PHPStan vs Psalm: What are the differences?

PHPStan and Psalm are both static analysis tools for PHP code. Let's explore the key differences between them.

1. Type Inference: One of the key differences between PHPStan and Psalm is their approach to type inference. PHPStan uses a strict type inference algorithm that can handle complex type systems and infer types even in the presence of dynamic behavior. On the other hand, Psalm uses a more conservative approach to type inference, focusing on strict typing and leveraging PHPDoc annotations to infer types.

2. Error Reporting: When it comes to error reporting, PHPStan provides a more detailed and comprehensive report compared to Psalm. PHPStan's error messages are quite verbose and provide useful information about the type issues, potential bugs, and even suggestions to fix them. Psalm, on the other hand, focuses on simplicity and provides more concise error messages, making it easier to understand and fix the reported issues quickly.

3. Level of strictness: PHPStan offers various levels of strictness that can be set depending on the project's requirements. It provides a fine-grained control over the level of strictness and allows developers to decide how strict they want the analysis to be. Psalm, on the other hand, is more opinionated and enforces a high level of strictness by default. While this can be beneficial for maintaining code quality, it may require more effort to fix all the reported issues.

4. Plugin Ecosystem: PHPStan has a vast plugin ecosystem that allows developers to extend its functionality further. It provides a wide range of community-supported plugins for different frameworks, libraries, and tooling integrations, making it highly customizable and adaptable. On the other hand, Psalm has a smaller plugin ecosystem and is more focused on providing a unified and consistent analysis experience out of the box.

5. Developer Community: Both PHPStan and Psalm have active developer communities, but they differ in terms of size and focus. PHPStan has a larger community with a broader range of contributors, which often results in more frequent updates and faster bug fixes. Psalm, on the other hand, has a smaller but dedicated community that focuses on rigorous testing and stability, ensuring a reliable analysis experience.

6. Documentation and Learning Resources: PHPStan has extensive documentation and a wide range of learning resources available, including tutorials, articles, and video tutorials. This extensive documentation makes it easier for developers to learn and get started with PHPStan. While Psalm also has documentation and learning resources available, they may not be as extensive as PHPStan.

In summary, while PHPStan focuses on providing strict type checking and static analysis to identify potential bugs and issues in PHP code, Psalm offers additional features such as Psalm plugins and advanced inference capabilities, making it a comprehensive solution for improving PHP code quality and maintainability.