Programming Elixir ≥ 1.6

Parallel Map—The “Hello, World” of Erlang

Devin Torres reminded me that every book in the Erlang space must, by law, include a parallel map function. Regular map returns the list that results from applying a function to each element of a collection. The parallel version does the same, but it applies the function to each element in a separate process.

spawn/pmap.exs

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.map(fn (pid) ->
         receive do { ^pid, result } -> result end
       end)
  end
end

Our method contains two transformations (look for the |> operator). The first transformation ...