Rethinking Java Design Patterns: From OOP to FP

The functional programming answer, to those who wonder how to integrate or combine it with object-oriented programming, is usually: Turtles all the way down.

This is an aphorism whose origin is credited to Richard Feynman. In his book, Surely You're Joking, Mr. Feynman !, published in 1985, he tells the story of one of his conferences on the nature of the universe, where he was challenged by someone in the audience, saying that the universe rests on a turtle. Feynman asked then what the turtle is resting on, and the answer was: "another bigger turtle".