Parameterized roles

This provides a nice example which may help....

  role Greet[Str $greeting] {
      method greet() { say $greeting }
  }

  class EnglishMan does Greet["Hello"] { }
  class Slovak does Greet["Ahoj"] { }
  class Lolcat does Greet["OH HAI"] { }

  EnglishMan.new.greet(); # Hello
  Slovak.new.greet();     # Ahoj
  Lolcat.new.greet();     # OH HAI