An introduction to namespaces in Dyalog APL.
00:00 What are namespaces and what are they used for?
00:35 Overview of this video
01:00 Namespaces as a container for APL stuff which prevent name conflicts
01:46 How to create a namespace with the system function ⎕NS and assign names and execute other expressions within it
02:28 Viewing the contents of a namespace with the workspace explorer or ]map user command
03:14 Pass by reference semantics and mutability
05:12 The root namespace # and the session object ⎕SE
06:08 Find the parent of a namespace with ##
06:29 Check if two references point to the same namespace with the match function ≡
06:35 Named and unnamed, anonymous namespaces
07:03 The result of dyadic ⎕NS, the namespace path character vector
07:32 Syntax of ⎕NS with an empty right argument. Creating subnamespaces in a single call.
08:16 Copying contents, code and data, from one namespace into another
09:22 Namespaces references are simple scalars
09:40 Convenient arrays of namespace references
10:40 Organise your application and make it modular
11:56 Namespaces as a dictionary or JSON object
12:24 Passing optional arguments to a function with defaults
