Namespaces in Dyalog APL

From a channel Lumen includes in full: Dyalog, the company behind the main APL implementation, posts tutorials and talks on APL itself — array notation, operators, IDE and debugging — taught by its own language designers; small and entirely instructional.

A 14-minute video from Dyalog's catalogue; the title names its topic.

Video by Dyalog, played through YouTube's embedded player.