TIL, 2018-02-22, Phrug Meetup

Musings

• I’ve been thinking about teaching programming lately. To be honest, I prefer teaching another programmer how to learn Rails, as opposed to from scratch because of mechanical things. It’s really difficult for me to navigate around using Windows.
• Reflecting on how I’m learning Elixir and how you compare it to learn.
• Ruby meetup: GraphQL, websockets via Phoenix, shipping a product.

Programming Elixir

• $ mix deps: List all dependencies/tasks.
• Mixfile:
  • aliases part: shortcuts for things you combine with each other.
• Processes chapter. I’m reading it for appreciation, but not sure how to use it yet.
  • I’m guessing you can fork the processes like background jobs?
  • Or do things like split database retrieval/make them parallel, not sequential?
  • Linking two processes: spawn_link.
  • Monitoring a process: spawn_monitor.

Parallel Map

• Awesome but I don’t really understand it that much. Will implement this in the future!

defmodule Parallel do
  def pmap(collection, fun) do
    me = self

    collection
    |> Enum.map(fn (elem) ->
        spawn_link fn -> (send me, { self, fun.(elem) }) end
      end)
    |> Enum.amp(fn (pid) ->
        receive do { ^ pid, result } -> result end
      end
    end
  end
end

iex> c("pmap.exs")
[Parallel]
iex> Parallel.pmap 1..10, &(&1 * &1) # Multiple first argument by itself?
[1, 4, 9...]