While Ruby is object oriented and imperative, it does have some features that allow for functional programming. In this talk we’ll compare Haskell, a functional programming language, with Ruby while exploring these common functional patterns: higher order functions, lazy evaluation, and memoization. Along the way we’ll explore how Ruby works internally, find out whether it’s a true functional language, and zoom in to take a close look at Ruby 2.0’s implementation of the new “Enumerator::Lazy” feature.