WeightedRandom.Backend offers a contract to all who implement it:

1. The main WeightedRandom package presents a novel interface for generating a list of probabilities or weights
2. The custom Backend module decides what to do with those probabilities once they are generated.

Using Backends

To use a different backend, you can either pass it in as an opt (see function docs), or you can put it in your config file:

config :weighted_random,
  backend: Your.Backend.Module

Developing a new backend

To create your own backend, copy and change an existing one (like WeightedRandom.Backend.WalkerAlias or WeightedRandom.Backend.Linear).

Your module must implement the callbacks listed below: preprocess/2, take/2, and optionally options/0.

The simplest backend might look like this.

defmodule My.Backend do
  use WeightedRandom.Backend

  defstruct [:list]

  @impl true
  def preprocess(probabilities, _opts) do
    struct(__MODULE__, %{list: probabilities})
  end

  @impl true
  def take(%__MODULE__{list: li}, count) do
    for _ <- 1..count do
      Enum.random(li)
    end
  end 

end

This backend doesn't actually apply probability, it is just a glorified Enum.rand(list) for now. But you can use it in any of the main functions that take an opt of backend

WeightedRandom.rand(0..10, weights, [backend: My.Backend])
=> 3