Clojure Development Skill
Tool Preference
When clojure-mcp tools are available (e.g., clojure_eval, clojure_edit), always use them instead of shell commands like ./bin/mage -repl. The MCP tools provide:
- Direct REPL integration without shell escaping issues
- Better error messages and feedback
- Structural Clojure editing that prevents syntax errors
Only fall back to ./bin/mage commands when clojure-mcp is not available.
@./../_shared/development-workflow.md @./../_shared/clojure-style-guide.md @./../_shared/clojure-commands.md
REPL-Driven Development Workflow
- Start with small, fundamental functions:
- Identify the core features or functionalities required for your task.
- Break each feature down into the smallest, most basic functions that can be developed and tested independently.
- Write and test in the REPL:
- Write the code for each small function directly in the REPL (Read-Eval-Print Loop). - Test it thoroughly with a variety of inputs, including typical use cases and relevant edge cases, to ensure it behaves as expected.
- Integrate into source code:
- Once a function works correctly in the REPL, move it from the REPL environment into your source code files (e.g., within appropriate namespaces).
- Gradually increase complexity:
- Build upon tested, basic functions to create more complex functions or components. - Compose smaller functions together, testing each new composition in the REPL to verify correctness step by step.
- Ensure dependency testing:
- Make sure every function is fully tested in the REPL before it is depended upon by other functions. - This ensures that each layer of your application is reliable before you build on it.
- Use the REPL fully:
- Use the REPL as your primary tool to experiment with different approaches, iterate quickly, and get immediate feedback on your code.
- Follow functional programming principles:
- Keep functions small, focused, and composable. - Use Clojure's functional programming features—like immutability, higher-order functions, and the standard library—to write concise, effective code.
How to Evaluate Code
Bottom-up Dev Loop
- Write code into a file.
- Evaluate the file's namespace and make sure it loads correctly with:
./bin/mage -repl --namespace metabase.app-db.connection- Call functions in the namespace with test inputs, and observe that the outputs are correct Feel free to copy these REPL session trials into actual test cases using
deftestandis. - Once you know these functions are good, return to 1, and compose them into the task that you need to build.
Critical Rules for Editing
- Be careful with parentheses counts when editing Clojure code
- After EVERY change to Clojure code, verify readability with
-check-readable - End all files with a newline
- When editing tabular code, where the columns line up, try to keep them aligned
- Spaces on a line with nothing after it is not allowed