Demonstration / training over some Elixir concepts for iWT Health.

1. Initial Umbrella Application

• mix new repeater --umbrella

2. New app
   • mix new repeater
   • Show basic testing
     • assert
     • file_name_test.exs
3. Basic Documentation
   • parameters
   • doc tests
     • Demonstrate basic doc test failure
4. Immutability (basic)
   • Show repeater tests
5. Parameter guard
   • Messed up the doc test (“5” instead of 5)
   • Show iex -S mix
   • Show recompile (change Repeating to Repeat - )
6. Parameter matching
7. Case pattern matching
8. Cond control structure
   • After show the with statement from this article:
   • Elixir's With Statement
9. Function matching - structs
   • Show namespace structure
10. Basic process spawning

• Repeater.Loop.start(“test”) - synchronous loop, “blocking”
• Repeater.Loop.async(“foo”) - asynchronous loop

11. Agent

• Holds state only
• Module-less: https://elixirschool.com/en/lessons/advanced/concurrency/#agents◦
• Show only running specific tests

12. New Supervisor App

• mix new chat --sup
• Creates same app but with /lib/chat/application.ex

13. GenServer

• Holds state and processes
• Note the cast / call differences

14. Chat.Supervisor

• Note that there isn’t a way to get the only server, somewhat useless

15. Add :chat_room atom name to Chat.Server

• Demonstrate in iex -S mix
  • Chat.Server.get_messages(:chat_room)
  • Chat.Server.add_message(:chat_room, “test”)
• Demonstrate supervisor restarting
  • Process.whereis(:chat_room)
  • Process.whereis(:chat_room) |> Process.exit(:kill)
  • Process.whereis(:chat_room)

16. Name registration from gproc & via_tuple

• via_tuple - Tells Elixir how to use a custom registry to register our process.
• {:via, module, term}
• {:via, gproc, gproc parameters}
• gproc params
  • :n - name
  • :l - local, meaning not registered on this cluster
  • {:chat_room, room_name} - actual name

• Elixir Documentation
• GenStage
• ExDoc

• Elixir Lang Guide
• ElixirSchool
• Process registry in Elixir: A practical example