs leverage Kotlin’s compiler safety. Limitations include working within Kotlin’s constraints, requiring careful design to avoid ambiguity.

Implications and Consequences

Subramaniam’s DSLs imply more readable domain code, aligning with business logic. They enhance maintainability in complex systems, though require upfront design effort. Consequences include broader adoption of Kotlin for domain-driven projects, with open-source examples fostering community contributions.

Conclusion

Subramaniam’s guide underscores Kotlin’s prowess for internal DSLs, offering a blueprint for fluent, maintainable domain code that elevates software design.

Links

• Lecture video: https://www.youtube.com/watch?v=JzTeAM8N1-o
• Lecturer’s X/Twitter: @venkat_s
• Lecturer’s LinkedIn: Venkat Subramaniam
• Organization’s X/Twitter: @AgileLearner
• Organization’s LinkedIn: Agile Developer