Week 09: Lambda and Lazy

• Side Effect-Free Programming

  After this unit, students should

  • be familiar with the concept of functions as side-effect-free programming constructs and its relation to functions in mathematics.
  • understand the importance of writing code that is free of side effects.
  • understand how functions can be first-class citizens in Java through using local anonymous class.
  • understand how we can succinctly use a lambda expression or a method reference in place of using local anonymous class.
  • understand how we can use currying to generalize to functions with higher arity.
  • understand how we can create a closure with lambda and environment capture.

• Box and Maybe

  After this unit, students should

  • appreciate the generality of the class Box<T> and Maybe<T>.
  • understand how passing in functions as parameters can lead to highly general abstractions.
  • understand how Maybe<T> preserves the "maybe null" semantics over a reference type by internalizing checks for null.

• Lazy Evaluation

  After this unit, students should

  • know what is lazy evaluation and how lambda expression allow us to delay the execution of a computation.
  • understand how memoization and the Lazy<T> abstraction allows us to evaluate an expression exactly once.