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

# Python

Build Python around pure transformations, immutable domain values, explicit capabilities, and typed Results with returns. Covers modules, types, state, composition, documentation, and behavioral tests.


[CommentsDocument Python caller-facing constraints, typed failure variants, and resource effects.](/packs/languages/python/comments)[ConditionalsUse early Python guards and explicit variant handling without exception-driven branching.](/packs/languages/python/conditionals)[ErrorsReturn typed Python failures and adapt external exceptions without authored raise or try/except.](/packs/languages/python/errors)[File structureKeep Python domain modules independent of presentation, runtime wiring, and resource adapters.](/packs/languages/python/file-structure)[Functional PythonUse 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.](/packs/languages/python/README)[FunctionsDeclare focused typed Python operations with named inputs and explicit failure contracts.](/packs/languages/python/functions)[NamingUse native Python casing and name concrete domain operations and values.](/packs/languages/python/naming)[ParadigmCompose pure Python functions and immutable domain values with explicit effect boundaries.](/packs/languages/python/paradigm)[StateProduce new Python domain values and prevent mutation hidden inside frozen records.](/packs/languages/python/state)[TestingVerify typed Python outcomes, real resource boundaries, and the supported returns typing setup.](/packs/languages/python/testing)[TypesValidate external Python values and model immutable domain alternatives with explicit typed contracts.](/packs/languages/python/types)[UtilitiesUse returns for typed composition and native Python iterators for straightforward transformations.](/packs/languages/python/utilities)