defmodule Requisito do
  @moduledoc """
  Documentation for Requisito.
  """

  @doc """
  conform takes a predicate and a value and checks whether or not
  the value conforms to the predicate.

  ## Examples

      iex> Requisito.conform( &Integer.is_odd/1, 27)
      true
      iex> Requisito.conform( &Integer.is_odd/1, 30)
      :requisito_invalid

  """
  @spec conform(fun(), any()) :: atom() | any()
  def conform(predicate, value) do
    if predicate.(value) do
      value
    else
      :requisito_invalid
    end
  end

  @doc """
  valid? returns a boolean indicating whether or not a value is
  a property of a particular predicate.

  ## Examples

    iex> Requisito.valid?(&Integer.is_odd/1, 27)
    true
    iex> Requisito.valid?(&Integer.is_odd/1, 10)
    false
  """
  @spec valid?(fun(), any()) :: boolean()
  def valid?(predicate, value) do
    property_result = predicate.(value)
    if is_boolean(property_result) do
      property_result
    else
      false
    end
  end

end