Final Form makes the assumption that your validation functions are "pure" or "idempotent", i.e. will always return the same result when given the same values. This is why it doesn't run the synchronous validation again (just to double check) before allowing the submission: because it's already stored the results of the last time it ran it.

Because immutable components also prevent their children from re-rendering, they should probably not have non-immutable children.

Null Components should never have children - they'd never be rendered.

Injector components should never be self-closing, and they should never wrap multiple children. We can fix this at code-time and not wait for the errors at runtime.

This naming convention helps developers understand the component’s contract