The blog post advocates for a layered approach to structuring Go applications, emphasizing separation of concerns and dependency inversion. It proposes organizing code into distinct layers – domain, service, handler – with each layer depending only on the layers beneath it. The domain layer houses core business logic and entities, the service layer orchestrates domain operations and handles application-specific logic, and the handler layer interacts with external systems like databases and HTTP requests. This layered structure promotes testability, maintainability, and clearer understanding of the codebase by enforcing boundaries and reducing dependencies between different parts of the application. This approach differs from strictly hexagonal architecture, allowing the service layer to orchestrate domain logic, and focuses on practical application over strict adherence to architectural patterns.
Component simplicity, in the context of functional programming, emphasizes minimizing the number of moving parts within individual components. This involves reducing statefulness, embracing immutability, and favoring pure functions where possible. By keeping each component small, focused, and predictable, the overall system becomes easier to reason about, test, and maintain. This approach contrasts with complex, stateful components that can lead to unpredictable behavior and difficult debugging. While acknowledging that some statefulness is unavoidable in real-world applications, the article advocates for strategically minimizing it to maximize the benefits of functional principles.
Hacker News users discuss Jerf's blog post on simplifying functional programming components. Several commenters agree with the author's emphasis on reducing complexity and avoiding over-engineering. One compelling comment highlights the importance of simple, composable functions as the foundation of good FP, arguing against premature abstraction. Another points out the value of separating pure functions from side effects for better testability and maintainability. Some users discuss specific techniques for achieving simplicity, such as using plain data structures and avoiding monads when unnecessary. A few commenters note the connection between Jerf's ideas and Rich Hickey's "Simple Made Easy" talk. There's also a short thread discussing the practical challenges of applying these principles in large, complex projects.
Successful abstractions manage complexity by isolating it. They provide a simplified interface that hides intricate details, allowing users to interact with a system without needing to understand its inner workings. A good abstraction chooses which details to expose and which to conceal, offering just enough information for effective use. This simplification reduces cognitive load and allows for easier composition and reuse of components. The key is finding the right balance: too much abstraction leads to leaky abstractions where the underlying complexity seeps through, while too little provides insufficient simplification.
HN commenters largely agreed with the author's premise that good abstractions hide complexity. Several pointed out that "leaky abstractions" are a common problem, where the underlying complexity bleeds through and negates the abstraction's benefits. One commenter highlighted the difficulty of finding the right balance, where an abstraction is neither too complex nor too simplistic, using the example of an overly abstracted car where the driver has no control over engine specifics. The value of predictable behavior within an abstraction was also emphasized, along with the importance of choosing the right level of abstraction for the task at hand, suggesting different levels for different users (e.g., library user vs. library developer). Some discussion focused on the definition of "complexity" itself, with suggestions that "complications" or "implementation details" might be more accurate terms. The lack of mention of Postel's Law (be conservative in what you send, liberal in what you accept) was noted by one commenter as a surprising omission.
Summary of Comments ( 16 )
https://news.ycombinator.com/item?id=43740992
Hacker News users generally praised the article for its clear explanation of layered architecture in Go, particularly appreciating the focus on dependency inversion and the practical "domain" layer example. Some debated the merits of layered architecture in general, with a few suggesting alternative approaches like hexagonal architecture or Clean Architecture, noting potential drawbacks like increased boilerplate. A recurring theme was the importance of considering the project's complexity before adopting a layered approach, with simpler projects potentially not needing such strict structure. Others shared related experiences and alternative approaches to organizing Go code, highlighting the "package by feature" method and discussing the challenges of maintaining large, complex codebases. Several commenters also appreciated the author's clear and concise writing style.
The Hacker News post titled "Layered Design in Go" (linking to an article about the same topic) generated several comments discussing the merits and drawbacks of the layered architecture approach in Go, along with alternative suggestions and experiences.
Several commenters appreciate the clarity and simplicity presented in the article. One user found the article a helpful reminder of good software engineering principles, applicable beyond just Go. Another agreed with the author's focus on dependency inversion, highlighting its crucial role in building testable and maintainable software. The conciseness of the article was also praised.
A recurring theme in the comments is the discussion of alternative approaches to layered architecture, particularly hexagonal architecture (also known as ports and adapters). Commenters pointed out the benefits of hexagonal architecture in terms of decoupling business logic from external dependencies, ultimately improving testability and flexibility. Some argued that while layered architecture might be suitable for simpler projects, hexagonal architecture offers greater advantages for more complex applications.
A few comments also delved into the specifics of dependency injection in Go. One commenter suggested using a "wire" tool for compile-time dependency injection, while others discussed the pros and cons of using interfaces for dependency injection. A point was raised about the potential overhead of interfaces in Go and the consideration of using concrete types for dependencies in performance-sensitive scenarios.
The discussion also touched upon the trade-offs between strict layering and practicality. One commenter argued that rigid adherence to layered architecture can sometimes lead to unnecessary abstraction and complexity. The idea of allowing some controlled violation of layering for pragmatic reasons was also proposed.
A few commenters shared their own experiences with layered and hexagonal architectures, offering real-world examples of where each approach proved beneficial. These anecdotal comments provided valuable context to the more theoretical discussions.
Overall, the comments on Hacker News presented a balanced view of layered architecture in Go. While acknowledging its simplicity and usefulness in certain contexts, the commenters also highlighted potential limitations and explored alternative architectural patterns like hexagonal architecture. The discussion was constructive and insightful, offering practical advice and diverse perspectives on software design in Go.