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Type conversion library for Erlang and Elixir.

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want lib want type.ex
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lib/want/type.ex 

defmodule Want.Type do

  @moduledoc """


  Behaviour for type casting modules.


  """



  defmacro __using__(_) do

    quote do

      @behaviour Want.Type

    end

  end



  @type opts    :: Keyword.t()

  @type schema  :: map()



  #


  # Cast an incoming value to a given type


  #


  @callback cast(input :: any(), opts() | schema()) :: {:ok, result :: any()} | {:error, reason :: any()}



  @doc """


  Determine whether a module represents a custom type.


  """

  @spec is_custom_type?(module()) :: boolean()

  def is_custom_type?(module) do

    case Code.ensure_compiled(module) do

      {:module, _}  -> Kernel.function_exported?(module, :cast, 2)

      _             -> false

    end

  end



  @doc """


  Invoke the `cast/2` function on the given custom type module.


  """

  @spec cast(module(), input :: any(), opts()) :: {:ok, result :: any()} | {:error, reason :: any()}

  def cast(module, input, opts),

    do: Kernel.apply(module, :cast, [input, opts])

end