> For AI agents: the complete documentation index is available at /llms.txt, the full documentation bundle is available at /llms-full.txt.

# Functional Python

Use pure functions, immutable domain values, explicit capabilities, and typed Results. Never author `raise` or `try`/`except` application control flow. Apply this pack to Python source and examples.

Read `bytefarm/engineering` through the installation index first. Use `returns` for typed failure and composition; its documented decorator/composition typing requires the compatible mypy plugin. A recommendation is not dependency installation authorization.

| Task               | Read                                                        |
| ------------------ | ----------------------------------------------------------- |
| Design behavior    | [Paradigm](/packs/languages/python/paradigm.md)             |
| Name declarations  | [Naming](/packs/languages/python/naming.md)                 |
| Organize modules   | [File structure](/packs/languages/python/file-structure.md) |
| Declare operations | [Functions](/packs/languages/python/functions.md)           |
| Model valid values | [Types](/packs/languages/python/types.md)                   |
| Handle branches    | [Conditionals](/packs/languages/python/conditionals.md)     |
| Return failures    | [Errors](/packs/languages/python/errors.md)                 |
| Transform state    | [State](/packs/languages/python/state.md)                   |
| Compose and reuse  | [Utilities](/packs/languages/python/utilities.md)           |
| Document contracts | [Comments](/packs/languages/python/comments.md)             |
| Verify behavior    | [Testing](/packs/languages/python/testing.md)               |

Identity: `bytefarm/python-functional`. Content version: `0.1.0`.