Simple Memoization in Elixir (using FastGlobal)

memoize.ex

defmodule Memoize do
  @moduledoc """
  Simple memoization helper built on top of FastGlobal.

  Remember to add `{:fastglobal, "~> 1.0"}` to your
  dependencies first.


  ## Usage

    def my_method do
      Memoize.run :my_method, fn ->
        # return something
      end
    end


  ## Other

  Author: Sheharyar Naseer
  License: MIT
  Website: https://sheharyar.me

  Find updates to this module at https://git.io/fNcBb
  """



  # Public API
  # ----------


  @doc """
  If previously saved value exists, return that else
  perform memoization for given key and function.
  """
  def run(key, fun) when is_atom(key) do
    case get!(key) do
      nil ->
        value = fun.()
        put!(key, value)
        value

      result ->
        result
    end
  end


  @doc "Force get value"
  defdelegate get!(key),        to: FastGlobal, as: :get

  @doc "Force put value"
  defdelegate put!(key, value), to: FastGlobal, as: :put

end