Kotlin function ownership

Core principle

Put a function on the smallest accurate semantic owner. Extension syntax changes call shape, not ownership.

Reject primitive, common, and library-owned extensions by default: they create false ownership, domain pollution, noisy completion/imports, and collisions.

Procedure

Apply in order.

1. Name the semantic owner

Name the operation and the concept that owns it. If ownership is unclear, stop before selecting syntax.

2. Reject a misleading receiver early

For String, primitives, collections, Flow, framework, or third-party receivers, require all: