Programming Elixir 1.3

Tasks

An Elixir task is a function that runs in the background.

tasks/tasks1.exs

defmodule Fib do
  def of(0), do: 0
  def of(1), do: 1
  def of(n), do: Fib.of(n-1) + Fib.of(n-2)
end

IO.puts "Start the task"
worker = Task.async(fn -> Fib.of(20) end)
IO.puts "Do something else"
# ...
IO.puts "Wait for the task"
result = Task.await(worker)

IO.puts "The result is #{result}"

The call to Task.async creates a separate process that runs the given function. The return value of async is a task descriptor (actually a PID and a ref) that we’ll use to identify the task later.

Once the task is running, the code continues with other work. When it wants to get the function’s value, it calls Task.await ...