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Type conversion library for Erlang and Elixir.

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want lib want boolean.ex
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lib/want/boolean.ex 

defmodule Want.Boolean do

  @moduledoc """

  Performs type conversions to boolean values.

  """

  use Want.Type



  @type result :: {:ok, boolean()} | {:error, binary()}



  @doc """

  Cast a value to a boolean.



  ## Examples



      iex> Want.Boolean.cast("true")

      {:ok, true}



      iex> Want.Boolean.cast("false")

      {:ok, false}



      iex> Want.Boolean.cast("TRUE")

      {:ok, true}



      iex> Want.Boolean.cast(1.0)

      {:ok, true}



      iex> Want.Boolean.cast(0)

      {:ok, false}



      iex> Want.Boolean.cast({:a, :b})

      {:error, "Failed to convert value {:a, :b} to boolean."}

  """

  @spec cast(value :: any()) :: result()

  def cast(value),

    do: cast(value, [])



  @spec cast(value :: any(), opts :: Keyword.t()) :: result()

  def cast(value, _opts) when is_atom(value) and value in [true, false],

    do: {:ok, value}

  def cast(value, _opts) when is_integer(value),

    do: {:ok, value != 0}

  def cast(value, _opts) when is_float(value),

    do: {:ok, value != 0.0}

  def cast(value, _opts) when is_binary(value) do

    cond do

      String.downcase(value) == "true"    -> {:ok, true}

      String.downcase(value) == "false"   -> {:ok, false}

      true                                -> {:error, "Failed to convert value #{inspect value} to boolean."}

    end

  end

  def cast(value, _opts),

    do: {:error, "Failed to convert value #{inspect value} to boolean."}

end