建立自定義 Sigil 和文件

每個 x sigil 呼叫各自的 sigil_x 定義

定義自定義印記

defmodule MySigils do
  #returns the downcasing string if option l is given then returns the list of downcase letters
  def sigil_l(string,[]), do: String.Casing.downcase(string)
  def sigil_l(string,[?l]), do: String.Casing.downcase(string) |> String.graphemes
  
  #returns the upcasing string if option l is given then returns the list of downcase letters
  def sigil_u(string,[]), do: String.Casing.upcase(string)
  def sigil_u(string,[?l]), do: String.Casing.upcase(string) |> String.graphemes
end