FP Best Practices

Use this skill for everyday functional programming decisions that shape composability, predictability, and long-term maintainability.

Use it especially when the task benefits from:

• clearer separation between pure logic and side effects
• smaller functions composed into pipelines
• types that make illegal states unrepresentable
• data transformations over mutations
• referential transparency and easier testing

Working Style

1. Write functions for the next reader, not just for the runtime.
2. Keep side effects at the edges; keep the core pure.
3. Prefer small, composable functions over clever all-in-one implementations.
4. Use types and names to reveal intent.
5. Let the data structure do the work when it can.