feat: add Idiom.direction/1 (#23)

closes #23

lib/idiom.ex

@@ -265,6 +265,8 @@ defmodule Idiom do
   @doc false
   defdelegate child_spec(options), to: Idiom.Supervisor
 
+  defdelegate direction(locale), to: Locales
+
   @type translate_opts() :: [
           namespace: String.t(),
           to: String.t(),

lib/idiom/locales.ex

@@ -5,6 +5,8 @@ defmodule Idiom.Locales do
   Locale identifiers consist of a language code, an optional script code, and an optional region code, separated by a hyphen (-).
   """
 
+  @rtl_languages ~w(ar dv fa ha he ks ps sd ur yi)
+
   @doc """
   Constructs a hierarchical list of locale identifiers from the given locale.
 
@@ -79,4 +81,23 @@ defmodule Idiom.Locales do
       parts -> Enum.take(parts, 2) |> Enum.join("-")
     end
   end
+
+  @doc """
+  Returns the writing direction of the script belonging to the locale.
+
+  ## Examples
+
+  ```elixir
+  iex> Idiom.Locales.direction("en-US")
+  :ltr
+
+  iex> Idiom.Locales.direction("ar")
+  :rtl
+  ```
+  """
+  @spec direction(String.t()) :: :ltr | :rtl
+  def direction(locale) do
+    language = get_language(locale)
+    if Enum.member?(@rtl_languages, language), do: :rtl, else: :ltr
+  end
 end

mix.exs

@@ -54,8 +54,7 @@ defmodule Idiom.MixProject do
 
   defp docs do
     [
-      main: "Idiom",
-      extras: ["Cheatsheet.cheatmd"]
+      main: "Idiom"
     ]
   end
 end