• What makes a good Elixir Program? -> What makes a good Program?
  • Easy to write
  • Easy to understand
  • Easy to change
• Programming is hard. Teaching programming is harder.
• OOP -> FP
  • Design Patterns are baggage in FP world
  • Mod.fun/arity is not quite enough
• Contexts
  • Dedicated modules that expose and group related functionality
  • Don't be afraid to make decisions (context names)

  • New comers are affected by Context thinking (explain Social Reaction to a new comer)

    defmodule Reaction do
      alias CommunityContent.Post
    
      def add_like(user, %Post{} = post)
    
      def get_stats(post)
    end
    
    defmodule Reaction.PostReaction do
      schema "post_reactions" do
        field :user_id, :id
        field :post_id, :id
        field :sentiment, :string
      end
    end
    

  • Experienced Erlang/Elixir developers are affected too
    • With Phoenix 1.1 => interleaved code
    • Clean up => "service" modules (like contexts)
    • It's important to have generators that encourages clean boundaries
• Phoenix 1.4: Monitoring & Metrics
  • Application Performance Monitor (APM)
    • Common Interface for
      • elixir monitoring
      • Monitoring services (Datadog, NewRelic, etc.)
    • Goals

      Efficiency

      Data collection must not take out the application under load

      Insights

      Metrics should provide actionable insights for non-experts

    • Available Metrics

      Gauge

      instantaneous measurement

      • CPU usage
      • Memory usage

      Meter/Timer

      rate of events over time with statistical distribution

      • requests per second

      Instrumenter

      compile-time hooks into application events

  • Breakpoint Debugger
  • Developer Dashboard
  • End-to-End Testing
    • Concurrent
    • Transactional

    • JavaScript tests:

      Call Phoenix endpoints to check-out/check-in Ecto Sandbox connection

      def checkout(conn, _params) do
        Phoenix.Ecto.Sandbox.checkout(conn)
      end
      
      def checkin(conn, _params) do
        Phoenix.Ecto.Sandbox.checkin(conn)
      end
      

  • Easier Contribution
    • 1st Contribution Sprint
    • Phoenix Guides are merged
• Phoenix/Elixir have enabled many people building many useful stuffs
  • Make the previously unachievable, achievable

-- from ElixirConf 2017 - Closing Keynote - Chris McCord - YouTube