Type Alias OptimizeProgressFn 

pub type OptimizeProgressFn = Arc<dyn Fn(OptimizeEvent) + Send + Sync>;

Arc rather than Box so the same callback can be cloned into the PondIndexProgress Arc that Lance’s IndexBuildProgress builder demands - otherwise intra-index stage events have no path back to the CLI spinner.

Aliased Type

pub struct OptimizeProgressFn { /* private fields */ }